Deepwater expansion and enhanced remineralization in the eastern equatorial Pacific during the last glacial maximum
Umling, Natalie E.
Thunell, Robert C.
MetadataShow full item record
Published estimates of the radiocarbon content of middepth waters suggest a decrease in ventilation in multiple locations during the last glacial maximum (LGM; 24.0–18.1 ka). Reduced glacial ventilation would have allowed respired carbon to accumulate in those waters. A subsequent deglacial release of this respired carbon reservoir to the atmosphere could then account for the observed increases in atmospheric CO2 and decline in atmospheric radiocarbon content. However, age model error and a release of 14C‐depleted mantle carbon have also been cited as possible explanations for the observed middepth radiocarbon depletions, calling into question the deep ocean's role in storing respired carbon during the LGM. Joint measurements of benthic foraminiferal carbon isotope values (δ13C) and cadmium/calcium (Cd/Ca) ratios provide a method for isolating the air‐sea component of a water mass from changes in remineralization. Here we use benthic foraminiferal δ13C and Cd/Ca records from the eastern equatorial Pacific to constrain changes in remineralization and water‐mass mixing over the last glacial‐interglacial transition. These records are complemented with elemental measurements of the authigenic coatings of foraminifera to monitor postdepositional changes in bottom water properties. Our results suggest an increase of deep waters at midwater depths consistent with a shoaling of the boundary between the upper and lower branches of Southern Ocean overturning circulation. Additionally, our records demonstrate increased organic matter remineralization in middepth waters during the LGM, suggesting that respired carbon did accumulate in middepth waters under periods of reduced ventilation.
Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography and Paleoclimatology 33 (2018): 563-578, doi:10.1029/2017PA003221.
Suggested CitationPaleoceanography and Paleoclimatology 33 (2018): 563-578
Showing items related by title, author, creator and subject.
Modern sedimentation in the Northern Barents Sea : input, dipersal and deposition of suspended sediments from glacial meltwater Pfirman, Stephanie L. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1984-08)The modern depositional environment of the northern epicontinental Barents Sea varies from proximal to distal glaciomarine. The regional surface sediment distribution is controlled by erosion of shallow banks of the ...
Indian monsoon variations during three contrasting climatic periods : the Holocene, Heinrich Stadial 2 and the last interglacial-glacial transition Zorzi, Coralie; Sanchez Goni, Maria Fernanda; Anupama, Krishnamurthy; Prasad, Srinivasan; Hanquiez, Vincent; Johnson, Joel E.; Giosan, Liviu (2015-06)In contrast to the East Asian and African monsoons the Indian monsoon is still poorly documented throughout the last climatic cycle (last 135,000 years). Pollen analysis from two marine sediment cores (NGHP-01-16A and ...
Surface exposure geochronology using cosmogenic nuclides : applications in Antarctic glacial geology Brook, Edward J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-09)Cosmogenic 3He, 26A1, and 10Be have been measured in a variety of Antarctic glacial deposits in the McMurdo Sound-Dry Valleys region. The goals of this project were to provide age constraints for Antarctic glacial events, ...