• A KRISHNAKANTA SINGH

      Articles written in Journal of Earth System Science

    • Evolution of Late Cretaceous to Palaeogene basalt–andesite–dacite–rhyolite volcanic suites along the northern margin of the Ladakh magmatic arc, NW Himalaya, India

      NONGMAITHEM LAKHAN A KRISHNAKANTA SINGH B P SINGH KSHETRIMAYUM PREMI GOVIND OINAM

      More Details Abstract Fulltext PDF

      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.

    • Geochemical characteristics of fluorine- and chlorine-bearing biotite from Tusham Ring Complex, NW India: Constraints on halogen distribution and geodynamic evolution

      NAVEEN KUMAR NARESH KUMAR RADHIKA SHARMA A KRISHNAKANTA SINGH

      More Details Abstract Fulltext PDF

      The present study is carried out to understand the factors controlling halogens present in biotites, role of halogens in metallogeny in context to the magmatic evolution of Tusham Ring Complex (TRC), NW Indian Shield. The investigated rocks are identified with hypersolvus, high-K calc-alkaline, peraluminous, ferroan-enriched and typical A-type granitoids affinity. They are enriched in SiO$_{2}$, Na$_{2}$O + K$_{2}$O, REEs (except Eu), LILE + HFSE, elevated in Fe/Mg, Ga/Al, Th/U, A/CNK ratio and depleted in CaO, MgO, Sr, Cr, Ni, P, Ti, V and Eu abundances. The sequential accumulation of incompatible trace elements (LILE, HFSE, REEs and others) in studied rocks overlaps almost entirely the range of rare metal granitoids and high heat-producing granitoids. The elemental geochemistry in conjunction with high abundances of F (0.80–7.11 wt%) and Cl (0.44–1.56 wt%) in biotite mineral collectively attribute to hydrothermal fluid activity and the subsequent mineralization around TRC region. Our new results suggest that the acidic magmatism that occurred in the TRC is considered as a part of the plume-related Neoproterozoic Malani Igneous Suite (MIS) anorogenic magmatism.

      $\bf{Highlights}$

      $\bullet$ The bulk geochemistry data and the high concentration of fluorine (0.80–7.11 wt%) and chlorine (0.44–1.56 wt %) in biotite mineral indicate halogen enriched magmatic source.

      $\bullet$ The halogen enriched magma is an important key to understand the magmatic evolution and metallogeny of Tusham Ring Complex.

      $\bullet$ The high concentration of rare metal, rare earth metals and radioactive elements suggests that the investigated granitoids are rare metal granitoids with high heat producing capacity.

      $\bullet$ The acid volcano-plutonic rocks of Tusham Ring Complex are important barcodes to reconstruct the Neoproterozoic Rodinia supercontinent and related tecto-magmatic activities occurred in NW Indian shield.

  • 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

© 2021-2022 Indian Academy of Sciences, Bengaluru.