Late Pleistocene evolution of the ocean's carbonate system

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doi: 10.1016/S0012-821X(01)00430-7
Author(s): Hodell, David A.; Charles, Christopher D.; Sierro, F. J.
Author Affiliation(s): Primary:
University of Florida, Department of Geological Sciences, Gainesville, FL, United States
Scripps Institution of Oceanography, United States
Universidad de Salamanca, Spain
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 192(2), p.109-124. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 43 refs.; illus., incl. 2 tables
Summary: We demonstrate that the carbonate record from a single site (Ocean Drilling Program Site 1089) in the deep South Atlantic represents a qualitative, high-resolution record of the temporal evolution of the carbonate saturation state of the deep sea. The record is especially notable because it is free from many of the complications that limit other records (low sedimentation rates, blurring by chemical erosion, bioturbation, etc.). The pattern of carbonate variability is characteristic of Indo-Pacific cores with high-carbonate glacials and low-carbonate interglacials. Wt% carbonate lags changes in benthic δ18O by an average of ∼7.6 kyr, and carbonate variations are in-phase with the rate of change (first derivative) of benthic δ18O. Intense dissolution occurs at the transition from interglacial to glacial periods and increased preservation occurs during deglaciations. These observations represent two fundamentally different responses of the marine carbonate system. The lagged response of carbonate to δ18O reflects a steady-state mass balance process whereby the lysocline adjusts to maintain alkalinity balance between riverine input and marine burial. The Site 1089 carbonate signal is remarkably similar to inferred changes in the Sr/Ca of seawater for the past 250 kyr, which implies that both carbonate dissolution and seawater Sr/Ca may be controlled by sea level-induced changes in the location of carbonate deposition (shelf-basin fractionation) during glacial to interglacial cycles. The transient change in preservation during the transitions into and out of glacial stages reflects a response of the carbonate system to a redistribution of alkalinity and DIC in the ocean (i.e. carbonate compensation). Comparison of the Site 1089 carbonate and Vostok pCO2 records suggests a role of deep-sea [CO32-] variations for governing at least some second-order features of the atmospheric pCO2 signal. In order to quantify this role, however, measurement of indices of dissolution along a true depth transect will be required to estimate the magnitudes of changes in deep-sea [CO32-]. Abstract Copyright (2001) Elsevier, B.V.
Year of Publication: 2001
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atlantic Ocean; Biochemistry; Calcium carbonate; Cape Basin; Carbon dioxide; Carbonate compensation depth; Carbonates; Cenozoic; Crosscorrelation; Deep-sea environment; Deglaciation; Foraminifera; Glacial environment; Glacial geology; Glaciation; Glaciomarine environment; High-resolution methods; Interglacial environment; Invertebrata; Isotope ratios; Isotopes; Leg 177; Lysoclines; Marine environment; Marine sediments; Mass balance; Microfossils; O-18/O-16; ODP Site 1089; Ocean Drilling Program; Oxygen; Paleo-oceanography; Paleocirculation; Pleistocene; Protista; Quaternary; Sea-level changes; Sediments; Solution; South Atlantic; Stable isotopes; Statistical analysis; Upper Pleistocene
Coordinates: S405611 S405611 E0095338 E0095338
Record ID: 2001075658
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands