• Login
    View Item 
    •   DSpace Home
    • Institute's contributions
    • Scholarly literature
    • View Item
    •   DSpace Home
    • Institute's contributions
    • Scholarly literature
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Geochemical characteristics of basalts from Andaman subduction zone: Implications on magma genesis at intraoceanic back-arc spreading centres

    Thumbnail
    View/Open
    Geolog_J_54_3489a.pdf (2.868Mb)
    Date
    2019
    Author
    Saha, A.
    Mudholkar, A.V.
    KameshRaju, K.A.
    Doley, B.
    Sensarma, S.
    Metadata
    Show full item record
    Abstract
    This study reports new petrological and geochemical data for the ocean floor volcanic rocks dredged from the back?arc basin of the Andaman Sea and elucidates their geochemical characteristics and petrogenetic aspects to provide insights into the melt generation processes, oceanic crust emplacement, and tectonomagmatic evolution of the Andaman back?arc basin. The studied samples are porphyritic basalts with olivine, plagioclase, and clinopyroxene representing the phenocrysts and the groundmass composition marked by plagioclase microlites, granular clinopyroxenes, and glass. Geochemical characteristics of these basalts reflect sub?alkaline, tholeiitic composition of precursor magma that experienced clinopyroxene?Ti magnetite fractionation. The overall geochemical trend for these basalts reflects LILE-HFSE-REE depleted MORB?type chemistry which is modified by input from subduction?derived components. Pronounced enrichment in selected LREE (Nd) and incompatible fluid?mobile trace elements like Ba with positive primitive mantle?normalized La and Sr anomalies in the majority of these basalts are attributed to transport and influx of slab?dehydrated fluids and sediments into the depleted back?arc mantle asthenosphere from the dehydrating subducted oceanic lithosphere in the volcanic arc front during initial stage of back?arc rifting in the Andaman Sea. The studied basalts were derived by 10%-30% partial melting of a heterogeneous spinel lherzolitic mantle at a shallow depth. The chemical heterogeneity of the spinel lherozolite source suggests an enrichment?depletion history of back?arc mantle correlatable with the transitional tectonic evolution of the back?arc basin from an initial rifting to matured spreading stage. The depleted MORB?type mantle (DMM) beneath a juvenile back arc experienced infiltration of fluids and subduction?derived components (SDC) from proximal subducting oceanic slab that gradually diminished with increasing distance from the arc and progressive back?arc spreading. The episodes of melt generation and magma genesis invoke a gradual geodynamic transition from incipient back?arc rifting to matured back?arc spreading stages in the tectonomagmatic evolution of the Andaman back?arc basin system. Oceanic crust generated during the incipient rifting stage sampled arc?type melts enriched and hydrated by subduction inputs and fluid flux, while oceanic crust formed during matured back?arc extension stage inherited trace element depleted MORB?type�
    URI
    https://doi.org/10.1002/gj.3345
    http://drs.nio.org/drs/handle/2264/8232
    Collections
    • Scholarly literature [9074]

    DSpace software copyright © 2002-2016  DuraSpace
    Contact Us | Send Feedback
    Theme by 
    Atmire NV
     

     

    Browse

    All of DSpaceCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    DSpace software copyright © 2002-2016  DuraSpace
    Contact Us | Send Feedback
    Theme by 
    Atmire NV