• Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/jess/122/05/1359-1371

    • Keywords

       

      Lockeia; Protovirgularia; Cruziana ichnofacies; Callovian; Jaisalmer Formation; Rajasthan.

    • Abstract

       

      A Lockeia-Protovirgularia ichnofauna representing the Cruziana ichnofacies is reported from a calcareous sandstone horizon of the Callovian Bada Bagh Member, Jaisalmer Formation, Rajasthan. The ichnoassemblage is characterized by Lockeia cunctator, L. siliquaria, Protovirgularia ?bidirectionalis, P. rugosa, Ptychoplasma vagans along with Palaeophycus tubularis, P. striatus, Heliophycus isp. And Lophoctenium isp. Use of numerical analysis yielding length to width ratio, slopes and coefficient of determination helps in confirming identification of ichnospecies of Lockeia. Fine morphological details of Lockeia and Protovirgularia, especially sharp and closely spaced chevrons of Protovirgularia, indicate that the substrate in which they were emplaced was stiff, resistant, dewatered and better consolidated. Therefore, it construes that this ichnoassemblage belonging to the classical Cruziana ichnofacies occurs in stiff softground and not a typical softground. Though the ichnofacies of this calcareous sandstone bed indicates low-medium energy condition under subtidal environment of deposition, underlying strata containing Arenicolites, Skolithos and Curvolithus of Skolithos ichnofacies indicate intertidal sandy shore environment with high energy conditions. Thus, it is concluded that this area was undergoing continuous, gradual deepening. However, the percentage of Thalassinoides, Ophiomorpha and Phycodes in the overlying bed is quite high suggesting an increase in the energy conditions resulting from a probable shallowing.

    • Author Affiliations

       

      Amruta R Paranjape1 Kantimati G Kulkarni1 Shweta S Gurav1

      1. Geology and Palaeontology Group, Agharkar Research Institute, Pune 411 004, India.
    • Dates

       
  • Journal of Earth System Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.