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Was there any deep water formation in the Mediterranean Sea before 8000 years BP?
OLR 11987) 34 ~9)
D. Submarine Geology and Geophysics
history, and continental margin erosion. Paleoceanography, 2(1): !-19. Tertiary benthic and planktonic foraminiferal oxygen isotope records are correlated to a standard geomagnetic polarity time scale, using improved chronostratigraphic control and additional Oligocene isotope data. Synchronous changes in benthic and planktonic 8~O values in the OligoceneMiocene are interpreted to represent, in part, ice growth and decay. The inferred ice growth correlates with erosion on passive continental margins as interpreted from seismic and chronostratigraphic records, and is consistent with a link between Oligocene-Miocene erosion and rapid glacioeustatic lowerings. Mechanisms and rates of sea level change were apparently different between the Early and Late Tertiary, with glacioeustatic changes restricted to the past 36 m.y. and pre-Oiigocene eustatic lowerings resulting from global spreading rate changes. Lamont-Doherty Geol. Observ., Palisades, NY 10964, USA. 87:5065 Mironov, A.N., 1985. On the age of deep-sea benthos fauna of Antarctic origin. Trudy zool. Inst., Leningr., 130:82-87. (In Russian, English abstract.) Antarctic deep-sea fauna are thought to have spread widely in conjunction with the general cooling that occurred during the Oligocene and Miocene and the establishment of Cenozoic deep-water circulation. North Atlantic fauna originating from Antarctic benthic species are more recent than their North Pacific counterparts, while the Arctic deep-sea fauna appear to be the most recent. (gsb) 87:5066 Morley, J.J., N.G. Pisias and Margaret Leinen, 1987. Late Pleistocene time series of atmospheric and oceanic variables recorded in sediments from the subarctic Pacific. Paleoceanography, 2(1):49-62. Time series analyses of atmospheric and oceanic variables in a NW Pacific record show the complex relationship of various segments of the climate system to changes in the Earth's orbit. Although the radiolarian faunal assemblages have prominent spectral peaks with 41,000 yr periods coherent with obliquity, only the transitional faunal assemblage contains variance focused at a frequency corresponding to the 100,000 yr period of eccentricity, and three series also show a 20,000 yr variance not coherent with a dominant spectral peak of precession. The findings suggest that during much of the last 460,000 years surface water characteristics in the subarctic Pacific were similar to those of today in the
761
Sea of Okhotsk, and that throughout much of the Late Pleistocene the Subarctic Front was positioned south of its present location. Lamont-Doherty Geol. Observ., Palisades, NY 10964, USA. 87:5067 Officer, C.B., Anthony Hallam, C.L. Drake and J.D. Devine, 1987. Late Cretaceous and paroxysmal Cretaceous/Tertiary extinctions. Nature, Lond., 326(6109): 143-149. The various geological signatures at Cretaceous/Tertiary time including iridium and other associated elements, microspherules, and shock deformation features are compatible with the suggestion that the transition is marked by a period of intense volcanism. The volatile emissions from this volcanism would lead to acid rain, reduction in the alkalinity and pH of the surface ocean, global atmospheric temperature changes, and ozone layer depletion. These environmental effects coupled with those related to the major sea level regression of the late Cretaceous provide the framework for an explanation of the selective nature of the observed extinction record. Earth Sci. Dept., Dartmouth College, Hanover, NH 03755, USA. 87:5068 Poutiers, J., 1987. Was there any deep water formation in the Mediterranean Sea before 8000 years BP? Deep-Sea Res., 34(2A):309-312. Modeling of water exchanges between the Mediterranean and Atlantic during Late Quaternary permits an understanding of the hydrologic and ecologic evolution of the Alborean Sea during this period. One is forced to conclude that deep water formation in the western Mediterranean Sea began about 8000 years BP. Dept. de Geol. et Oceanogr., Univ. de Bordeaux I, 33405 Talence, France.
87:5069 Raisbeck, G.M., F. Yiou, D. Bourles, C. Lorius, J. Jouzel and N.I. Barkov, 1987. Evidence for two intervals of enhanced re°Bedeposition in Antarctic ice during the last glacial period. Nature, Lond., 326(6110):273-277. The authors have measured a much more detailed concentration profile for ~°Be than previously reported for a Vostok, Antarctica core. The results confirm a ~°Be 'peak,' lasting ~ 1000-2000 years, at ~60,000 yrBP, and show another similar peak at ~35,000 yrBP. The latter peak was also observed in the Dome C core. Possible sources for these peaks, and their potential as stratigraphic markers, are discussed. Lab. Rene Bernas, 91406 Orsay, France.
D. Submarine Geology and Geophysics
history, and continental margin erosion. Paleoceanography, 2(1): !-19. Tertiary benthic and planktonic foraminiferal oxygen isotope records are correlated to a standard geomagnetic polarity time scale, using improved chronostratigraphic control and additional Oligocene isotope data. Synchronous changes in benthic and planktonic 8~O values in the OligoceneMiocene are interpreted to represent, in part, ice growth and decay. The inferred ice growth correlates with erosion on passive continental margins as interpreted from seismic and chronostratigraphic records, and is consistent with a link between Oligocene-Miocene erosion and rapid glacioeustatic lowerings. Mechanisms and rates of sea level change were apparently different between the Early and Late Tertiary, with glacioeustatic changes restricted to the past 36 m.y. and pre-Oiigocene eustatic lowerings resulting from global spreading rate changes. Lamont-Doherty Geol. Observ., Palisades, NY 10964, USA. 87:5065 Mironov, A.N., 1985. On the age of deep-sea benthos fauna of Antarctic origin. Trudy zool. Inst., Leningr., 130:82-87. (In Russian, English abstract.) Antarctic deep-sea fauna are thought to have spread widely in conjunction with the general cooling that occurred during the Oligocene and Miocene and the establishment of Cenozoic deep-water circulation. North Atlantic fauna originating from Antarctic benthic species are more recent than their North Pacific counterparts, while the Arctic deep-sea fauna appear to be the most recent. (gsb) 87:5066 Morley, J.J., N.G. Pisias and Margaret Leinen, 1987. Late Pleistocene time series of atmospheric and oceanic variables recorded in sediments from the subarctic Pacific. Paleoceanography, 2(1):49-62. Time series analyses of atmospheric and oceanic variables in a NW Pacific record show the complex relationship of various segments of the climate system to changes in the Earth's orbit. Although the radiolarian faunal assemblages have prominent spectral peaks with 41,000 yr periods coherent with obliquity, only the transitional faunal assemblage contains variance focused at a frequency corresponding to the 100,000 yr period of eccentricity, and three series also show a 20,000 yr variance not coherent with a dominant spectral peak of precession. The findings suggest that during much of the last 460,000 years surface water characteristics in the subarctic Pacific were similar to those of today in the
761
Sea of Okhotsk, and that throughout much of the Late Pleistocene the Subarctic Front was positioned south of its present location. Lamont-Doherty Geol. Observ., Palisades, NY 10964, USA. 87:5067 Officer, C.B., Anthony Hallam, C.L. Drake and J.D. Devine, 1987. Late Cretaceous and paroxysmal Cretaceous/Tertiary extinctions. Nature, Lond., 326(6109): 143-149. The various geological signatures at Cretaceous/Tertiary time including iridium and other associated elements, microspherules, and shock deformation features are compatible with the suggestion that the transition is marked by a period of intense volcanism. The volatile emissions from this volcanism would lead to acid rain, reduction in the alkalinity and pH of the surface ocean, global atmospheric temperature changes, and ozone layer depletion. These environmental effects coupled with those related to the major sea level regression of the late Cretaceous provide the framework for an explanation of the selective nature of the observed extinction record. Earth Sci. Dept., Dartmouth College, Hanover, NH 03755, USA. 87:5068 Poutiers, J., 1987. Was there any deep water formation in the Mediterranean Sea before 8000 years BP? Deep-Sea Res., 34(2A):309-312. Modeling of water exchanges between the Mediterranean and Atlantic during Late Quaternary permits an understanding of the hydrologic and ecologic evolution of the Alborean Sea during this period. One is forced to conclude that deep water formation in the western Mediterranean Sea began about 8000 years BP. Dept. de Geol. et Oceanogr., Univ. de Bordeaux I, 33405 Talence, France.
87:5069 Raisbeck, G.M., F. Yiou, D. Bourles, C. Lorius, J. Jouzel and N.I. Barkov, 1987. Evidence for two intervals of enhanced re°Bedeposition in Antarctic ice during the last glacial period. Nature, Lond., 326(6110):273-277. The authors have measured a much more detailed concentration profile for ~°Be than previously reported for a Vostok, Antarctica core. The results confirm a ~°Be 'peak,' lasting ~ 1000-2000 years, at ~60,000 yrBP, and show another similar peak at ~35,000 yrBP. The latter peak was also observed in the Dome C core. Possible sources for these peaks, and their potential as stratigraphic markers, are discussed. Lab. Rene Bernas, 91406 Orsay, France.