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      https://www.ias.ac.in/article/fulltext/jess/129/0108

    • Keywords

       

      Subduction; Khardung volcanic suites; Neo-Tethyan; Ladakh magmatic arc

    • Abstract

       

      This paper describes a comprehensive geochemical study of basalt–andesite–dacite–rhyolite volcanic association in the Khardung volcanic suite along the northern margin of the Ladakh magmatic arc. This volcanic association is outcropped mainly in the segment of the further north of the Khardung village to Khalsar delineating from the Ladakh magmatic arc by $\sim$2 km thick porphyritic sill. The closed association of basalt–andesite–dacite–rhyolite volcanic within a volcanic suite suggests that these rocks may be genetically inter-related and might have derived from the same parental magma source. Felsic lavas (dacite–rhyolite) show $\rm{SiO}_{2}$ range from 64.75 to 79.11 wt.%, while intermediate lavas (basaltic andesite–andesite) ranges from 50.80 to 51.81 wt.% with mafic lavas (basalt) span from 53.39 to 62.05 wt.%. These volcanic suites show enrichment in LIL elements (Rb, Ba, Th, U, and Pb) and depletion in Nb, P, and Ti, which can be evident in spider diagrams with pronounced to mild Eu negative anomalies in REE patterns. Previous reports on zircon U–Pb ages of the Khardung volcanics range between 60 and 69.7 Ma confirm an upper bound eruption age of this volcanic suite as pre-collision continental arc magmas. Hence, the results of geochemical modelling suggest that the Khardung mafic–intermediate-felsic lavas were generated from the melting of 1–4% spinel and garnet-bearing lherzolite sources. The generated parental magmas were modified by crustal materials during the magma ascent along with fractional crystallization and were metasomatized by slab-derived fluids released from the subducting Neo-Tethyan oceanic crust during the Late Cretaceous to Palaeogene in the northern margin of the Ladakh magmatic arc.

    • Author Affiliations

       

      NONGMAITHEM LAKHAN1 A KRISHNAKANTA SINGH1 B P SINGH2 KSHETRIMAYUM PREMI3 GOVIND OINAM1

      1. Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India.
      2. Department of Geology, Banaras Hindu University, Varanasi 221 005, India.
      3. Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee 247 667, India.
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