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Enhanced Carbonate Dissolution Associated With Deglacial Dysoxic Events in the Subpolar North Pacific
Author(s) -
Payne Calie R.,
Belanger Christina L.
Publication year - 2021
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 - 10.1029/2020pa004206
Subject(s) - foraminifera , benthic zone , carbonate , oceanography , oxygen minimum zone , geology , seafloor spreading , abyssal zone , chemistry , upwelling , organic chemistry
Abstract Here we use volume density ( ρ V ) measurements as a metric of size‐normalized weights for Neogloboquadrina pachyderma , a planktonic foraminifer, from upper OMZ and abyssal depth sites in the Gulf of Alaska over the past ∼20,000 years to test for covariation between carbonate preservation and OMZ intensity. We find that dissolution of N. pachyderma is most intense at the upper OMZ site where oxygenation is generally lower than at the abyssal site. We also examine Uvigerina peregrina , a benthic foraminifer, at the upper OMZ site and find that the lowest ρ V measurements in both taxa occur during deglacial and early Holocene dysoxic events. We use computed tomography images to confirm that changes in ρ V are related to shell thickness, observe dissolution features, and test for growth influences on ρ V . Further, we use stepwise selection of multiple regression models in which coregistered environmental proxies are potential predictors of ρ V and find that the best supported models retain negative associations between ρ V and the concentration of redox‐sensitive metals and the relative abundance of dysoxia‐tolerant and opportunistic benthic foraminifera, indicating that low ρ V is associated with low‐oxygen conditions and pulsed availability of organic matter at the seafloor. Taken together, our results suggest the primary driver of carbonate dissolution here is related to organic carbon respiration at the seafloor. This highlights the importance of metabolic dissolution in understanding the inorganic carbon cycle and the role regions with high‐organic carbon export, such as OMZs, can have as CO 2 sources as metabolic dissolution intensifies.