Blanc, P. L.;
Duplessy, J. C.
||Nature (London), 283(5747), p.553-555. Publisher: Macmillan Journals, London, United Kingdom. ISSN: 0028-0836 CODEN: NATUAS
|| In English. 20 refs.; illus.
||There is evidence that in Mesozoic and Palaeogene times both north and south subpolar areas had a mild climate. Unlike the present day climatic symmetry, with warm equatorial regions and ice-covered polar regions, a strong planetary asymmetry developed in the middle Miocene when the antarctic ice cap was established, while the northern high latitudes remained unglaciated. The symmetry was restored when a Northern Hemisphere continental ice cover was established approx 3 myr ago in the middle Pliocene. These changes influenced the formation of deep water in the ocean. At present the cold, dense bottom waters originate in only two high latitude areas--the Weddell Sea producing Antarctic Bottom Water, and the Norwegian Sea producing Norwegian Sea Overflow Water, which, after mixing, is a major component of the North Atlantic Deep Water. The production of cold deep water in the Southern Ocean started at the Eocene-Oligocene boundary. Presented here is new evidence from isotope analyses of benthic Foraminifera from DSDP site 116, indicating that the production of oxygenated deep water in the North Atlantic Ocean started in the late middle-Miocene, approx 12 myr ago. (Auth.)
|Year of Publication:
DSDP Deep Sea Drilling Project
12 Stratigraphy, Historical Geology and Paleoecology;
DSDP Site 116;
Deep Sea Drilling Project;
North Atlantic Deep Water;
||GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from the Antarctic Bibliography, United States