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Gas hydrates on the northern California continental margin
1020
D. SubmarineGeologyand Geophysics
Boll. Geofis. teor. appl., 27(107):185-195. Geophys. Lab., Univ. of Thessaloniki, Greece.
area.
86:6964 Parmentier, E.M. and W.F. Haxby, 1986. Thermal stresses in the oceanic lithosphere: evidence from geoid anomalies at fracture zones. J. geophys. Res., 91(B7):7193-7204. Theoretical models which examine the effect of thermal stresses at fracture zones show that an anomaly of the predicted form can be observed in geoid profiles which cross fracture zones. Specifically, the models predict the development of thermal bending moments which depend on lithosphere thickness or age and therefore change across fracture zones. Including the effect of varying thermal bending moments, thin plate theory predicts vertical, nonisostatic displacements of the lithosphere by plate flexure. The general form of this geoid anomaly differs sufficiently from other predicted components of the geoid anomaly at fracture zones to be discernible. The anomaly due to thermal stresses has been clearly identified in geoid profiles across the Clarion and Udintsev fracture zones; its amplitude is well predicted if cooling lithosphere begins to accumulate elastic stresses at a temperature of 700°C, consistent with the maximum depth of seismicity in the oceanic lithosphere. Dept. of Geol. Sci., Brown Univ., Providence, RI 02912, USA.
86:6965 Sato, Tamao, 1985. Rupture characteristics of the 1983 Nihonkai-Chubu (Japan Sea) earthquake as inferred from strong motion accelerograms. J. Phys. Earth, 33(6):525-557. Earthquake and Volcano Observ., Hirosaki Univ., Hirosaki, Japan.
86:6966 Scordilis, E.M., G.F. Karakaisis, B.G. Karacostas, D.G. Panagiotopoulos, P.E. Comninakis and B.C. Papazachos, 1985. Evidence for transform faulting in the Ionian Sea: the Cephalonia Island earthquake sequence of 1983. Pure appl. Geophys., 123(3):388-397. Fault plane solutions and aftershock locations of the January 17, 1983 earthquake (M~= 7.0) in the Ionian islands indicate a right-lateral strike-slip motion with a thrust component, along a NE-SW-striking fault. This fault is proposed to be of transform type, located in the northwesternmost part of the Hellenic Arc. Geophys. Lab., Univ. of Thessaloniki, Greece.
OLR (1986)33 (12)
86:6967 Spence, William, 1986. The 1977 Sumba earthquake series: evidence for slab pull force acting at a subduction zone. J. geophys. Res., 91(B7):72257239. Seismicity exists to a depth of ~650 km in the very old plate beneath the Sunda-Banda Arc, and that plate's negative buoyancy causes very large slab pull forces inferred to have partially decoupled the subducted plate from that overriding it. This decoupling permits slab pull stresses to be guided updip to the region of the Sumba main shock, which in turn provides a bending moment at the trench and explains the deformation and timing observed for the entire Sumba earthquake series. Increasing stresses at the shallow subduction zone lead to a subduction zone earthquake; the released oceanic plate undergoes a pulse of downdip strain which could exceed the seismic moment of the main shock. USGS, Box 25046, Denver, CO 80225, USA.
D330. Oil and gas 86:6968 Brewster, John, John Dangerfield and Helen Farrell, 1986. The geology and geophysics of the Ekofisk Field waterflood. Mar. Petrol. Geol., 3(2):139169. Elf Aquitaine Narge, P.O. Box 168, N-4001 Stavanger, Norway.
86:6969 Hatton, I.R., 1986. Geometry of allochthonous Chalk Group members, Central Trough, North Sea. Mar. Petrol. Geol., 3(3):79-98. Kerr-McGee Oil Ltd., 75 Davies St., London W1Y IFA, UK.
86:6970 Johnson, H.D., T.A. Mackay and D.J. Stewart, 1986. The Fulmar oil-field (central North Sea): geological aspects of its discovery, appraisal and development. Mar. Petrol. Geol., 3(2):99-125. Sarawak Shell Berhad, Lutong, Miri, State of Sarawak, Federation of Malaysia.
86:6971 Warnke, D.A. (comment), M.E. Field and K.A. Kvenvolden (reply), 1986. 'Gas hydrates on the
OLR (1986)33(12)
D. SubmarineGeologyand Geophysics
northern California continental margin.' Geology, geol. Soc. Am., 14(6):536-538. Dept. of Geol. Sci., Calif. State Univ., Hayward, CA 94542, USA.
1021
Quaternary bottom currents on the Faro Drift; Mississippi Fan fine-grained turbidites; sidescan sonar in the study of cartography and sedimentary dynamics; correlations of Quaternary deposits on the Hellenic margin; and mytilids as natural traps for hydrothermal phases on the EPR. (msg)
D340. Manganese nodules, etc. D370. Miscellaneous 86:6972 Chave, K.E., C.L. Morgan and W.J. Green, 1986. A geochemical comparison of manganese oxide deposits of the Hawaiian Archipelago and the deep sea. Appl. Geochem., 1(2):233-240. Data are presented on the composition of manganese crusts collected within the Hawaiian Exclusive Economic Zone (HEEZ). Shallow crusts ( ~ 1500 m) are composed of five distinct phases (silicate, apatite, iron oxide, manganese oxide, and non-associated copper), whereas the deep crusts display no obvious inter-elemental organization based on dendrograms. The mean composition of HEEZ crusts differs from that of eastern Tropical Pacific nodules in that crusts are comparatively rich in As, Pb, Co, Ce, Fe, and Ti, whereas nodules have comparatively more Cu, Ni, and Sr. Compositional differences between shallow crusts and nodules are discussed in terms of (l) element source; (2) Mn-oxide mineralogy; and (3) redox conditions in the adjacent seawater. It is concluded that the major difference between crust and nodules is due to metal sources; water column for crusts, sediments for nodules. Dept. of Oceanogr., Univ. of Hawaii, Honolulu, HI 96822, USA.
D360. Books, collections (general) 86:6973 Biju-Duval, Bernard (organizer), 1986. INew research in geological oeeanography.l [Special Session, Geological Society of France, Paris, 3-4 December 1984.] Bull. Soc. g~ol. Fr., (8)II(3):359460; 12 papers. (In French, English abstracts.) A broad cross-section of topics are discussed in these papers including morphologic and sedimentary variations in the Clarion-Clipperton Fracture Zone; new data on the northern Red Sea axial valley; morphology and evolution of seamounts of the northern Portugese margin; the altimetric geoid on the southwest Indian Ridge; preliminary cruise results of the northern Mozambique margin; Late
86:6974 Saull, V.A., 1986. Opinion. Wanted: alternatives to plate tectonics. Geology, geol. Soc. Am., 14(6): p.536. 'If plate tectonics remains the only well-known, plausible global tectonic model, the pressure on the individual investigator to interpret his or her observations to suit it will continue to be nearly irresistible. The subsequent publication of this interpretation then will seem to constitute additional evidence that all is well with this remarkable model, and that we are truly fortunate to be living during a time when geologic processes are so completely understood.' Unfortunately, application of plate tectonics to regional geology does not provide determinate histories, nor is regional geologic history uniquely interpretable by applying plate models. There could be a better global tectonic model, but few seem interested in finding one. Dept. of Geol. Sci., McGill Univ., Montreal, PQ H3A 2A7, Canada. (fcs)
86:6975 Webb, S.C. and C.S. Cox, 1986. Observations and modeling of seafloor microseisms. J. geophys. Res., 91(B7):7343-7358. While extensive programs of short-period ocean bottom seismology have been established for more than 20 years, long-period instruments are much more difficult to deploy; the level of seismic noise at the deep seafloor is essentially unknown at periods > 1 0 sec and poorly known at shorter periods. Long-period instruments require precise leveling and a firm foundation. Two new types of seafloor instrumentation circumvent these problems and provide useful, although indirect, measurements of seafloor seismic noise. In this paper we describe the results of three experiments with two emphases: to describe the spectra of seafloor noise observed with these transducers, and to explain the physical processes involved and model the amplitude of the noise. WHOI, Woods Hole, MA 02543, USA.
D. SubmarineGeologyand Geophysics
Boll. Geofis. teor. appl., 27(107):185-195. Geophys. Lab., Univ. of Thessaloniki, Greece.
area.
86:6964 Parmentier, E.M. and W.F. Haxby, 1986. Thermal stresses in the oceanic lithosphere: evidence from geoid anomalies at fracture zones. J. geophys. Res., 91(B7):7193-7204. Theoretical models which examine the effect of thermal stresses at fracture zones show that an anomaly of the predicted form can be observed in geoid profiles which cross fracture zones. Specifically, the models predict the development of thermal bending moments which depend on lithosphere thickness or age and therefore change across fracture zones. Including the effect of varying thermal bending moments, thin plate theory predicts vertical, nonisostatic displacements of the lithosphere by plate flexure. The general form of this geoid anomaly differs sufficiently from other predicted components of the geoid anomaly at fracture zones to be discernible. The anomaly due to thermal stresses has been clearly identified in geoid profiles across the Clarion and Udintsev fracture zones; its amplitude is well predicted if cooling lithosphere begins to accumulate elastic stresses at a temperature of 700°C, consistent with the maximum depth of seismicity in the oceanic lithosphere. Dept. of Geol. Sci., Brown Univ., Providence, RI 02912, USA.
86:6965 Sato, Tamao, 1985. Rupture characteristics of the 1983 Nihonkai-Chubu (Japan Sea) earthquake as inferred from strong motion accelerograms. J. Phys. Earth, 33(6):525-557. Earthquake and Volcano Observ., Hirosaki Univ., Hirosaki, Japan.
86:6966 Scordilis, E.M., G.F. Karakaisis, B.G. Karacostas, D.G. Panagiotopoulos, P.E. Comninakis and B.C. Papazachos, 1985. Evidence for transform faulting in the Ionian Sea: the Cephalonia Island earthquake sequence of 1983. Pure appl. Geophys., 123(3):388-397. Fault plane solutions and aftershock locations of the January 17, 1983 earthquake (M~= 7.0) in the Ionian islands indicate a right-lateral strike-slip motion with a thrust component, along a NE-SW-striking fault. This fault is proposed to be of transform type, located in the northwesternmost part of the Hellenic Arc. Geophys. Lab., Univ. of Thessaloniki, Greece.
OLR (1986)33 (12)
86:6967 Spence, William, 1986. The 1977 Sumba earthquake series: evidence for slab pull force acting at a subduction zone. J. geophys. Res., 91(B7):72257239. Seismicity exists to a depth of ~650 km in the very old plate beneath the Sunda-Banda Arc, and that plate's negative buoyancy causes very large slab pull forces inferred to have partially decoupled the subducted plate from that overriding it. This decoupling permits slab pull stresses to be guided updip to the region of the Sumba main shock, which in turn provides a bending moment at the trench and explains the deformation and timing observed for the entire Sumba earthquake series. Increasing stresses at the shallow subduction zone lead to a subduction zone earthquake; the released oceanic plate undergoes a pulse of downdip strain which could exceed the seismic moment of the main shock. USGS, Box 25046, Denver, CO 80225, USA.
D330. Oil and gas 86:6968 Brewster, John, John Dangerfield and Helen Farrell, 1986. The geology and geophysics of the Ekofisk Field waterflood. Mar. Petrol. Geol., 3(2):139169. Elf Aquitaine Narge, P.O. Box 168, N-4001 Stavanger, Norway.
86:6969 Hatton, I.R., 1986. Geometry of allochthonous Chalk Group members, Central Trough, North Sea. Mar. Petrol. Geol., 3(3):79-98. Kerr-McGee Oil Ltd., 75 Davies St., London W1Y IFA, UK.
86:6970 Johnson, H.D., T.A. Mackay and D.J. Stewart, 1986. The Fulmar oil-field (central North Sea): geological aspects of its discovery, appraisal and development. Mar. Petrol. Geol., 3(2):99-125. Sarawak Shell Berhad, Lutong, Miri, State of Sarawak, Federation of Malaysia.
86:6971 Warnke, D.A. (comment), M.E. Field and K.A. Kvenvolden (reply), 1986. 'Gas hydrates on the
OLR (1986)33(12)
D. SubmarineGeologyand Geophysics
northern California continental margin.' Geology, geol. Soc. Am., 14(6):536-538. Dept. of Geol. Sci., Calif. State Univ., Hayward, CA 94542, USA.
1021
Quaternary bottom currents on the Faro Drift; Mississippi Fan fine-grained turbidites; sidescan sonar in the study of cartography and sedimentary dynamics; correlations of Quaternary deposits on the Hellenic margin; and mytilids as natural traps for hydrothermal phases on the EPR. (msg)
D340. Manganese nodules, etc. D370. Miscellaneous 86:6972 Chave, K.E., C.L. Morgan and W.J. Green, 1986. A geochemical comparison of manganese oxide deposits of the Hawaiian Archipelago and the deep sea. Appl. Geochem., 1(2):233-240. Data are presented on the composition of manganese crusts collected within the Hawaiian Exclusive Economic Zone (HEEZ). Shallow crusts ( ~ 1500 m) are composed of five distinct phases (silicate, apatite, iron oxide, manganese oxide, and non-associated copper), whereas the deep crusts display no obvious inter-elemental organization based on dendrograms. The mean composition of HEEZ crusts differs from that of eastern Tropical Pacific nodules in that crusts are comparatively rich in As, Pb, Co, Ce, Fe, and Ti, whereas nodules have comparatively more Cu, Ni, and Sr. Compositional differences between shallow crusts and nodules are discussed in terms of (l) element source; (2) Mn-oxide mineralogy; and (3) redox conditions in the adjacent seawater. It is concluded that the major difference between crust and nodules is due to metal sources; water column for crusts, sediments for nodules. Dept. of Oceanogr., Univ. of Hawaii, Honolulu, HI 96822, USA.
D360. Books, collections (general) 86:6973 Biju-Duval, Bernard (organizer), 1986. INew research in geological oeeanography.l [Special Session, Geological Society of France, Paris, 3-4 December 1984.] Bull. Soc. g~ol. Fr., (8)II(3):359460; 12 papers. (In French, English abstracts.) A broad cross-section of topics are discussed in these papers including morphologic and sedimentary variations in the Clarion-Clipperton Fracture Zone; new data on the northern Red Sea axial valley; morphology and evolution of seamounts of the northern Portugese margin; the altimetric geoid on the southwest Indian Ridge; preliminary cruise results of the northern Mozambique margin; Late
86:6974 Saull, V.A., 1986. Opinion. Wanted: alternatives to plate tectonics. Geology, geol. Soc. Am., 14(6): p.536. 'If plate tectonics remains the only well-known, plausible global tectonic model, the pressure on the individual investigator to interpret his or her observations to suit it will continue to be nearly irresistible. The subsequent publication of this interpretation then will seem to constitute additional evidence that all is well with this remarkable model, and that we are truly fortunate to be living during a time when geologic processes are so completely understood.' Unfortunately, application of plate tectonics to regional geology does not provide determinate histories, nor is regional geologic history uniquely interpretable by applying plate models. There could be a better global tectonic model, but few seem interested in finding one. Dept. of Geol. Sci., McGill Univ., Montreal, PQ H3A 2A7, Canada. (fcs)
86:6975 Webb, S.C. and C.S. Cox, 1986. Observations and modeling of seafloor microseisms. J. geophys. Res., 91(B7):7343-7358. While extensive programs of short-period ocean bottom seismology have been established for more than 20 years, long-period instruments are much more difficult to deploy; the level of seismic noise at the deep seafloor is essentially unknown at periods > 1 0 sec and poorly known at shorter periods. Long-period instruments require precise leveling and a firm foundation. Two new types of seafloor instrumentation circumvent these problems and provide useful, although indirect, measurements of seafloor seismic noise. In this paper we describe the results of three experiments with two emphases: to describe the spectra of seafloor noise observed with these transducers, and to explain the physical processes involved and model the amplitude of the noise. WHOI, Woods Hole, MA 02543, USA.