Propagation of the thrust system and erosion in the Lesser Himalaya: Geochemical and sedimentological evidence

The geomorphology and sedimentology of the Tista megafan, Darjeeling Himalaya: Implications for megafan building processes

“…As the thrust front migrated basinward, the older foreland sediments (mainly the Siwaliks) were deformed, exhumed and eroded and the foreland basin shifted further south (Burbank et al, 1996). Since the early Cenozoic, the drainage disposition and alluvial sedimentation patterns in the foreland were influenced by interaction between the tectonism, climate and extant basin configuration (Burbank et al, 1996;Huyghe et al, 2001;Yin, 2006;Najman, 2006). The modern foreland alluvial plain is characterised by an axial drainage flowing broadly west to east and a transverse drainage system, flowing out of the mountain belt, in a southerly direction.…”

“…Study of the large sediment bodies of megafans flanking mountain belts is important as they preserve the record of rates and timing of tectonic activity and the climatic setting affecting the orogenic belt from which the basin-filling drainage emanates (Huyghe et al, 2001;Leier et al, 2005;Densmore et al, 2007). A number of case studies document the essential geomorphic character and sedimentation model of the megafans (Geddes, 1960;Gohain and Prakash, 1990;Singh et al, 1993;Shukla et al, 2001;Horton and DeCelles, 2001;Assine, 2005;Wilkinson et al, 2006).…”

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“…In particular, we aim to test the hypothesis that major changes in the structural evolution of the Himalaya were driven by the changing strength of summer monsoon precipitation. For instance, the southward migration of the main thrust detachment fault to the location of the Main Boundary Thrust after 10 Ma may have accelerated the unroofing of the Lesser Himalayan Duplex and may be linked to the change in monsoon strength at ~8 Ma (Huyghe et al, 2001;Bollinger et al, 2004). Because Site U1457 is located in the distal fan and we estimated reasonably high sedimentation rates based on seismic ties to industrial wells with age control on the outer western continental shelf of India, the site was also designed to document high-resolution changes in weathering, erosion, and paleoenvironment during the Quaternary that can be related to millennial-scale monsoonal changes linked to solar and ice sheet-related forcing.…”

Detrital zircon U–Pb geochronology of the Siwalik Group of the Nepal Himalaya: implications for provenance analysis

“…Sedimentological, petrologic, thermochronologic, geochronological, and geochemical studies can provide much information on sedimentary geology such as exhumation, fluvial environment and facies, rates of sedimentation and sediment provenance (Nakayama and Ulak 1999;Huyghe et al 2005;Ravikant et al 2011;Chirouze et al 2012;Guilbaud et al 2012). In this regard, foreland basin sediments of the Siwalik Group have been extensively studied to reconstruct the paleogeography (Miall 1995;DeCelles and Giles 1996;Sinclair 1997;DeCelles et al 1998a), constrain the rate and timing of Himalayan exhumation (Dickinson 1985;DeCelles and Giles 1996;Mugnier et al 1999) and understand paleohydrology (Huyghe et al 2001(Huyghe et al , 2005Ulak 2005). Along the Nepal Himalaya, geochronological studies have established depositional age from 13.2 Ma spanning a period till 1 Ma (DeCelles et al 1998a, b;Ojha et al 2000;DeCelles et al 2001DeCelles et al , 2004Szulc et al 2006;Chirouze et al 2012), which corresponds to the age ranges yielded by paleomagnetic studies (Appel et al 1991;Harrison et al 1993;Gautam and Rösler 1999;Gautam et al 2012).…”