Chun, Cecily O. J. et al. (2010): Paleoredox changes across the Paleocene-Eocene Thermal Maximum, Walvis Ridge (ODP Sites 1262, 1263, and 1266); evidence from Mn and U enrichment factors

Leg/Site/Hole:
ODP 208
ODP 208 1262
ODP 208 1263
ODP 208 1266
Identifier:
2013-034375
georefid

10.1029/2009PA001861
doi

Creator:
Chun, Cecily O. J.
University of California at Santa Cruz, Institute of Marine Sciences, Santa Cruz, CA, United States
author

Delaney, Margaret L.
author

Zachos, James C.
author

Identification:
Paleoredox changes across the Paleocene-Eocene Thermal Maximum, Walvis Ridge (ODP Sites 1262, 1263, and 1266); evidence from Mn and U enrichment factors
2010
Paleoceanography
American Geophysical Union, Washington, DC, United States
25
4
An understanding of sediment redox conditions across the Paleocene-Eocene thermal maximum (PETM) ( approximately 55 Ma) is essential for evaluating changes in processes that control deep-sea oxygenation, as well as identifying the mechanisms responsible for driving the benthic foraminifera extinction. Sites cored on the flanks of Walvis Ridge (Ocean Drilling Program Leg 208, Sites 1262, 1266, and 1263) allow us to examine changes in bottom and pore water redox conditions across a approximately 2 km depth transect of deep-sea sediments of PETM age recovered from the South Atlantic. Here we present measurements of the concentrations of redox-sensitive trace metals manganese (Mn) and uranium (U) in bulk sediment as proxies for redox chemistry at the sediment-water interface and below. All three Walvis Ridge sites exhibit bulk Mn enrichment factors (EF) ranging between 4 and 12 prior to the warming, values at crustal averages (Mn EF = 1) during the warming interval, and a return to pre-event values during the recovery period. U enrichment factors across the PETM remains at crustal averages (U EF = 1) at Site 1262 (deep) and Site 1266 (intermediate depth). U enrichment factors at Site 1263 (shallow) peaked at 5 immediately prior to the PETM and dropped to values near crustal averages during and after the event. All sites were lower in dissolved oxygen content during the PETM. Before and after the PETM, the deep and intermediate sites were oxygenated, while the shallow site was suboxic. Our geochemical results indicate that oxygen concentrations did indeed drop during the PETM but not sufficiently to cause massive extinction of benthic foraminifera.
English
Serial
Coverage:Geographic coordinates:
North:-27.1100
West:1.3400East: 2.4700
South:-28.3300

Stratigraphy; actinides; Atlantic Ocean; C-13/C-12; calcium carbonate; carbon; Cenozoic; chemostratigraphy; concentration; cores; diagenesis; dissolved oxygen; Eh; enrichment; Eocene; isotope ratios; isotopes; Leg 208; lithofacies; manganese; marine environment; metals; Ocean Drilling Program; ODP Site 1262; ODP Site 1263; ODP Site 1266; oxygen; paleo-oceanography; Paleocene; Paleocene-Eocene Thermal Maximum; paleoclimatology; Paleogene; solutes; South Atlantic; stable isotopes; Tertiary; trace metals; uranium; Walvis Ridge;

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