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https://doi.org/10.4154/gc.2019.29
Meso/Micro-texture analysis of the landslide-dam outburst sediments in the Upper Jinsha River, SE Tibetan Plateau
Jian Chen
; School of Engineering and Technology, China University of Geosciences Beijing, Beijing 100083, China
Zhijiu Cui
; College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
Chao Liu
; Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
Wendy Zhou
orcid.org/0000-0002-3323-7560
; Department of Geology and Geological engineering, Colorado School of Mines, Colorado 80401, USA
Ruichen Chen
; School of Engineering and Technology, China University of Geosciences Beijing, Beijing 100083, China
Abstract
Outburst sediments are widely distributed in the Upper Jinsha River in the Southeastern (SE) Tibetan Plateau. In order to understand the sedimentary characteristics of these sediments, gravel fabric, particle size distribution and quartz sand surface textures were used to analyze the mesotextures and microtextures of the Xuelongnang outburst sediments. It was determined that these sediments usually have a short transport distance, and are distributed over a distance of approximately 3.5 km. The gravel fabric and particle size distribution analysis represent the different mesotextures with different transport distances and suggest gradually changing hydrodynamic conditions. The statistical data of quartz surface textures exhibit the transformation process of quartz sands by outburst flood. The variation from abundant sub-angular shapes (> 75%); to common V-shaped percussion cracks, solution crevasse, medium relief, and chatter marks (50% to 75%); to rare meandering ridge, underwater polished surface, large conchoidal fracture (> 100 μm), directional etch pits, and crystalline overgrowths (< 5%), present the features in different combinations to other sedimentary environments. The microtexture characteristics of landslide-dam outburst deposits are also consistent with those of the mesotextures. As the distance from the residual dam increased, the quartz grain microtextures showed gradual or abrupt changes, such as increased frequencies of V-shaped percussion cracks, decreased frequencies of the adhering particles, and growth of the solution crevasses. These findings could potentially be used as a discriminant mark to distinguish outburst sediment from other types of sediments, e.g., subaqueous, eolian, glacial, etc.
Keywords
Hrčak ID:
232025
URI
Publication date:
17.12.2019.
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