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Controls on deglacial changes in biogenic fluxes in the North Pacific Ocean

Citation

Kohfeld, KE and Chase, Z, Controls on deglacial changes in biogenic fluxes in the North Pacific Ocean, Quaternary Science Reviews: International Multidisciplinary Review and Research Journal, 30, (23-24) pp. 3350-3363. ISSN 0277-3791 (2011) [Refereed Article]


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DOI: doi:10.1016/j.quascirev.2011.08.007

Abstract

The subarctic North Pacific Ocean holds a large CO2 reservoir that is currently isolated from the atmosphere by a low-salinity layer. It has recently been hypothesized that the reorganization of these high- CO2 waters may have played a crucial role in the degassing of carbon dioxide to the atmosphere during the last deglaciation. This reorganization would leave some imprint on paleo-productivity records. Here we present 230Th-normalized biogenic fluxes from an intermediate depth sediment core in the Northwest Pacific (RC10-196, 54.7N, 177.1E, 1007 m) and place them within the context of a synthesis of previously-published biogenic flux data from 49 deep-sea cores north of 20N, ranging from 420 to 3968 m water depth. The 230Th-normalized opal, carbonate, and organic carbon fluxes from RC10-196 peak approximately 13,000 calendar years BP during the Bølling/Allerød (B/A) period. Our data synthesis suggests that biogenic fluxes were in general lowest during the last glacial period, increased somewhat in the Northwest Pacific during Heinrich Event 1, and reached a maximum across the entire North Pacific during the B/A period. We evaluate several mechanisms as possible drivers of deglacial change in biogenic fluxes in the North Pacific, including changes in preservation, sediment focusing, sea ice extent, iron inputs, stratification, and circulation shifts initiated in the North Atlantic and North Pacific. Our analysis suggests that while micronutrient sources likely contributed to some of the observed changes, the heterogeneity in timing of glaciogenic retreat and sea level make these mechanisms unlikely causes of region-wide contemporaneous peaks in export production. We argue that paleoobservations are most consistent with ventilation increases in both the North Pacific (during H1) and North Atlantic (during B/A) being the primary drivers of increases in biogenic flux during the deglaciation, as respectively they were likely to bring nutrients to the surface via increased vertical mixing and shoaling of the global thermocline.

Item Details

Item Type:Refereed Article
Keywords:Palaeoproductivity, North Pacific, iron
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Palaeoclimatology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Chase, Z (Associate Professor Zanna Chase)
ID Code:75120
Year Published:2011
Web of Science® Times Cited:28
Deposited By:IMAS Research and Education Centre
Deposited On:2012-01-11
Last Modified:2012-04-12
Downloads:1 View Download Statistics

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