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Carbon and oxygen isotope,compositions of the carbonate facies in the Vindhyan Supergroup, central India

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Title Carbon and oxygen isotope,compositions of the carbonate facies in the Vindhyan Supergroup, central India
 
Creator BANERJEE, S
BHATTACHARYA, SK
SARKAR, S
 
Subject precambrian carbonates
sequence stratigraphy
isotopic composition
stable isotopes
belt supergroup
son valley
evolution
limestone
geochemistry
successions
facies
meteoric water
diagenesis
vindhyan
proterozoic
 
Description The Vindhyan sedimentary succession in central India spans a wide time bracket from the Paleoproterozoic to the Neoproterozoic period. Chronostratigraphic significance of stable carbon and oxygen isotope ratios of the carbonate phase in Vindhyan sediments has been discussed in some recent studies. However, the subtle controls of facies variation, depositional setting and post-depositional diagenesis on stable isotope compositions are not yet clearly understood. The Vindhyan Supergroup hosts four carbonate units, exhibiting a wide variability in depositional processes and paleogeography. A detailed facies-specific carbon and oxygen isotope study of the carbonate units was undertaken by us to investigate the effect of these processes and to identify the least altered isotope values. It is seen that both carbon and oxygen isotope compositions have been affected by early meteoric water diagenesis. The effect of diagenetic alteration is, however, more pronounced in case of oxygen isotopes than carbon isotopes. Stable isotope compositions remained insensitive to facies only when sediments accumulated in a shallow shelf setting without being exposed. Major alteration of original isotope ratios was observed in case of shallow marine carbonates, which became exposed to meteoric fluids during early diagenetic stage. Duration of exposure possibly determined the magnitude of alteration and shift from the original values. Moreover, dolomitization is found to be accompanied by appreciable alteration of isotope compositions in some of the carbonates. The present study suggests that variations in sediment depositional settings, in particular the possibility of subaerial exposure, need to be considered while extracting chronostratigraphic significance from delta C-13 data.
 
Publisher INDIAN ACADEMY SCIENCES
 
Date 2011-08-02T01:15:58Z
2011-12-26T12:53:36Z
2011-12-27T05:40:07Z
2011-08-02T01:15:58Z
2011-12-26T12:53:36Z
2011-12-27T05:40:07Z
2006
 
Type Article
 
Identifier JOURNAL OF EARTH SYSTEM SCIENCE, 115(1), 113-134
0253-4126
http://dx.doi.org/10.1007/BF02703029
http://dspace.library.iitb.ac.in/xmlui/handle/10054/8604
http://hdl.handle.net/10054/8604
 
Language en