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Deep-sea sedimentation in the equatorial western Pacific Ocean
1012
D. SubmarineGeologyand Geophysics
86:6909 Moran, P.J., R.E. Reichelt and R.H. Bradbury, 1986. An assessment of the geological evidence for previous Acanthaster outbreaks. Coral Reefs, 4(4):235-238.
A review of data presented as evidence for past outbreaks of the crown-of-thorns starfish (Frankel, 1977, 1978) plus data from previous starfish surveys showed that sedimentary remains of Acanthaster planci were not related to recent outbreaks at the same site, suggesting that past outbreaks cannot be inferred from A. planci evidence in older sediments. Australian Inst. of Mar. Sci., PMB No. 3, Townsville MC, Qld. 4810, Australia. (gsb)
D120. Sedimentary processes (deposition, diagenesis, etc.) 86:6910 Dickson, R.R. and I.N. McCave, 1986. Nepheloid layers on the continental slope west of Porcupine Bank [E. North Atlantic]. Deep-Sea Res., 33 (6A):791-818.
BNLs are well developed on the west slope of Porcupine Bank, particularly between the 400 and 600 m isobaths. The main zone of BNL formation is marked by a doming of temperature and density isopleths and by a 'chimney' in salinity in the overlying water column; individually mixed but discrete layers in T,S and nephels suggest boundary mixing followed by detachment, lateral injection and hence interleaving of layers. The layers are believed to be formed by bottom erosion under internal tides and waves. Under northerly (long-slope) winds the 9°C isotherm is drawn up the slope, the density gradient steepens close to the bed and the slope of the characteristic for M 2 tidal frequency comes close to the bottom slope/3 at the point where maximum intensity BNLs are observed. Temperature spectra under these conditions show increased total energy and it is thought that high-frequency internal waves also propagate along the sharpened density surface to impinge on the slope. MAFF, Fish. Lab., Lowestoft, Suffolk NR33 OHT, UK. 86:6911 Orszag-Sperber, Fabienne, Pierre Freytet, Christian Montenat and P.O. d'Estevou, 1986. Sulfate metasomatism of Miocene carbonate sediments, on the west margin of the Red Sea. C. r. A cad. Sci., Paris, (S~r. II)302(17):1079-1084. (In French, English abstract.)
OLR (1986)33 (12)
The morphology created during Miocene rifting of the Red Sea strongly influenced the distribution of sediments. Below Mid-Miocene evaporite, the carbonates are replaced by sulfates. This transformation affects such a large volume of sediments that it can create difficulty in distinguishing between sedimentary and diagenetic evaporites. Lab. de Petrol. sedim, et Paleontol., Univ. Paris-XI, 91405 Orsay Cedex, France. 86:6912 Underwood, M.B. and C.R. Norville, 1986. Deposition of sand in a trench-slope basin by unconfined turbidity currents. Mar. Geol., 71(3-4):383392. Dept. of Geol., Univ. of Missouri, Columbia, MO 65211, USA. 86:6913 Zhao, Quanji, 1986. Deep-sea sedimentation in the equatorial western Pacific Ocean. [An analysis of several surficial and core samples.] Acta oceanol. sin. (English version), 5(1):90-98. First Inst. of Oceanog., State Oceanic Admin., Qingdao, People's Republic of China.
D130. Sediments
(rocks, formations, type,
composition, etc.) 86:6914 Blaise, Bertrand, B.D. Bornhold, Henri Maillot and Herv6 Chamley, 1985. Observations on recent environments, north Juan de Fuca Ridge (NE Pacific). Revue G~ol. dynam. G~ogr. phys., 26(4): 201-213. (In French, English abstract.)
A mineralogical and geochemical study of Quaternary sediments on the northern segment of the Juan de Fuca Ridge was undertaken to determine the relative contribution of continental, marine and hydrothermal sources. A succession of two distinct lithologic units, with associated mineral assemblages, reflects the passage from a relatively dry, cold continental climate to the present wet, temperate climate. Average sedimentation rates of 20 cm/1000 years were determined. The presence of coarse turbiditic sediments on the summit of a volcanic knoll is believed to be the result of recent tectonics associated with active rifting and volcanism. Although sediments are dominated by continentally derived material, a definite marine influence is apparent in the increasing concentration of Ni, Co and Cu in cores farther offshore. Univ. des Sci. et Tech. de Lille, Lab. de Sedim. et Geochim., UA CNRS 719, 59655 Villeneuve d'Ascq, France.
D. SubmarineGeologyand Geophysics
86:6909 Moran, P.J., R.E. Reichelt and R.H. Bradbury, 1986. An assessment of the geological evidence for previous Acanthaster outbreaks. Coral Reefs, 4(4):235-238.
A review of data presented as evidence for past outbreaks of the crown-of-thorns starfish (Frankel, 1977, 1978) plus data from previous starfish surveys showed that sedimentary remains of Acanthaster planci were not related to recent outbreaks at the same site, suggesting that past outbreaks cannot be inferred from A. planci evidence in older sediments. Australian Inst. of Mar. Sci., PMB No. 3, Townsville MC, Qld. 4810, Australia. (gsb)
D120. Sedimentary processes (deposition, diagenesis, etc.) 86:6910 Dickson, R.R. and I.N. McCave, 1986. Nepheloid layers on the continental slope west of Porcupine Bank [E. North Atlantic]. Deep-Sea Res., 33 (6A):791-818.
BNLs are well developed on the west slope of Porcupine Bank, particularly between the 400 and 600 m isobaths. The main zone of BNL formation is marked by a doming of temperature and density isopleths and by a 'chimney' in salinity in the overlying water column; individually mixed but discrete layers in T,S and nephels suggest boundary mixing followed by detachment, lateral injection and hence interleaving of layers. The layers are believed to be formed by bottom erosion under internal tides and waves. Under northerly (long-slope) winds the 9°C isotherm is drawn up the slope, the density gradient steepens close to the bed and the slope of the characteristic for M 2 tidal frequency comes close to the bottom slope/3 at the point where maximum intensity BNLs are observed. Temperature spectra under these conditions show increased total energy and it is thought that high-frequency internal waves also propagate along the sharpened density surface to impinge on the slope. MAFF, Fish. Lab., Lowestoft, Suffolk NR33 OHT, UK. 86:6911 Orszag-Sperber, Fabienne, Pierre Freytet, Christian Montenat and P.O. d'Estevou, 1986. Sulfate metasomatism of Miocene carbonate sediments, on the west margin of the Red Sea. C. r. A cad. Sci., Paris, (S~r. II)302(17):1079-1084. (In French, English abstract.)
OLR (1986)33 (12)
The morphology created during Miocene rifting of the Red Sea strongly influenced the distribution of sediments. Below Mid-Miocene evaporite, the carbonates are replaced by sulfates. This transformation affects such a large volume of sediments that it can create difficulty in distinguishing between sedimentary and diagenetic evaporites. Lab. de Petrol. sedim, et Paleontol., Univ. Paris-XI, 91405 Orsay Cedex, France. 86:6912 Underwood, M.B. and C.R. Norville, 1986. Deposition of sand in a trench-slope basin by unconfined turbidity currents. Mar. Geol., 71(3-4):383392. Dept. of Geol., Univ. of Missouri, Columbia, MO 65211, USA. 86:6913 Zhao, Quanji, 1986. Deep-sea sedimentation in the equatorial western Pacific Ocean. [An analysis of several surficial and core samples.] Acta oceanol. sin. (English version), 5(1):90-98. First Inst. of Oceanog., State Oceanic Admin., Qingdao, People's Republic of China.
D130. Sediments
(rocks, formations, type,
composition, etc.) 86:6914 Blaise, Bertrand, B.D. Bornhold, Henri Maillot and Herv6 Chamley, 1985. Observations on recent environments, north Juan de Fuca Ridge (NE Pacific). Revue G~ol. dynam. G~ogr. phys., 26(4): 201-213. (In French, English abstract.)
A mineralogical and geochemical study of Quaternary sediments on the northern segment of the Juan de Fuca Ridge was undertaken to determine the relative contribution of continental, marine and hydrothermal sources. A succession of two distinct lithologic units, with associated mineral assemblages, reflects the passage from a relatively dry, cold continental climate to the present wet, temperate climate. Average sedimentation rates of 20 cm/1000 years were determined. The presence of coarse turbiditic sediments on the summit of a volcanic knoll is believed to be the result of recent tectonics associated with active rifting and volcanism. Although sediments are dominated by continentally derived material, a definite marine influence is apparent in the increasing concentration of Ni, Co and Cu in cores farther offshore. Univ. des Sci. et Tech. de Lille, Lab. de Sedim. et Geochim., UA CNRS 719, 59655 Villeneuve d'Ascq, France.