Facies Sequence and Cryptic Imprint of Sag Tectonics in the Late Proterozoic Sirbu Shale, Central India

  1. Wladyslaw Altermann3 and
  2. Patricia L. Corcoran4
  1. S. Sarkar1,
  2. S. Chakraborty1,
  3. S. Banerjee2 and
  4. P. K. Bose1

Published Online: 12 MAR 2009

DOI: 10.1002/9781444304312.ch17

Precambrian Sedimentary Environments: A Modern Approach to Ancient Depositional Systems

Precambrian Sedimentary Environments: A Modern Approach to Ancient Depositional Systems

How to Cite

Sarkar, S., Chakraborty, S., Banerjee, S. and Bose, P. K. (2002) Facies Sequence and Cryptic Imprint of Sag Tectonics in the Late Proterozoic Sirbu Shale, Central India, in Precambrian Sedimentary Environments: A Modern Approach to Ancient Depositional Systems (eds W. Altermann and P. L. Corcoran), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304312.ch17

Editor Information

  1. 3

    Institut für Allgemeine und Angewandte Geologie, Ludwig-Maximilians-Universität München, Luisenstrasse 37, D-80333 Munich, Germany

  2. 4

    Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia, B3H 3J5, Canada

Author Information

  1. 1

    Department of Geological Sciences, Jadavpur University, Calcutta-700 032, India

  2. 2

    Department of Earth Sciences, IIT Bombay, Powai, Mumbai-400 076, India

Publication History

  1. Published Online: 12 MAR 2009
  2. Published Print: 18 FEB 2002

ISBN Information

Print ISBN: 9780632064151

Online ISBN: 9781444304312

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Keywords:

  • facies sequence and cryptic imprint of sag tectonics in late proterozoic Sirbu Shale, Central India;
  • upper section of late proterozoic Sirbu Shale, central India - dominated shelf and lagoonal palaeoenvironment;
  • sag tectonics in Sirbu shale;
  • facies package;
  • deformation structures

Summary

This paper examines the upper section (<185 m) of the late Proterozoic Sirbu Shale, central India, laid down in a storm-dominated shelf and lagoonal palaeoenvironment. Five of the six facies are laterally extensive, cyclical, interbedded shale-siltstone/fine sandstone. They generally have gradational mutual transitions and are amenable to palaeogeographical interpretation. The sixth facies is a coarse sandstone of low textural/ mineralogical maturity, confined to a localized occurrence and encased by one of the deeper shelf facies. The coarser interbeds bear storm signatures in all the facies. Current-formed features below storm beds record dominantly shore-parallel flow, although a shore-normal component is also evident. In the westward-opening intracratonic sag basin where deposition took place, the shelf succession built up as an overall prograding highstand systems tract that is divisible into a number of metre-scale parasequences. Slump features on top of each of the parasequences correlate the intervening marine flooding events with NE–SW extensional events and resultant landward subsidence. Fischer plots of parasequences reveal another, cryptic low-frequency depositional cyclicity. Troughs in the Fischer curves, denoting the longer cycle, roughly coincide with selective occurrence of NE–SW trending slide planes, implying superimposition of a NW–SE extension on the more frequent NE–SW extension. Enhanced subsidence is thus suggested at longer intervals owing to simultaneous orthogonal extension. The NE–SW extension reflects occasional readjustment of underlying rift blocks, whereas the NW–SE extension was possibly related to a plate-margin process. The resultant shelf basin probably assumed a NW–SE elongated, oval geometry with a dominant NE or landward-sloping flank. Plotting of shelf succession thickness downwards from a datum plane at a large number of locations simulates a three-dimensional basin configuration, as predicted from the inferred basin dynamics.