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Radionuclide and biomarker proxies of past ocean circulation and productivity in the Arabian Sea
Author(s) -
Pourmand A.,
Marcantonio F.,
Bianchi T. S.,
Canuel E. A.,
Waterson E. J.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl022612
Subject(s) - oceanography , thermohaline circulation , holocene , water column , geology , environmental science , latitude , biomarker , last glacial maximum , glacial period , paleoceanography , climatology , chemistry , paleontology , biochemistry , geodesy
We present new excess 231 Pa/ 230 Th activity ratios and lipid biomarker results from northeastern Arabian Sea sediments (core 93KL) spanning the past 50 ka in an effort to constrain further the relationship between climate at low and high latitudes. 231 Pa/ 230 Th activity ratios are maintained at values significantly higher than the water‐column production ratio of 0.093. Average 231 Pa/ 230 Th activity ratios are lower during the last glacial period than during the Holocene. The lowest 231 Pa/ 230 Th activity ratios coincide with the timing of Heinrich Events 1–5. Profiles of lipid biomarker fluxes and 231 Pa/ 230 Th activity ratios from 32 to 12 ka show similar patterns, suggesting that 231 Pa is more efficiently scavenged relative to 230 Th at times when diatoms make up a proportionally larger part of the primary biomass signal. In the Holocene, high 231 Pa/ 230 Th activity ratios may indicate enhanced 231 Pa export from the southern to the northern Indian Ocean via intensified thermohaline circulation.