Wednesday, July 18, 2012

A Look Back...10 Years

Use of cave deposits as paleoclimate indicators requires that the minerals preserve geochemical tracers of environmental conditions, a factor that may be compromised if minerals are altered.  To explore the utility of these features, Frisia et al. examined the genesis, nature (morphology, isotope geochemistry, and mineralogy), distribution, and alteration of aragonite in cave deposits in France.  The data revealed that calcite and several habits of aragonite can grow in the same cave system, and that calcite replaced aragonite in less than 1 ka. The results also showed that the “isotope signal of different aragonite habits may reflect conditions of formation rather than climate parameters” and that isotopes in calcite varied markedly, depending on if it were primary or replacing aragonite.  In both cases, however, the data highlighted the need for careful integration of geochemical, textural, trace element, and isotopic data for assessing the utility of speleothems to characterize past climate.

Aragonite-calcite relationships in speleothems (Grotte de Clamouse, France): Environment, fabrics, and carbonate geochemistry by  Silvia Frisia, Andrea Borsato, Ian J. Fairchild, Frank McDermott and Enrico M. Selmo

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