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<p>The Upper Paleocene–Lower Eocene Tura Formation, encountered in most oil wells of the Upper Assam Shelf, India, rests non-conformably over the Precambrian granitic basement. Its type section is well exposed in the West Garo Hills of Meghalaya, India. Petrographic and geochemical analyses of the sandstones have been employed to determine their provenance, tectonic setting, and prevailing paleoenvironmental conditions. The Tura sandstones are mainly classified as quartz arenite, sublitharenite, and some subarkosic types. Geochemical data, including trace elements and rare earth elements (REEs), indicate that the sandstones were predominantly derived from felsic sources. Tectonic discrimination diagrams suggest that the sandstones were deposited in an active margin setting. The sandstones were derived from source areas that experienced semi-humid to humid climatic conditions with moderate to intense degrees of chemical weathering, as indicated by paleoweathering indices such as the Chemical Index of Alteration (CIA: 79.10), Chemical Index of Weathering (CIW: 84.20), and Index of Compositional Variability (ICV: 7.67).</p>

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Provenance, tectonic setting and paleoenvironment of the Tura Sandstone Formation, Northeast India: An integrated approach

  • 期刊论文

  • 发表日期：

    2025年8月24日

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  • Pradip Borgohain,
  • Devojit Bezbaruah,
  • Yadav Krishna Gogoi,
  • Anurag Bharadwaj,
  • Bishal Singh,
  • Garima Konwar,
  • Dipankar Saikia,
  • Mondip Sarma,
  • Bubul Bharali

摘要

The Upper Paleocene–Lower Eocene Tura Formation, encountered in most oil wells of the Upper Assam Shelf, India, rests non-conformably over the Precambrian granitic basement. Its type section is well exposed in the West Garo Hills of Meghalaya, India. Petrographic and geochemical analyses of the sandstones have been employed to determine their provenance, tectonic setting, and prevailing paleoenvironmental conditions. The Tura sandstones are mainly classified as quartz arenite, sublitharenite, and some subarkosic types. Geochemical data, including trace elements and rare earth elements (REEs), indicate that the sandstones were predominantly derived from felsic sources. Tectonic discrimination diagrams suggest that the sandstones were deposited in an active margin setting. The sandstones were derived from source areas that experienced semi-humid to humid climatic conditions with moderate to intense degrees of chemical weathering, as indicated by paleoweathering indices such as the Chemical Index of Alteration (CIA: 79.10), Chemical Index of Weathering (CIW: 84.20), and Index of Compositional Variability (ICV: 7.67).