Provenance tracking deduced by multiple thermochronometers on detrital minerals from the Yarlung-Tsangpo, southeast Tibet
Date Issued
2014
Date
2014
Author(s)
Huang, Shao-Yi
Abstract
Tibetan plateau is one of the most phenomenal orogens in the world. The spectacular landscape provides the opportunity to understand the fundamental mechanisms of mountain building process from varied disciplines such as geomorphology, geochemistry, and geophysics. Like many other orogenic belts around the world, the expedition into the plateau can be hampered by the inaccessibility of intended outcrops. These rough terrains, however, are often the most crucial outcrops to reveal the tectonic picture of the regime. Alternatively, sediments collected from the downstream of selected watershed can reflect a synthetic picture and provide integrated information in a catchment scale. With appropriate strategies and targets, we can therefore establish a comprehensive understanding toward the aimed tributaries and distinguish the veiled governing forces.
In this study, we used multiple thermo-chronometers to detect the provenance of modern sediments from two tributaries of Yarlung-Tsangpo River, southeast Tibet. Results from zircon fission track (ZFT), apatite fissiontrack (AFT), Ar-Ar single grain analysis on K-feldspar and U/Pb-ZFT double dating all indicate the occurrence of grains with young thermal ages prevailing in the Lhasa River. This remarkable young population is not significantly detected in the Nyang River, another tributary east of Lhasa River. The discrepancy of age population between the two catchments suggests that the fundamental surface process must be different. Zircon U/Pb and fission track double dating suggests that the young age component represent the recent exhumation episode in Lhasa River. Comparisons between downstream, upstream sediments and in situ rock samples inside Lhasa River explicate that the provenance of the young grains is related to the major structure, Gulu Rifting belt. The high percentage of these young grains suggests a focused denudation in a restricted area of the Lhasa River, mostly along the Nyainqentanglha range.
Subjects
核飛跡定年
氬氬定年
鈾鉛定年
熱定年
源區研究
古露張裂帶
SDGs
Type
thesis
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