Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Squeezing river catchments through tectonics: Shortening and erosion across the Indus Valley, NW Himalaya

Sinclair, H.D., Mudd, S.M., Dingle, E., Hobley, D. E. J. ORCID: https://orcid.org/0000-0003-2371-0534, Robinson, R. and Walcott, R. 2017. Squeezing river catchments through tectonics: Shortening and erosion across the Indus Valley, NW Himalaya. Geological Society of America Bulletin 129 (1-2) , pp. 203-217. 10.1130/B31435.1

Full text not available from this repository.

Abstract

Tectonic displacement of drainage divides and the consequent deformation of river networks during crustal shortening have been proposed for a number of mountain ranges, but never tested. In order to preserve crustal strain in surface topography, surface displacements across thrust faults must be retained without being recovered by consequent erosion. Quantification of these competing processes and the implications for catchment topography have not previously been demonstrated. Here, we use structural mapping combined with dating of terrace sediments to measure Quaternary shortening across the Indus River valley in Ladakh, NW Himalaya. We demonstrate ~0.21 m k.y.–1 of horizontal displacement since ca. 45 ka on the Stok thrust in Ladakh, which defines the southwestern margin of the Indus Valley catchment and is the major back thrust to the Tethyan Himalaya in this region. We use normalized river channel gradients of the tributaries that drain into the Indus River to show that the lateral continuation of the Stok thrust was active for at least 70 km along strike. Shortening rates combined with fault geometries yield vertical displacement rates that are compared to time-equivalent erosion rates in the hanging wall derived from published detrital 10Be analyses. The results demonstrate that vertical displacement rates across the Stok thrust were approximately twice that of the time-equivalent erosion rates, implying a net horizontal displacement of the surface topography, and hence narrowing of the Indus Valley at ~0.1 m k.y.–1. A fill terrace records debris-flow emplacement linked to thrust activity, resulting in damming of the valley and extensive lake development. Conglomerates beneath some of the modern alluvial fans indicate a northeastward shift of the Indus River channel since ca. 45 ka to its present course against the opposite side of the valley from the Stok thrust. The integration of structural, topographic, erosional, and sedimentological data provides the first demonstration of the tectonic convergence of drainage divides in a mountain range and yields a model of the surface processes involved.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Subjects: Q Science > Q Science (General)
Publisher: Geological Society of America
ISSN: 0016-7606
Funders: NERC, Carnegie Trust
Date of First Compliant Deposit: 25 October 2016
Date of Acceptance: 26 July 2016
Last Modified: 01 Nov 2022 11:37
URI: https://orca.cardiff.ac.uk/id/eprint/95598

Citation Data

Cited 18 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item