U/Ca in benthic foraminifers: A proxy for the deep-sea carbonate saturation
Journal
Geochemistry, Geophysics, Geosystems
Journal Volume
12
Journal Issue
6
Date Issued
2011
Author(s)
Abstract
The ocean plays a major role in the global carbon cycle, and attempts to reconstruct past changes in the marine carbonate system are increasing. The speciation of dissolved uranium is sensitive to variations in carbonate system parameters, and previous studies have shown that this is recorded in the uranium-to-calcium ratio (U/Ca) of the calcite shells of planktonic foraminifera. Here we test whether U/Ca ratios of deep-sea benthic foraminifera are equally suited as an indicator of the carbonate system. We compare U/Ca in two common benthic foraminifer species (Planulina wuellerstorfi and Cibicidoides mundulus) from South Atlantic core top samples with the calcite saturation state ([CO32-] = [CO32-] in situ - [CO32-]sat) of the ambient seawater and find significant negative correlations for both species. Compared with planktonic foraminifera, the sensitivity of U/Ca in benthic foraminifera to changes in [CO32-] is about 1 order of magnitude higher. Although [CO32-] exerts the dominant control on the average foraminiferal U/Ca, the intertest and intratest variability indicates the presence of additional factors forcing U/Ca. Copyright 2011 by the American Geophysical Union.
Subjects
benthic foraminifera; carbonate saturation state; U/Ca
SDGs
Other Subjects
Calcite; Carbonate minerals; Carbonation; Seawater; Uranium; Benthic foraminifera; Benthic foraminifers; Carbonate system; Core-top samples; Global carbon cycle; In-situ; Marine carbonates; Negative correlation; Planktonic foraminifera; Saturation state; South Atlantic; Calcium carbonate; benthic foraminifera; calcium; carbon cycle; carbonate system; deep sea; planktonic foraminifera; speciation (chemistry); uranium; Cibicidoides; Foraminifera; Planulina
Type
journal article