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    A late Oligocene tectono-volcanic event in East Kalimantan and the implications for tectonics and sedimentation in Borneo

    Moss, S.J. and Carter, Andrew and Baker, S. and Hurford, A.J. (1998) A late Oligocene tectono-volcanic event in East Kalimantan and the implications for tectonics and sedimentation in Borneo. Journal of the Geological Society 155 (1), pp. 177-192. ISSN 0016-7649.

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    New apatite fission-track data, K–Ar radiometric ages, and major and trace element geochem- istry from the northern part of the Kutai Basin, Borneo document a major regional tectono-volcanic episode. Apatite fission-track data from late Cretaceous sandstones indicate a period of rapid cooling in the late Oligocene. Cooling, initiated by a rapid temperature drop of over 40°C within c. 2 Ma might have been caused by increased denudation associated with tectonic movements. Rapid cooling is also concomitant with a phase of igneous activity. New K–Ar radiometric ages of andesitic–dacitic high-level intrusive rocks and associated volcanic rocks give ages of 23–18 Ma, which correlate with the regionally extensive late Oligocene–Miocene Sintang Intrusives Suite. These andesitic–dacitic high-level intrusive rocks also have geochemical characteristics of arc-related rocks. The sedimentary response to this tectono-volcanic event is the eastwards shift of the western basin margin and the inception of deltaic deposition around the newly re-defined basin margins. Up to 9 km of sediment was deposited in the basin during Miocene delta progradation, covering thick sequences of Palaeogene bathyal shales, providing an excellent décollement surface for later inversion. Elsewhere in Borneo and adjacent areas of SE Asia, major events recorded in the late Oligocene to early Miocene include major thrust imbrication and volcanic arc activity, the cause of which is unclear: Possibilities include the collision of Australia with the Philippine Sea Plate, the counter-clockwise rotation of Borneo in the Neogene and the initial impingement of blocks of South China origin with northern Borneo–south Palawan.


    Item Type: Article
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
    Depositing User: Sarah Hall
    Date Deposited: 29 Jul 2019 16:08
    Last Modified: 02 Aug 2023 17:53


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