Tibetan basement rocks near Amdo reveal "missing" mesozoic tectonism along the Bangong suture, central Tibet

Jerome H. Guynn, Paul Kapp, Alex Pullen, Matthew Heizler, George Gehrels, Lin Ding

Research output: Contribution to journalArticlepeer-review

356 Scopus citations

Abstract

The U-Pb and 40Ar/39Ar studies of a unique exposure of crystalline basement along the Jurassic-Early Cretaceous Bangong suture of central Tibet reveal previously unrecognized records of Mesozoic metamorphism, magmatism, and exhumation. The basement includes Cambrian and older orthogneisses that underwent amphibolite facies metamorphism coeval with extensive granitoid emplacement at 185-170 Ma. The basement cooled to ∼300 °C by 165 Ma and was exhumed to upper crustal levels in the hanging wall of a south-directed thrust system during Early Cretaceous time. We attribute Jurassic metamorphism and magmatism to the development of a continental arc during Bangong Ocean subduction, and Early Cretaceous exhumation to northward continental underthrusting of the Lhasa terrane beneath the Qiangtang terrane. We speculate that a Jurassic arc extended regionally along the length of the Bangong suture, but in all other places in Tibet has been buried, either depositionally or structurally, beneath supracrustal assemblages.

Original languageEnglish (US)
Pages (from-to)505-508
Number of pages4
JournalGeology
Volume34
Issue number6
DOIs
StatePublished - Jun 1 2006

Keywords

  • Bangong suture
  • Continental arcs
  • Continental collision
  • Terrane accretion
  • Tibet

ASJC Scopus subject areas

  • Geology

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