Inside story: An X-ray computed tomography method for assessing dissolution in the tests of planktonic foraminifera

Johnstone, Heather J.H. and Schulz, Michael and Barker, Stephen and Elderfield, Henry (2010) Inside story: An X-ray computed tomography method for assessing dissolution in the tests of planktonic foraminifera. Marine Micropaleontology, 77 (1-2). p. 58. ISSN 03778398 DOI 10.1016/j.marmicro.2010.07.004

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Official URL: http://dx.doi.org/10.1016/j.marmicro.2010.07.004

Abstract

X-ray computed tomography (CT) provides an insight into the progression of dissolution in the tests of planktonic foraminifera. Four species of foraminifera (G. ruber [white], G. sacculifer, N. dutertrei and P. obliquiloculata) from Pacific, Atlantic and Indian Ocean core-top samples were examined by CT and SEM. Inner chamber walls began to dissolve at Δ[CO32−] values of 12–14 μmol/kg. Close to the calcite saturation horizon, dissolution and precipitation of calcite may occur simultaneously. Inner calcite of G. sacculifer, N. dutertrei and P. obliquiloculata from such sites appeared altered or replaced, whereas outer crust calcite was dense with no pores. Unlike the other species, there was no distinction between inner and outer calcite in CT scans of G. ruber. Empty calcite crusts of N. dutertrei and P. obliquiloculata were most resistant to dissolution and were present in samples where Δ[CO32−] ≈ − 20 μmol/kg. Five stages of preservation were identified in CT scans, and an empirical dissolution index, XDX, was established. XDX appears to be insensitive to initial test mass. Mass loss in response to dissolution was similar between species and sites at ~ 0.4 μg/μmol/kg. We provide calibrations to estimate Δ[CO32−] and initial test mass from XDX.

Item Type: Article
Uncontrolled Keywords: 2010AREP; IA61;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Marine Micropaleontology
Volume: 77
Page Range: p. 58
Identification Number: 10.1016/j.marmicro.2010.07.004
Depositing User: Sarah Humbert
Date Deposited: 06 Nov 2010 12:30
Last Modified: 23 Jul 2013 10:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/1960

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