Three dimensional view of paleooceanic events in the NE Atlantic during the late Pliocene onset of N. hemisphere glaciation

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6457141

Loubere, P

Presently, the NE Atlantic has a distinctly three layered water column composed of sub-polar surface waters; warm, saline Mediterranean Intermediate Water; and North Atlantic Deep Water (NADW). The flow of Mediterranean water into the Norwegian Sea contributes to the formation of NADW. A detailed view of the paleooceanic evolution of the NE Atlantic water column during the onset of Northern Hemisphere glaciation is provided by a comparison of the planktonic Foraminiferal, benthic Foraminiferal, isotopic and sedimentologic records of DSDP Sites 548 (1253 m. water, sample spacing of less than 10,000 years), 116 (1151 m. water) and 552A (2311 m. water). At the surface, an initial cooling event occurred between 3.3 and 2.9 Myr, bracketing the global benthic positive oxygen isotope shift. Following the cooling event, surface conditions became much more variable with a dominant cyclicity of 42,000 years. Hence, the cooling event may represent a time of important permanent change in the high latitude climatic system. At mid-depth, the first Late Pliocene indication of Mediterranean Water was found at 2.8 Myr. There maybe a causative link between the latter event and the appearance of Mediterranean Water along with its possible intrusion into the Norwegian Sea. Progressive surface cooling began at 2.6 Myr and led to glaciations by 2.4 Myr. Glacial periodicity was dominated by a 42,000 year cycle, with little sign of the 100,000 year period. During the glaciations there was an inverse response in the benthic fauna between intermediate and abyssal depths; indicating a deep circulation behavior different from the Pleistocene.

• Research Organization: Northern Illinois Univ. DeKalb (USA)
• OSTI ID: 6457141
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
580500 -- Oceanography-- (1980-1989)
ANIMALS
ATLANTIC OCEAN
CENOZOIC ERA
CHEMISTRY
CURRENTS
FORAMINIFERA
GENERAL CIRCULATION MODELS
GEOLOGIC AGES
GEOLOGIC HISTORY
GLACIERS
HYDROGEN COMPOUNDS
INVERTEBRATES
ISOTOPE RATIO
MATHEMATICAL MODELS
MICROORGANISMS
OCEANIC CIRCULATION
OCEANOGRAPHY
OXYGEN COMPOUNDS
PALEOCLIMATOLOGY
PALEONTOLOGY
PROTOZOA
SARCODINA
SEAS
SEAWATER
SEDIMENTS
SURFACE WATERS
TEMPERATURE GRADIENTS
TERTIARY PERIOD
WATER
WATER CHEMISTRY
WATER CURRENTS