Skip to Main Content
GEOREF RECORD

Tectonics drives rapid exhumation of the western Himalayan syntaxis; evidence from low-temperature thermochronometry of the Neelum Valley region, Pakistan

Syed Ali Turab, Kurt Stuwe, Finlay M. Stuart, David M. Chew and Nathan Cogne
Tectonics drives rapid exhumation of the western Himalayan syntaxis; evidence from low-temperature thermochronometry of the Neelum Valley region, Pakistan
Lithosphere (December 2017) 9 (6): 874-888

Abstract

Reconstructing the geometry of exhumation in the western Himalayan syntaxis region around Nanga Parbat is of critical importance to understanding how tectonics and surface processes interact during orogenesis. In order to determine the role played by the main Himalayan thrusts, we combine apatite U-Pb dating with apatite and zircon (U-Th-[Sm])/He analyses as well as apatite fission track dating from the Neelum valley region of Azad Jammu and Kashmir, Pakistan. Apatite U-Pb ages range from Proterozoic to mid-Miocene and can be separated into three age groups depending on the degree to which they have been affected by Himalayan tectonothermal events. Pooled fission track ages range from 7.0 + or - 0.4 to 2.2 + or - 0.4 Ma (1sigma ), apatite He ages range from 8.7 + or - 0.2 to 2.0 + or - 0.2 Ma, and zircon He ages range from 20.0 + or - 0.4 to 6.1 + or - 0.1 Ma. The data support rapid regional cooling at 10-8 Ma caused by the removal of 5-6 km of crust. This is synchronous with the initiation of movement along the Main Boundary thrust. Stream power analysis of the Neelum River catchment indicates a high normalized steepness index (ksn) of >500 m0.9 along the major river and lower ksn in the headwaters. The boundary between the different apatite U-Pb age groups and the transition from high ksn to lower ksn values coincide with the mapped trace of the Main Central thrust, corroborating the presence of the thrust in the southwestern part of the region. Compiling all apatite fission track cooling ages from the Nanga Parbat syntaxis region shows that cooling age contours are parallel to the major thrusts. Collectively these data provide convincing support for the contention that the well-established pattern of exhumation known from much of the Himalayan front continues around to the western syntaxis of the Himalayas.


ISSN: 1941-8264
EISSN: 1947-4253
Serial Title: Lithosphere
Serial Volume: 9
Serial Issue: 6
Title: Tectonics drives rapid exhumation of the western Himalayan syntaxis; evidence from low-temperature thermochronometry of the Neelum Valley region, Pakistan
Affiliation: Universitaet Graz, Institut fuer Erdwissenschaften, Graz, Austria
Pages: 874-888
Published: 201712
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 63
Accession Number: 2018-016551
Categories: GeochronologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, geol. sketch maps
N34°19'60" - N35°10'00", E73°40'00" - E74°30'00"
N33°00'00" - N36°00'00", E72°00'00" - E78°10'00"
Secondary Affiliation: Scottish Universities Environmental Research Center, GBR, United KingdomTrinity College Dublin, IRL, Ireland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201809
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal