Cretaceous-Tertiary structural evolution of the north central Lhasa terrane, Tibet

John E. Volkmer, Paul A Kapp, Jerome H. Guynn, Qingzhou Lai

Research output: Contribution to journalArticle

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Abstract

In the north central Lhasa terrane of Tibet, two distnct structural levels of an east-west striking thrust system are exposed along the north trending late Cenozoic Xiagangjiang rift. Upper Paleozoic strata deformed by the south directed Langgadong La thrust, and Cretaceous strata involved in variably north and south directed thrusting characterize these lower and upper structural levels, respectively. These two structural levels are separated by the Tagua Ri passive roof thrust. Balanced cross section restoration suggests that the thrust system accommodated ∼103 km(∼53%) shortening. The 40Ar/ 39Ar results, together with an interpretation of synthrust deposition of Upper Cretaceous strata, suggest that the majority of shortening occurred during the Late Cretaceous-Paleocene. Cretaceous strata lie unconformable on Permian rocks; volcanic tuffs directly above the unconformity yield U-Pb zircon ages of ∼131 Ma. Upper Cretaceous strata record a change from shallow marine to nonmarine deposition, indicating uplift above sea level during this time. The overall south directed vergence of the thrust belt is consistent with substantial crustal thickening in central Tibet by large-scale northward underthrusting of Lhasa terrane basement beneath the Qiantang terrane prior to the Indo-Asian collision. The documented decoupling of contractional deformation at shallow crustal levels appears to be a regional characteristic of Tibet from at least the Bangong suture in the north to the Tethyan Himalaya to the south. This style of deformation explains the absence of basement exposures and major denudation in this region despite substantial crustal shortening.

Original languageEnglish (US)
Article numberTC6007
JournalTectonics
Volume26
Issue number6
DOIs
StatePublished - Dec 2007

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Tibet
strata
thrust
terrane
Cretaceous
Sea level
Roofs
Restoration
basements
Rocks
crustal shortening
roofs
crustal thickening
denudation
sea level
restoration
decoupling
Paleocene
unconformity
roof

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Cretaceous-Tertiary structural evolution of the north central Lhasa terrane, Tibet. / Volkmer, John E.; Kapp, Paul A; Guynn, Jerome H.; Lai, Qingzhou.

In: Tectonics, Vol. 26, No. 6, TC6007, 12.2007.

Research output: Contribution to journalArticle

Volkmer, John E. ; Kapp, Paul A ; Guynn, Jerome H. ; Lai, Qingzhou. / Cretaceous-Tertiary structural evolution of the north central Lhasa terrane, Tibet. In: Tectonics. 2007 ; Vol. 26, No. 6.
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