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Paleocirculation and Ventilation History of Southern Ocean Sourced Deep Water Masses During the Last 800,000 Years
Author(s) -
Williams Thomas J.,
Hillenbrand ClausDieter,
Piotrowski Alexander M.,
Allen Claire S.,
Frederichs Thomas,
Smith James A.,
Ehrmann Werner,
Hodell David A.
Publication year - 2019
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2018pa003472
Subject(s) - oceanography , geology , glacial period , north atlantic deep water , benthic zone , foraminifera , interglacial , paleoceanography , last glacial maximum , bottom water , water mass , polar front , deep sea , isotopes of carbon , circumpolar deep water , total organic carbon , holocene , thermohaline circulation , paleontology , ecology , biology
Most conceptual models of ocean circulation during past glacial periods invoke a shallowed North Atlantic‐sourced water mass overlying an expanded, poorly ventilated Southern Ocean (SO)‐sourced deep water mass (Southern Component Water or SCW), rich in remineralized carbon, within the Atlantic basin. However, the ventilation state, carbon inventory, and circulation pathway of SCW sourced in the Pacific sector of the SO (Pacific SO) during glacial periods are less well understood. Here we present multiproxy data—including δ 18 O and δ 13 C measured on the benthic and planktic foraminifera Cibicidoides wuellerstorfi , and Neogloboquadrina pachyderma , and productivity proxies including percent CaCO 3 , total organic carbon, and Ba/Ti—from a sediment core located in the high‐latitude (71°S) Pacific SO spanning the last 800 kyr. Typical glacial δ 13 C values of SCW at this core site are ~0‰. We find no evidence for SCW with extremely low δ 13 C values during glacials in the high‐latitude Pacific SO. This leads to a spatial gradient in the stable carbon isotope composition of SCW from the high‐latitude SO, suggesting that there are different processes of deep‐ and bottom‐water formation around Antarctica. A reduced imprint of air‐sea gas exchange is evident in the SCW formed in the Atlantic SO compared with the Pacific SO. A spatial δ 13 C gradient in SCW is apparent throughout much of the last 800,000 years, including interglacials. A SO‐wide depletion in benthic δ 13 C is observed in early MIS 16, coinciding with the lowest atmospheric p CO 2 recorded in Antarctic ice cores.