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Microbially originated wrinkle structures on sandstone and their stratigraphic context: Palaeoproterozoic Koldaha Shale, central India

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Title Microbially originated wrinkle structures on sandstone and their stratigraphic context: Palaeoproterozoic Koldaha Shale, central India
 
Creator BANERJEE, S
JEEVANKUMAR, S
 
Subject sedimentary structures
deposits
transition
vindhyan
mats
preservation
supergroup
evolution
life
palaeoproterozoic sand wrinkles
microbial mat
genetic process
stratigraphic context
koldaha shale
 
Description Wrinkle structures on sandstone beds are abundant and present in diverse forms in the Palaeoproterozoic Koldaha Shale, Vindhyan basin, central India. The inferred palaeogeography of sedimentation ranges from offshore marine to terrestrial, the wrinkled sandstones belonging to the relatively deeper marine part. Good preservation of ultramicroscopic microbial elements within these sandstones strongly supports a microbial mat origin of the wrinkles, which was facilitated by development of an oxygen depleted condition immediately beneath the sediment-water interface, as depicted in early pyrite growth. Later, impermeable shale encasing the sandstone beds arrested further scope for destruction of the microbial elements. Trapping of fine detritus by microbial filaments is documented by the invariable occurrence of a silty clay veneer on the wrinkled surfaces, and by its characteristic texture. Wrinkle morphology has been classified and an attempt has been made to understand the origin of each of the varieties, and to visualize the processes that acted upon the microbial mats to produce the wrinkle structures in their specific palaeogeographic context. The general palaeogeographic bias in occurrence of the sandy wrinkles is well reflected in their concentration in the lower part of the highstand systems tracts (HST's), one superposed above the other, comprising the Koldaha Shale. The smaller-scale palaeogeographic control is indicated by compartmentalization of two wrinkle varieties in the upper and the basal intervals of the HST's, and overlapping occurrence of other varieties in the medial interval with apparent preference for either the upper or the lower levels. © 2005
 
Publisher ELSEVIER SCIENCE BV
 
Date 2011-07-25T20:23:20Z
2011-12-26T12:51:57Z
2011-12-27T05:38:49Z
2011-07-25T20:23:20Z
2011-12-26T12:51:57Z
2011-12-27T05:38:49Z
2005
 
Type Article
 
Identifier SEDIMENTARY GEOLOGY, 176(1-2), 211-224
0037-0738
http://dx.doi.org/10.1016/j.sedgeo.2004.12.013
http://dspace.library.iitb.ac.in/xmlui/handle/10054/6775
http://hdl.handle.net/10054/6775
 
Language en