In situ δ7Li, Li/Ca, and Mg/Ca analyses of synthetic aragonites
Gabitov, R. I.
Schmitt, A. K.
McKeegan, K. D.
Gaetani, Glenn A.
Cohen, Anne L.
Watson, E. B.
Harrison, T. M.
MetadataShow full item record
In situ secondary ion mass spectrometry (SIMS) analyses of δ7Li, Li/Ca, and Mg/Ca were performed on five synthetic aragonite samples precipitated from seawater at 25°C at different rates. The compositions of δ7Li in bulk aragonites and experimental fluids were measured by multicollector inductively coupled plasma–mass spectrometry (MC-ICP-MS). Both techniques yielded similar δ7Li in aragonite when SIMS analyses were corrected to calcium carbonate reference materials. Fractionation factors α7Li/6Li range from 0.9895 to 0.9923, which translates to a fractionation between aragonite and fluid from −10.5‰ to −7.7‰. The within-sample δ7Li range determined by SIMS is up to 27‰, exceeding the difference between bulk δ7Li analyses of different aragonite precipitates. Moreover, the centers of aragonite hemispherical bundles (spherulites) are enriched in Li/Ca and Mg/Ca relative to spherulite fibers by up to factors of 2 and 8, respectively. The Li/Ca and Mg/Ca ratios of spherulite fibers increase with aragonite precipitation rate. These results suggest that precipitation rate is a potentially important consideration when using Li isotopes and elemental ratios in natural carbonates as a proxy for seawater composition and temperature.
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 12 (2011): Q03001, doi:10.1029/2010GC003322.
Showing items related by title, author, creator and subject.
Temperature and carbonate ion effects on Mg/Ca and Sr/Ca ratios in benthic foraminifera : aragonitic species Hoeglundina elegans Rosenthal, Yair; Lear, Caroline H.; Oppo, Delia W.; Linsley, Braddock K. (American Geophysical Union, 2006-02-21)Core top samples from Atlantic (Little Bahama Banks (LBB)) and Pacific (Hawaii and Indonesia) depth transects have been analyzed in order to assess the influence of bottom water temperature (BWT) and aragonite saturation ...
Wang, Zhaohui Aleck; Lawson, Gareth L.; Pilskaln, Cynthia H.; Maas, Amy E. (John Wiley & Sons, 2017-01-22)The Gulf of Maine (GoME) is a shelf region especially vulnerable to ocean acidification (OA) due to natural conditions of low pH and aragonite saturation states (Ω-Ar). This study is the first to assess the major oceanic ...
Neodymium isotopes and concentrations in aragonitic scleractinian cold-water coral skeletons - modern calibration and evaluation of palaeo-applications Struve, Torben; van de Flierdt, Tina; Burke, Andrea; Robinson, Laura F.; Hammond, Samantha J.; Crocket, Kirsty C.; Bradtmiller, Louisa I.; Auro, Maureen E.; Mohamed, Kais J.; White, Nicholas J. (Elsevier, 2017-01-27)Cold-water corals (CWCs) are unique archives of mid-depth ocean chemistry and have been used successfully to reconstruct the neodymium (Nd) isotopic composition of seawater from a number of species. High and variable Nd ...