Timing of an extensional detachment during convergent orogeny; new Rb-Sr geochronological data from the Zanskar shear zone, northwestern Himalaya

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doi: 10.1130/0091-7613(1998)026<0223:TOAEDD>2.3.CO;2
Authors:Inger, Simon
Author Affiliations:Primary:
University of Leeds, School of Earth Sciences, Leeds, United Kingdom
Volume Title:Geology (Boulder)
Source:Geology (Boulder), 26(3), p.223-226. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613
Publication Date:1998
Note:In English. With GSA Data Repository Item 9824. 20 refs.; illus., incl. 1 table, sketch map
Summary:The Zanskar shear zone of northwest India forms the western segment of the South Tibetan detachment system, a north-dipping normal fault and shear zone that unroofed high-grade metamorphic rocks during contraction of the Himalayan orogen. New Rb-Sr mineral ages from the shear zone and its footwall show that ductile deformation was ongoing at 26 Ma, and continued to 16 Ma in some sections. The nature of the deformation varies along strike; displacement at 25 Ma or earlier in the western section did not result in a large thermal offset. By contrast, the sections to the east display substantial ductile thinning at midcrustal levels that was superseded by brittle detachments as the system continued to exhume rocks of the High Himalayan crystalline sequence. The implication is that the Zanskar shear zone may have had a smaller offset in the west and cut down-section to the east. The time of the bulk of the deformation of this structure is determined to be similar to that of the equivalent structure in most of the eastern and central Himalaya.
Subjects:Absolute age; Cenozoic; Continental crust; Crust; Crustal thinning; Dates; Decollement; Deformation; Ductile deformation; Exhumation; Faults; Mica group; Middle crust; Miocene; Muscovite; Neogene; Normal faults; Orogeny; Paleogene; Plate convergence; Rb/Sr; Shear zones; Sheet silicates; Silicates; Tectonics; Tertiary; Asia; Himalayas; India; Indian Peninsula; Jammu and Kashmir; Zanskar Range
Coordinates:N333000 N343000 E0770000 E0760000
Abstract Numbers:98M/2236
Record ID:1998025825
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
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