Large normal-sense displacement on the South Tibetan fault system in the eastern Himalaya

F. J. Cooper, B. A. Adams, C. S. Edwards, Kip Hodges

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The extensional South Tibetan fault system (STFS) crops out for more than 2000 km along the length of the Himalayan range crest. Interpretations of the signifi cance of this structure in Himalayan tectonics vary. While many regard it as rooted northward beneath Tibet, with offset estimates ranging as high as >200 km, others regard it as a relatively minor, rootless structure. Such inconsistent interpretations are possible because, except for the Everest region, where glacial erosion has exposed a cross section of the STFS, there are few direct constraints on the amount of slip on this feature. Arguments for very large displacements have been based on indirect lines of evidence (e.g., geothermobarometric data) that are multiply interpretable. However, new fi eld work and remote sensing data reported here directly support the petrologic arguments for large displacements, at least in the eastern Himalaya. Near the western boundary of Bhutan, the trace of the STFS is apparently offset ∼70 km across a NNE-SSW-trending graben, the Yadong cross structure. This offset has been attributed by previous authors to left-lateral slip along the Jomolhari fault system, which bounds the eastern edge of the graben. In fact, the basal structure of the STFS is not offset, but forms a regionally continuous low-angle detachment surface. The outcrop pattern of the structure, kinematic indicators in fault-related tectonites, and the lack of matchable correlative hanging wall and footwall units require a minimum displacement of ∼65 km for the detachment. Such displacements are comparable with estimates for major contractional structures in the eastern Himalaya, such as the Main Central thrust system, and confi rm the importance of STFS extension in the evolution of the orogenic system.

Original languageEnglish (US)
Pages (from-to)971-974
Number of pages4
JournalGeology
Volume40
Issue number11
DOIs
StatePublished - Nov 2012

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graben
glacial erosion
hanging wall
footwall
outcrop
thrust
cross section
kinematics
remote sensing
tectonics
crop
indicator

ASJC Scopus subject areas

  • Geology

Cite this

Large normal-sense displacement on the South Tibetan fault system in the eastern Himalaya. / Cooper, F. J.; Adams, B. A.; Edwards, C. S.; Hodges, Kip.

In: Geology, Vol. 40, No. 11, 11.2012, p. 971-974.

Research output: Contribution to journalArticle

Cooper, F. J. ; Adams, B. A. ; Edwards, C. S. ; Hodges, Kip. / Large normal-sense displacement on the South Tibetan fault system in the eastern Himalaya. In: Geology. 2012 ; Vol. 40, No. 11. pp. 971-974.
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