Shallow subsurface stratigraphy and alluvial architecture of the Kosi and Gandak megafans in the Himalayan foreland basin, India

Sinha, Rajiv; Ahmad, Jawed; Gaurav, Kumar; Morin, Guillaume

doi:10.1016/j.sedgeo.2013.06.008

Cited by 45 publications

(29 citation statements)

References 35 publications

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“…In the vertical section, the basin‐scale transitions translate into a general trend where dominantly fine‐grained overbank deposits with minor volumes of isolated, coarser channel fills are progressively followed upwards in the stratigraphy by more sand rich, larger and increasingly amalgamated channel bodies, with lesser volumes of preserved mud‐prone overbank strata (Figure a,b; see stratigraphic model in Weissmann et al, ; but also Singh et al, ; Willis, ; Nakayama & Ulak, ; Shukla et al, ; Uba et al, ; Nichols & Fisher, ; Chakraborty et al, ; Wilson et al, ; Owen, Nichols et al, ; Owen et al, ). Such upward thickening and coarsening trends have been recognized in modern fans as indicative of fan progradation (Chakraborty & Ghosh, ; Sinha, Ahmad, Gaurav, & Morin, ), and interpreted from ancient systems (e.g. DeCelles & Cavazza, ; Uba et al, ; Weissmann et al, ; Owen, Nichols et al, ; Owen et al, ).…”

Section: Discussion On Vertical and Lateral Trendsmentioning

confidence: 91%

Stratigraphic complexity in fluvial fans: Lower Eocene Green River Formation, Uinta Basin, USA

Wang

Plink‐Björklund

2019

Basin Research

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In this study, measured outcrop sections and geolocated photomosaics are integrated with areal mapping of channel dimensions, degree of amalgamation, calculations of channel‐to‐floodplain ratios and sedimentary facies variability to study and quantify the channel and floodplain deposits in the Sunnyside Delta Interval of the Lower Eocene Green River Formation in the Uinta Basin, Utah. Vertically, sand content and bed thickness increases, due to an increase in the channel‐to‐floodplain ratio, channel size and the degree of channel amalgamation. Laterally, the channel‐to‐floodplain ratio, channel size, the degree of channel amalgamation and the sand content in channel facies decreases in the paleo‐downstream direction. Such vertical and lateral transitions identify the Sunnyside Delta Interval as a fluvial fan (or distributive fluvial system). However, the vertical and lateral transitions occur at multiple spatial scales, demonstrating considerable stratigraphic complexity as compared to the existing facies and architectural models suggested for fluvial megafans and distributive fluvial systems. The smallest‐scale transitions are identified as avulsion‐related packages that form the building blocks of the stratigraphy, whereas the intermediate‐ and largest‐scale transitions are suggested to be related to lobe and whole fan progradation respectively. This documented complexity indicates the significance of self‐organization in building fluvial fan stratigraphy, and demonstrates that changes in the degree of channel amalgamation or in channel‐to‐floodplain ratio are not linked to accommodation changes. On facies scale, an abundance of Froude supercritical‐flow and high‐deposition‐rate facies, in‐channel mud deposits, and in‐channel bioturbation and desiccation indicate deposition in rivers with highly variable discharge. Such discharge conditions suggest seasonally and inter‐annually variable precipitation conditions in the US Western Interior in the Early Eocene.

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Section: Discussion On Vertical and Lateral Trendsmentioning

confidence: 91%

Stratigraphic complexity in fluvial fans: Lower Eocene Green River Formation, Uinta Basin, USA

Wang

Plink‐Björklund

2019

Basin Research

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“…It is also worth noting that many large Himalayan rivers are typically characterised by high avulsion frequencies, with rivers commonly revisiting past courses. For example, the Kosi River in the eastern Ganges basin shows an average avulsion frequency of 24 years 79 . However, in the western Ganges basin, rivers such as the Sutlej and the Yamuna flow in incised valleys that are deeply entrenched in abandoned alluvial plains (Fig.…”

Section: Discussionmentioning

confidence: 99%

Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements

et al. 2017

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Urbanism in the Bronze-age Indus Civilisation (~4.6–3.9 thousand years before the present, ka) has been linked to water resources provided by large Himalayan river systems, although the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers. Here we analyse the sedimentary architecture, chronology and provenance of a major palaeochannel associated with many of these settlements. We show that the palaeochannel is a former course of the Sutlej River, the third largest of the present-day Himalayan rivers. Using optically stimulated luminescence dating of sand grains, we demonstrate that flow of the Sutlej in this course terminated considerably earlier than Indus occupation, with diversion to its present course complete shortly after ~8 ka. Indus urban settlements thus developed along an abandoned river valley rather than an active Himalayan river. Confinement of the Sutlej to its present incised course after ~8 ka likely reduced its propensity to re-route frequently thus enabling long-term stability for Indus settlements sited along the relict palaeochannel.

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“…Modern examples range from monsoonal domain rivers (e.g., Singh and Bhardwaj, 1991;Singh et al, 1993Singh et al, , 2007Shukla et al, 2001;Jain and Sinha, 2004;, where mean annual precipitation may exceed 1100-1600 mm (Sinha et al, 2014), to arid subtropics with mean annual precipitation of only a few hundred mm (e.g., Williams, 1971;Sneh, 1983;Fisher et al, 2008). Similar to the uniform lithosomes, the variable lithosomes with flood units reveal the lack of efficient base flow, and prevailing deposition from high-magnitude floods.…”

Section: Lithosomes With Variable Flood Unitsmentioning

confidence: 99%

Morphodynamics of rivers strongly affected by monsoon precipitation: Review of depositional style and forcing factors

Plink‐Björklund

2015

Sedimentary Geology

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Keywords:Monsoon Subtropical River morphodynamics Discharge range High-magnitude river floods Monsoonal and subtropical river facies models Rivers that receive significant amounts of their surface water supply from monsoon precipitation characteristically experience seasonal floods, and display seasonally highly variable discharge, controlled by the monsoon trough passage and its related cyclones. The intense summer rainfall causes high-magnitude floods, whereas rivers only transmit a low base flow during the dry winters. For many rivers in the sub-humid to arid subtropics, bordering the monsoon domain, the monsoon rain is also the main source of surface water recharge. However, such rivers may receive monsoon rain and transmit discharge only during abnormal or strengthened monsoon seasons. This annual discharge variability or range, as compared to the mean annual discharge, distinguishes the monsoonal and subtropical rivers from the rivers in equatorial tropics and temperate perennial precipitation zones, where the annual range is relatively small compared to the annual mean discharge. This review explores the effects of this seasonal and yearly variable rainfall, and the resultant highly peaked discharge pattern on river morphodynamics, and presents a comparison of modern and ancient monsoonal and subtropical river deposits. The field datasets and literature analyses discussed herein provide recognition criteria for monsoon-controlled river deposits, by documenting the diversity of the sedimentary facies, macroforms (bar forms), and architectural elements common in ancient and modern monsoon-controlled rivers. The review demonstrates that seasonal and inter-annual precipitation range is a key control on river morphodynamics, and resultant sedimentary facies characteristics, rather than the specific climate zone or average annual precipitation.

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Shallow subsurface stratigraphy and alluvial architecture of the Kosi and Gandak megafans in the Himalayan foreland basin, India

Cited by 45 publications

References 35 publications

Stratigraphic complexity in fluvial fans: Lower Eocene Green River Formation, Uinta Basin, USA

Stratigraphic complexity in fluvial fans: Lower Eocene Green River Formation, Uinta Basin, USA

Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements

Morphodynamics of rivers strongly affected by monsoon precipitation: Review of depositional style and forcing factors

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