Southeastern Tibetan Plateau serves as the dominant sand contributor to the Yangtze River: Evidence from Pb isotopic compositions of detrital K‐feldspar

Abstract

There is as yet no consensus as to the dominant source of sediment transported to the oceans: the steep tectonically active highlands, or the gently sloping lowlands? In this study, new Pb isotopic analyses of detrital K‐feldspar have been combined with published data to constrain sand supply in the Yangtze River, one of the largest fluvial sediment transport systems on Earth. Tributaries draining southeastern Tibet have predominantly unradiogenic K‐feldspar sand grains. K‐feldspar in the middle Yangtze comprises c. 50% of grains of this kind, confirming that the southeastern Tibetan tributaries are the dominant sediment contributors. K‐feldspars characteristic of tributaries of the middle‐lower reaches are not strongly represented in the trunk Yangtze, indicating that they contribute little sediment. Our study demonstrates that tectonic uplift in southeastern Tibet is the primary control on sand supply. This is consistent with quartz 10Be data and with bulk‐sand petrography, indicating a major contribution of detritus from steep mountainous terrain.

Introduction to the special issue “Tibetan tectonics and its effect on the long‐term evolution of climate, vegetation and environment”

“…They further infer that this late Eocene drainage change was one of the responses to coeval topographic uplift in the southeastern Tibetan Plateau. Along the upper, middle and lower courses of the Yangtze River, Zhang, Daly, et al (2021) use lead (Pb) isotopic analysis on potassium feldspar crystals to address the debate concerning the relative contribution to sediment production from the steep, tectonically active highlands or the gently sloping lowlands. They find that sediments in the Yangtze trunk are mostly sourced from the upper Yangtze tributaries draining the southeastern Tibetan Plateau, highlighting the dominant role of the tectonically active highlands in sediment production. Chemical and physical weathering have long been recognized as a key mechanism that regulates the climate by impacting the global carbon cycle through organic carbon burial and weathering processes that either consume or release CO 2 , depending on the composition of the parent rock (path 7 in Figure 2).…”

“…To communicate the latest advances on this coupled tectonic, climatic, and biological system, we have launched a special virtual issue in Terra Nova and solicited submissions of 20 papers in total. The papers cover a wide range of topics that fall in the following, partially overlapping, categories: (a) Pre‐India–Asia collision tectonic configuration (Liu, Liu, et al, 2021; Zhang, Liu, et al, 2021); (b) post‐collision deformation that are subdivided into three sub‐categories, including (1) Himalayan geology (Fu et al, 2020; Liu, Wang, et al, 2021; Xu et al, 2021), (2) intracontinental deformation (Pan et al, 2021; Pang et al, 2021; Pei et al, 2021; Wang, Replumaz, et al, 2022; Zhang, Zhang, et al, 2021), and (3) exhumation and topographic evolution (He et al, 2020; Ma et al, 2021; Wang, Wang, et al, 2021; Zhang, Li, et al, 2021); (c) sedimentary system: source to sink studies, climatic forcing, and river incision (Feng et al, 2021; Wen et al, 2022; Yang et al, 2021; Zhang, Daly, et al, 2021); and (d) climatic and biospheric influence of the Tibetan Plateau (Averyanova et al, 2021). Research locations of this special issue are distributed across the plateau, spanning from the frontal Himalayas in the south to the Qilian Shan and Tian Shan ranges in the north, and extending into the continental interior (e.g.…”

“…(1) Himalayan geology (Fu et al, 2020;Liu, Wang, et al, 2021;Xu et al, 2021), (2) intracontinental deformation (Pan et al, 2021;Pang et al, 2021;Pei et al, 2021;Wang, Replumaz, et al, 2022;, and (3) exhumation and topographic evolution (He et al, 2020;Ma et al, 2021;Wang, Wang, et al, 2021;; (c) sedimentary system: source to sink studies, climatic forcing, and river incision (Feng et al, 2021;Wen et al, 2022;Yang et al, 2021;Zhang, Daly, et al, 2021); and (d) climatic and biospheric influence of the Tibetan Plateau (Averyanova et al, 2021). Research locations of this special issue are distributed across the plateau, spanning from the frontal Himalayas in the south to the Qilian Shan and Tian Shan ranges in the north, and extending into the continental interior (e.g.…”

Pliocene to Early Pleistocene Drainage Reorganization in Eastern Tibet Inferred From Detrital Zircons

“…Originating on the Qiangtang terrane in the Tibetan Plateau hinterland, the upper Yangtze River, known as the Jinsha River, is successively joined by several large tributaries in eastern Tibet, including the Yalong, Dadu, and Anning rivers (Figure 1a). Rapid incision of these rivers during the late Cenozoic not only sculpted the high‐elevation, low‐relief topography in eastern Tibet (Clark et al., 2004; Ouimet et al., 2010), but also provided abundant erosional debris to the eastern China Plain and the East Asian marginal seas (Z. Zhang et al., 2021).…”

“…Rapid incision of these rivers during the late Cenozoic not only sculpted the high-elevation, low-relief topography in eastern Tibet (Clark et al, 2004;Ouimet et al, 2010), but also provided abundant erosional debris to the eastern China Plain and the East Asian marginal seas (Z. Zhang et al, 2021).…”