Unbalanced sediment budgets in the catchment-alluvial fan system of the Kuitun River (northern Tian Shan, China): Implications for mass-balance estimates, denudation and sedimentation rates in orogenic systems - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Geomorphology Année : 2014

Unbalanced sediment budgets in the catchment-alluvial fan system of the Kuitun River (northern Tian Shan, China): Implications for mass-balance estimates, denudation and sedimentation rates in orogenic systems

Marc Jolivet
Laurie Barrier
Stephane Dominguez
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Laure Guerit
Gloria Heilbronn
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  • IdRef : 184668670

Résumé

Mass balances are often used to calculate sediment fluxes in foreland basins and denudation rates in adjacent mountain ranges on intermediate to long timescales (from a few tens of thousand to a million years). Here, we study the simple Quaternary catchment-alluvial fan system of the Kuitun River, in northern Tian Shan, to discuss some ideas about sediment storage, release, and bypass in relatively short (100 km long) sediment routing systems. This study shows that the Kuitun catchment and piedmont areas clearly present evidence of a significant and temporary storage of sediments during the Pleistocene. These sediments were then excavated and delivered farther into the foreland basin during the Holocene. The difference between the volumes of materials released from the catchment and piedmont areas (5.5 ± 1.7 km3) and the volume stored in a contemporaneous fan downstream (2.6 ± 0.6 km3) indicates that the latter did not trap the whole sediment load transported by the river. The alluvial fan was bypassed by 27 to 78% of this load toward its distal alluvial plain. If this value is well estimated, it implies a major volumetric partitioning of the deposits between the fan and the alluvial plain, with a very high sedimentation rate in the fan (1.97 ± 0.52 mm*y− 1) and a much lower one downstream (0.11 ± 0.11 mm*y− 1). However, this volumetric partitioning might only occur during periods with a very specific hydrological regime such as the Holocene deglaciation. Eventually, the peculiar sediment storage and release pattern within the Kuitun catchment and piedmont areas during the Pleistocene and Holocene complicates the calculation of mean paleodenudation rates using either sediment budgets or in situ produced cosmogenic nuclides.

Domaines

Géomorphologie
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Dates et versions

insu-00985283 , version 1 (29-04-2014)

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Marc Jolivet, Laurie Barrier, Stephane Dominguez, Laure Guerit, Gloria Heilbronn, et al.. Unbalanced sediment budgets in the catchment-alluvial fan system of the Kuitun River (northern Tian Shan, China): Implications for mass-balance estimates, denudation and sedimentation rates in orogenic systems. Geomorphology, 2014, 214, pp.168-182. ⟨10.1016/j.geomorph.2014.01.024⟩. ⟨insu-00985283⟩
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