Studying the grain-size dependent compositional variability in modern river sediments provides a key to decipher the information stored in the sedimentary archive and reconstruct the evolution of the Earth’s surface ...Studying the grain-size dependent compositional variability in modern river sediments provides a key to decipher the information stored in the sedimentary archive and reconstruct the evolution of the Earth’s surface in the past. Bedload sand along the Xigaze cross section of the Yarlung Tsangpo(upper Brahmaputra River) ranges in mean grain size from 0.72 Φ to 3.21 Φ, is moderately to poorly sorted and slightly platykurtic to moderately leptokurtic with sub-angular to sub-spherical grains. Litho-feldspatho-quartzose to feldspatholitho-quartzose sand(Q 43%-65%;F 13%-44%;L 11%-28%) contains 3.4%-14.4% heavy minerals including amphibole(64%-89%), epidote(4%-11%), chloritoid(0-10%), and clinopyroxene(2%-6%). The marked textural and compositional variability observed across the Xigaze transect of the Yarlung Tsangpo mainstem is controlled by both fluvial and aeolian processes, including repeated reworking by westerly and glacial winds,as well as by local contributions from northern and southern tributaries draining the Lhasa Block and the Himalayan Belt, respectively. The modern sedimentary case here will shed new light on interpreting paleogeography and provenance.展开更多
基金supported financially by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK0204)the National Natural Science Foundation of China Project(Grant No.4200020124)the Jiangsu Shuangchuang(Mass Innovation and Entrepreneurship)Talent Program(Grant No.JSSCBS20210014)。
文摘Studying the grain-size dependent compositional variability in modern river sediments provides a key to decipher the information stored in the sedimentary archive and reconstruct the evolution of the Earth’s surface in the past. Bedload sand along the Xigaze cross section of the Yarlung Tsangpo(upper Brahmaputra River) ranges in mean grain size from 0.72 Φ to 3.21 Φ, is moderately to poorly sorted and slightly platykurtic to moderately leptokurtic with sub-angular to sub-spherical grains. Litho-feldspatho-quartzose to feldspatholitho-quartzose sand(Q 43%-65%;F 13%-44%;L 11%-28%) contains 3.4%-14.4% heavy minerals including amphibole(64%-89%), epidote(4%-11%), chloritoid(0-10%), and clinopyroxene(2%-6%). The marked textural and compositional variability observed across the Xigaze transect of the Yarlung Tsangpo mainstem is controlled by both fluvial and aeolian processes, including repeated reworking by westerly and glacial winds,as well as by local contributions from northern and southern tributaries draining the Lhasa Block and the Himalayan Belt, respectively. The modern sedimentary case here will shed new light on interpreting paleogeography and provenance.
