Cenozoic and Mesozoic metamorphism in the Longmenshan orogen: Implications for geodynamic models of eastern Tibet

DOI 5 Citations

Description

New zircon U-Pb and mica 40Ar/39Ar dating combined with structural studies in the Longmenshan orogen confirm that most of the upper crustal deformation in the eastern margin of Tibet is Mesozoic. However, at lower structural levels, apatite U-Pb and monazite electron microprobe dating reveals a previously unknown domain of Cenozoic (ca. 65 Ma) Barrovian-type metamorphism and deformation. This discovery shows that the crust in the eastern margin of Tibet was already a substantial thickness around the time of the India-Asia collision. Associated deformation has a N-S-oriented stretching lineation, implying that deformation was not driven by topographic gradients in the Tibetan Plateau. The observed moderate amounts of distributed postmetamorphic E-W shortening can probably explain the present thickness of the continental crust in the area. These results do not support models of crustal thickening caused by solid-state lateral flow of midcrustal metamorphic rocks.

Journal

  • Geology

    Geology 31 (9), 745-, 2003

    Geological Society of America

Citations (5)*help

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Details 詳細情報について

  • CRID
    1360011143928016256
  • NII Article ID
    30021157302
  • DOI
    10.1130/g19562.1
  • ISSN
    00917613
  • Data Source
    • Crossref
    • CiNii Articles
    • OpenAIRE

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