A comparison of fluvial megafans in the Cordilleran (Upper Cretaceous) and modern Himalayan foreland basin systems

Empirical observations used to constrain controls on large global modern river systems typically use catchment delineations depicting drainage patterns of rivers to oceans. A key component in the spatial and temporal discharge of sediment to oceans are terrestrial sinks that act as buffers and sequestrate sediment and nutrients along its route, however, a global catchment model depicting the drainage patterns of rivers to terrestrial sinks does not currently exist. We propose a new global terrestrial sink catchment (GTSC) database that delineates the distribution of high-resolution global river networks in relation to mapped modern terrestrial sinks. The results show a distinct set of characteristics defining the morphology, climate, lithology and sediment discharge of source catchments contributing to terrestrial sinks by tectonic regime. Foreland, intracratonic, extensional and strike-slip tectonic regimes are characterized by small, numerous, densely spaced and wide source catchments where the largest source catchment contributes on average 50%, 43%, 36% and 36%, respectively, of the total suspended sediment load. Forearc and passive margin tectonic regimes are characterized by few, large source catchments where the largest source catchment contributes on average 64% and 63% of the total suspended sediment load. In contrast to forearc and passive margin settings, foreland, intracratonic, extensional and strike-slip settings show source catchments with a range of lithologies and a dominance of seasonal climates, which will likely increase along-strike variability in sediment discharge to their terrestrial sink. The variability of along-strike sediment discharge, sediment composition and source-derived perturbations in sediment discharge to the terrestrial sink will influence the sediments stored and propagation of sediment discharge signals. On geological timescales, marine sedimentary successions and the sediment routing system, likely represents the characteristics of remobilized terrestrial sink sediments during millennial scale perturbations in water discharge. The GTSC database provides a valuable resource to further our quantitative understanding on the role of the terrestrial sink on the broader sediment routing system.

show abstract

“…Such fans have been well documented in literature (DeCelles and Cavazza, 1999;Leier et al, 2005;Weissmann et al, 2015).…”

Section: Source Catchment Climatementioning

confidence: 90%

The distribution of rivers to terrestrial sinks: Implications for sediment routing systems

2018

View full text Add to dashboard Cite

show abstract

“…Modified after Champagnac et al (2008). al., 2014; Abrahami, 2015) but compares well to older systems (e.g. Campanian-Maastrichtian Hams Fork formation in Utah; DeCelles and Cavazza, 1999) and is consistent with the Lannemezan megafan building phase encompassing the early middle Miocene to Pliocene (i.e. ∼ 15 Myr).…”

Section: Megafan Buildingmentioning

confidence: 68%

“…They occupy a key position in the sediment routing system and, as such, have been widely used as recorders of external forcing on landscape evolution in a variety of settings. Controls on the building and incision of these deposits, through alternating phases of aggradation and erosion, have been shown to be related to climatic changes (Barnard et al, 2006;Arboleya et al, 2008;Assine et al, 2014), tectonic activity (DeCelles and Cavazza, 1999), base-level oscillations (Harvey, 2002) or a combination of those factors (Abrams and Chadwick, 1994;Dade and Verdeyen, 2007;Schlunegger and Norton, 2014). Laboratory experiments reproducing alluvial fan dynamics have helped understanding of the respective roles of these controls on fan morphology, facies changes and cyclic erosion-deposition processes (Kim and Muto, 2007;Nicholas et al, 2009;Rohais et al, 2011;Guerit et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan–mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (northern Pyrenees, France)

et al. 2017

View full text Add to dashboard Cite

Abstract. Alluvial megafans are sensitive recorders of landscape evolution, controlled by both autogenic processes and allogenic forcing, and they are influenced by the coupled dynamics of the fan with its mountainous catchment. The Lannemezan megafan in the northern Pyrenean foreland was abandoned by its mountainous feeder stream during the Quaternary and subsequently incised, leaving a flight of alluvial terraces along the stream network. We use numerical models to explore the relative roles of autogenic processes and external forcing in the building, abandonment and incision of a foreland megafan, and we compare the results with the inferred evolution of the Lannemezan megafan. Autogenic processes are sufficient to explain the building of a megafan and the long-term entrenchment of its feeding river on time and space scales that match the Lannemezan setting. Climate, through temporal variations in precipitation rate, may have played a role in the episodic pattern of incision on a shorter timescale. In contrast, base-level changes, tectonic activity in the mountain range or tilting of the foreland through flexural isostatic rebound do not appear to have played a role in the abandonment of the megafan.

show abstract

“…Megafans are generally defined by their large size (10 3 -10 5 km 2 ), low gradient (0.1°-0.01°), sediment texture (varying from boulders to silt and mud) and depositional process (predominantly fluvial) [8,73]. Table 4 summarizes some general statistics of the Jarrahi fans in comparison to other fluvial-dominated fans around the world.…”

Section: Comparison To Other Fluvial-dominated Fansmentioning

confidence: 99%

Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran)

2010

View full text Add to dashboard Cite

This paper presents a multidisciplinary approach for studying the evolution of an alluvial fan system in Lower Khuzestan (SW Iran). The study draws on previously collected data from geological and archaeological field campaigns and new data derived from the interpretation of satellite imagery and historical textual sources. Three alluvial fans were identified, successively deposited by the Jarrahi river in progressively downstream/westward direction. Judging from archaeological and historical evidence, the successive phases appear to coincide with a relocation of settlement and irrigation activities. The distributary system of the present-day fan developed over a period of less than four centuries. It is suggested that management of levee breaks by man played a key role in such rapid fan development and in maintaining extremely low gradients. Judging from the extensive patterns of ancient irrigation canals, human activity also played an important role in the formation of the earlier fans.

show abstract

A comparison of fluvial megafans in the Cordilleran (Upper Cretaceous) and modern Himalayan foreland basin systems

Cited by 147 publications

References 0 publications

The distribution of rivers to terrestrial sinks: Implications for sediment routing systems

The distribution of rivers to terrestrial sinks: Implications for sediment routing systems

Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan–mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (northern Pyrenees, France)

Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran)

Contact Info

Product

Resources

About