Abstract
The presence of unique elevated low relief relict landscape in the transient Dibang catchment, at the orographic edge of Tibet-Himalaya in the tectonically active Namcha Barwa syntaxial zone, is modelled to understand evolving regional landscape, drainage reorganization and tectonics. This elevated low relief landscape represents a Mio-Pliocene abandoned paleo-channel of the Yarlung river, which was captured by the headward eroding Siang river owing to >600 m base level advantage. The river capture caused isolation of the Dibang river, which evolved as a transient parched catchment since 3–6 Ma after loss of ~17 times drainage area and 4–17 times discharge. The drainage area and discharge gained by the Siang river triggered enormous incision causing aneurysm leading to the accelerated growth of the Tsangpo gorge and affected regional tectonics. This paleo-drainage reorganization is reflected in the Mio-Pliocene sedimentation pattern in the southern Tibet-Himalaya and foreland basins.
Highlights
The landscape evolution in an active mountain belt is a function of competing processes of tectonic uplift and erosion into positive feedback by the drainage system[1,2,3,4,5,6,7,8]
The presence of relict fluvial landscape at a higher elevation, the provenance study of sediments aided by thermochronology and tectonics have been the important proxies in understanding the large drainage reorganization in the region around the syntaxis[1,3,6,28,29,30,31,32,33,34,35]
To understand the status of the observed elevated low relief zone in the Dibang basin (Figs. 1, S1) and its role in regional drainage reorganization, we modeled the regional landscape to constrain the paleo-base level, surface uplift and timing through transient signals in the river profile analysis, volume-for time substitution, drainage divide migration, piracy and area loss feedback and regional correlation to comprehend regional landscape www.nature.com/scientificreports evolution
Summary
The landscape evolution in an active mountain belt is a function of competing processes of tectonic uplift and erosion into positive feedback by the drainage system[1,2,3,4,5,6,7,8]. 1d, S1c), which defines the modified preexisting/ relict surface[12,13] This low relief sub-catchment has unique morphometry with lower drainage density, slope frequency, and higher hypsometry integrals in comparison to the rest of the Dibang catchment 1, S1) and its role in regional drainage reorganization, we modeled the regional landscape to constrain the paleo-base level, surface uplift and timing through transient signals (knickpoint modeling) in the river profile analysis, volume-for time substitution, drainage divide migration, piracy and area loss feedback and regional correlation to comprehend regional landscape evolution. The slope-area analysis confirms the mobile nature of the knickpoints, which is adjusting as incision wave by headward propagation of local base-level from the mountain front (Fig. S1b) These knickpoints of the Dibang basin were modelled to estimate the net surface uplift and paleo-relief from the reconstructed paleo-base level of the relict reaches The paleo-base level reconstruction uses the stream power scaling law, which relates local channel slope (S) to contributing drainage area (A) through the channel parameters of steepness (ks) and concavity (q)[44]
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