Geologic and U-Pb geochronologic evidence for early Paleozoic tectonism in the Dadeldhura thrust sheet, far-west Nepal Himalaya

G. E. Gehrels, P. G. DeCelles, T. P. Ojha, B. N. Upreti

Research output: Contribution to journalArticle

118 Scopus citations

Abstract

The Dadeldhura thrust sheet inm western Nepal consists of Proterozoic-Lower Paleozoic sedimentary and plutonic rocks, and their metamorphic equivalents, that rest structurally on Proterozoic strata of the Lesser Himalayan sequence. Although regional metamorphism and ductile deformation were widespread during Tertiary thrust emplacement, relicts of early Paleozoic tectonism are preserved locally. New field and geochronologic studies, together with the findings of previous workers, indicate that this early Paleozoic tectonism included: (1) regional metamorphism to at least garnet grade, (2) regional folding of a thick metamorphic sequence into a broad east-west trending syncline, (3) outcrop-scale folding of metasedimentary rocks, (4) emplacement of Cambro-Ordovician granitic bodies during and after the metamorphism and deformation, (5) uplift and erosion of the metamorphic sequence, with garnet-grade rocks locally exposed at the surface, and (6) derivation of Ordovician conglomeratic sandstones from the early Paleozoic orogen. Similar records of metamorphism, deformation, and uplift/erosion have been found in other regions of the Himalaya, indicating that rocks of the Dadeldhura thrust sheet were originally involved in a regionally extensive orogenic system. Future tectonic models of Himalayan orogenesis must accommodate this early Paleozoic event.

Original languageEnglish (US)
Pages (from-to)385-408
Number of pages24
JournalJournal of Asian Earth Sciences
Volume28
Issue number4-6
DOIs
StatePublished - Dec 15 2006

Keywords

  • Geochronology
  • Himalaya
  • Paleozoic
  • Tectonics

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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