Effects of ocean acidification on the marine calcium isotope record at the Paleocene-Eocene Thermal Maximum

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doi: 10.1016/j.epsl.2015.03.010
Author(s): Griffith, Elizabeth M.; Fantle, Matthew S.; Eisenhauer, Anton; Paytan, Adina; Bullen, Thomas D.
Author Affiliation(s): Primary:
University of Texas, Arlington, Department of Earth and Environmental Sciences, Arlington, TX, United States
Other:
Pennsylvania State University, United States
Helmholtz Centre for Ocean Research Kiel, Germany
University of California, Santa Cruz, United States
U. S. Geological Survey, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.419, p.81-92. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 66 refs.; illus., incl. 4 tables
Summary: Carbonates are used extensively to reconstruct paleoclimate and paleoceanographic conditions over geologic time scales. However, these archives are susceptible to diagenetic alteration via dissolution, recrystallization and secondary precipitation, particularly during ocean acidification events when intense dissolution can occur. Despite the possible effects of diagenesis on proxy fidelity, the impacts of diagenesis on the calcium isotopic composition (δ 44Ca) of carbonates are unclear. To shed light on this issue, bulk carbonate δ 44Ca was measured at high resolution in two Pacific deep sea sediment cores (ODP Sites 1212 and 1221) with considerably different dissolution histories over the Paleocene-Eocene Thermal Maximum (PETM, ∼ 5.5 Ma). The δ 44Ca of marine barite was also measured at the deeper Site 1221, which experienced severe carbonate dissolution during the PETM. Large variations (∼0.8 ppm) in bulk carbonate δ 44Ca occur in the deeper of the two sites at depths corresponding to the peak carbon isotope excursion, which correlate with a large drop in carbonate weight percent. Such an effect is not observed in either the 1221 barite record or the bulk carbonate record at the shallower Site 1212, which is also less affected by dissolution. We contend that ocean chemical changes associated with abrupt and massive carbon release into the ocean-atmosphere system and subsequent ocean acidification at the PETM affected the bulk carbonate δ 44Ca record via diagenesis in the sedimentary column. Such effects are considerable, and need to be taken into account when interpreting Ca isotope data and, potentially, other geochemical proxies over extreme climatic events that drive sediment dissolution. Abstract Copyright (2015) Elsevier, B.V.
Year of Publication: 2015
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Acidification; Alkaline earth metals; Barite; Ca-44/Ca-40; Calcium; Carbonate compensation depth; Carbonates; Cenozoic; Diagenesis; East Pacific; Equatorial Pacific; Isotope ratios; Isotopes; Leg 198; Leg 199; Marine environment; Metals; North Pacific; Northeast Pacific; Northwest Pacific; ODP Site 1212; ODP Site 1221; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleogene; Reconstruction; Recrystallization; Sea water; Secondary minerals; Shatsky Rise; Stable isotopes; Sulfates; Tertiary; West Pacific
Coordinates: N322700 N322700 E1574300 E1574300
N120200 N120200 W1434200 W1434200
Record ID: 2015060455
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands