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Durham University

Department of Geography

Departmental Research Projects

Publication details

Jamieson, S.S.R., Sinclair, H.D., Kirstein, L.A. & Purves, R.S. Tectonic forcing of longitudinal valleys in the Himalaya: morphological analysis of the Ladakh Batholith, North India. Geomorphology. 2004;58:49-65.

Author(s) from Durham

Abstract

Longitudinal valleys form first order topographic features in many mountain belts. They are commonly located along faults
that separate tectonic zones with varying uplift histories. The Indus Valley of Ladakh, northern India, runs northwestwards
following the boundary between the relatively undeformed Ladakh Batholith to the north–east and the folded and thrusted
Zanskar mountains to the south–west. In this region the Shyok Valley, on the northern side of the batholith, approximately
parallels the course of the Indus. This study investigates geomorphic variations in transverse catchments that drain the Ladakh
Batholith, into the Indus and Shyok rivers. The batholith has been divided into three zones based on varying structural
characteristics of its northeastern and southwestern boundaries. Morphometric analysis of 62 catchments that drain into the
Indus and Shyok valleys was carried out using three digital datasets, and supported by field observations. Morphometric
asymmetry is evident in the central zone where the Shyok valley is considered tectonically inactive, but the Indus Valley is
bound by the northeastwardly thrusting Indus Molasse and the batholith. In this zone the catchments that drain into the Indus
Valley are more numerous, shorter, thinner and have lower hypsometric integrals than those that drain into the Shyok. By
linking these observations with the regional geology and thermochronological data it is proposed that high sediment discharge
from the deformed Indus Molasse Indus Valley has progressively raised base levels in the Indus Valley and resulted in sediment
blanketing of the opposing tectonically quiescent catchments that drain southwestwards off the batholith. The Indus Molasse
thrust front has propagated at least 36 km towards the Ladakh Batholith over the last 20 Ma. Hence it is proposed that this long
term asymmetric structural deformation and exhumation has forced the Indus longitudinal valley laterally into the Ladakh
Batholith resulting in the morphometric asymmetry of its transverse catchments.

Department of Geography