Open AccessA first look at paleotemperature prospects from Mg in coccolith carbonate: Cleaning techniques and culture measurements
Author(s) -
Stoll Heather M.,
Ruiz Encinar Jorge,
Ignacio Garcia Alonso J.,
Rosenthal Yair,
Probert Ian,
Klaas Christine
Publication year - 2001
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2000gc000144
Subject(s) - carbonate , calcite , coccolith , organic matter , geology , mineralogy , environmental chemistry , algae , dolomite , inductively coupled plasma mass spectrometry , chemistry , mass spectrometry , chromatography , botany , organic chemistry , biology
Although coccolith calcite is abundant in carbonate sediments, it has not been previously utilized for Mg/Ca paleothermometry. Cleaning experiments with synthetic composite samples (reagent CaCO 3 powder and organic matter from noncalcifying marine algae Chlorella ) are used to evaluate which traditional and/or novel cleaning methods permit us to recover the known carbonate Mg/Ca ratio. The most effective cleaning treatment, causing the least effect on carbonate chemistry and most complete and rapid oxidation of algal organic matter, was oxidation in an equal volume mixture of sodium hypochlorite (2.8%) and hydrogen peroxide (30%). However, in some organic‐ rich samples this method may not remove sufficient noncarbonate Mg to permit precise determination of carbonate Mg/Ca. Mg/Ca ratios in small culture samples may be determined precisely (relative standard deviation of 0.65%) using sector field inductively coupled plasma‐mass spectrometry. Measurements of Mg/Ca in coccoliths from several species suggest that temperature may be an important control over Mg partitioning in coccolith calcite, although cleaning issues are likely to be an important limitation on paleoceanographic application.