Expanded oxygen minimum zones during the late Paleocene-early Eocene; hints from multiproxy comparison and ocean modeling

Online Access: Get full text
doi: 10.1002/2016PA003020
Author(s): Zhou, X.; Thomas, E.; Winguth, A. M. E.; Ridgwell, A.; Scher, H.; Hoogakker, B. A. A.; Rickaby, R. E. M.; Lu, Z.
Author Affiliation(s): Primary:
Syracuse University, Department of Earth Sciences, Syracuse, NY, United States
Other:
Yale University, United States
University of Texas at Arlington, United States
University of California at Riverside, United States
University of South Carolina, United States
University of Oxford, United Kingdom
Volume Title: Paleoceanography
Source: Paleoceanography, 31(12), p.1532-1546. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. NSF grants OCE-1232620, OCE-1232413, and OCE-1536630. 110 refs.; illus., incl. 1 table
Summary: Anthropogenic warming could well drive depletion of oceanic oxygen in the future. Important insight into the relationship between deoxygenation and warming can be gleaned from the geological record, but evidence is limited because few ocean oxygenation records are available for past greenhouse climate conditions. We use I/Ca in benthic foraminifera to reconstruct late Paleocene through early Eocene bottom and pore water redox conditions in the South Atlantic and Southern Indian Oceans and compare our results with those derived from Mn speciation and the Ce anomaly in fish teeth. We conclude that waters with lower oxygen concentrations were widespread at intermediate depths (1.5-2 km), whereas bottom waters were more oxygenated at the deepest site, in the Southeast Atlantic Ocean (>3 km). Epifaunal benthic foraminiferal I/Ca values were higher in the late Paleocene, especially at low-oxygen sites, than at well-oxygenated modern sites, indicating higher seawater total iodine concentrations in the late Paleocene than today. The proxy-based bottom water oxygenation pattern agrees with the site-to-site O2 gradient as simulated in a comprehensive climate model (Community Climate System Model Version 3), but the simulated absolute dissolved O2 values are low (< ∼35 µmol/kg), while higher O2 values (∼60-100 µmol/kg) were obtained in an Earth system model (Grid ENabled Integrated Earth system model). Multiproxy data together with improvements in boundary conditions and model parameterization are necessary if the details of past oceanographic oxygenation are to be resolved. Abstract Copyright (2016), American Geophysical Union. All Rights Reserved.
Year of Publication: 2016
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Alkaline earth metals; Atlantic Ocean; Calcium; Cenozoic; Cerium; Chemical composition; Chordata; Community Climate System Model 3; Dysaerobic environment; Eh; Eocene; Foraminifera; Halogens; I/Ca; Invertebrata; Iodine; Kerguelen Plateau; Leg 113; Leg 119; Leg 208; Lower Eocene; Manganese; Marine environment; Maud Rise; Metals; Microfossils; Numerical models; ODP Site 1262; ODP Site 1263; ODP Site 690; ODP Site 738; Ocean Drilling Program; Osteichthyes; Paleo-oceanography; Paleocene; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleoenvironment; Paleogene; Pisces; Protista; Rare earths; South Atlantic; Southern Ocean; Statistical analysis; Teeth; Tertiary; Upper Paleocene; Vertebrata; Walvis Ridge; Weddell Sea
Coordinates: S271100 S271100 E0013500 E0013400
S283200 S283200 E0024700 E0024700
S650938 S650937 E0011218 E0011218
S624233 S624232 E0824715 E0824714
Record ID: 2017048001
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom