A simple mixing explanation for late Pleistocene changes in the Pacific-South Atlantic benthic δ13C gradient
The fact that the deep-ocean benthic δ 13 C minimum shifted from the North Pacific to the South Atlantic during the Last Glacial Maximum is often interpretted as evidence of a change in deep water circulation, such as the development of deep water ventilation in the North Pacific or a decrease in So...
| Published in: | Climate of the Past |
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| Main Author: | |
| Format: | Text |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/cp-6-305-2010 https://cp.copernicus.org/articles/6/305/2010/ |
| Summary: | The fact that the deep-ocean benthic δ 13 C minimum shifted from the North Pacific to the South Atlantic during the Last Glacial Maximum is often interpretted as evidence of a change in deep water circulation, such as the development of deep water ventilation in the North Pacific or a decrease in Southern Ocean overturning. This study re-evaluates the implications of changes in benthic δ 13 C gradients by comparing Pacific Deep Water (PDW) δ 13 C measurements with the values expected for the null hypothesis that PDW ventilation sources remained unchanged throughout the Late Pleistocene. The δ 13 C compositions of PDW, Northern Component Water (NCW) and Southern Component Water (SCW) are estimated from regional benthic δ 13 C stacks of 3–6 sites. Changes in PDW δ 13 C and PDW-SCW δ 13 C gradients over the past 800 kyr are found to be well described by a constant mixture of 60% NCW and 40% SCW plus a constant Pacific remineralization offset of −0.5‰. Thus, a change in PDW ventilation cannot be inferred solely on the basis of changes in the Pacific-South Atlantic benthic δ 13 C gradient. |
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