Submarine geology and geophysics

324

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pollution: the ranking of their self-cleansing capacity. J. Shoreline Mgmt, 2(3):223-240. Technion-Israel Inst. of Tech., Haifa, Israel. 88:2060 Varnavas, S.P., A.G. Panagos and G. Laios, 1987. Trace elements in surface sediments of Navarino Bay, Greece. Environ. Geol. Wat. Sci., 10(3): 159168. Dept. of Geol., Univ. of Patras, Patras, Greece.

C240. Corrosion 88:2061 Latanision, R.M., 1987. Current and projected impact of corrosion science and engineering. Mater. Perform., 26(10):9-16.

The 33rd Sagamore Army Materials Research Conference, (July 1986) was directed toward the theme 'Corrosion Prevention and Control.' This paper summarizes the civilian keynote presentation and addresses the importance of corrosion science and engineering in technologies of interest to the Army and to virtually all civilian and military activity. H.H. Uhlig Corrosion Lab., MIT, Cambridge, MA 02139, USA. 88:2062 Schillmoller, C.M. and B.D. Craig, 1987. Nickel steels in arctic service. Mater. Perform., 26(10): 46-49.

Nickel has beneficial effects on fracture toughness at low temperatures, mechanical properties of thick section forgings, and enhanced weldability of steels. There is a limitation on the use of nickel steels with 1% nickel or higher in sour service, imposed by NACE Standard MR0175-80. Materials include

nickel steels for structural applications and those specific to oil and gas production. The emerging use of highly alloyed nickel-containing materials is also discussed. Schillmoller Assoc., 10103 Fondren, Houston, TX 77086, USA.

C280. Books, collections

(general)

88:2063 Issaq, H.J. and Jack Cazes (eds.), 1987. Forty years of chromatography. Special issue. J. liquid Chromatog., 10(8-9): 1539-2022; 24 papers. The two opening papers chronicle the development of liquid chromatography over the last forty years, emphasizing the versatility and wide applicability of LC methods (especially in biotechnology), and predict directions of future development. The remaining papers are not, for the most part, descriptions of specific LC applications, but rather theoretical, methodological (outlining new or modified techniques), or overviews of a particular branch of LC. (gsb) 88:2064 Litherland, A.E., K.W. Allen and E.T. Hall (eds.), 1987. Ultra-high-sensitivity mass spectrometry with accelerators. Phil. Trans. R. Soc., (A)323(1569):1-172. 11 papers. An overview of accelerator mass spectrometry (AMS) is followed by reports on radiocarbon dating, environmental analysis (roBe, 26A1, and 36C1), and new detection capabilities. The latter include determination of heavy elements at low concentrations, attempts to detect fractionally charged particles (such as quarks), and single atom detection by the related technique of resonance ionization spectroscopy. (gsb)

D. SUBMARINE GEOLOGY AND GEOPHYSICS DI0. Apparatus and methods 88:2065 Clark, R.K., T.H. Fay and C.L. Walker, 1987. Bathymetry calculations with Landsat 4 TM imagery under a generalized ratio assumption.

AppL Opt., 26(19):4036-4038. Phys. Dept., Univ. of South Alabama, Mobile, AL 36688, USA. 88:2066 Senior, J.L., 1987. High resolution seismic surveying on tidal fiats in southwest Netherlands. Leading Edge, 6(11):36-39,48.

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D. SubmarineGeologyand Geophysics

Annual reflection seismic surveys have been conducted on the tidal sand falts in Zeeland since 1977 to acquaint students with shallow high-resolution seismic reflection techniques. The surveying is part of a course for students interested in seismology which involves 20 hours of lecture, 2-3 days of fieldwork, and 24 hours of data processing and interpretation. Survey results have proved 'surprisingly good' and find application in the identification of seismic facies, sedimentary features, and subsurface tectonic structures, as well as in unraveling basin histories and obtaining information on rock parameters, such as porosity and grain size. Internatl. Sci. Services, Zeist, Netherlands. (hbf)

325

88:2070 Hamilton, T.D. and J.P. Galloway (eds.), 1987. Geologic studies in Alaska by the U.S. Geological Survey during 1986. Short papers describing results of recent geologic investigations and lists of published reports. Circ. U.S. geol. Surv., 998:195pp.

D50. Subsurface structure 88:2071 Enfield, M.A. and M.P. Coward, 1987. The structure of the West Orkney Basin, northern Scotland. J. geol. Soc., Lond., 144(6):871-884. Dept. of Geol., Imperial College, London SW7 2BP, UK.

D40. Area studies, surveys, bathymetry 88:2067 Akmet'yev, M.A., V.I. Koporulin, A.O. Mazarovich, A.V. Rikhter and D.I. Frikh-Khar, 1985. Geology of S~o Vicente Island, Cape Verde Archipelago. Dokl. Earth Sci. Sect. (a translation of Dokl. Akad. Nauk SSSR), 284(5):60-63. Geol. Inst. and Inst. of Economic Geol., Petrol., Mineral. and Geochem., Acad. of Sci., Moscow, USSR. 88:2068 Brett, Robin et al., 1987. Special section: the southern Juan de Fuca Ridge: hydrothermal fluids, sulfides, and geophysical studies. J. geophys. Res., 92(Bll):11,281-11,432; 15 papers. Results of a variety of analyses of samples and data collected during a series of dives by DSRV Alvin in 1984 are presented, which demonstrate the usefulness of the 'consortium approach' to sample analysis. Included are descriptions of the geology and morphology of the vent area; geophysical studies of structure; faunal composition and organic encrustations; the mineralogy and petrology of the sulfiderich samples; fluid inclusions; composition and chemistry of hydrothermal solutions; composition of black-smoker particulates; Be, S, Nd-Sn, Rb-Sr, and Pb isotopes of the sulfides; stable isotopes; metals; volatiles; and heat flow across the Cascadia Basin. (hbf) 88:2069 Canals, M. and H. Got, 1986. Morphology of the continental slope of the Gulf of Lion: a structural and sedimentary result. Vie Milieu, 36(3):153163. (In French, English abstract.) Lab. de Geol. mar., Dept. de Estratigrafia, Univ. de Barcelona, Spain.

88:2072 Morton, J.L., N.H. Sleep, W.R. Normark and D.H. Tompkins, 1987. Structure of the southern Juan de Fuca Ridge from seismic reflection records. J. geophys. Res., 92(B11): 11,315-11,326. Twenty-four-channel seismic reflection records were obtained from the axial region. Two profiles are normal to the strike of the spreading center and intersect the ridge at latitude 44°40"N and 45°05"N; a third profile extends south along the ridge axis from latitude 45°20"N and crosses the Blanco Fracture Zone. Processing of the axial portions of the cross-strike lines resolved a weak reflection centered beneath the axis at a depth similar to seismically detected magma chambers on the East Pacific Rise and a Lau Basin spreading center; the reflector may represent the top of an axial magma chamber. In the migrated sections the top of the probable magma chamber is relatively flat and 1-2 km wide, and the subbottom depth is greater where the depth to the ridge axis is greater. USGS, 345 Middlefield Rd., Menlo Park, CA 94025, USA.

D60.

Geomorphology(fans,

canyons, etc.)

88:2073 Lan, Xianhong, Daoxiu Ma, Mingguang Xu, Qingwei Zhou and Guangwei Zhang, 1987. Some geochemical indicators of the Pearl River Delta and their facies significance. Mar. Geol. Quat. Geol., 7(1):39-49. (In Chinese, English abstract.) Inst. of Mar. Geol., Ministry of Geol. and Mineral Resour., Qingdao, People's Republic of China.

326

D. Submarine Geology and Geophysics

D70. Coasts, beaches, marshes 88:2074 Abdelrhman, M.A. and K.W. Bedford, 1987. Recognition of spatial structures and ensemble averages in the benthic boundary layer, d. geophys. Res., 92(C11): 11,825-11,844. A pattern recognition method is, for the first time, adapted and used to investigate different and similar structures (patterns) of velocity and acoustically measured suspended sediment concentration profiles in the lowest 2 m of the BBL at Tiana Beach, Long Island. This layer is subject to interactions between differently scaled forcing fields which result in structures difficult to predict using existing time average or boundary layer methods. A deterministic mathematical methodology is implemented to recognize spatial structures in the data and classify them in an optimum number of classes. Spatial pattern analysis indicates that ~70% of the above mentioned data are represented by only 5-20% of its size. Spatial patterns different from those predicted from theory or experience are recognized. Dept. of Ocean and Coastal Engng, Univ. of Florida, Gainesville, FL 32611, USA. 88:2075 Brown, Louis, 1987. I°Be as a tracer of erosion and sediment transport. Chem. Geol., 65(3-4):189-196. Be is retained by soil and sediment components to a high degree, having partition coefficients with water ranging from 105 to 106. This characteristic and a 1.5 × 106-a half-life make the radioisotope ~°Be an excellent tracer of sediment transport. Measurements of the isotope in a wide variety of terrestrial material now allow determination of its course in soil profiles, erosion, transport, and sedimentation. Although oceans and continents can, to a first approximation, be considered separately, interactions in coastal waters play a special role and a curious recycling takes place in some island-arc volcanoes. Dept. of Terrestrial Magnetism, Carnegie Inst., Washington, DC 20015, USA. 88:2076 Cai, Yue-e, Weijie Cheng and Aizhi Cai, 1987. Sedimentary environment of Xiamen Bay. Mar. Geol. Quat. Geol., 7(1):27-38. (In Chinese, English abstract.) Xiamen Univ., Xiamen, People's Republic of China. 88:2077 Corapcioglu, M.Y. and S. Mathur, 1987. Pressure change and surface expansion in salt marshes due to tidal inundation. Wat. Resour. Res., 23(10): 1996-2000.

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Sudden tidal inundation in an unflooded soil creates a head gradient at the surface of the unsaturated soil above the water table. When water infiltrates the soil under this gradient, the suction head in the unsaturated domain decreases, and pore pressure in the saturated zone increases with time, resulting in swelling of highly compressible marsh soils. A I-D mathematical model is used to obtain a numerical solution for pore pressure change and swelling. Results, presented graphically at spatial and temporal points of interest for a constant depth of ponding of water at the marsh surface from tidal inundation, show that swelling of soil is primarily governed by the initial head gradient across the sediment-water interface. Dept. of Civ. and Environ. Engng, Washington State Univ., Pullman, WA, USA. 88:2078 Debenay, J.-P., 1987. Carbonate sedimentation in a complex rcefal environment: the southwestern lagoon of New Caledonia. Bull. Soc. g~ol. Fr., (8)III(4):769-776. (In French, English abstract.) Dept. de Geol., Fac. Sci., Univ. de Dakar Fann, Dakar, Senegal. 88:2079 DeLaune, R.D., C.J. Smith, W.H. Patrick Jr. and H.H. Roberts, 1987. Rejuvenated marsh and bay-bottom accretion on the rapidly subsiding coastal plain of U.S. Gulf Coast: a second-order effect of the emerging Atchafalaya Delta. Estuar. coast. Shelf Sci., 25(4):381-389. The Atchafalaya Delta represents the initial stages of a new delta cycle which has resulted from capture of Mississippi River flow by the hydraulically more efficient Atchafalaya River. Using ~37Cs and 2~°Pb dating techniques, maximum sedimentation of delta-flanking environments was found in bay bottoms and marshes closest to the emerging delta. In addition to increasing shoreline progradation, the added sediment is providing nutrients for plant productivity, the organic source needed for vertical marsh accretion. Results show that the major area of coastal progradation will be in the immediate vicinity of the delta and along down-drift coasts. Updrift marshes away from the delta are accreting at a slower rate and are likely to continue experiencing rapid rates of deterioration. Center for Wetland Resour., Louisiana State Univ., Baton Rouge, LA 70803-7511, USA. 88:2080 E1-Sayed, M,Kh., 1987. Chemistry of modern sediments in a hypersaline lagoon, north of Jeddah, Red Sea. Estuar. coast. Shelf Sci., 25(4):467-480.

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D. Submarine Geology and Geophysics

Dept. of Oceanogr., Faculty of Sci., Alexandria Univ., Alexandria, Egypt. 88:2081 Gromoll, L., 1987. Sedimentary associations of the southwestern part of the Baltic Sea. A contribution to the knowledge about the laws of distribution of sediments in the shelf areas. Z. geol. Wiss., 15(3):355-372. (In German.) 88:2082 Harrison, S.J. and A.P. Phizacklea, 1987. Vertical temperature gradients in muddy intertidal sediments in the Forth Estuary, Scotland. Limnol. Oceanogr., 32(4):954-963.

Measurements of subsurface temperature and atmospheric variables were made from an instrument tower at Skinflats on the extensive intertidal mudfiats of the Forth Estuary. There was a marked seasonal change in the direction and magnitude of gradients. Gradients developed at low water were related to antecedent net radiant energy influx at the mud surface and latent heat flux into the atmospheric boundary layer. The relationship between the change in gradient during an incoming tide and the time of high water showed a well-defined association. Dept. of Environ. Sci., Univ. of Stirling, FK9 4LA, Scotland.

88:2083 Hsu, S.A., 1987. Scaling the rate of wind-blown sand transport by paxameterization of the turbulent energy equation. Coast. Engng, Amst., 11(3):283290.

Two types of transport rate equations are in operational use; one employs the dimensional rate at which work is done by fluid in moving the particles, and the other uses a special nondimensional Froude number scaling. Both methods can be explained by utilizing the turbulent energy equation applicable in the atmospheric surface boundary layer under near neutral stability conditions and thus both have theoretical foundations. Coastal Studies Inst., School of Geosci., Louisiana State Univ., Baton Rouge, LA 70803, USA.

88:2084 Moskovkin, V.M. and N.V. Yesin, 1985. Optimal control of the [coastal] abrasion process. Dokl. Earth Sci. Sect. (a translation of Dokl. Akad. Nauk SSSR), 284(5):224-227. Southern Div., Shirshov Inst. of Oceanol., Acad. of Sci., Gelendzhik, USSR.

327

D80. Reefs and atolls 88:2085 Pirazzoli, P.A., G. Delibrias, L.F. Montaggioni, J.F. Sali~ge and C. Vergnaud-Grazzini, 1987. Rate of reef flat lateral growth and recent morphological evolution of the Atoll of Reao, Tuamotu Islands, French Polynesia. Annls Inst. oc~anogr., Paris, 63(1):57-68. (In French, English abstract.) CNRS Intergeo, 191, rue Saint-Jacques, 75005 Paris, France. 88:2086 Stanley, G.D. Jr., 1987. Travels of an ancient reef. The odyssey of a coral island is just part of the epic of continental drift. Nat. Hist., 96(11):36-42.

When the first fossils were excavated from a limestone outcrop in the Wallowa Mountains of Oregon in 1985, they were found to be the remains of a tropical coral reef that thrived 218-210 Mya during the late Triassic. Further research showed that the coral species were identical to specimens found 13,000 miles away in the Alps. The author explains the mystery in terms of the global geography of Triassic times (the Tethys Sea and the Panthalassa spawned islands with reefs) and the dynamic processes of plate tectonics (the movement of seafloor plates transported the islands around what is now known as the Pacific rim to form displaced terranes). (wbg)

88:2087 Zhang, Mingshu et al., 1987. Wind-driven model of reef facies--a new working hypothesis. Mar. Geol. Quat. Geol., 7(2):1-9. (In Chinese, English abstract.)

Most geologists believe that transgression and regression are the causes of asymmetric reef patterns, but other explanations, such as the wind-driven model, have been suggested on the basis of detailed studies of reef complex sediments recovered from drill holes on the Xisha Islands. Sea level change is a significant factor for the growth pattern of reefs; however, islands also play important roles. In the Northern Hemisphere, the northeast trade winds dominate the low latitudes; during glacial stages, increases in wind velocity and temperature gradient move the lime-sand islands windward by causing erosion on the windward side and accretion leeward. A vertical sequence from the top down would reveal shifts from basinal to talus facies to reef framework to backreef gravel to backreef sand to island facies or eolian deposits. Inst. of Mar. Geol., Ministry of Geol. and Mineral Resour., Qingdao, People's Republic of China.

328

D. SubmarineGeologyand Geophysics

D120. Sedimentary processes (deposition, diagenesis, etc.)

OLR (1988)35 (4)

88:2088 Buscail, Roselyne and Andr~ Monaco, 1987. Flux of particle matter and biogeochemical processes at the sediment-water interface. Bull. Soc. g~ol. Fr., (8)III(4):715-722. (In French, English abstract.)

88:2091 Mumpton, F.A. (ed.) and M.W. Bodine Jr. (workshop convenor, organizing committee chairman), 1986. Studies in diagenesis. Papers presented at a U.S. Geological Survey workshop on diagenesis in sedimentary rocks, Golden, Colorado, March 1982. Bull. U.S. geol. Surv., 1578:368pp; 25 papers.

Characteristics of particle fluxes at the head of a submarine canyon (Lacaze-Duthiers Canyon, Gulf of Lion) are compared with biogeochemical properties of the bottom layer (345 m). Preliminary data show an important fine particle flux which increases linearly between 100-315 m; a biogenic fraction (39-45% of total mass flux); a lithogenic fraction (50-60% of total); and a fecal pellet flux increasing with depth. Differences between sedimentary particles and the deposited sediments do not seem to be due to oxidizing activity of benthic fauna. Lab. Sedimentol. et Geochim. Mar. de Perpignan, U.A. 715, Univ. Perpignan, Av. de Villeneuve, 66025 Perpignan, France.

The volume is divided into sections which reflect the themes of the half-day technical sessions of the workshop, which dealt with different aspects of the diagenesis of sedimentary rocks---chemical, carbonate, and the diagenesis of fine clastic and coarse clastic rocks. An overview of sediment cycling and diagenesis is presented and each section is introduced by a review paper treating its theme-sediment-fluid interactions in early diagenesis, the diagenesis of limestones, and burial diagenesis of sandstones. The balance of the volume consists of survey research papers describing field, laboratory, and theoretical investigations of modern and ancient rocks. (hbf)

88:2089 Hesse, Reinhard, S.K. Chough and Allan Rakofsky, 1987. The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel. Can. J. Earth Sci., 24(8): 1595-1624. During the last glacial period the Northwest Atlantic Mid-Ocean Channel played a major role in the depositional history of the Labrador Sea and northwest Atlantic in controlling sedimentation of a broad lens of turbidites which interfinger laterally in the Labrador Basin with pelagic and contourite facies. The meandering channel, a depositionalerosional feature formed by submarine mass flows, contains thick-bedded, coarse-grained turbidites and gravel layers. Old channel positions on seismic profiles indicate the channel has migrated laterally up to 30 km west and east. Levees along its entire length extend laterally into turbidite plains 60-100 km wide. Turbidity current activity in the channel probably started with onset of glaciation in the Mid-Pliocene and ceased about 7000 BP. The sedimentation rate for overbank deposition on the levees between 11,000 and 7000 BP is 13 cm/1000 yr. Dept. of Geol. Sci., McGill Univ., 3450 Univ. St., Montreal, PQ H3A 2A7, Canada. 88:2090 Lamboy, Michel, 1987. Genesis of phosphate grains from fragments of echinoderm skeletons: processes and meaning. Bull. Soc. g~ol. Fr., (8)III(4): 759-768. (In French, English abstract.) Dept. Geol., Univ. Rouen, BP 67, 76130 Mont Saint Aignan, France.

D130. Sediments

(rocks, formations, type,

composition, etc.) 88:2092 Brunner, C.A. and M.T. Ledbetter, 1987. Sedimentological and micropaleontological detection of turhidite muds in hemipelagic sequences. An example from the Late Pleistocene levee of Monterey Fan, central California continental margin. Mar. Micropaleont., 12(3):223-239. Electronic particle counter analysis of the silt fraction of samples taken at l-cm intervals from the western levee of the Monterey Fan and measurements of the major axes of foraminifers picked from samples of turbidite units were used to demonstrate that turbiditic muds can be distinguished from hemipelagic muds by recognition of grading in mean silt particle size, coarseness of silt mean size, and particle-size frequency distributions of the silt fraction. Analysis also shows that fossil assemblages in turbidite muds are hydraulically sorted and subtly altered; inclusion of sorted fossil faunas in high resolution biostratigraphy and paleoceanography leads to incorrect interpretation. Dept. of Paleontol., Univ. of Calif., Berkeley, CA 94720, USA. 88:2093 Dalrymple, R.W. and O.C. Maass, 1987. Clay mineralogy of Late Cenozoic sediments in the CESAR cores, Alpha Ridge, central Arctic Ocean. Can. J. Earth Sci., 24(8): 1562-1569.

OLR (1988)35 (4)

D. SubmarineGeologyand Geophysics

The clay-sized fraction of the silty and arenaceous lutites is predominantly mica (40-60%), with 10-20% kaolinite and chlorite, and ~ 5 % smectite, quartz, plagioclase and potassium feldspar. Calcite and dolomite occur intermittently in the upper 1.2 m; dissolution is probably responsible for their absence in other units. The silty lutites have a constant mineralogy throughout the 4.5 m section; some arenaceous intervals in the upper 2.1 m have markedly higher amounts of kaolinite, calcite, dolomite and, to a lesser extent, smectite. The silty lutites were most likely derived from the Beaufort Sea shelf during nonglacial periods; distinctive components in the sandy layers suggest transportation from the Canadian Arctic Islands and Greenland by glacial ice. Absence of kaolinite peaks in the lower half of the core implies the western Arctic Islands were not glaciated prior to 2.1 Ma, supporting previous findings that the Arctic climate was warmer in the Pliocene. Dept. of Geol. Sci., Queen's Univ., Kingston, ON K7L 3N6, Canada. 88:2094 Jeong, K.-S., S.-J. Han and J.-K. Kang, 1986. Distribution characteristics of chemical elements in core sediments from the northeastern equatorial Pacific (KONOD-1 area). Ocean Res., KORDI, 8(2): 1-15.

Analysis of some elements indicates that the area is typically a tectonically inactive depositional environment. Sediments consist of detrital clays (8384%); biogenic (5.7-7.0%), hydrogenous (2.5-3.9%), and hydrothermal sediments (1.8-2.1%); and sea salts (6.2-8.8%). A1, Fe, Si, and Ti exist mostly in detrital phase. Mn, Ni, Cu and Co are mostly in hydrogenous phase, and Ba, Ca, Mg, P are in biogenic phase. The hydrothermal fraction contributes from 0.6 to 28% of the total Si, Cu, Zn, Mn, Ni, and Fe content. Geol. Oceanogr. Lab., KORDI, Seoul, Korea. 88:2095 Knight, R.J. and J.R. McLean (eds.), 1986. Shelf sands and sandstones. Can. Soc. Petrol. Geol. Mem., 11:347pp; 20 papers.

Contributions from sedimentologists, treating many aspects of modem and ancient shelf sand deposits and sandstones from locations around the world, provide a sampling of the topics discussed at a symposium held at the University of Calgary, Alberta, June 15-17, 1984. The memoir is organized into sections dealing with tectonic controls; sediment supply, transport, and dispersal; storm-dominated shelf processes and shelf products; tidedominated shelves; and comparisons of storm- and wave-dominated shelves. Abstracts of symposium

329

papers are included. Petro-Canada, P.O. Box 2844, Calgary, AB T2P 3E3, Canada. (hbf) 88:2096 Liu, Xiging, 1987. Relict sediments in China continental sheff. Mar. Geol. Quat. Geol., 7(1): 1-14. (In Chinese, English abstract.) Inst. of Mar. Geol., Ministry of Geol. and Mineral Resour., Qingdao, People's Republic of China. 88:2097 Nemoto, Kenji, Takeshi Sato, Shinnosuke Izu, Hirofuni Ogawa and Shigeyuki Hirose, 1987. Geomorphology and sediments on the continental margin off Miho Peninsula, Suruga Bay. J. Fac. mar. Sci. Technol., Tokai Univ., 24:83-97. (In Japanese, English abstract.) 88:2098 Sastry, A.V.R., A.S.R. Swamy and K. Vasudev, 1987. Heavy minerals of beach sands along Visakhapatnam-Bhimunipatnam, east coast of India. Indian J. mar. Sci., 16(1):39-42. Dept. of Geol., Andhra Univ., Waltair 530 003, India. 88:2099 Seralathan, P. and A. Seetaramaswamy, 1987. Geochemistry of modem deltaic sediments of the Cauvery River, east coast of India. Indian J. mar. Sci., 16(1):31-38. School of Mar. Sci., Cochin Univ. of Sci. and Tech., Cochin 682 016, India. 88:2100 Shanmugam, G., J.G. McPherson (comment), T.M. Thornburg and L.D. Kulm (reply), 1987. Sedimentation in the Chile Trench: depositional morphologies, lithofacies, and stratigraphy. Discussion and reply. Geol. Soc. Am. Bull., 99(4): 598-600.

Problems arising from the selection of nomenclature for the Chile Trench lithofacies associated with a modem submarine fan truncated along its outer edge by an axial channel are discussed, and the use of the term 'lobe' for an erosional feature is questioned. Thomberg and Kulm reply that 'lobe' is used strictly in a morphological sense for a radial projection from a point source and is not equated with a depositional lobe. No ancient analogs of the Chile Trench strata are suggested, and there is no vertical sequence analysis, only a model of trench stratigraphy which predicts such a sequence. (hbf) 88:2101 Ten Haven, H.L., M. Baas, J.W. De Leeuw, P.A. Schenck and H. Brinkhuis, 1987. Late Quaternary Mediterranean sapropels. II. Organic geo-

330

D. SubmarineGeologyand Geophysics chemistry and palynology of S t sapropels and associated sediments. Chem. Geol., 64(1-2):149167.

The organic matter of the sapropels is of mixed marine, terrigenous, and bacterial origin and the continentally derived component increases seaward and with depth. The sapropelic intervals deposited on the Nile Cone have an expanded thickness and 'diluted' organic content due to a higher sedimentation rate. An increasing discharge from the river Nile seems to be the driving force for formation of S~ sapropels, and a model for sapropel formation based on this assumption is proposed. Inst. of Petroleum and Organic Geochem., ICH-5, KFA Julich GmbH, P.O. Box 1913, D-5170 Julich, FRG.

D140. Submarine hydrology (springs, hydrothermal deposits, etc.) 88:2102 Baker, E.T. and G.J. Massoth, 1987. Characteristics of hydrothermal plumes from two vent fields on the Juan de Fuca Ridge, northeast Pacific Ocean. Earth planet. Sci. Letts, 85(1-3):59-73.

Plumes emanating from major vent fields on the Southern Symmetrical Segment (SSS) and Endeavor Segment (ES) were mapped. At both fields, emissions from point and diffuse sources coalesced into a single 200-m thick plume elongated in the direction of current flow and with temperature anomalies of 0.024).05C ° and light attenuation anomalies of 0.014).08 m ~. Temperature anomalies in the core were uniform as far downcurrent as mapped, but light attenuation trends were non-uniform and differed between plumes, apparently because of different vent fluid chemistries. Heat flux was 1700___1100 MW from the ES and 580_+351 MW from the SSS. Particle flux varied with distance. PMEL, NOAA, 7600 Sand Point Way NE, Seattle, WA 98115-0070, USA. 88:2103 Chen, J.H., 1987. U, Th, and Pb isotopes in hot springs on the Juan de Fuca Ridge. J. geophys. Res., 92(B11): 11,411-11,415.

Concentrations and isotopic compositions of U, Th, and Pb in three hydrothermal fluids from the ridge were determined. Pb contents ranged 34-87 ng/g, U 1.3-3.0 ng/g, and Th from 0.2 to 7.7 pg/g. The samples showed large enrichments of Pb and Th relative to seawater and some depletion of U. Particles from the fluids contained significant amounts of Th and Pb. 234U/23su values show a 234U enrichment relative to equilibrium value and have a

OLR (1988)35 (4)

seawater signature. The Pb isotopic composition of the fluids resembles that of 21°N East Pacific Rise and has a uniform mid-ocean ridge basalt signature. The hydrothermal systems at oceanic spreading ridges have circulated through a large volume of basalt; therefore, Pb in these fluids may represent the best average value of the local oceanic crust. Div. of Geol. and Planetary Sci., Calif. Inst. of Tech., Pasadena, CA 91125, USA. 88:2104 Drits, V.A., N.A. Lisitsyna and V.I. Cherkashin, 1985. New mineral varieties of the hydrotalcitemanasseite group, low-temperature alteration products of basalt and voicanogenic sediments on the ocean floor. Dokl. Earth Sci. Sect. (a translation of Dokl. Akad. Nauk SSSR), 284(5): 140-143. Geol. Inst., Acad. of Sci., Moscow, USSR. 88:2105 Feely, R.A. et al., 1987. Composition and dissolution of black smoker particulates from active vents on the Juan de Fuca Ridge. J. geophys. Res., 92(B11): 11,347-11,363.

Active high temperature vents were sampled for particulates using the Grassle pump; individual mineral phases were identified and elemental compositions and particulate morphologies determined. Grain size and current meter data were used in a deposition model of individual phase dispersal. For many of the larger sulfide and sulfate particles, predicted dispersal is only over several hundreds of meters. Field and laboratory studies were conducted to determine sulfate and sulfide mineral dissolution rates. Results indicate that for some minerals (anhydrite, marcasite) total dissolution occurs within hours-weeks of formation while individual crystals of more stable minerals (pyrite, sphalerite, chalcopyrite) may persist for considerable periods after deposition. Pacific Mar. Environ. Lab., NOAA, 7600 Sand Point Way N.E., Seattle, WA 98115, USA. 88:2106 Gramberg, I.S. et al., 1985. Spatial periodicity in the occurrence of endogenous activity on the East Pacific Rise. Dokl. Earth Sci. Sect. (a translation of Dokl. Akad. Nauk SSSR), 284(5):100-102.

To date less than 1% of ocean rift zones have been studied systematically; to optimize future studies, a method for predicting the location of sites of hydrothermal activity is needed. Previous studies have shown a recurrence frequency of 15 to 265 km for hydrothermal systems in slow-spreading zones and of 1 to 100 km in moderate-to-fast spreading zones. An analysis of available data on heat flux and

OLR (1988) 35 (4)

D. Submarine Geology and Geophysics

spreading rate for the East Pacific Rise between 23°N and 46°30"S leads to the conclusion that 'the width of the rise at the 3000-m and 3500-m depth contour and the distance between transform faults contain a harmonic component with a period of 180 to 220 km and a derivative period of about 370 km.' All-Union Inst. of Geol. and Min. Resour. of the Oceans, Leningrad, USSR. (hbf)

88:2107 Hinkley, T.K. and Mitsunobu Tatsumoto, 1987. Metals and isotopes in Juan de Fuca Ridge hydrothermal fluids and their associated solid materials. J. geophys. Res., 92(Bll):11,40011,410. The STSr/S6Sr ratio of the hydrothermal solution (HTS) is larger than that of basalt at the southern vent field of the Juan de Fuca Ridge (SJFR). Both the Sr isotopic ratio for HTS and the water/rock interaction ratio lie between those at two sites farther south on the EPR (13 ° and 21°N). These parameters may be closely related to subsurface temperatures, magma ascent rates, extent of faulting, and framework surface areas. For these three sites, there is no steady geographical progression of these parameters or of spreading rate, with increasing latitude northward. Relatively high 2°rPb/2°4pb values at the SJFR suggest a potential anomalous radiogenic heat source and the Nd/Sm ratio suggests light REE enrichment. Sr isotopic compositions provide strong evidence that at least two of the solids types are precipitates from their individually associated fluids. USGS, Box 25046, Denver Fed. Center, Denver, CO 80225, USA.

88:2108 Kawahata, Hodaka, Minoru Kusakabe and Yoshiko Kikuchi, 1987. Strontium, oxygen, and hydrogen isotope geochemistry of hydrothermally altered and weathered rocks in DSDP Hole 504B, Costa Rica Rift. Earth planet. Sci. Letts, 85(4):343-355. DSDP Hole 504B, drilled into 6 Ma crust and penetrating 1.35 km, can be divided into four zones: Zone I, oxic submarine weathering; Zone II, anoxic alteration; Zones III and IV, hydrothermal alteration to greenchist facies. In Zone III there is intense veining of pillow basalts; Zone IV consists of altered sheeted dikes. Isotopic geochemical signatures in relation to alteration zones are reported and discussed along with data on alteration temperatures and fluid inclusion measurements. Basement rocks are not completely hydrothermally altered, and about 32% of the greenstones have escaped alteration. It is concluded that 1 g of fresh basalt is required to make 1 g of end-member solution from fresh seawater in water-rock reactions. Dept. of Geol., Univ. of Toronto, ON M5S IA1, Canada.

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88:2109 Lalou, Claude and Evelyne Brichet, 1987. On the isotopic chronology of submarine hydrothermal deposits. Chem. Geol., 65(3-4):197-207. The chronology of hydrothermal deposits, generally metallic sulfides or Mn- and Fe-oxides, may help in evaluating the importance and frequency of hydrothermal events, which may influence the chemistry of the oceans. In the natural radioactive series different disequilibria can act as good chronometers because they cover different time spans. The applications of 23°Th/234U, 21°pb/Pb and 22STh/22SRa methods covering 1000-350,000, 0-150, and 0-15 a, respectively, are discussed. The different assumptions needed to employ these radionuclides as chronometers, as well as the problems inherent in the methods are explained, and examples of their application to the Galapagos hydrothermal mounds, the Mid-Atlantic Ridge, and the East Pacific Rise are discussed. Centre des Faibles Radioactivites, Lab. mixte CNRS-CEA, F-91190 Gif-sur-Yvette, France.

88:2110 Lewis, J.B., 1987. Measurements of groundwater seepage flux onto a coral reef: spatial and temporal variations. Limnol. Oceanogr., 32(5): 1165-1169. Dept. of Biol., McGill Univ., 1205 Ave. Dr. Penfield, Montreal, PQ H3A 1B1, Canada. 88:2111 Normark, W.R., J.L. Morton and S.L. Ross, 1987. Submersible observations along the southern Juan de Fuca Ridge: 1984 A/fin program. J. geophys. Res., 92(B11): 11,283-11,290. Operations focused on specific volcanologic, structural, and hydrothermal problems identified during preceding photographic, dredging, acoustic imaging, and geophysical studies along a 12-km-long section of the ridge. A continuously maintained net of seafloor-anchored acoustic transponders allowed the observations from Alvin to be directly tied to all previous U.S.G.S. data sets and N O A A water column surveys from 1984 to the present. We review the dive program and present a brief synthesis of the geology of the vent sites together with sample and track line compilations. USGS, 345 Middlefield Rd., Menlo Park, CA 94025, USA.

88:2112 Philpotts, J.A., P.J. Aruscavage and K.L. Von Damm, 1987. Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge. J. geophys. Res., 92(B11): 11,327-11,333.

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The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low. There appear to be differences in fluid compositions both within and between the three vent areas. The Juan de Fuca hydrothermal fluids contain more Fe but otherwise have relative elemental abundances fairly similar to those in 13°N (East Pacific Rise) fluids, albeit at higher levels. In contrast, fluids from 21 °N (East Pacific Rise) and Galapagos have lower K / R b and much lower Sr and Na abundances. USGS, MS 923, Reston, VA 22092, USA. 88:2113 Shanks, W.C. III and W.E. Seyfried Jr., 1987. Stable isotope studies of vent fluids and chimney minerals, southern Juan de Fuca Ridge. Sodium metasomatism and seawater sulfate reduction. J. geophys. Res., 92(B11): 11,387-11,399.

This study presents the first results of sulfur isotope analyses of simultaneously collected chimney sulfides and fluid H2S. Also, 634S analyses were completed on fluid SO4, on sulfide-rich particles, and on samples from different paragenetic zones within chimneys. The results allow comparison of real-time S isotope variations in the vent fields with past variations recorded in chimney stratigraphy, leading to new insights on coupling of hydrothermal alteration processes and sulfate reduction in the ascending fluid. USGS, 954 Natl. Center, Reston, VA 22092, USA. 88:2114 Valette-Silver, J.N., F. Tera, J. Klein and R. Middleton, 1987. Beryllium 10 in hydrothermal vent deposits from the East Pacific Ridges. Role of sediments in the hydrothermal processes. J. geophys. Res., 92(B11): 11,364-11,372. ~°Be concentrations were determined for 31 hydrothermal sulfides, six oxyhydroxides, seven basalts, and five sediments from hydrothermally active areas of the East Pacific Rise, Galapagos Rift, Guaymas Basin, and the Gorda and Juan de Fuca ridges, and for massive sulfides from the Oman ophiolites. Values ranged from 0.04 × 106 atoms/g to 125 x 106 atoms/g and showed systematic variations with sample location and type. Concentrations for mid-ocean ridge basalts are of the order of 0.3 × 106 atoms/g and reach 3800 x 106 atoms/g for pelagic sediments collected near the EPR. Sulfides low in ~°Be are found on mid-ocean basalt and sulfides with high ~°Be occur on thick piles of

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young sediments. Oxyhydroxides from Juan de Fuca chimneys are always rich in ~°Be. Mechanisms proposed to explain these data include mechanical entrapment of sediments in the chimneys, ~°Be leaching from ocean crust sediments, and passive adsorption of l°Be from seawater. Dept. of Chem. and Biochem., Univ. of Maryland, College Park, MD 20742, USA. 88:2115 Von Damm, K.L. and J.L. Bischoff, 1987. Chemistry of hydrothermal solutions from the southern Juan de Fuca Ridge. J. geophys. Res., 92(B11): 11,33411,346. Fluids from three vent fields, sampled in September 1984, are uniquely high in chloride (up to twice the seawater value) and metal content. Simple vaporliquid phase separation could not have produced both the high chlorinity and gas concentrations observed. The elevated chlorinity may be due to either subsurface formation of a degassed brine, subsequently mixed in small amounts with hydrothermal seawater which has not undergone phase separation, or dissolution of a chloride-rich phase combined with a small loss of gas during sampling, or a combination of these. Measured temperatures were all less than 300°C, but quartz geothermometry suggests the fluids equilibrated at ) 3 4 0 ° C . Quartz geobarometry agrees with geophysical estimates of depth to the local magma chamber. Environ. Sci. Div., Oak Ridge Natl. Lab., P.O. Box X, MS 036, Oak Ridge, TN 37831, USA.

D170. Historical geology, stratigraphy 88:2116 Anderson, R.Y., Eileen Hemphill-Haley and J.V. Gardner, 1987. Persistent Late PleistoceneHolocene seasonal upwelling and varves off the coast of California. Quat. Res., 28(2):307-313.

An analysis of samples from continental slope bottom sediments and a sediment trap show that the millimeter-scale laminations observed in cores are in fact light and dark varves. The light laminae are enriched in siliceous phytoplankton deposited during summer upwelling; the dark laminae include more terrigenous material deposited in the fall and winter. It is concluded that seasonal upwelling along the California coast has persisted since the Late Pleistocene, but was stronger before the PleistoceneHolocene transition. Dept. of Geol., Univ. of New Mexico, Albuquerque, NM 87131, USA. (hbf)

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88:2117 Bardsley, W.E., 1987. A detail-preserving smoothing technique with application to high-resolution ocean core data. Computers, Geosciences, 13(4): 433-438. A simple, nonlinear data-smoothing method is presented which 'reduces noise while preserving and enhancing any shifts,' or abrupt transitions of values. The method is suggested for the analysis of isotope data from deep sea cores used to establish glacial and interglacial paleoclimates. Dept. of Earth Sci., Univ. of Waikato, Hamilton, New Zealand. (hbf) 88:2118 Barnola, J.M., D. Raynaud, Y.S. Korotkevich and C. Lorius, 1987. Vostok ice core provides 160,000year record of atmospheric CO z. Nature, Lond., 329(6138):408-414. Direct evidence of past atmospheric CO 2 changes has been extended to the past 160,000 years from the Vostok ice core. These changes are most notably an inherent phenomenon of change between glacial and interglacial periods. Besides this major 100,000-year cycle, the CO 2 record seems to exhibit a cyclic change with a period of some 21,000 years. Lab. de Glaciologie et de Geophys. de l'Environ., BP 96, 38402 Saint Martin d'Heres Cedex, France. 88:2119 Berger, W.H., J.S. Killingley and E. Vincent, 1987. Time scale of the Wisconsin/Holocene transition. Oxygen isotope record in the western equatorial Pacific. Quat. Res., 28(2):295-306. An analysis of new and published oxygen isotope data for the west equatorial Pacific indicates no significant input of meltwater to the ocean prior to 14,000 ~4C yrBP and supports previously suggested late-onset scenarios of deglaciation. A revised 3~80-radiocarbon age curve is similar to earlier ones (Berger et al., 1977; Berger, 1982) but does not show a mid-transition reduction in the rate of deglaciation or a glacial maximum near 15,000 BP. Scripps Inst. of Oceanogr., La Jolla, CA 92093, USA. (hbf) 88:2120 Braterman, P.S. and A.G. Cairns-Smith, 1987. Photoprecipitation and the banded iron-format i o n s - s o m e quantitative aspects. Orig. Life, 17(3-4): 221-228. The oxidative deposition of iron in the banded iron-formations can be quantitatively accounted for by direct abiotic photo-oxidation. Within this model, Fe supply was the limiting factor, the Precambrian ocean surfaces were iron-depleted, and hydrogen was released into the atmosphere at a rate controlled

333

by Fe(II) mixing. Other mechanisms operating in parallel are not excluded, and the Fe(II) budget suggests that recirculation by reaction with reduced carbon was important by ~2.5 b.y.BP. Dept. of Chem., Univ. of Glasgow, GI2 8QQ, Scotland. 88:2121 Burton, Rande, C.G.St.C. Kendall and Ian Lerche, 1987. Out of our depth: on the impossibility of fathoming eustasy from the stratigraphic record. Earth-Sci. Rev., 24(4):237-277. Although many methods have been used in the attempt to distinguish eustatic sea level changes from the effects of sediment compaction, crustal flexuring, and thermo-tectonic processes, mathematical modelling demonstrates that, at best, it is only possible to obtain the sum of tectonic basement subsidence and sea level variations. At present the best approximations of eustatic changes are derived by combining relative sea level charts based on sediment onlap at continental margins and oxygen isotope responses to glacial events. It is suggested that graphic simulations of the sedimentary fill of basins be used to generate a family of solutions for eustatic changes and then those models which best fit the known geology be selected and used to obtain limits on the input variables. An example is provided of one such simulation on a hypothetical continental margin. Sohio Petroleum, Lincoln Centre, Dallas, TX 75240, USA. (hbf) 88:2122 Calvert, S.E., J.S. Vogel and J.R. Southon, 1987. Carbon accumulation rates and the origin of the Holocene sapropel in the Black Sea. Geology, geol. Soc. Am., 15(10):918-921. A detailed radiocarbon chronology and carbon and carbonate stratigraphy of cores from two Black Sea sites suggest a need for revision of the theory that ascribes sapropel formation to water-column anoxia. The sapropel layer at the deeper water site dates from 1600 to 6600 BP and at the shallower site from 4000 to 6000 BP. Carbon accumulation was twice that of the overlying modern sediment at the deep water site and approximately equal at the shallower site. The data indicate that sapropel formation was probably due to increased production during the change from freshwater lake to marine water, and not to anoxia. Dept. of Oceanogr., Univ. of British Columbia, Vancouver, BC V6T IW5, Canada. (hbf) 88:2123 Chen, Yijian and Henry Polach, 1987. Validity of ~4C ages of carbonates in sediments. Mar. Geol. Quat. Geol., 7(2):131-139. (In Chinese, English abstract.)

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This review is based on geological surveys in Australia and China, and on more than 300 published ~4C dates. The three identified ~-~Cabundance peaks are unrelated to environment and C source, while ~4C ages put them into a period corresponding to past humid warm climate. It is concluded that the major error in caliche dating is due to incorporation of old limestone, while error in nodule dating is related to their slow growth rate. Thus caliche predate and nodules postdate deposition times. 8~C values cannot be used to correct for limestone or atmospheric contaminations. Inst. of Geol., State Seismol. Bur., Beijing, People's Republic of China. 88:2124 Colman, S.M., K.L. Pierce and P.W. Birkeland, 1987. Suggested terminology for Quaternary dating methods. Quat. Res., 28(2):314-319.

Suggestions for a consistent terminology for Quaternary dating methods and results are presented. Dating methods may be classified by type into sideral, isotopic, radiogenic, chemical and biological, geomorphic, and correlation methods. Results should reflect confidence level and be reported in terms of numerical, calibrated, relative, or correlated-age. The descriptors numerical, rather than absolute, and age or age-estimate, rather than date, and the abbreviations ka and Ma for most ages are favored. Calendar dates are acceptable for ages determined by sidereal methods and yr B.P. for ages determined by radiocarbon methods. USGS, Woods Hole, MA 02543, USA. (hbf) 88:2125 Crowley, T.J., J.G. Mengel and D.A. Short, 1987. Gondwanaland's seasonal cycle. Nature, Lond., 329(6142):803-807.

A 2-D energy balance climate model has been used to simulate the seasonal temperature cycle on a supercontinent-sized land mass. Experiments with idealized and realistic geography indicate that the land-sea configuration in high latitudes exerts a strong influence on the magnitude of summer warming. These simulations provide significant insight into the evolution of climate during the Palaeozoic, and raise questions about the presumed pre-eminent role of CO 2 in explaining long-term climate change. Appl. Res. Corp., ARC Tech., 305 ArgueUo Dr., College Station, TX 77840, USA. 88:2126 Donovan, S.K., 1987. Mass extinctions: confusion at the boundary. [Report.] Nature, Lond., 329(6137):p.288.

Although geochemical investigations on the abundances of ~J3C and iridium in the Precambri-

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an/Cambrian boundary section have been variously interpreted, a new paleontological study (Crimes, 1987) on faunal activity as evidenced by trace fossils indicates that the metazoans in boundary strata were not perceptibly influenced by an extinction event. Dept. of Geol., Univ. of the West Indies, Mona, Kingston 7, Jamaica, West Indies. (hbf) 88:2127 Gaffin, Stuart, 1987. Phase difference between sea level and magnetic reversal rate. Nature, Lond., 329(6142):816-819.

A negative correlation and a phase difference of 10 Myr exists between recent data on long-term eustatic sea level change and geomagnetic reversal rate for the past 150 Myr. The same phase difference (but with a positive correlation) could theoretically have existed between this eustatic sea level data and seafloor creation rate. In light of the ridge-volume hypothesis of long-term eustasy, the analysis suggests the view that seafloor creation rate (and/or subduction rate) and geomagnetic reversal rate are closely associated and perhaps synchronized in their changes. Dept. of Geol. and Geophys., Yale Univ., P.O. Box 6666, New Haven, CT 06511, USA. 88:2128 Gartner, Stefan, Jinder Chow and R.J. Stanton Jr., 1987. Late Neogene paleoceanography of the eastern Caribbean, the Gulf of Mexico, and the eastern equatorial Pacific. Mar. Micropaleont., 12(3):255-304.

As late as the Mid-Pliocene, a deep water connection existed between the Pacific and Caribbean/Gulf of Mexico, and a shallower seaway existed between the two into the Late Pliocene. Final closure probably coincided with the initial buildup of a Northern Hemisphere ice sheet. The most important floral change occurred about 0.9 m.y., marking a change in ocean circulation toward a warm, stably stratified tropical surface ocean, little affected by high latitude climatic changes. Dept. of Oceanogr., Texas A&M Univ., College Station, TX 77840, USA. 88:2129 Genthon, C. et al., 1987. Vostok ice core: climatic response to CO z and orbital forcing changes over the last climatic cycle. Nature, Lond., 329(6138): 414-418.

Vostok climate and CO2 records suggest that CO 2 changes have had an important climatic role during the Late Pleistocene in amplifying the relatively weak orbital forcing. The existence of the 100-kyr cycle and the synchronism between Northern and Southern hemisphere climates may have their origin in the large glacial-interglacial CO L changes. Lab. de

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D. SubmarineGeologyand Geophysics

Geochim. Isotopique, 91191 Gif sur Yvette Cedex, France. 88:2130 Gudjonsson, L., 1987. Local and global effects on the Early Pliocene Mediterranean stable isotope records. Mar. Micropaleont., 12(3):241-253.

Stable isotope analyses of the planktonic foraminifer Globigerinoides obliquus from South Calabria, Italy, yielded detailed Early Pliocene oxygen and carbon records directly calibrated to the numerical time scale. Two major local Mediterranean signals are recognized: (1) rapid alternations of 'wet' and 'dry' climatic conditions with an average periodicity of 0.02 Ma, considered to reflect fluctuations in precipitation and run-off volume; and (2) superimposed longer-term alternations of relatively 'wetter' and relatively 'drier' intervals reflecting intensification of precipitation or latitudinal shifts of precipitation zones. After reducing these local overprints to a minimum, the isotope records were compared with previously published ones from the Pacific and Atlantic. Two approximately contemporaneous isotope 'events' were found but in general there is little similarity between Mediterranean and extra-Mediterranean records. Our records probably reflect Mediterranean paleoclimatologic and paleoceanographic development rather than global climatic signals. Dept. of Stratigraphy/Micropaleontol., State Univ. of Utrecht, Budapestlaan 4, 3508 TA Utrecht, Netherlands. 88:2131 Healy, Terry, Helmut Erlenkeuser, Kyaw Winn and Friederich Werner, 1987. Theoretical post-glacial sedimentation rates for a semi-enclosed sea; example of the Kieler Bucht, western Baltic. Boreas, 16(3):207-213. The theoretical rates of fine sediment deposition over the last l0 ka have been deduced and plotted. Assumptions are that the bay has remained a closed sedimentary system, and that the fine sediments deposit in water deeper than l0 m. A sharp peak of activity is indicated between 7.5 and 8.5 kaBP with low rates prior to 9.5 ka and since 6 ka. Comparison of rates obtained from dated cores extracted from different parts of the Kieler Bucht with the theoretical curve shows general conformity, and confirms that peak rates exceeding 3 mm/a, averaged over 100-200 years, occurred between 8 and 9 ka, with a minor activity peak between 3 and 4 ka. Overall consistency supports the view that the bay has acted as a closed sedimentary basin during the Holocene marine transgression and subsequently. Dept. of Earth Sci., Univ. of Waikato, Hamilton, New Zealand.

33~

88:2132 Holm, N.G., 1987. Possible biological origin of banded iron-formations from hydrothermal solutions. Orig. Life, 17(3-4):229-250.

A combined hydrothermal/biogenic model is suggested for the origin of banded Fe-forrnations, based mainly on the distribution of trace elements such as Mn, Co, Cu, Zn, and P in modern biogenic metalliferous sediments and Proterozoic banded Fe-formations, but also on C isotope data of carbonates and reduced elemental carbon. The wide lateral microband continuity of many banded Feformations could be explained by injection, interleaving and horizontal spreading of chemically reduced hydrothermal solutions in an early ocean with limited free 02, where Fe would be precipitated slowly as an effect of mainly microbiological oxidation. Periods of Fe precipitation from hot hydrothermal solutions would alternate with periods of silica precipitation from cool hydrothermal solutions. Univ. of Stockholm, Dept. of Geol., S-106 91 Stockholm, Sweden. 88:2133 Hull, A.G., 1987. A Late Holocene marine terrace on the Kidnappers Coast, North Island, New Zealand. Some implications for shore platform development processes and uplift mechanism. Quat. Res., 28(2):183-195. Dept. of Geol. Sci., Univ. of Calif., Santa Barbara, CA 93106, USA. 88:2134 Jacquin, Thierry, 1987. The two anoxic events in South Atlantic during Cretaceous time. Bull. Soc. g~ol. Fr., (8)III(4):705-713. (In French, English abstract.)

Black shales were deposited during two major anoxic phases; the first (Barremian to Middle Albian) occurred during initial opening of the South Atlantic. The presence of evaporitic minerals within the anoxic sediments implies an euxinic environment with a high Na content. Cyclic stratification is due to variations of planktonic productivity in the superficial waters. The second period (Upper Cenomanian to Santonian) reached maximum anoxic conditions during the Lower and Middle Turonian. For this interval there is no evidence for euxinic conditions in a strongly alkaline environment, and alternations of deposits are due to variations of redox conditions at the seafloor. Inst. Sci. de la Terre et UA CNRS 157, 6, bd Gabriel, 21100 Dijon, France. 88:2135 Jouzel, J. et al., 1987. Vostok ice core: a continuous isotope temperature record over the last climatic cycle (160,000 years). Nature, Lond., 329(6138): 403-408.

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A continuous deuterium profile along the 160,000year Vostok ice core (Antarctica) is interpreted in terms of atmospheric temperature changes. This climatic record is the awaited terrestrial complement of the deep-sea records supporting the existence of a relation between the Pleistocene climate and orbital forcing. Lab. de Geochim. Isotopique, 91191 Gif sur Yvette Cedex, France.

A mammoth tooth and a mastodon tooth, both found at ~ 5 0 m on the continental shelf northeast of Boston and dated to ~11 ka, indicate that the previously undated -50 m low relative sea level stand may have occurred during Late Wisconsinan time (~I1 ka). The find indicates that these animals were New England inhabitants ~1000 yr before their extinction. USGS, Woods Hole, MA 02543, USA. (gsb)

88:2136 Ocean Drilling Program (Leg 114 scientific drilling party), 1987. In the subantarctic Atlantic Ocean [ODP] Leg 114 finds complete sedimentary record. Geotimes, 32(10):23-25.

88:2139 Oreshkina, T.V., 1986. Neogene paleoclimates of the subarctic region of the Pacific Ocean based on diatom data. Int. Geol. Rev., 28(12): 1460-1467.

The 2300 m of sediment collected from seven sites in the Antarctic and subantarctic South Atlantic provide a high quality database for events in southern oceans over the last 90 m.y. The Late Cretaceous to Quaternary sedimentary sequences include representatives of all major fossil groups and an almost complete magnetostratigraphic record. A hiatus at all sites at about 23.5 m.y. is associated with the opening of Drake Passage that led to an intensification of circum-Antarctic circulation with major climatic and biological consequences. Although 'cooler assemblages' of planktonic organisms appeared at 23 m.y., evidence for severe cooling is not found until 6.5 m.y., and cyclic deposits from 2.9 m.y. on probably reflect glacial-interglacial fluctuations of calcareous and biosiliceous sedimentation. Ocean Drilling Prog., Texas A&M Univ., College Station, TX 77840, USA. (hbf) 88:2137 Ocean Drilling Program (Leg 115 shipboard scientific party), Jan Backman and Robert Duncan (co-chief scientists), 1987. New studies of the Indian Ocean. Nature, Lond., 329(6140):586-587.

Results obtained on the first of a nine-leg program of exploration in the Indian Ocean include new data supporting volcanic hotspot activity along the Ninetyeast Ridge and the Mascarene PlateauChagos-Maldive-Laccadive Island Ridge and a connection to the Deccan flood basalts in western India, and new evidence of variations in carbonate production and dissolution in these tropical waters over the past 36 Myr. The data from Leg 115 basement sites also indicate about 7 ° of true polar wander over the past 35 Myr at these locations. (hbf) 88:2138 Oldale, R.N., F.C. Whitmore Jr. and J.R. Grimes, 1987. Elephant teeth from the western Gulf of Maine, and their implications. Natn. geogr. Res., 3(4):439-446.

Diatom assemblages from onshore sections and DSDP cores from the North Pacific (52-29°N) are used to reconstruct the Neogene paleoclimates of the region. Rare Early Miocene diatoms confirm the theory that intense silica deposition did not begin until the end of the Early Miocene. During the Middle Miocene pelagic associations included many warm-water species, and pelagic and neritic associations were similar to those found in the Pacific mid-latitudes. An expansion of cold-water neritic types at the end of the Pliocene marks the onset of glaciation in the high latitudes of the Northern Hemisphere. (hbf) 88:2140 Pujos, Annick, 1987. Establishment of the equatorial Pacific water circulation and of calcareous nannofossil assemblages during the Neogene (DSDP Leg 85). II. The uplift of the Isthmus of Panama and its consequences between 7 and 2 Ma. Bull. Soc. g~ol. Fr., (8)III(4):731-736. (In French, English abstract.) Calcareous nannofossils from Mio-Pliocene sediments recovered from the central and eastern parts of the high-productivity area were studied in detail. Two main geologic events occurred during the Neogene which modified water mass circulation; between 15 and 7 Ma, Antarctic glaciation influenced greatly the Pacific circulation and between 7 and 2 Ma the progressive uplift of the Isthmus of Panama gave rise to a tropical and an equatorial upwelling, which changed the distribution of discoasters and Coccolithus pelagicus, and triggered the recent Pacific circulation. Dept. Geol. Oceanogr., Univ. Bordeaux I, av. des Facultes, 33400 Talence, France. 88:2141 Saint-Marc, Pierre, 1987. Paleoeeanographic data on the Paleocene strata from the northeastern part of the Walvis Ridge, South Atlantic. Bull. Soc. g~ol. Fr., (8)III(4):749-758. (In French, English abstract.)

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D. SubmarineGeologyand Geophysics

Foraminiferal assemblages indicate a lower bathyal environment for Paleocene deposits above the CCD but near the foraminiferal lysocline. A large hiatus at the Cretaceous/Cenozoic boundary suggests the development of a vigorous, deep-water flow due to cooling of surface waters around Antarctica. A study of the paleobathymetry of the Danian deposits indicates progressively increasing depth; their carbonate content and dissolution of the microfauna divide the strata into three phases marking shifts from cold water circulation to a marked warming of surface waters and increased deposition of CaCO 3. Lab. Micropaleontol. et Geol. Mar., Univ. Nice, Parc Valrose, 06034 Nice cedex, France. 88:2142 Skogseid, Jakob and Olav Eldholm, 1987. Early Cenozoic crust at the Norwegian continental margin and the conjugate Jan Mayen Ridge. J. geophys. Res., 92(B11): 11,471-11,491. Multichannel seismic profiles of the Voting Plateau margin and northern Jan Mayen Ridge provide a framework for the Early Tertiary history of areas which were adjacent prior to the Norwegian Sea opening. It is proposed that their Paleogene histories were quite similar and that two acoustic basement reflectors were formed in the Early Eocene by extrusion of flow basalts. From the opening to anomaly 23 time, oceanic seafloor was generated by Icelandic-type spreading; during this subaerial spreading, basalt flows also covered the adjacent thinned and intruded continental crust. The most elevated parts of the Voting marginal high did not subside below shallow water depths before the Oligocene/Miocene. It is suggested that the Vering margin and Jan Mayen Ridge are 'volcanic' passive margins. The evolution of this margin type may relate to initial uplift due to rifting in previously thinned crust. Dept. of Geol., Univ. of Oslo, P.O. Box 1047, N-0316 Blindern, Oslo 3, Norway. 88:2143 Southon, J.R., T.L. Ku, D.E. Nelson, J.L. Reyss, J.C. Duplessy and J.S. Vogel, 1987. *°Be in a deep-sea core: implications regarding t°Be production changes over the past 420 ka. Earth planet. Sci. Letts, 85(4):356-364. A globigerinid ooze core from the eastern North Atlantic contains a depositional record of the first 11 6~sO stages covering the last 423 ka, and deposition rates of ~°Be averaged over each stage show a scatter of + 40% about the mean value of 6.6 × 108 atoms cm 2 ka J. After correction for changes in lithology, the data show l°Be production rates varied no more than _+25%, and were not systematic in that high or low ~°Be rates appear associated with either cold or

~T

warm climates. On the time scale of this investigation it is unlikely that the shielding effect of the solar wind has deviated more than +_25%, or the geomagnetic field intensity by more than a factor of 1.6 from their long-term averages. Marine deposition of ~°Be is strongly influenced by sedimentation of clay particles which appear 10 times more efficient than carbonates as a carrier of ~°Be to bottom sediments. Dept. of Archaeol., Simon Fraser Univ., Burnaby, BC V5A 156, Canada. 88:2144 Teng, L.S. and H.-J. Lo, 1985. Sedimentary sequences in the island arc settings of the coastal range, eastern Taiwan. Acta geol. taiwan., 23:7798. A detailed study of the sedimentary sequences of the northern segment of the Luzon Arc system, the Tuluanshan Arc and associated reefs, the forearc basin deposits, and the trench complex is presented. It is inferred that the Tuluanshan Arc began to develop in the Late Oligocene in response to east-dipping subduction, and that by the Late Miocene, when volcanic deposits were at sea level or above, fringing reefs and forearc basin turbidites formed. Finally, the arc system collided with the continental margin in the Middle Pliocene. Dept. of Geol., Natl. Taiwan Univ., Taipei, Taiwan. (hbf) 88:2145 Volk, Tyler, 1987. Feedbacks between weathering and atmospheric CO z over the last 100 million years. Am. J. Sci., 287(8):763-779. The dependence of weathering rate on temperature and pCO 2 and on changes in the terrestrial biosphere, and the link betweenpCO 2 in the atmosphere and in soils are investigated. Results suggest that when terrestrial productivity becomes two, four, or eight times the present level, global temperature rises from geophysical forcing on the CO2-greenhouse drop by 1°, 2 °, or 3C ° respectively, implying that the terrestrial biosphere can moderate climate change through changes in the levels of soil pCO 2. Dept. of Appl. Sci., New York Univ., New York, NY 10003, USA. (hbf) 88:2146 Walker, J.C.G., 1987. Was the Archaean biosphere upside down? Nature, Lond., 329(6141):710-712. Photosynthesis produces reduced organic carbon and an oxidized partner in equivalent molar amounts. On the anoxic Archaean Earth, the oxidized partner was probably iron, which is markedly less soluble and mobile than organic carbon. The oxidized partner would have settled downward more rapidly than the reduced partner, resulting in

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accumulation of excess oxidant in sediments and stagnant pools. An equivalent excess of the more volatile reduced compounds would have been left behind in ocean and atmosphere as dissolved organic C and gaseous hydrocarbons. Therefore, the Archaean biosphere may have been oxidizing at the bottom and reducing on top. Dept. of Atmos. and Oceanic Sci. and Geol. Sci., Univ. of Michigan, Ann Arbor, MI 48109, USA. 88:2147 Yang, Shengming, 1987. Characteristics of Quaternary sedimentation in Honghai Bay, Guangdong Province. Mar. Geol. Quat. Geol., 7(1):81-90. (In Chinese, English abstract.) Second Mar. Geol. Investigation Brigade, Ministry of Geol. and Mineral Resour., Guangzhou, People's Republic of China. 88:2148 Zhou, Yaoqi, 1987. The Pacific impact event. Mar. GeoL Quat. Geol., 7(1):15-26. (In Chinese, English abstract.)

Research on the circum-Pacific tectonic system, terranes, and reconstruction of the Pacific Plate confirm the hypothesis that the Pacific Ocean, as well as the 'ring basins' on the Moon and planets, may have formed by huge impact events, which resulted in break-up of the lithosphere and flow of basalt magma out of the asthenosphere beneath the crater bottoms. The basins on the Moon and planets, however, were formed about 3000 Mya, but the Pacific Ocean formed later at the end of the Permian, as indicated by the Permo-Triassic boundary clay, big organic extinction event, large magnetic reversal, sudden changes in atmospheric temperature and composition, 'terrestrial radical expansion,' huge seawater losses, and an acceleration of the Earth's rotation. Terranes around the Pacific are residual blocks of the paleo-Pacific continent. Inst. of High Energy Phys., Acad. Sinica, Beijing, People's Republic of China.

D180. Paleontology (see also E-BIOLOGICAL OCEANOGRAPHY) 88:2149 Blanc-Vernet, Laure, 1987. Benthic Foraminifera and Pliocene--Quaternary environments in the western North Atlantic from DSDP data. Bull. Soc. g~ol. Ft., (8)III(4):723-729. (In French, English abstract.)

Fossil benthic Foraminifera in northeast American margin sediments exhibit characteristic assemblage

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alternation correlated with different bottom water masses and indicate some major climatic events that occurred in the NW Atlantic during the Pliocene and Quaternary. During glacial periods, the North Atlantic Deep Water assemblage decreases and is replaced by an Osangularia umbonifera-dominant fauna (at the deepest site), or in shallower areas by an Uvigerina peregrina fauna sometimes with high percentages of Pyrgo murrhina and Globulimina spp. On the slope, occurrences of displaced neritic species are frequent during periods of climatic deterioration. Five major events have been recognized: 4.1 Ma; 3.1-3, 2.3-2.2, and 1.8-1.6 Ma and at the top of the Pleistocene. Lab. Geol. Mar., Centre d'Oceanol, de Marseille, U.A. 41 du CNRS, Fac. Sci. Luminy, 13288 Marseille cedex 9, France. 88:2150 Boltovskoy, Demetrio, 1987. Sedimentary record of radiolarlan biogeography in the equatorial to antarctic western Pacific Ocean. Micropaleontology, 33(3):267-281.

Analysis of 18 surface sediment samples (1°-64°S, along approx. 180 ° E) yielded 195 Recent radiolarian taxa. Clustering of species and samples, and further examination of distribution patterns allowed definition of five climatic zones, several species groups and isolated species with variable degrees of selective loading on the five areas. Specific diversities were highest in the tropical zone, and a secondary peak occurred at the northern edge of the transition zone; the latter area was barren of endemic and probably of characteristic taxa. A zonation of the transect, based on a family and suborder level radiolarian census, was similar to one based on species, suggesting that the distribution of these higher-level categories is meaningful in ecological terms. Dept. de Ciencias Biol., Univ. de Buenos Aires, 1428 Buenos Aires, Argentina. 88:2151 Boltovskoy, Esteban, 1987. Tertiary benthic Foraminifera in bathyal deposits of the Quaternary World Ocean. J. foram. Res., 17(4):279-285. On the basis of a study of bathyal benthic Foraminifera of the World Ocean (19 DSDP holes, 1084 samples, approximately 250,000 specimens), the following percentages of Tertiary species were found in Quaternary deposits: Paleocene, 25.8%; Eocene, 44.8%; Oligocene, 67.5%; Early Miocene, 73.6%; Middle Miocene, 78.0%; Late Miocene, 87.1%; Pliocene, 93.3%. These conclusions are drawn from strictly comparable data, since all identifications were made by a single investigator. Museo Argentino de Ciencias Nat. B. Rivadavia, Av. A. Gallardo 470, 1405 Buenos Aires, Argentina.

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88:2152 Boltovskoy, Esteban, 1987. [Cenozoic benthic Foraminifera from DSDP Site 167, in the central Pacific bathyal zone.I Revta esp. Micropaleont., 19(1):5-32. (In Spanish, English abstract.) Identified in 45 samples were 150 Cenozoic benthic foraminiferal taxa. The Paleocene section was characterized by Nuttallides truempyi, Pullenia charapatoensis, and .4nomalina praespissiformis. Eocene deposits were dominated by N. truempyi and, in lesser numbers, Oridorsalis umbonatus and Cibicides kullenbergi. Oligocene dominants (C. kullenbergi, O. umbonatus, A . globulosa, Epistominella exigua, Eponides bradyi, and P. osloensis) are similar to those of the Pliocene/Quaternary. Major faunal turnovers occurred between the Paleocene and Eocene and the Eocene and Oligocene. Two less conspicuous faunal breaks are recognized between the Middle Miocene and Pliocene and the Pliocene and Quaternary. Mus. Argentino de Ciene. Nat. B. Rivadavia y Consejo Nac. de Invest. Cient. y Tec., Argentina. 88:2153 BrOnnimann, Paul, 1987. On the chamber arrangement and other morphological aspects of CanepMa Boitovskoy 1961. Micropaleontology, 33(3): 242-253. 90, Chemin de Bedex, 1226-Thonex/ Geneva, Switzerland. 88:2154 Butterlin, Jacques, 1986. Origin and evolution of the lepidocycHnes [Foraminifera] from the Caribbean region. Comparisons and relations with the lepidocyclines from the other regions of the world. Revue Micropal~ont., 29(4):203-219. (In French, English abstract.) Inst. de Phys. du Globe de Paris, Tour 24, 4, place Jussieu, 75252 Paris Cedex 05, France. 88:2155 Farley, M.B., 1987. Palynomorphs from surface water of the eastern and central Caribbean Sea. Micropaleontology, 33(3):254-262. Dept. of Geosci., Pennsylvania State Univ., University Park, PA 16802, USA. 88:2156 Kellogg, D.E. and T.B. Kellogg, 1987. Microfossil distributions in modern Amundsen Sea sediments. Mar. Micropaleont., 12(3):203-222. Microfossil analyses of filtered seawater and sea ice allow comparisons of biocoenosis with thanatocoenosis in the sediments. Three biotic provinces are distinguished; the outer shelf region (north of Thurston Island) is characterized by high abundances of planktonic and calcareous benthic fora-

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minifers; the southern province (Pine Island Bay) is marked by very low abundances of all microfossil groups, possibly because the floating ice terminus retreated only during the last 100 years; the eastern margin province is characterized by abundances of diatoms and arenaceous benthic foraminifers, which probably record the presence of the Amundsen Sea polynya in this area during the last 1000-2500 yr. Inst. for Quaternary Studies and Dept. of Geol. Sci., Univ. of Maine, Orono, ME 04469, USA. 88:2157 Li, Qianyu, 1987. Origin, phylogenetic development and systematic taxonomy of the Tenmtella Plexus (GIobigerinitidae, Globigerininina). J. foram. Res., 17(4):298-320. Dept. of Geol., Zhongshan Univ., Guangzhou, People's Republic of China. 88:2158 Lipson-Benitah, S., 1987. A paleoceanographic approach to the planktonic foraminiferal zone. Examples from the Cretaceous-Paleogene biostratigraphy. Revue Micropal~ont., 30(1): 13-23. (In French, English abstract.) The phylozone, the total range zone and the interval zone based on planktonic foraminifers are critically reviewed. Their use in the Cretaceous-Paleogene biostratigraphy shows that a causal link exists between the selected category of zone and the prevailing oceanic control. During highstands characterized by polytaxic conditions the three kinds of zone are established. During lowstands characterized by oligotaxic conditions the establishment of an interval zone based on the range of primitive or more tolerant species is favoured. Paleoceanographic changes are accurately recorded in the plankton (and reflected in the corresponding zone) if the foraminifers already achieved an adequate degree of selective adaptation. Paleontol. Lab., Israel Inst. of Petroleum and Energy, 26, University St., Tel Aviv 69975, Israel. 88:2159 Matsuoka, Kazumi, J.P. Bujak and Togo Shimazaki, 1987. Late Cenozoic dinoflagellate cyst biostratigraphy from the west coast of northern Japan. Micropaleontology, 33(3):214-229. Five dinoflagellate cyst Oppel-zones are proposed for the Miocene to Holocene in the west coast of northern Japan based on several selected species. Age justification for these zones utilizes planktonic Foraminifera, Radiolaria, calcareous nannofossils, and diatom zonations previously established in the same area of northern Japan. The five zones are compared with other Late Cenozoic dinoflageUate cyst zonations, and it is concluded that many species

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have varying stratigraphic ranges in different biogeographic provinces. Dept. of Geol., Nagasaki Univ., Nagasaki, Japan. 88:2160 McDougaU, Kristin, 1987. Maestrichtian benthic foraminifers from Ocean Point, North Slope, Alaska. J. foram. Res., 17(4):344-366. The Ocean Point benthic foraminiferal assemblages contain species that migrated from the U.S. Gulf Coast, North American Interior and Europe during the Campanian, and from Europe during the Maestrichtian. These faunal affinities suggest that seaways connected the Arctic to the North American Interior and Atlantic during the Campanian and that a shallow seaway connected the Arctic to the Atlantic during the Early Maestrichtian. USGS, 345 Middlefield Rd., Menlo Park, CA 94025, USA. 88:2161 Penney, D.N., 1987. Application of Ostracoda to sea-level studies. Boreas, 16(3):237-247. Ostracoda are probably better indicators of past sea level than heretofore realized, because very characteristic low diversity, high productivity faunas occur in upper reaches of the estuarine environment, and a fair amount of knowledge exists concerning their ecology. Details are given on faunas present in each estuarine facies, and on how death assemblages can be distinguished from life assemblages. Sea level can be estimated to an accuracy of 50 cm to 100 cm in some NW European microtidal areas; further research is required on macrotidal coasts to ascertain whether they can be used to pinpoint sea level here. Examples of Ostracoda proving of value in sea-level studies are given for North Denmark, The Netherlands, East Ireland, and the Gulf of Gascony. Lab. of Palaeontol. and Stratigr., Geol. Dept., Aarhus Univ., DK-8000 Aarhus C, Denmark. 88:2162 Sancetta, Constance, 1987. Three species of Coscino. discus Ehrenberg from North Pacific sediments examined in the light and scanning electron microscopes. Micropaleontology, 33(3):230-241. Lamont-Doherty Geol. Observ., Palisades, NY 10964, USA. 88:2163 Seiglie, G.A. and M.B. Baker, 1987. Duquepsammiidae, a new family, and Duquepsammia, a new genus of agglutinated foraminifers. Micropaleontology, 33(3):263-266. Chevron U.S.A., Southern Region, P.O. Box 1635, Houston, TX 77251, USA.

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88:2164 Sigal, Jacques, 1987. A zonal scale for the Mediterranean Cretaceous deposits, with some related comments, particularly at the Daulan level. Revue Micropaldont., 30(1):32-51. (In French, English abstract.) Coll. de France, Station Marcelin Berthelot, 92360 Meudon-la-Foret, France. 88:2165 Tasch, Paul, 1987. Fossil Conchostraca of the Southern Hemisphere and continental drift. Paleontology, biostratigraphy, and dispersal. Mere. geol. Soc. Am., 165:290pp. New measurements, photographs, and emended descriptions have been added to previously published findings on conchostracan biogeology, paleoecology, and systematic taxonomy to provide a comprehensive update on the occurrence of fossil conchostracans in the Southern Hemisphere. Because they are primarily freshwater forms, they are well suited to trace nonmarine dispersal across the continents. The data refute misconceptions on the restricted horizontal and vertical distribution of genera and species. On the basis of present information on endemism on the generic level, only five indigenous genera are recognized in the Mesozoic of South America, one in the Carboniferous of Australia, and one in the Triassic of India. Nat. Sci./Geol. Dept., Wichita State Univ., Wichita, KS 67208, USA. (hbf) 88:2166 Whatley, Robin and Graham Coles, 1987. The Late Miocene to Quaternary Ostracoda of Leg 94, Deep Sea Drilling Project. Revta esp. Micropaleont., 19(1):33-97. A study of the Ostracoda at all 6 sites of Leg 94 has revealed a higher diversity for the Neogene and Quaternary than previously recorded from DSDP studies in the Atlantic. The 172 samples yielded 88 species from 43 genera, including 22 new species and one new genus. The highest diversity and incidence for most sites occurs in the Mid Pliocene. Diversity is relatively low in the Late Miocene and high in the Quaternary. Global paleoceanographic events are clearly depicted in a graph of origination and extinction of species. Energy levels at Site 609 seem abnormally high, surprisingly low at Site 610, and high only in the Late Pliocene at Site 611. Micropalaeontol. Div., Dept. of Geol., Univ. Coll. of Wales, Aberystwyth, Dyfed, UK. 88:2167 Zotto, M., W.S. Drugg and D. Habib, 1987. Kimmeridgian dinoflagellate stratigraphy in the southwestern North Atlantic. Micropaleontology, 33(3): 193-213.

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D. SubmarineGeologyand Geophysics

Restudy of the dinoflagellate stratigraphy reveals six species which indicate that the lowermost part of the sedimentary section is not older than Kimmeridgian. The first appearance datums of four of these species in the Pictonia baylei ammonite zone permits a maximum age close to, or at, the Kimmeridgian/ Oxfordian boundary. Correlation of mutually occurring species at DSDP Sites 100 and 534 suggests that the interval from the first appearance of Occisucysta balios to directly above the last appearance of Stephanelytron scarburghense can be used to distinguish the Kimmeridgian sensu gallico. In the Tethyan province, the Kimmeridgian/ Tithonian boundary is tentatively placed between the last appearance of S. scarburghense and the first appearance of Cometodinium whitei. Grad. School, CUNY, New York, USA.

D200. Gravity, geodesy, magnetism 88:2168 Achache, Josr, Abdeslam Abtout and J.-L. Le Mou~l, 1987. The downward continuation of Magsat crustal anomaly field over southeast Asia. J. geophys. Res., 92(Bll):11,584-11,596. A general method for the local downward continuation at ground level of geopotentials measured by low-orbiting satellites at different altitudes is proposed. It is applied to Magsat data over southeast Asia. Two independent maps of the vertical component of the anomaly field at a constant altitude near ground level reveal similar anomalies and confirm the correlation of the Magsat-derived anomaly field with the mosaic structure of the continental crust in southeast Asia. Lab. de Geomagnet, et Paleomagnet., Inst. de Phys. du Globe de Paris, 4, Place Jussieu, 75252 Paris Cedex 05, France. 88:2169 Cazenave, Anny, Marc Monnereau and Dominique Gibert, 1987. Seasat gravity undulations in the central Indian Ocean. Phys. Earth planet. Interiors, 48(1-2): 130-141. In the SE Indian Ocean, geoid and gravity maps derived from satellite data show clear evidence of a lineated pattern between the SE Indian Ridge and the southern branch of the Ninetyeast Ridge. Power spectra of gravity and geoid data over the Indo-Australian Plate confirm undulations oriented N40°E of ~200 km wavelength, and of ~10 mGal and ( 1 m amplitude, respectively. These undulations appear at plate ages of ~ 1 0 Ma, are well developed between 10 and 40 Ma, then vanish beyond ages >40 Ma. The wavelength remains

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constant with increasing plate age. Such geoid undulations are not seen west of the SE Indian Ridge (over the Antarctic Plate). Where observed, they have a sinusoidal signature quite different from the typical step-like signature of fracture zones. The lineations observed have characteristics comparable to those reported by Haxby and Weissel in the central Pacific and interpreted as evidence of small-scale convection occurring in a low viscosity layer just beneath the lithosphere. Groupe de Recherche de Geodesic Spatiale, Centre Natl. d'Etudes Spatiales, Toulouse, France. 88:2170 Murthy, K.S.R., T.C.S. Rao and M.M.M. Rao, 1987. Delineation of structural lineaments from marine magnetic anomalies off Lawson's Bay (Visakhapatnam), east coast of India. Indian J. mar. Sci., 16(1):19-21. Natl. Inst. of Oceanogr., Reg. Centre, Waltair, Visakhapatnam 530 017, India. 88:2171 Park, C.-H., S.-R. Kim, S.-J. Hun and J.-K. Kang, 1986. Interpretation of the magnetic anomalies in the northeastern equatorial Pacific (KONOD-I area). Ocean Res., KORDI, 8(2):17-27. (In Korean, English abstract.) Spectral analysis of magnetic anomaly data was used to determine the depths of magnetic basement (5500, 5800, 5700, and 5400 m from the northernmost to the southernmost profile). The greatest difference between calculated magnetic and acoustic basement depths was only 300 m. In the eastern part of the survey area, magnetic anomalies show a lineation of NI0°W, due to normal and reversal magnetization polarities. In the western part, the dominance of low amplitude, normal polarity implies that the anomalies are in crust formed during the Cretaceous quiet period. The age of the anomalies is estimated at 76~9 m.y. There is no evidence here for the fracture zone between Clarion and Clipperton fracture zones postulated by Sclatter et al. (1971). Geol. Oceanogr. Lab., KORDI, Seoul, Korea. 88:2172 Rao, T.C.S., S. Lakshminarayana and K.V.L.N.S. Sarma, 1987. Magnetic anomalies in central Bengal Fan. Indian J. mar. Sci., 16(1):15-18. Total magnetic field anomalies recorded are analysed and the depths to the magnetic basement are computed using the analytical signal and the Werner deconvolution methods. West and east of 85°E, the basement layer delineates the basement high and the graben, both trending nearly parallel to the east coast of India. The basement high recorded from the present studies nearly coincides with the 85°E ridge

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and the western flank of the graben reported earlier in this region. Natl. Inst. of Oceanogr., Reg. Centre, Waltair, Visakhapatnam 530 017, India. 88:2173 Shyu, C.-T., 1986. Inversion of magnetic data by fixed rectangular block-shaped bodies..4cta oceanogr. taiwan., 17:143-155. A method for rapidly determining magnetization distribution in the subsurface by direct inversion of magnetic anomalies is proposed. A number of fixed blocks are used to model the structure, and then blocks with less magnetization intensity are deleted to achieve the final result. Two significant magnetic anomalies immediately offshore of Ilan Plain are analyzed by this method. The magnetic basement and magnetization intensity for the anomaly in the Kueishantao area is calculated to be 0.5 km and 157 gammas; values for the anomaly east of Litze are 2 km and 271 gammas. 88:2174 Thomas, H.H., 1987. A model of ocean basin crustal magnetization appropriate for satellite elevation anomalies. J. geophys. Res., 92(B11):11,60911,613. A model is developed which will serve as background to which anomalous magnetizations can be contrasted and as a beginning point for studies of tectonic modification of normal ocean crust. It is based on published data on the petrology and magnetization of the ocean crust and consists of viscous magnetization and induced magnetization estimated for individual crustal layers. Thermal and chemical remanent magnetization are excluded from the model because seafloor spreading anomalies are too short in wavelength to be resolved at satellite altitudes. The exception to this is found at the oceanic magnetic quiet zones where thermal and chemical remanent magnetization must be considered along with viscous magnetization and induced magnetization. Geophys. Branch, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

D210. Heat flow 88:2175 Moran, J.E. and C.R.B. Lister, 1987. Heat flow across Cascadia Basin near 47°N, 128°W. J. geophys. Res., 92(B11): 11,416-11,432. Some 200 heat flow measurements were made along a flow line crossing the Juan de Fuca Ridge crest near 47°N with all but one located in the thickly sedimented Caseadia Basin. The raw heat flow

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means of the multipenetration stations do not decrease regularly with increasing distance from the spreading center; the lowest measurements are 70 km from the ridge crest on the turbidite sediment fill of the basin. A basement outcrop near these sites appears to cause the low heat flow by ventilating hydrothermal circulation beneath the sediments. In the eastern part of the basin the sedimentation correction to observed heat flow becomes significant. Extrapolated basement temperatures reach nearly 200°C beneath the eastern basin, a region where the magnetic anomalies become noticeably weaker than those closer to the ridge. Peace Corps, P.O. Box 1094, Suva, Fiji.

D240. Local or regional tectonics 88:2176 Choi, D.R. (comment), Michael Celaya, Robert McCabe and Thomas Hilde (reply), 1987. [Discussion of]: 'Bent structural trends of Japan: flexural-slip folding related to the Neogene opening of the Sea of Japan' and 'Kinematic model for the opening of the Sea of Japan and bending of the Japanese islands.' Geology, geol. Soc. Am., 15(10):981-982. 88:2177 Devdariani, A.S., E.I. Korkina and T.M. Akivis, 1987. Sedimentation and isostatic subsidence of continental margins of Atlantic type. Geologiya Geofiz., Novosibirsk, 7:32-39. (In Russian, English abstract.) 88:2178 Eguchi, Takao, Motoo Ukawa and Yukio Fujinawa, 1987. Mieroearthquakes and tectonics around an outer rise: the Zenisu Ridge, Japan. Phys. Earth planet. Interiors, 48(1-2):47-63. Eight ocean bottom seismometers were deployed for 25 days in 1985; hypocenters of approximately 40 microearthquakes were identified around the Zenisu Ridge, distributed mainly on the southern half flank. No earthquakes were located within the upper layer of the Philippine Sea Plate. Focal depths range from 18 to 35 km, indicating the earthquakes occurred within the lower layer of the mechanically strong part of the lithosphere. The composite focal plane solution of the microearthquakes that occurred on the ridge was a strike-slip or reverse fault type, having P-axis in the WNW. The tectonic origin of the earthquakes was found in the bending, with a regional compression, of the Philippine Sea Plate along the eastern Nankai-Suruga T r o u g h . Lamont-Doherty Geol. Observ., Palisades, NY 10964, USA.

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88:2179 Gao, Jinman, Guosheng Li, Giaosong Sun and Shousheng Liang, 1987. Geomorphic characteristics of Okinawa Trough. Mar. Geol. Quat. Geol., 7(1):51-61. (In Chinese, English abstract.)

continental crust and low velocity, high temperature upper mantle material. Gravity anomalies reveal trends within the areas of crustal thinning and suggest that a triple junction may be evolving. Inst. fur Geophys., Univ. Hamburg, FRG. (hbf)

The Okinawa Trough is a marginal basin ~ 1000 km long and 150 km wide between the East China Sea shelf and the Ryukyu Arc. A survey of its complex bottom topography shows that it has been affected by strong tectonic movements producing downfaulted geomorphic units. The trough can be divided from NW to SE into slope, bottom basin, and Ryukyu Island slope. A SW-NE taphrogenic extension and the NE-SW migration of spreading centers have produced four distinct zones. Two developmental stages can be recognized--a taphrogenic structural stage and a volcanic structural stage. The trough is presently in the initial stage of back-arc extension and will become increasingly oceanic in nature. Inst. of Mar. Geol., Ministry of Geol. and Mineral Resour., Qingdao, People's Republic of China.

88:2152 Otofuji, Y.-I. and Takaaki Matsuda, 1987. Amount of clockwise rotation of southwest Japan---fan shape opening of the southwestern part of the Japan Sea. Earth planet. Sci. Letts, 85(1-3):289-301.

88:2180 Kashai, E.L. and P.F. Croker, 1987. Structural geometry and evolution of the Dead Sea-Jordan Rift System as deduced from new subsurface data. Tectonophysics, 141(1-3):33-60.

Deep borehole data and seismic reflection profiles reveal new details on the faults within the Dead Sea-Jordan Rift System, defined here as 'a sinistral transform connecting an incipient oceanic ridge-the Red Sea--with an upthrusted collision zone, the Taurus range.' Shearing due to the opening of the Red Sea and the motion of the Arabian subplate has taken place along a series of en-echelon strike-slip faults, which probably have a common root and which die out toward the north without being cut off by any major cross faults. Motion along the rift began prior to the Middle Miocene and has continued intermittently to the present. Oil Exploration Investments Ltd., Tel Aviv, Israel. (hbf) 88:2181 Makris, J. and A. Ginzburg, 1987. The Afar Depression: transition between continental rifting and seafloor spreading. Tectonophysics, 141(13):199-214.

Reinterpretation of seismic refraction and gravity data collected in the 1970s on the Afar Depression, and newly available magnetic and seismic data indicate that the area marks a transition zone between continental rifting in Kenya and seafloor spreading in the Red Sea and Gulf of Aden. The Quaternary volcanics, lacustrine deposits, and evaporites of the area are underlain by greatly attenuated

Paleomagnetic measurements on welded tufts (58112 Ma) from the central part of southwest Japan and previously published data on younger igneous rocks define the change of paleomagnetic field direction for southwest Japan during the Late Mesozoic/Cenozoic period. The results establish that while the eastern margin of Eurasia (including southwest Japan) rotated with respect to the main part of Eurasia during the last 100 Ma, SW Japan has rotated clockwise an additional 40 ° since 20 Ma with respect to the eastern margin of Eurasia. This implies that SW Japan rotated by an opening of the southwestern Japan Sea, which widens northeastward, in a fashion analogous to that of CorsoSardinia and the Ligurian Sea in the Mediterranean, and suggests that the fan-shaped opening is a specific feature of the rifting of continental slivers at continental rims. Dept. of Earth Sci., Kobe Univ., Kobe 657, Japan.

D250. Plate and global tectonics 88:2183 Joffe, Sam and Zvi Garfunkel, 1987. Plate kinematics of the circum Red Sea--a re-evaluation. Tectonophysics, 141(1-3):5-22.

New information published in the past decade on the positions of plate boundaries is used to develop kinematic models for the Red Sea and Gulf of Aden. Newly calculated positions for the location of the Red Sea opening and the Gulf of Aden indicate 30 km of post-Miocene displacement along the Dead Sea transform and show that the opening of the Red Sea and Gulf of Aden was less than their widths. It is estimated that 200 km of separation occurred prior to centralized seafloor spreading and that the total extension prior to spreading was about 250%, irrespective of the rate of plate separation. Dept. of Geophys., Stanford Univ., Stanford, CA 94305, USA. (hbf) 88:2184 Maung, Hla, 1987. Transcurrent movements in the Burma-Andaman Sea region. Geology, geol. Soc. Am., 15(10):911-912.

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The Burma Plate and the Indoburman Ranges and Andaman-Nicobar Ridge are identified as two platelets formed by decoupling along major transcurrent faults. Both platelets are being dragged northward by the movement of the Indian Plate. It is hypothesized that the two arcs formed by the Indoburman Ranges and Andaman-Nicobar Ridge are the result of northward translation of a single arc, which caused the southern Andaman-NicobarSumatra section to rotate into the Burma Plate, bending the southern segment of the arc and producing the compression that formed the Pegu Yoma folding. Myamna Oil Corp., P.O. Box 1049, Rangoon, Burma. (hbf)

is a relatively recent volcano ( < 1 Ma) composed of olivine tholeiites. Robinson Crusoe is an older, deeply dissected island with several volcanic centers. The older lavas are predominantly olivine tholeiites; some alkali basalt flows occur in the higher part of the succession, and basanite flows are restricted to younger parasitic centers. The characteristics of Alexander Selkirk tholeiites suggest higher degrees of mantle partial melting than their counterparts on Robinson Crusoe. Trace element and isotopic data suggest remelting of source regions modified by migration of small degree partial melts over a long period. Dept. of Geol., Univ. of Nottingham, NG7 2RD, UK.

88:2185 Stoddard, P.R., 1987. A kinematic model for the evolution of the Gorda Plate. J. geophys. Res., 92(B11): 11,524-11,532.

88:2188 Bloomer, S.H., 1987. Geochemical characteristics of boninite- and tholeiite-series volcanic rocks from the Mariana forearc and the role of an incompatible element-enriched fluid in arc petrogenesis. Spec. Pap. geol. Soc. Am., 215:151-164.

The Pacific-side magnetic lineation pattern is matched using a kinematic model which incorporates northward and southward propagating ridge segments and ridge rotation. By superimposing flexural-slip style deformation on the resulting Gorda-side lineations, and allowing convergent motion at the Mendocino Fracture Zone, the Gorda magnetic pattern is also successfully predicted. A similar model, which does not allow convergence at the Mendocino Fracture Zone, fails to produce the observed lineation pattern. Model predictions of the amount of material that would be 'obducted' at the Mendocino due to convergence between the Gorda and Pacific agree with bathymetric and density estimates of the amount of material located along the Mendocino Ridge. Dept. of Geol. Sci., Northwestern Univ., Evanston, IL 60208, USA.

D280. Volcanism, magmatism 88:2186 Aoki, Hitoshi, Yusuke Yagi, Mitsuyuki Kukino and Hiroshi Moriya, 1987. [Petrochemistry of] Rocks of the Erimo Seamount and its neighbouring seamounts. J. Fac. mar. Sci. Technol., Tokai

Univ., 24:65-68. (In Japanese, English abstract.) 88:2187 Baker, P.E., A. Gledhill, P.K. Harvey and C.J. Hawkesworth, 1987. Geochemical evolution of the Juan Fernandez Islands, SE Pacific. J. geol. Soc., Lond., 144(6):933-944.

The two main islands, some 180 km apart, are intraplate hotspot volcanoes with an age difference of ~ 3 Ma. The younger island of Alexander Selkirk

Chemical data for samples of typical tholeiitic and boninitic (silica-saturated, high Mg series) suites obtained from the landward slope of the Mariana Trench are discussed. Both series are spatially related in the forearc and include primitive, littlefractionated rocks. The least fractionated samples of both series have similar concentrations of Ba, Sr, Zr, and Ce and similar ratios of moderately and highly incompatible elements. Modelling suggests that these rocks are the product of a mixture of a depleted ORB melt and an incompatible element enriched fluid with the more depleted portions giving rise to boninitic melts and the less depleted portions producing tholeiitic melts. Dept. of Geol., Duke Univ., Box 6729, College Station, Durham, NC 27708, USA. (hbf) 88:2189 Brett, Robin, H.T. Evans Jr., E.K. Gibson Jr., J.W. Hedenquist, M.-V. Wandless and M.A. Sommer, 1987. Mineralogical studies of sulfide samples and volatile concentrations of basalt glasses from the southern Juan de Fuca Ridge. J. geophys. Res., 92(B11): 11,373-11,379.

Sulfide samples from Alvin dives resemble those from the same area described by Koski et al (1984). Major minerals include sphalerite, wurtzite, pyrite, marcasite, isocubanite, anhydrite, and chalcopyrite. Two new minerals formed at low temperatures were found: a hydrated Zn, Fe hydroxy-chlorosulfate and a (Mn, Mg, Fe) hydroxide or hydroxy-hydrate. Lizardite, starkeyite, and anatase were also found for the first time in such an environment. Sulfide geothermometry involving the system Cu-Fe-S indicates a vent temperature of <328°C for one

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D. Submarine Geology and Geophysics

sample, and fluid inclusion studies give pressurecorrected homogenization temperatures of 268 ° and 285°C. CO2 contents yield an entrapment depth of 2200 m of seawater, the depth from which the samples were collected. USGS, 959 Natl. Center, Reston, VA 22092, USA. 88:2190 Chen, J.-C. and C.-B. Huang, 1986. Geochemical comparison between coastal range andesites, eastern Taiwan and andesites from the central Philippines. Acta oceanogr, taiwan., 17:156-173. Inst. of Oceanogr., Natl. Taiwan Univ., Taipei, Taiwan. 88:2191 Evans, C.A., 1987. Oceanic magmas with aikalic characteristics; evidence from basal cumulate rocks in the Zambales ophiolite, Luzon, Philippine Islands. Spec. Pap. geol. Soc. Am., 215: 139-150.

Data on the mineralogy and composition of the basal cumulate sections of the Zambales Ophiolite, which are assumed to represent early stages of crystal fractionation within a crustal magma chamber, indicate that different sections were derived from alkalic magma and magma depleted in magmaphilic elements. The composition of the basal chromites of the Coto section is comparable to that of chromite in alkalic basalts and differs from chromite phenocrysts in normal MORB, whereas the assemblage from overlying rocks is consistent with a derivation from normal MORB-like material. The Acoje section includes a thick olivine-dominated basal cumulate with low TiO 2 chromite, apparently derived from TiO 2 depleted magma. Chromite may be an important indicator for tracing the evolution of early oceanic magmas or primitive magmas involved in the formation of oceanic crust. LamontDoherty Geol. Observ., Palisades, NY 10964, USA.

0abf) 88:2192 Garcia, M.O. and A.A. Presti, 1987. Glass in garnet pyroxenite xenoliths from Kaula Island, Hawaii: product of infiltration of host nepbelinite. Geology, geol. Soc. Am., 15(10):904-906. Hawaii Inst. of Geophys., Univ. of Hawaii, Honolulu, HI 96822, USA. 88:2193 Gudmundsson, Agust, 1987. Formation and mechanics of magma reservoirs in Iceland. Geophys. Jl R. astr. Soc., 91(1):27-41.

It can be demonstrated that magma in the proposed magma layer beneath Iceland flows toward regions

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of reduced crustal thickness, where magma accumulates as partially molten reservoirs in the magma layer, which can produce surface eruptions or feed molten crustal magma chambers, a process facilitated by stress barriers that lead to the formation of thick sills. Ideal sites for stress barriers and magma chambers are formations where individual layers have different elastic properties. Using the estimated volumes of exposed plutons, it is found that the volume of individual eruptions from elastic crustal magma chambers in Iceland is less than 0.25 km 3 and typical central volcano eruptions are about 0.02 km 3. For eruptions of the order of 1 km 3, reservoirs must supply magma during the eruption. Nordic Volcanol. Inst., Univ. of Iceland, IS-101 Reykjavik, Iceland. 88:2194 Gust, D.A. and M.R. Perfit, 1987. Phase relations of a high-Mg basalt from the Aleutian Island Arc: implications for primary island arc basalts and high-A! basalts. Contr. Miner. Petrology, 97(1):718.

Results of experimental investigations of a typical, primitive high-Mg basalt from the Makushin volcanic field provide new constraints on petrogenetic models for primary island-arc basalts. Anhydrous experiments conducted at a wide range of pressures produced phase relations similar to those for primitive MORB and 'support a model in which high-A1 basalts are generated by moderate amounts of crystal fractionation from more primitive basaltic magmas near the arc crust-mantle boundary.' Library Info. Center, Lunar and Planetary Inst., 3303 Nasa Rd. 1, Houston, TX 77058, USA. (hbf) 88:2195 Hegner, E. and M. Tatsumoto, 1987. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge. J. geophys. Res., 92(Bll):11,38011,386.

Pb, Sr, and Nd isotopes of seven basalt glasses from the southern Juan de Fuca Ridge (SJFR) are almost identical. Four samples have uniform abundances of U, Th, Rb, Nd, Sm, Pb, and Sr, indicating they are comagmatic. The 2°6Pb/2°4pb ratios are intermediate between ridge basalts from south of the ridge and more radiogenic basalts from the northern JFR and NE Pacific seamounts. Sr and Nd isototz:_c compositions closely resemble data of other ridge basalts from the northernmost East Pacific Rise. Eight sulfides from three SJFR hydrothermal vent sites have Pb isotopic compositions very similar to those of the associated basalts. Sr and Nd isotopic ratios of a single sulfide sample lie on a mixing curve between seawater and basalt data, indicating the sulfide

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precipitated after hydrothermal solutions mixed with ambient seawater. Dept. of Geol. Sci., Univ. of Saskatchewan, Saskatoon S7N 0W0, Canada. 88:2196 Juan, V.C., 1985. The study of igneous rocks in Taiwan viewed in perspective. Acta geol. taiwan., 23:1-8.

Petrographic studies from the past thirty years on the basalts and andesitic rocks of Taiwan are reviewed, and the geographic location, magma type, tectonic settings and appropriate references for each rock type are presented in tables for the eastern, northern, and western petrographic provinces. Igneous formations of particular interest to investigators include: the Kuanshan igneous complex, a partial ophiolite in eastern Taiwan and the adjacent offshore; the Tatun volcanic group and the highalumina Hunglushan in the outskirts of Taipei; and the basalts of the Penghu Islands and KuanhsiChutung district in western Taiwan. Includes ca. 50 references. Dept. of Geol., Natl. Taiwan Univ., Taipei, Taiwan. (hbf) 88:2197 Kashintsev, G.L., A.A. Peyve and G.B. Rudnik, 1987. Subalkaline volcanism in the Mid-Indian Ocean Basin. Int. Geol. Rev., 29(1):73-80.

Dredge haul samples from the slopes of a large volcanic structure or seamount near 1°S, 84°E in the Indian Ocean consist of plagioclase-olivine basalts, plagioclase hawaiite-mugearites, trachyandesites, and numerous transitional types. Rocks from the upper part of the volcano are composed largely of tuff breccias, described as pumiceous bleached trachyandesite with crystalloclasts of biotite, clinopyroxene, and feldspar, cemented by calcite. The lower flanks are covered by lumps of basaltoids with some tuff-breccias. The presence of anomaly 34 north of the structure limits its age to no greater than 80 Ma, or Late Cretaceous. Inst. of Oceanol., Acad. of Sci., Moscow, USSR. (hbf) 88:2198 Mascarenhas, Antonio, 1986. Application of electron microprobe technique to the characterization of volcanic sands. Mahasagar, 19(4):221-231. Lab. de Sedimentol. et Geochim. Mar., Univ. de Perpignan, 66025 Perpignan, France. 88:2199 McNutt, S.R. and R.J. Beavan, 1987. Eruptions of Pavlof Volcano and their possible modulation by ocean load and tectonic stresses. J. geophys, Res., 92(B11): 11,509-11,523.

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Nine magmatic eruptions at Pavlof Volcano on the Alaska Peninsula from 1973 to 1984 occurred between September 9 and November 20. Volumes of erupted material range from 0.1-15.9 X 106 m 3 at an average rate of 3 x l06 m 3 yr-L The volumes for two eruptions are based on eyewitness reports; the others are estimated on the basis of a derived relationship between eruption volume and harmonic tremor duration and amplitude. A significant correlation exists between the eruptions and yearly nontidal variations in sea level and may result from ocean loading induced volume changes beneath the volcano, which are calculated to be 0.02 to 2 times eruption volumes. It is postulated that the volcano acts as a long-period volume strain meter, with lava being preferentially erupted when strain beneath the volcano is compressive. The volcano did not erupt from 1978-1980, when tilt, seismic, and sea level data indicate deep aseismic slip may have occurred. Calif. Div. of Mines and Geol., 630 Bercut Drive, Sacramento, CA 95814, USA. 88:2200 Monjaret, M.-C., Herv6 Bellon, Patrick Maillet and Jacques R~cy, 1987. The New Hebrides back-arc troughs volcanism (Leg 2 SEAPSO cruise of R/V Jean.Charcot in southwestern Pacific): preliminary K-At ages and petrological data. C. r. Acad. Sci., Paris, (Srr. II)305(7):605-609. (In French, English abstract.) G.I.S., Oceanol. et Geodynam., U.B.O., 6, ave. Le Gorgeu, 29287 Brest Cedex, France. 88:2201 Nelson, D.O. and K.L. Nelson, 1987. Ge~hemicai comparison of alkaline volcanism in oceanic and continental settings; Clarion Island versus the eastern Trans-Peeos magnetic province. Spec. Pap. geol. Soc. Am., 215:317-334.

Data on alkaline rock series from the older (30-38 Ma) continental, eastern Trans-Pecos magmatic province (TPMP) and the young (1-1.7 Ma) oceanic Clarion Island (CI) west of the EPR are compared. Although CI rocks are sodic, show a trend toward increasing silica undersaturation, and vary from alkali basalt to phonolite, and TPMP rocks show both sodic and potassic trends, go from nephelinenormative to quartz-normative, and vary from basanite to high-silica comendite, similar trace element and compositional trends for many elements suggest similar histories and possibly similar sources. A high-pressure pyroxene-dominated fractionation process, recognized on CI and suggested for TPMP, could explain the evolution of magma toward lower silica content, and different depths of fractionation could explain the observed differences. Dept. of

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D. Submarine Geology and Geophysics

Geol., Sul Ross State Univ., Alpine, TX 79832, USA. (hbf) 88:2202 Okitsu, Hirohumi, Yoichi Utsunomiya, Masanori Ishikawa and Hitoshi Aoki, 1987. On the volcanic rocks dredged in the northwestern sea off Hachijo Island. J. Fac. mar. Sci. Technol., Tokai Univ., 24:69-81. (In Japanese, English abstract.)

Mineralogical and petrochemical examination indicate that the rocks are part of a high-alkali tholeiite suite, in contrast to the low-alkali tholeiite volcanic rocks on Izu Islands. The conclusion is consistent with the hypothesis that volcanic islands of lowalkali tholeiite have been derived from high-alkali tholeiite. 88:2203 Sharkov, Ye.V. and A.A. Tsvetkov, 1985. Igneous activity of principal ocean morphostructures and some of its geodynamic aspects. Dokl. Earth Sci. Sect. (a translation of Dokl. Akad. Nauk SSSR), 284(5): 174-176.

Computer analysis of data on igneous rocks characteristic of four geodynamic environments (extension, intraplate, transform, and aseismic ridge) has identified six distinct igneous rock series--tholeiitic, calcalkalic, subalkalic K-Na and K, and alkalic K - N a and K. By applying these findings to DSDP drillhole data on petrology and trace elements, it is possible to distinguish principal morphostructures for tholeiitic, subalkalic K - N a and alkalic K - N a rock series; the remaining types are absent in the oceans. Results imply that igneous activity in rift and intraplate zones is largely independent of crust type, but subject to physicochemical and geodynamic processes and that the evolution of oceanic lithosphere, following its formation at spreading centers, is relatively complex. Inst. of Economic Geol., Petrol., Mineralogy and Geochem., Acad. of Sci., Moscow, USSR. (hbf) 88:2204 Taras, B.D. and S.R. Hart, 1987. Geochemical evolution of the New England seamount chain: isotopic and trace-element constraints. Chem. Geol., 64(1-2):35-54.

Samples from the New England Seamount (NES) chain in the northwest Atlantic have isotopic and trace element characteristics typical of alkaline volcanics from ocean islands and exhibit considerable interseamount variation, while intraseamount chemical heterogeneity is substantially less. The only apparent geographic trend in chemistry is an increase in radiogenic Pb southeast along the chain.

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NES isotopic characteristics necessitate at least three distinct source components with substantial involvement of 'radiogenic Pb' type mantle. Similarities between the NES, Canaries, Azores, and Ahaggar imply some type of systematic geographic distribution of the 'radiogenic Pb' component. Dept. of Earth, Atmos. and Planetary Sci., MIT, Cambridge, MA 02139, USA. 88:2205 Thompson, R.N., 1987. Phase-equilibria constraints on the genesis and magnmtic evolution of oceanic basalts. Earth-Sci. Rev., 24(3):161-210.

The genesis and evolution of the magmas of oceanic spreading centers, here termed ridge basalts, and of ocean islands, as exemplified by Kilauea Volcano, are reviewed. A summary of geophysical data emphasizes the limitations of the postulate that spreading centers are underlain by extensive, permanent shallow-level magma chambers, and published data are used to constrain a discussion of the relative importance of processes in oceanic magmatism: polybaric fractional crystallization; magma mixing; and variable degrees of partial fusion of mantle with diverse compositions. Whether the primary magmas of ridge basalts are picritic or basaltic is debated and it is concluded that ridge basalts originate by small-to-moderate degrees of essentially anhydrous mantle fusion (up to 25%) over a pressure range of 5 to 25 kb, leaving a lherzolite residuum. Includes ca. 200 references. Dept. of Geol. Sci., Univ. of Durham, South Rd., Durham, DHI 3LE, UK. 88:2206 Vidal, Philippe, Claude Dupuy, H.G. Barsczus and Catherine Chauvel, 1987. Mantle heterogeneities and origin of basalts from Marquesas (Polynesia). Bull. Soc. g~ol. Fr., (8)111(4):633-642. (In French, English abstract.)

This article presents a review of the mantle isotopic heterogeneities including current ideas concerning processes responsible for their development. Basalt genesis from the Marquesas Archipelago is addressed using both isotopes (Sr, Nd and Pb) and trace elements. The basalt geochemical characteristics are correlated with petrographic type and support a model of interaction between magmas of deep origin, variably marked by an enriched mantle and Saint Helen-Tubuai mantle type, with the depleted upper mantle. The contribution of the upper mantle dominates. The large geochemical difference between Marquesas and Hawaii basalts indicates there is no unique model for the genesis of oceanic intraplate volcanism. UA 10 CNRS et Univ., 5 rue Kessler, 63038 Clermont-Ferrand, France.

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D290. Crust, mantle, core 88:2207 Arndt, N.T. and S.L. Goldstein, 1987. Use and abuse of crust-formation ages. Geology, geol. Soc. Am., 15(10):893-895. Although some Nd model ages, especially those which coincide with U-Pb zircon ages or other independent evidence of age, may indicate crust formation age--the time at which the sample of continental crust separated from the mantle--many Nd model ages reflect a mixing of mantle materials at different times. It is recommended that the term crust-formation age be discarded in favor of crustalresidence age or Nd model age, in order to avoid misinterpretations about the time of first crustal development. Max Planck Inst. fur Chemie, Saarstr. 23, Postfach 3060, D-6500 Mainz, FRG. (hbf) 88:2208 Calmant, St6phane, 1987. The elastic thickness of the lithosphere in the Pacific Ocean. Earth planet. Sci. Letts, 85(1-3):277-288. The effective elastic thickness Te of oceanic lithosphere along Pacific chains is determined by computing the deflection of a continuous elastic plate under the load of volcanoes and constrained by Seasat geoid heights. South central Pacific estimates of 14 km for the Marquesas and 6 km or less for the Pitcairn-Mururoa-Gloucester chain are in good agreement with previous work. Around the Line Islands and Easter chain T e values are low. Higher values are found for a Samoan island and along the Hawaiian-Emperor seamounts. North Pacific values agree with the trend of increasing Te with the square root of plate age at loading time, but south central Pacific values are much lower and are only partly explained by thermal perturbations. Centre Natl. d'Etudes Spatiales, 18, Ave. Edouard Belin, 31055 Toulouse Cedex, France. 88:2209 Diament, M. and N. Baudry, 1987. Structural trends in the Southern Cook and Austral archipelagoes (south central Pacific) based on an analysis of Seasat data: geodynamic implications. Earth planet. Sci. Lefts, 85(4):427-438. Seasat data reveal the existence of two directions, the azimuths of which are NI50 ° and N95 ° respectively. The first, which intersects the Austral Archipelago close to the island of Maria, is interpreted as evidence for the existence of an ancient hotspot with a trace copolar to the Emperor chain. The second, located south of the Cook Archipelago, is underlined by geoid signatures of fracture zone type; these are

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interpreted as a possible consequence of some recent intraplate deformation. Lab. de Geophysique, Batiment 509, Univ. Paris-Sud, 91405 Orsay Cedex, France. 88:2210 Gerlach, D.C., J.C. Stormer Jr. and P.A. Mueller, 1987. Isotopic geochemistry of Fernando de Norouha [Archipelago, W. Atlantic]. Earth planet. Sci. Letts, 85(1-3):129-144. Volcanic and hypabyssal rocks (12-3 Ma) can be divided into two age-compositional groups with variable and distinct isotopic compositions, suggesting at least two components in their sources. One component is characterized by high Rb/Sr and low g, possibly derived from delaminated, subcontinental lithosphere; the other has high g and low Rb/Sr, similar to St. Helena lavas. A third component is suggested by correlated compositions in the latest alkaline Si-undersaturated lavas and may be derived from depleted mantle. The isotopic variations in conjunction with increasing alkalinity with time are consistent with temporal depletion of a low-g, high Rb/Sr component and increasing contributions from a high-g component. Dept. of Terrestrial Magnetism, Carnegie Inst., 5241 Broad Branch Rd., N.W., Washington, DC 20015, USA. 88:2211 Kappel, E.S. and W.R. Normark, 1987. Morphometric variability within the axial zone of the southern Juan de Fuca Ridge. Interpretation from Sea MARC II, Sea MARC I, and deep-sea photography. J. geophys. Res., 92(B11): 11,29111,302. An integrated analysis for the southernmost continuous segment of the Juan de Fuca Ridge shows that generalizations about tectonic and volcanic processes at spreading ridges must consider both the temporal scale of processes as well as the physical scales of observations if predictive models are to be successful. Comparison of the morphometric expression within the major hydrothermal vent area and the rest of the southernmost ridge segment suggests that the mapped distribution of hydrothermal vents may reflect the extent of survey effort rather than uniqueness of geologic setting. Joint Oceanogr. Inst. Inc., 1755 Mass. Ave., N.W., Washington, DC 20036, USA. 88:2212 Keen, C.E., G.S. Stockmal, H. Welsink, G. Quinlan and B. Mudford, 1987. Deep crustal structure and evolution of the rifted margin northeast of Newfoundland: results from LITHOPROBE East. Can. J. Earth Sci., 24(8):1537-1549.

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Deep intracrustal reflectors help determine the nature of extensional tectonics and associated sedimentary basin evolution on the rifted margin; the line also crosses the ocean-continent transition and helps define structure in that region. Brittle extension of the upper crust was accommodated along at least one subhorizontal level of drcollement. The most obvious deformation involves the shallowest level of drcollement on which high-angle planar normal faults detach. A deeper level is inferred from low-angle listric normal faults penetrating the lower crust. There is no evidence for a unidirectional low-angle shear zone controlling extension. Data support a model in which there are several episodes of stretching, more significant in the lower than the upper lithosphere. At the oceancontinent transition, the oceanic crust thickens as it dips beneath the rifted continental crust, perhaps from production of basaltic magma and its migration to crustal levels during rifting. Bedford Inst. of Oceanogr., Geol. Survey of Canada, Dartmouth, NS B2Y 4A2, Canada. 88:2213 Kerr, R.C. and J.R. Lister, 1987. The spread of subducted lithospheric material along the midmantle boundary. Earth planet. Sci. Letts, 85(13):241-247. If, as studies suggest, the bulk density of subducted lithosphere at the mid-mantle boundary is intermediate between the densities of the upper and lower mantle, lithospheric material will intrude along this boundary driven by buoyancy forces resulting from compositional density differences between the intrusion and its surroundings. The rate of spread, given by a balance between these buoyancy forces and viscous resistance of the mantle to motion, indicates lithospheric material can propagate 10002000 km in a hundred million years, and can cover the entire boundary in one to six billion years. This spreading may be reflected in the global distribution of the isotopic characteristics of oceanic basalts. Dept. of Appl. Math. and Theoretical Phys., Univ. of Cambridge, Silver St., Cambridge CB3 9EW, UK. 88:2214 Lana, Xavier and Ramon Carbonell, 1987. Surface harmonic expansion methodology in restricted domains of the Earth's surface--application to the Indian Ocean. J. Geophys. (Z. Geophys.), 61(3): 158-167. A dense distribution of Rayleigh-wave group velocities (fundamental mode) throughout the Indian Ocean is obtained by means of spherical harmonic expansion of the inverse group velocity and standard least-squares methods. Results allow a qualitative

349

discussion of the upper part of the Indian Ocean's lithosphere and especially display high velocities around the Rodrigues triple junction. The number of group velocities mapped should allow a quantitative study of the upper part of this lithosphere. Dept. de Geodinamica, Geofisica y Paleontol., Facultad de Fisica, Avenida Diagonal 645, E-08028 Barcelona, Spain. 88:2215 Mori, Jim, Chris McKee and Horst Letz, 1987. The central New Britain earthquake of May 10, 1985: tensional stresses in the frontal arc. Phys. Earth planet. Interiors, 48(1-2):73-78. Aftershocks of the M s 7.1 central New Britain earthquake show a shallow fault 0 to 20 km in depth, dipping steeply (75-85 °) toward the south and extending for about 50 km in an east-west direction. This is consistent with the focal mechanism which can be interpreted as left-lateral motion on a nodal plane oriented NI00°E and dipping 80 ° to the south-southwest. The orientation of the principal stress axes indicates this frontal arc region is under tensional stresses. Rabaul Volcanol. Observ., Rabaul, Papua New Guinea. 88:2216 Mori, Toshio, 1987. Variations in the geoelectric field with relation to crustal conditions of the Earth. Geophys. Mag., 42(2):41-104. Three categories of geoelectric variations--electric variations induced by temporal magnetic variations, those due to dynamo interaction of conductive liquid with the geomagnetic field, and self-potential variations accompanying geophysical or geochemical changes of state--are discussed on the basis of observational data from the eastern part of Hokkaido, at the seafloor off Tokai, and data obtained using telegraphic lines in the Kanto and Tokai regions. In general, variations off Tokai with periods longer than 12 hours are linked to the motion of seawater, and those with shorter periods are due to geomagnetic variations. A method to eliminate variations induced by geomagnetic variations in observed electric fields is described. (hbf) 88:2217 Morris, E.M. and J.D. Pasteris (eds.), 1987. Mantle metasomatism and alkaline magmatism. [Symposium on Alkalic Rocks and Kimberlites, South-Central Section Meeting, Geological Society of America, April 15-16, 1985.] Spee. Pap. geol. Soe. Am, 215:383pp; 24 papers. The papers in this volume were selected to provide a representative cross section of material discussed at

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the symposium. Presentations focused on the origin of the alkaline magmas, kimberlites, and alkalic rocks, and served to emphasize that alkaline magmatism occurs in practically all tectonic and petrologic settings. The contents are arranged in order of: mantle processes associated with alkaline magmatism; kimberlite and oceanic systems; occurrences on the continental margins; and continental alkalics. Abstracts of the remaining papers and a multi-page index complete the volume. Dept. of Geol., Sul Ross State Univ., Alpine, TX 79832, USA. (hbf) 88:2218 Noller, J.S., S.H. Kirby and J.E. Nielson-Pike (eds.), 1987. Geophysics and petrology of the deep crust and upper mantle. A workshop sponsored by the U.S. Geological Survey and Stanford University. Circ. U.S. geol. Surv., 956:88pp; 34 papers. Extended abstracts of workshop reports are presented. The introductory section highlights the main themes--the mechanisms of crustal growth, the nature of the crust-mantle boundary, the origin of deep, flat-lying crustal reflectors, seismic anisotropy, and fluids in the deep lithosphere--and includes overviews of the investigations described in sections on the composition and structure of the continental crust and upper mantle; the deformation, preferred orientation and property anisotropy in the continental lithosphere; the physical state and processes of the continental lithosphere; and chemical and physical state of the mantle related to the transport and reactions of fluids and melts. (hbf) 88:2219 Pandey, O.P. and J.G. Negi, 1987. Signals of degeneration of the sub-crustal part of the Indian lithosphere since the break-up of Gondwanaland. Phys. Earth planet. Interiors, 48(1-2):1-4. A comparison of Magsat anomalies of continental fragments of the Gondwanaland supercontinent reveals a striking similarity across all rifted continental margins, except the western and southern margins of India. The magnetized crust has remained largely unchanged elsewhere since the break-up of Gondwanaland. A similar analysis of satellite derived free-air gravity anomalies indicates continuity across rifted margins with the exception of India. These anomalies characterize existing differences in crustal and upper-mantle structures, and causal dependence on relative mobility of the Gondwanic continents. After the break-up, only the Indian continental structure suffered dramatic change, possibly due to its northward drift from Antarctica during Late Cretaceous-Early Tertiary. Natl. Geophys. Res. Inst., Hyderabad 500007, A.P., India.

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88:2220 Picard, L., 1987. The Eiat (Aqaba)--Dead Sea--Jordan subgraben system. Tectonophysics, 141(1-3):2332. The Elat-Dead Sea-Jordan rift zone is divided into distinct subgrabens, separated by pivotal uplifted areas. The subgrabens are usually asymmetric with the sense of asymmetry changing from west to east and vice versa along the length of the rift zone. Most faults are meridional, N-S trending, or submeridional, NNE-SSW trending. Transverse faulting is extremely rare thus opposing the 'key-stone' theory and also the rhomb chain model. The Levantine chain of subgrabens are but an infra-Pleistocene initial stage in the Afro-Arabian rift system. Israel Acad. of Sci. and Humanities, Jerusalem, Israel. 88:2221 Reilinger, Robert, 1987. Reanalysis of crustal warping in coastal Maine. Geology, geol. Soc. Am., 15(10):958-961. Reanalysis of leveling and tide-gauge data indicate leveling-circuit misclosures in one of the surveys used to calculate the rate of 99 mm/yr subsidence for the Passamaquoddy Bay region. When the erroneous data are removed, the remaining leveling observations yield a subsidence rate of 1-2 mm/yr, consistent with rates calculated from tide-gauge data and with estimates based on geological observations of postglacial deformation. Earth Resour. Lab., Dept. of Earth, Atmos. and Planetary Sci., MIT, Cambridge, MA 02139, USA. (hbf) ~:2222

Schlich, Roland, Marc Munschy, J.-M. Marthelot, J.-Y. Royer and Marc Schaming, 1987. Jean Charcot survey of the Rodrignez Triple Junction (Indian Ocean): preliminary results. Bull. So¢. g~oL Ft., (8)III(4):693-697. (In French, English abstract.) Inst. Phys. du globe de Strasbourg, Lab. Geophys. Mar., 5, rue Rene Descartes, 67084 Strasbourg cedex, France. 88:2223 Storetvedt, K.M., 1987. Evidence for ocean--continent crust boundary beneath the abyssal plain of the east central Atlantic. Phys. Earth planet. Interiors, 48(1-2):115-129. Evidence from margin sedimentation, deep-sea diapirism, salinity concentration in DSDP-IPOD cores, and distribution of deep-sea barite and palygorskite-sepiolite assemblages indicate that the central Atlantic developed from a wide rift basin within a continental setting. Seafloor spreading around 90 Ma BP is identified by a sharp change

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D. SubmarineGeologyand Geophysics

from reducing to oxygenated conditions and the onset of a major sedimentary hiatus. Commencement of seafloor spreading probably explains the worldwide Cenomanian transgression and extensive sedimentary basins in the interior of major continental blocks. The proposed model implies that vertical crustal dynamics are as important as spreading in the development of oceanic lithosphere, and that central Atlantic spreading is probably confined to the region of the elevated Mid-Atlantic Ridge. Inst. of Geophys., Univ. of Bergen, Allegt. 70,5000 Bergen, Norway.

D330. Oil and gas 88:2224 Burroughs, R.H., 1986. Seafloor area within reach of petroleum technology. Ocean Mgmt, 10(2): 125135. Depth capabilities of offshore oil technologies have increased substantially; recent drilling operations have been conducted in water as deep as 2119 m and oil and gas production facilities have been installed in 311 m of water. The potential impact is computed yearly using annual depth records converted into area of seafloor. In the western Gulf of Mexico, deep water production capability had exceeded the bathymetric limits and area of the geologic shelf by 1975. On a global scale, if depth is the sole constraining factor, up to 53 million km 2 or 15% of ocean-area is now open to exploratory drilling. This is equivalent to 37% of all land area above sealevel. Using the same bathymetric constraint up to 23 million km 2 worldwide became available for production by 1978. Grad. Prog. in Mar. Affairs, Univ. of Rhode Island, Kingston, RI 02881-0817, USA. 88:2225 Larminie, F.G., 1987. The history and future of North Sea oil and gas: an environmental perspective. Phil. Trans. R. So¢., (B)316(1181):487-493. The development of impact assessment techniques and practices and the evolution of monitoring of the physical, chemical and biological environment offshore and onshore, with reference to platforms, subsea pipelines, pipeline landfalls and terminal construction and operation is discussed. A brief account of the development of environmental protection management practices and their application to the design, construction, operation and management of major production projects follows. The paper concludes with a look at the environmental conditions likely to be established as the industry moves into the northern North Sea and areas such as

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the West Shetland Basin, and their significance for the petroleum industry. British Petroleum Co., Britannic House, Moor Lane, London EC2Y 9BU, UK. 88:2226 Miller, B.M., 1987. The muPETROL expert system for classifying world sedimentary basins. A microcomputer-based expert system with computer models for classifying world sedimentary basins as an aid to assessing petroleum resources. Bull. U.S. geol. Surv., 1810:87pp. Preliminary results of the first phase of the muPETROL expert system, which consists of nine basin models and an introduction and tutorial model, are presented. Procedures for acquisition of data base information and the development of the basin models are discussed. The system is operational and can be used for basin analysis and for classifying sedimentary basins using the criteria developed by Klemme (1975, 1983). (hbf) 88:2227 Staff, 1987. Deep water report. Offshore, 47(10):2939; 3 papers. Three articles discuss the deep water economic climate: deepwater acreage is being snapped up because of the relaxation on terms. Deep water holes are still being drilled or planned--ten of them (in over 3000 ft of water) this past year. Holding down costs is the subject of the third article. (fcs)

D340. Manganese nodules, etc. 88:2228 Chukhrov, F.V., V.A. Drits and A.I. Gorshkov, 1987. Structural transformations of manganese oxides in oceanic nodules. Int. Geol. Rev., 29(1): 110-121. The crystal structure of the manganese oxides frequently found in Fe-Mn nodules--vernadite, birnessite, the buserites, and asbolanes--are reviewed, and models are suggested for solid-state transformations among them. The presence of layered structures occurring in sequences along the c-axis and an octahedral Mn 4+ as the main component for each mineral favors such transformations. In the laboratory Co- and Zn-buserites have already been converted to the corresponding asbolanes. Inst. of Petrography, Mineralogy, and Geochem,, Acad. of Sci., Moscow, USSR. (hbf) 88:2229 Yu, E.-F., J.-C. Chen and Z.-Y. Huang, 1986. Chemical and radiochemical characteristics of

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D. SubmarineGeologyand Geophysics manganese nodules from the Philippine Sea. A cta oceanogr, taiwan., 17:69-83.

The thorium and ionium contents of manganese nodules dredged from the Philippine Sea were measured, and the mineralogy and chemistry of the nodules were studied by x-ray diffraction and atomic absorption spectrophotometry. The nodules consist largely of akaganeite, birnessite, and todorokite. Mn content increases with and is approximately equal to Fe content. Cu + Ni + Co values range from 2500 to 11,000 ppm and show a positive correlation with the Co/Zn ratios, which range from 2 to 10.5. Outer layers of the nodules are generally enriched in Fe, Mn, and Zn and inner layers are enriched in K and Ca. It is suggested that the nodules were formed by hydrogenous precipitation together with upward diagenetic migration of certain elements from underlying sediments. Inst. of Earth Sci., Acad. Sinica, Taipei, Taiwan.

D360. Books, collections (general) 88:2230 Ben-Avraham, Zvi (ed.), 1987. Sedimentary basins within the Dead Sea and other rift zones. Selected papers from an international workshop, held in Ramot Village, Israel, April 28-May 1, 1985. Special issue. Tectonophysics, 141(1-3):275pp; 20 papers. Much new information on the nature and origin of the sedimentary basins of the Dead Sea Rift was reported. Three sections deal with regional studies--plate kinematics, the subgraben system, basin structural geometry and evolution, mechanical aspects of horsts, pull-apart basins, and push-up swells, seismicity, and structural implications of palynological evidence; local studies--the Hula Basin, two Neogene basins east and west of the Sea of Galilee, thermal history, southern Arava tectonics, Gulf of Elat, the Sinai triple junction, and mineralization associated with rifting; and other rift zones--the Afar Depression, Malawi and Tanganyika rifts, Strait of Sicily, the transcurrent fault system along the north African passive margin, and new geophysical experiments in the Rhinegraben Rift. (hbf) 88:2231 Carmichael, I.S.E. and H.P. Eugster (eds.), 1987. Thermodynamic modeling of geological materials: minerals, fluids and melts. Revs Mineralogy, 17:499pp; 13 papers.

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The reviews in this volume are based upon material presented as a short course (October 22-25, 1987) sponsored by the Mineralogical Society of America. Individual chapters represent up-to-date summaries authored by active researchers on the topics covered. Models are described for crystalline solutions; the thermodynamics of aqueous solutions of liquid-like density and molecular fluids at elevated pressures and temperatures; mineral solubility in concentrated brines; multicomponent melts; and the thermodynamic relations and petrologic applications of magmatic systems. Other topics treated from a more general thermodynamic geochemical viewpoint include: phase equilibria in simple mineral systems; multicomponent systems containing several solid solutions; aqueous species and solubilities of minerals in supercritical electrolyte solutions; igneous fluids; ore fluids; and mineral solubilities and speciation in supercritical metamorphic fluids. (hbf) 88:2232 Vistelius, A.B. (ed.), 1987. Special issue on conceptual models. A session of the 27th International Geological Congress (Moscow 1984). Mathl Geol., 19(7):587-728; 8 papers. Conceptual, stochastic models are the basis of mathematical geology. The seminal papers were published between about 1943 and 1947. This session took a new look at such models as they apply to one area of geology--jzranites. And it took a look at how well the models interface 'reality.' One paper is concerned not with granites but with evapontes.

(fcs)

D370. Miscellaneous 88:2233 Wilhelms, D.E. (with sections by) J.F. McCauley and N.J. Trask, 1987. The geologic history of the Moon. Prof. Pap. U.S. geoL Surv., 1348:302pp. Even before any lunar samples were taken, the techniques of photogeology, geomorphology and stratigraphy (for there are major geologic units whose relative chronology is determined) had resuited in a broad-stroke lunar geology. The later analysis and dating of lunar samples was steered by what was already known, and used to add to or confirm existing thinking. This synthesis/review is based on those two approaches. It is chiefly meant for working geoscientists who want an update and review of what is known about the moon. Includes ca. 750 references, an index, and 12 color plates. (fcs)