Expansion of subarctic water masses in the North Atlantic and Pacific oceans and implications for mid-Pleistocene ice sheet growth
McClymont, Erin L. (University of Durham. Department of Geography)
Rosell Melé, Antoni (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Haug, Gerald H. (Geological Institute. Department of Earth Sciences)
Lloyd, Jerry M. (University of Durham. Department of Geography)

Data:	2008
Resum:	Past surface ocean circulation changes associated with the mid-Pleistocene transition, 0. 9-0. 6 Ma, were reconstructed in the northern North Atlantic (ODP 983) and the northwest Pacific (ODP 882), using proxies for subarctic/subpolar water mass distributions (%C37:4 alkenone) and sea surface temperature (U37K). Both sites experienced a secular expansion of subarctic waters from ∼1. 15 Ma, spanning both glacial and interglacial intervals. After 0. 9 Ma, low %C37:4 at Site 983 records a northward retreat of subarctic waters during interglacials in the Atlantic, while continued high glacial %C37:4 indicate extensive subarctic waters during glacial maxima associated with the development of the larger late Pleistocene ice sheets. In contrast, a secular decline in %C37:4 occurred at Site 882 from 0. 9 to 0. 5 Ma, marking a more gradual retreat of subarctic conditions in the Pacific. It is proposed that the expansion of subarctic waters between 1. 15 and 0. 9 Ma exerted negative feedbacks to the moisture supply to the ice sheet source regions and may account for the apparent delayed ice sheet response to atmosphere-ocean circulation changes associated with the mid-Pleistocene transition that began as early as 1. 2 Ma.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; Versió publicada
Matèria:	Paleoclimatology ; Paleoceanography ; Oceans ; Atmosphere ; Hydrosphere ; Cryosphere interactions
Publicat a:	Paleoceanography, Vol. 23, Issue 4, p. PA4214 (December 2008) , ISSN 1944-9186

DOI: 10.1029/2008PA001622

12 p, 584.0 KB

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