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Author Sadekov, Aleksey Yu. ♦ Eggins, Stephen M. ♦ Deckker, Patrick De
Source CiteSeerX
Content type Text
File Format PDF
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Electron Microprobe Mapping ♦ Mg Ca Distribution ♦ Planktonic Foraminifera Specie ♦ Mmol Mol ♦ Symbiont-free Specie ♦ Mg Ca ♦ Vital Effect ♦ Mg Ca Variation ♦ Individual Test ♦ Symbiotic Specie ♦ Difference Equates ♦ Past Oceanic Temperature ♦ High-mg Ca ♦ Symbiont-bearing Specie ♦ Temperature Change ♦ Past Seawater Temperature ♦ Neogloboquadrina Incompta ♦ Investigated Specie Display Large Variation ♦ Globigerinoides Ruber ♦ Calcification Temperature ♦ Careful Evaluation ♦ Modern Planktonic Foraminifer Specie ♦ Reliable Reconstruction ♦ Low Mg Ca ♦ Pachyderma Dex ♦ Mg Ca Composition ♦ Compositional Band ♦ Apparent Calcification Temperature Change ♦ Water Column
Abstract [1] The distribution of Mg/Ca within the tests of eight modern planktonic foraminifer species has been characterized using electron microprobe mapping. Species include several that are commonly used for estimation of past seawater temperatures (Globigerinoides ruber, G. sacculifer, Neogloboquadrina incompta (synonym of N. pachyderma dex.), N. dutertrei, and G. truncatulinoides). Each of the investigated species displays large variations in Mg/Ca composition within individual tests. However, the pattern of Mg/Ca variation is notably different between symbiont-bearing and symbiont-free species. In symbiotic species, cyclic Mg/Ca compositional banding occurs that is characterized by narrow (<1–3 mm), high-Mg/Ca (typically 8–11 mmol/mol) bands, intercalated between broader low Mg/Ca (typically 1– 5 mmol/mol) bands. This factor of 2–3 difference equates to an apparent calcification temperature change of 10C or more. Such temperature changes are considered highly improbable and suggest vital effects significantly modify the incorporation of Mg/Ca into the tests of symbiont-bearing species. These vital effects remain poorly understood and demand further careful evaluation as they may need to be accounted for when making reliable reconstructions of past oceanic temperatures. Symbiont-free species typically have fewer and broader compositional bands that may reflect more closely changes in calcification temperature as these species migrate within a water column.
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Publisher Date 2005-01-01