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Carbon and oxygen isotopic variations in peritidal stromatolite cycles, Paleoproterozoic Kajrahat Limestone, Vindhyan basin of central India

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Title Carbon and oxygen isotopic variations in peritidal stromatolite cycles, Paleoproterozoic Kajrahat Limestone, Vindhyan basin of central India
 
Creator BANERJEE, SANTANU
BHATTACHARYA, S K
SARKAR, SUBIR
 
Subject paleoproterozoic
stable isotopes
stromatolite cycles
subaerial exposure
vindhyan
 
Description Variations of carbon and oxygen isotopic ratios in response to cyclical sea level fluctuations have been documented from a Paleoproterozoic peritidal stromatolite succession. The upper division of the Kajrahat Limestone, Vindhyan Supergroup of central India consists of several shallowing upward stromatolite cycles identified by regular and systematic changes in stromatolite size. Normally, larger stromatolites are followed upward in the succession by smaller stromatolites and microbial laminites that occupy the top of the cycle. Desiccation cracks are found in all the facies indicating subaerial exposure. We investigated the stable isotope compositional variations across nine complete stromatolite cycles showing frequent subaerial emergence. Carbon and oxygen isotopic values of the limestones, in general, are comparable to contemporary marine values available from earlier studies but show regular depletion in response to shallowing of the water level. The δ13C and δ18O values of the limestones vary within an individual stromatolite cycle; depleted values characterize the topmost part of the cycles. The isotope pattern is explained by micritic carbonate deposition in different sub environments of the shallow marine domain having different salinity and variable duration of exposure. These variations also probably caused the observed scatter in δ13C and δ18O values of supratidal microbial laminites.
 
Publisher Elsevier
 
Date 2009-06-19T04:18:06Z
2011-11-25T15:01:58Z
2011-12-26T13:04:34Z
2011-12-27T05:50:28Z
2009-06-19T04:18:06Z
2011-11-25T15:01:58Z
2011-12-26T13:04:34Z
2011-12-27T05:50:28Z
2007
 
Type Article
 
Identifier Journal of Asian Earth Sciences 29(5-6), 823-831
http://dx.doi.org/10.1016/j.jseaes.2006.05.006
1367-9120
http://hdl.handle.net/10054/1528
http://dspace.library.iitb.ac.in/xmlui/handle/10054/1528
 
Language en