Climate in Earth History Studies in Geophysics (1982) / Chapter Skim
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12 Role of Ocean Gateways in Climate Change
12 Role of Ocean Gateways in Climate Change
Pages 118-125
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From page 118... ...
The first deals with a brief summary of the role of the oceans (and their geometry) in heat transfer and thus, ultimately, as a source of climatic change.
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From page 119... ...
By way of contrast the presence of the Antarctic Circumpolar Current in the southern hemisphere prevents penetration of westerly boundary current beyond 40° 5 and serves to isolate the Antarctic continent from major sources of precipitation. This brief summary gives an idea of the role that the oceans play in transporting heat energy and their role as a stabilizing force in maintaining the climatic status quo.
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From page 120... ...
A significant circulation event occurred during the late Jurassic—the opening or extension of a seaway through Central America, linking the "Atlantic" and "Pacific" Oceans for the first time in the equatorial region. Coupled with the gradual opening of the Norbh Atlantic by seafloor spreading, this allowed the development of a circumglobal equatorial current system, which has continued, essentially unabated, until relatively recent time [about 3 million years ago (Ma)
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From page 121... ...
MAR Ne PAUNA EKPELLeO] FRCN YETHYS ~ ~RANEAN'I SEA :;, PRCVIN;CAL e80TEOOBAP; C [SECTS" AND~FAYN A,.TURN,OV ER, Trans-Atlantic flow of warm, equatorial waters from the Tethys into the equatorial Pacific via the Central America Seaway resulted in a circumglobal equatorial current that served as the main dispersal agent of tropical faunal and floral elements throughout the Late Mesowic and Cenowic (Berggren and Hollister, 1974, 1977)
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From page 122... ...
In the southern hemisphere the northward transit of India diverted the westward flowing Pacific-equatorial current into the counterclockwise subtropical gvre, which penetrated southward, past eastern Australia into the nascent gateway that was opening up between Australia and Antarctica. Isolation of the warm Pacific gyres at these high southerly labtudes led, through adiabatic cooling and evaporation, to precipitanon on the Antarctic continent, which eventually led to fu I continental glacial conditions.
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From page 123... ...
. This cooling event is difficult to link with the development or termination of a structural barrier to flow of water masses because of the disparity in the data that exist on the timing of various events in the North Atlantic However, the concomitant effects of the severance of the Tethys Seaway and the subsidence of the Iceland-Faeroe Ridge (linking the Arctic polar sea and the Atlantic Ocean)
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From page 124... ...
Perhaps one of the most significant late Neogene paleogeographic events was the elevation of the Isthmus of Panama, which resulted in the termination of the marine gateway linking the Atlantic and Pacific Oceans, at 3.S Ma (Berggren and Hollister, 1974)
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From page 125... ...
. Oxygen and carbon isotope analyses of Cretaceous and Tertiary microfotsils from Shatsky Rise and other sites in the North Pacific Ocean, in Initial Peports At the Deep Sea Drilling Project 32, U.S.
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