Melezhik, V.A., Fallick, A.E., Smirnov, Y.P. and Yakovlev, Y.N. (2003) Fractionation of carbon and oxygen isotopes in 13C-rich Palaeoproterozoic dolostones in the transition from medium-gradegreenschist facies: a case study from the Kola Superdeep Drillhole. Journal of the Geological Society, 160(1), pp. 71-82.
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Abstract
Samples from the Kola Superdeep Drillhole (12 262 m), a deep drillhole (1060 m), and from the surface, seaprated by only around 10 km, provided a unique opportunity for direct tracing of delta(13)C and delta(18)O changes through a low- to high-grade greenschist-facies transition within impure, C-13-rich Palaeoproterozoic dolostones. The least-altered dolostones have delta(13)C of +9 parts per thousand and delta(18)O of 22 parts per thousand. The metamorphic transition is expressed by dolomite + calcite, + quartz K-feldspar - tremolite + calcite(2) dolomite calcite, and defined by C-13 depletion of calcite(2) (c. 3.0 parts per thousand), calcite, (1.0-2.0 parts per thousand) and dolomite (<1 parts per thousand) which is associated with a Rayleigh distillation process. delta(18)O shows a considerable resetting in all carbonate components by around 6 parts per thousand caused by a Rayleigh distillation process coupled with isotopic exchange between the carbonates and fluids with an external source of oxygen. The retrograde alteration is expressed by the formation of quartz-chlorite veinlets within tectonically bound zones of brecciated and sheared dolostones. The maximum 180 depletion in dolomite (9 parts per thousand) and calcite(1) (c. 4 parts per thousand) were probably controlled by infiltration into permeable zones of external fluids associated with retrograde alteration; delta(13)C remains largely unaffected.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Fallick, Professor Anthony |
Authors: | Melezhik, V.A., Fallick, A.E., Smirnov, Y.P., and Yakovlev, Y.N. |
Subjects: | Q Science > QE Geology |
College/School: | College of Science and Engineering > Scottish Universities Environmental Research Centre |
Journal Name: | Journal of the Geological Society |
Publisher: | Geological Society of London |
ISSN: | 0016-7649 |
Copyright Holders: | © Copyright The Geological Society of London |
First Published: | First published in Journal of the Geological Society 160(1)71-82 |
Publisher Policy: | Reproduced in accordance with the copyright policy of the publisher |
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