• Internal geometry of a thrust sheet, eastern Proterozoic belt, Godavari Valley, South India

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    • Keywords


      Cleavage duplex; external zone; Godavari Valley; imbricate fan; mesoscopic folds; thrust sheet; Proterozoic

    • Abstract


      A small thrust sheet, named Pedda Gutta thrust sheet, consisting of calcareous to cherty argillites and cherts, and juxtaposed against tidal-intertidal cross-bedded quartzites and stromatolitic and sileceous limestone in the eastern Proterozoic belt, Godavari Valley, exhibits structures comparable in style to those of the external zone of a fold-thrust mountain belt. A wide spectrum of periodic and aperiodic mesoscopic folds varying from upright ones with rounded hinges and attenuated limbs, through noncylindrical kinks to whalebacks and sheath-like forms have developed within the small volume of the thrust sheet, the preserved thickness of which is of the order of 50 metres (comparable in scale to cleavage duplexes). Cleavage development is also heterogeneous across the width of the sheet. Displacement transfer from faults to folds and vice-versa is a common feature.

      On the basis of the distribution of the mesoscopic structures of varying style within the sheet and localization of fault rocks, three slices (wedges) have been recognized, each bounded on the east by a thrust which is steep at the current erosion level but interpreted to be of listric form making the thrust network comparable in architecture, though not in scale, to a hinterland (west) dipping imbricate fan.

    • Author Affiliations


      Dilip Saha1

      1. Geological Studies Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Calcutta - 700035, India
    • Dates

  • Journal of Earth System Science | News

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