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dc.contributor.authorDoley, B.
dc.contributor.authorSaha, A.
dc.contributor.authorVerencar, A.
dc.contributor.authorMohan, M.R.
dc.date.accessioned2022-10-30
dc.date.accessioned2023-03-01T09:15:33Z
dc.date.available2022-09-27
dc.date.available2023-03-01T09:15:33Z
dc.date.issued2022
dc.identifier.citationGeochemistry, vol.82(3); 2022; Article no: 125899
dc.identifier.issn0009-2819
dc.identifier.otherhttps://www.sciencedirect.com/science/article/abs/pii/S0009281922000393
dc.identifier.urihttps://doi.org/10.1016/J.CHEMER.2022.125899
dc.identifier.urihttps://drs.nio.org/drs/handle/2264/8973
dc.description4.127
dc.description.abstractThe submarine volcanoes, located in the southern part of Andaman Sea, north eastern Indian Ocean, result from the subduction of the Indo-Australian Plate beneath the Southeast Asian Plate and represent one of the less studied submarine volcanism among the global arc systems.The present study provides new petrological and geochemical data for the recovered rocks from the submarine volcanoes and documents the petrogenetic evolution of Andaman arc system.Geochemical attributes classify the studied samples as basaltic andesite, andesite, dacite to rhyodacite reflecting sub-alkaline, intermediate to acidic composition of the magma.Petrographic studies of the basaltic andesites and andesites show plagioclase [An38-An57 in basaltic andesites; An27-An28 in andesites] and clinopyroxene as dominant phenocrystal phase in a cryptocrystalline groundmass.Plagioclase (An25-An45) marks the principal phenocrystal phase in dacite with sub-ordinate proportion of biotite and amphibole of both primary and secondary origin along with minor amount of K-feldspar.The submarine volcanic rocks from Andaman arc system exhibit pronounced LILE, LREE enrichments and HFSE (negative Nb, Ta and Ti anomalies), MREE and HREE depletion thereby endorsing the influence of subduction zone processes in their genesis.Elevated abundances of Th with relatively higher LREE/HFSE than LILE/HFSE, LILE/LREE suggest significant contribution of sediments from the subducting slab over slab-dehydrated aqueous fluids towards mantle wedge metasomatism thereby modifying the sub-arc mantle.Partial melting curves calculated using the non-modal batch melting equation suggest primary magma generated due to ~31-35 % degree of partial melting of spinel lherzolite mantle beneath the arc system.Fractional crystallization model suggests fractionation of 45 % plagioclase, 40 % clinopyroxene, 5-10 % amphibole and 5-10 % biotite which is consistent with the petrographic observations.Further, the assimilation-fractional-crystallization (AFC) model for the studied rocks indicates nominal crustal contamination.Therefore, this study infers that the melt evolution history for the Andaman arc volcanic rocks can be translated in terms of (i) generation of precursor magma by ~31-35 % partial melting of a spinel lherzolite mantle wedge, metasomatized predominantly by subducted slab sediments and (ii) the parent magma generation was ensued by fractionation dominated melt differentiation with nominal input from arc crust.
dc.languageen
dc.publisherElsevier
dc.relation.isreferencedbySCI
dc.rightsOnly the author version of the copright reserved papers uploaded. Contact drs@nio.org for any complaints regarding copyright violations
dc.titleMelt generation and trace element fractionation of intermediate arc magma from Andaman subduction zone
dc.typeJournal Article
dc.affiliation.authorCSIR-National Institute of Oceanography, Dona Paula, Goa, India


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