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    Provenance, routing and weathering history of heavy minerals from coastal placer deposits of southern Vietnam

    Nguyen, H. and Carter, Andrew and Hoang, L.V. and Vu, S.T. (2018) Provenance, routing and weathering history of heavy minerals from coastal placer deposits of southern Vietnam. Sedimentary Geology 373 , pp. 228-238. ISSN 0037-0738.

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    Abstract

    Heavy mineral rich sands along the coastal margin of southern Vietnam often contain commercial deposits of ilmenite and zircon but their origin is unknown. A multi-method approach based on petrology, geochemistry and detrital zircon geochronology was used to define the provenance and transport history of these mainly Quaternary sands. A trend of progressive enrichment of ilmenite TiO2 content, from north to south, was observed. This reflects increased levels of weathering attributed to a wider coastal margin and shelf in the south combined with a succession of erosion and reburial events associated with interstadial and interglacial sea-level changes. Weathering took place during lowstands. Detrital zircon U-Pb age signatures collected from 25 major river outlets along the coast of Vietnam helped to locate potential sand sources. Prominent age groups spanning 90-120 Ma and 220-250 Ma with a minor group at 400-500 Ma are present in all of the detrital zircon U-Pb age distributions of contemporary beach sands and Quaternary coastal dune placer deposits. Proterozoic grains are also present but constitute < 10% of dated grains. The main source terrain for the placer sands is southern Vietnam where there are widespread outcrops of Mesozoic magmatic rocks. Detrital zircon U-Pb age signatures from river sands that drain this area are identical to zircon age distributions in placer sands. River sands from northern Vietnam, the Mekong and its delta contain abundant Paleozoic and Proterozoic zircons, which are largely absent from the placer sands, and so are ruled out as primary sources.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Ilmenite, Zircon U-Pb, Provenance, Vietnam, Weathering, Seal-level change
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Divisions > Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Research Centres and Institutes: Earth and Planetary Sciences, Institute of
    Depositing User: Andy Carter
    Date Deposited: 12 Jul 2018 15:46
    Last Modified: 29 Jun 2020 04:53
    URI: http://eprints.bbk.ac.uk/id/eprint/22940

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