Spatial coincidence of rapid inferred erosion with young metamorphic massifs in the Himalayas

Abstract

A spatially distributed rate-of-erosion index (EI) based on models of bedrock river incision documents a strong spatial correspondence between areas of high erosion potential and young metamorphic massifs as well as structural highs throughout the Himalayas. The EI is derived from slopes and drainage areas calculated from a hydrologically corrected digital elevation model (GTOPO30) combined with precipitation data (IIASA) to generate synthetic annual stream discharges. These variables drive three generalized process models to produce EI maps that, while differing in detail, provide an internally consistent, spatially continuous index of large-scale erosion rates. The large spatial variation in potential erosion rates in the Himalayas suggested by the EI patterns contrasts with the uniform convergence of the Indian subcontinent. If these EI gradients persist through time, they support the emerging view of a positive feedback between localized, rapid erosion and upward advection of lower crust.

Cenozoic river profile development in the Upper Lachlan catchment (SE Australia) as a test of quantitative fluvial incision models

“…The stream power incision law has been widely used to numerically model landscape development [e.g., Anderson, 1994;Tucker and Slingerland, 1994;Willett, 1999] as well as to infer rock uplift rates directly from fluvial profile forms [Finlayson et al, 2002;Kirby and Whipple, 2001;Snyder et al, 2000].…”

“…Therefore the detachment-limited stream power model may be useful to study incision on a local scale [e.g., Kirby and Whipple, 2001;Snyder et al, 2000] but its use on regional scales [e.g., Finlayson et al, 2002;Royden et al, 2000] appears problematic. In numerical SPMs the problem may be circumvented by combining detachment-limited and transport-limited stream power algorithms, with the one that predicts the lowest incision being taken as the rate-limiting process [e.g., Densmore et al, 1998;Tucker and Slingerland, 1994;Whipple and Tucker, 2002].…”

<sup>10</sup>Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

“…The eastern Himalayan syntaxis has been proposed as a typical example of how active tectonic deformation, thermal weakening of the crust, and steep topography could be selfsustained by intense erosion and rapid exhumation of crustal material within the framework of the tectonic aneurysm model (Zeitler et al, 2001). Although the extent and nature of this coupling has recently been challenged (Bendick and Ehlers, 2014;Wang et al, 2014;King et al, 2016), there is ample evidence for superimposed rapid exhumation (Burg et al, 1998;Seward and Burg, 2008;Zeitler et al, 2014;Bracciali et al, 2016) and active erosion (Finlayson et al, 2002;Finnegan et al, 2008;Stewart et al, 2008;Enkelmann et al, 2011;Larsen and Montgomery, 2012;Lang et al, 2013) in a focused area around the Namche Barwa-Gyala Peri massif (NBGPm), where the course of the Tsangpo-Brahmaputra is marked by a sharp bend to the south-west (Fig. 1).…”

Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

“…High topographic relief, steep river profiles, and elevated stream power all indicate high erosion rates throughout the Himalaya (Finlayson et al, 2002;Vance et al, 2003). Particularly the eastern and western syntaxes are areas of high exhumation and erosion (1-10 mm yr −1 ) (Burbank et al, 1996;Burg et al, 1998;Finnegan et al, 2008;Stewart et al, 2008;Zeitler et al, 2001).…”