Open AccessMillennial‐scale surface and subsurface paleothermometry from the northeast Atlantic, 55–8 ka BP
Author(s) -
Peck V. L.,
Hall I. R.,
Zahn R.,
Elderfield H.
Publication year - 2008
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1029/2008pa001631
Subject(s) - globigerina bulloides , geology , oceanography , thermocline , sea surface temperature , glacial period , marine isotope stage , meltwater , water column , climatology , last glacial maximum , holocene , interglacial , paleontology , foraminifera , benthic zone
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 18 O) 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 18 O 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.