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Millennial-scale surface and subsurface paleothermometry from the northeast Atlantic, 55–8 ka BP

Peck, Victoria Louise, Hall, Ian Robert, Zahn, Rainer and Elderfield, H. 2008. Millennial-scale surface and subsurface paleothermometry from the northeast Atlantic, 55–8 ka BP. Paleoceanography 23 (3) , PA3221. 10.1029/2008PA001631

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Abstract

We present high-resolution records of upper ocean temperatures derived from Mg/Ca ratios of surface-dwelling Globigerina bulloides and subsurface-dwelling Neogloboquadrina pachyderma sinistral and the relative abundance of N. pachyderma sinistral for the period 55–8 ka BP from NE Atlantic sediment core MD01-2461. Millennial-scale temporal variability and longer-term trends in these records enable us to develop a detailed picture of past ocean conditions such as a weakening of thermocline intensity from marine isotope stage 3 (MIS 3) to the last glacial maximum (LGM). The correspondence of all temperature proxies and convergence of paired oxygen isotope (δ 18O) records from both planktonic species implies a breakdown in the thermocline and year-round mixing of the upper water column through the LGM, perhaps related to decreasing insolation and additional cooling in association with the expansion of the circum–North Atlantic ice sheets. Millennial-scale divergence in surface and subsurface temperatures and δ 18O across the last glacial correspond to meltwater release and the development of a strong halocline associated with both Heinrich (H) events and instabilities of the NW European ice sheet. During such episodes, G. bulloides Mg/Ca appears to record ambient, even warming summer sea surface temperatures across H events while the other proxies record maximum cooling.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/1944-9186/ (accessed 20/02/2014).
Publisher: American Geophysical Union
ISSN: 0883-8305
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 02:38
URI: http://orca.cf.ac.uk/id/eprint/11280

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