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    Cenozoic exhumation history of the Alborz Mountains, Iran: new constraints from low-temperature chronometry

    Rezaeian, M. and Carter, Andrew and Hovius, N. and Allen, M.B. (2012) Cenozoic exhumation history of the Alborz Mountains, Iran: new constraints from low-temperature chronometry. Tectonics 31 (2), ISSN 0278-7407.

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    Abstract

    The Alborz Mountains in the north of the Turkish-Iranian Plateau mainly developed in the Cenozoic as a consequence of the closure of Neo-Tethys and continental collision between Arabia and Eurasia. Cenozoic growth of the fold-and-thrust belt exploited an older Palaezoic-Mesozoic crustal fabric but the extent to which this governed the overall form of the mountain belt is unclear. To determine when and how the Alborz mountain belt has grown, apatite fission track (AFT) and (U-Th)/He (AHe) thermochronometry were performed on 46 bedrock samples collected along 8 transects across the range. AFT central ages range from 157 ± 24 Ma to 10 ± 1 Ma with most ages falling between 40 Ma and 10 Ma. AHe ages range from 17 ± 2 Ma to 6 ± 1 Ma. The data revealed enhanced exhumation ca. 35 ± 5 Ma, minor exhumation between ca. 30–20 Ma and an increase in exhumation thereafter. This pattern matches the tripartite Mid-Cenozoic stratigraphy of Central Iran, where Upper Oligocene-Lower Miocene carbonates are sandwiched between terrestrial clastic formations. The most intriguing thermochronometric signal found is a major acceleration of exhumation that initiated in the late Miocene to early Pliocene, recorded by the AHe data. There does not appear to be a direct tectonic cause for Pliocene intensified erosion, as convergence rates between Arabia and Eurasia have remained relatively constant. Enhanced exhumation at this time may reflect a climatically induced intensification of erosion during Caspian isolation and base level fall, or a regional tectonic re-organization of the Arabia-Eurasia collision, or both.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Alborz Mountains, U-Th/He, apatite fission track, doubly vergent orogen, exhumation
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Sarah Hall
    Date Deposited: 18 Oct 2013 14:41
    Last Modified: 11 Oct 2016 11:55
    URI: http://eprints.bbk.ac.uk/id/eprint/8528

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