• Carbonaceous material in Larji–Rampur window, Himachal Himalaya: Carbon isotope compositions, micro Raman spectroscopy and implications

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      https://www.ias.ac.in/article/fulltext/jess/130/0239

    • Keywords

       

      Carbonaceous material; stable carbon isotope; Raman spectroscopy; Larji–Rampur window; Himachal Himalaya.

    • Abstract

       

      This work focuses on the natural graphitic carbonaceous material (GCM) distributed in metasedimentary and crystalline rocks in and around Larji–Rampur tectonic window, Himachal Himalaya. The GCM, associated with the ore mineralization, is mostly flaky, however, it is also granular and amorphous. The micro Raman spectroscopy of representative samples confirms that the studied GCM is mostly disordered graphite and rarely poorly ordered graphite, but well crystalline ordered graphite is also present. The carbon isotope compositions reflecting the source of carbon in GCM at various locations attribute that the carbon was mostly sedimentary organic carbon which has been metamorphosed to disordered graphite, however, the ${\delta}^{13}$C of the inorganic carbon contents in metabasalts from Bhallan signify the involvement of fluid possibly derived from the mantle. Limited ${\delta}^{13}$C$_{inorganic}$ data in a range from 0 to -11%, points to the heavier carbon probably derived from the diagenetic carbonates or dissolved organic matter. Overall, the carbon isotope compositions of GCM from the Larji–Rampur window reject diversity in carbon source and mixing of carbon reservoirs, which can adequately be explained by the Proterozoic marine carbon cycling. A close linkage in the depositional processes of GCM with ore mineralization in the area is also invoked.

      $\bf{Highlights}$

      $\bullet$ The graphitic carbonaceous material (GCM) is present in and around Larji–Rampur tectonic window, Himachal Himalaya, at places associated with ore mineralization.

      $\bullet$ Micro Raman spectroscopy confirms the presence that this GCM is mostly disordered graphite though the ordered graphite is also present uncommonly.

      $\bullet$ The ${\delta}^{13}$C values vary widely from –1.5‰ to –33.5‰. The ${\delta}^{13}$C compositions are heterogeneous and complex carbon systematics is apparent. In addition to the predominant sedimentary organic carbon form Proterozoic marine carbon, it was also derived from carbonate source, carbon from the fluids, and rarely but possibly from the mantle source.

      $\bullet$ A close linkage in the formation and evolution processes of the GCM with the ore mineralization is also invoked.

    • Author Affiliations

       

      SHRUTI RANA1 RAJESH SHARMA1 SANTOSH KUMAR2

      1. Wadia Institute of Himalayan Geology, 33, General Mahadeo Singh Road, Dehradun 248 001, India.
      2. Department of Geology, Kumaun University, Nainital, India.
    • Dates

       
  • Journal of Earth System Science | News

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