Landslide-Induced Weathering in Tectonically Active Mountains: Evidence From Dissolved Radiogenic Uranium Isotopes
Landslide-Induced Weathering in Tectonically Active Mountains: Evidence From Dissolved Radiogenic Uranium Isotopes
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构造活跃山脉中滑坡引起的风化：来自溶解的放射性铀同位素的证据
DOI：
10.3389/feart.2022.825818
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发表时间：
2022-03
影响因子：
2.9
通讯作者：
Gaojun Li
中科院分区：
文献类型：
--
作者：
Laifeng Li;Gen K. Li;Le Li;Gaojun Li
了解以滑坡为主的集水区的风化过程对于评估滑坡在化学风化和全球碳循环中的作用至关重要。以往的研究主要集中在滑坡影响景观的溶质浓度，但很少注意开发滑坡引起的风化通量的同位素示踪剂。最近的工作发现，溶解在河水中的放射性铀同位素是密切相关的流域排水陡峭的山，滑坡被认为是一个主要的侵蚀机制，剥蚀率，这表明铀同位素的潜力，以跟踪滑坡引起的风化通量。本文对青藏高原东缘岷江流域一组不同滑坡活动的流域河水样品中的溶解放射性铀同位素（234 U/238 U比值）进行了研究。我们从数字地形分析和2008年Mw7.9汶川地震引发的同震滑坡的库存地图中获得了滑坡活动的三个指标：滑坡的归一化体积，平均集水区坡度角，以及坡度比阈值角更陡的部分，超过该阈值角，斜坡机械不稳定。河流溶解的234 U/238 U比值与滑坡活动指标呈负相关，这可能反映了滑坡对溶解的234 U/238 U比值的影响。从机理上讲，加强基岩滑坡将加速新鲜岩石的暴露，促进基岩风化和矿物中所含的234 U和238 U的一致溶解;减少滑坡活动和加强风化将导致234 U通过α反冲喷射优先积累溶质中的238 U，从而增加溶解的234 U/238 U。我们的研究结果提供了现场证据，使用河流溶解的234 U/238 U的比例来追踪滑坡驱动的风化通量，在上升的山脉化学风化过程中提供了新的光。
Understanding weathering processes in landslide-dominated catchments is critical for evaluating the role of landslides in chemical weathering and the global carbon cycle. Previous studies have focused on solute concentrations in landslide-impacted landscapes, but have paid less attention to developing isotopic tracers of landslide-induced weathering fluxes. Recent work found that the dissolved radiogenic uranium isotopes in river water are closely related to the denudation rates in catchments draining steep mountains where landslides are thought to be a major erosion mechanism, suggesting the potential of uranium isotopes to trace landslide-induced weathering fluxes. Here we compile the dissolved radiogenic uranium isotopes (234U/238U ratios) in the river water samples from a group of catchments with variable landslide activities in the Minjiang River Basin at the eastern margin of the Tibetan Plateau. We derive three metrics of landslide activity from the analyses of digital topography and an inventory map of the co-seismic landslides triggered by the 2008 Mw7.9 Wenchuan earthquake: the normalized volume of landslides, the mean catchment slope angle, and the fraction of slopes steeper than a threshold angle beyond which slopes are mechanically unstable. The riverine dissolved 234U/238U ratios correlate negatively with the metrics of landslide activity in each catchment, which likely reflect the influence of landslides on the dissolved 234U/238U ratios. Mechanistically, enhanced bedrock landsliding would accelerate the exposure of fresh rock, promoting bedrock weathering and congruent dissolution of 234U and 238U contained in minerals; reduced landslide activities and enhanced regolith weathering would lead to preferential accumulation of 234U against 238U in solutes through alpha-recoil ejection, thus increasing dissolved 234U/238U. Our findings provide field evidence of using the riverine dissolved 234U/238U ratio to trace weathering fluxes driven by landslides, shedding new light on chemical weathering processes in uplifting mountains.
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DOI：
10.12029/gc2017z103
发表时间：
2017-09
期刊：
--
影响因子：
--
作者：
Tianzhu Ye;Chong Huang;Z. Deng
通讯作者：
Tianzhu Ye;Chong Huang;Z. Deng
影响因子：
5
作者：
R. Emberson;A. Galy;N. Hovius
通讯作者：
R. Emberson;A. Galy;N. Hovius
影响因子：
3.9
作者：
Li, Gen;West, A. Joshua;Hilton, Robert G.
通讯作者：
Hilton, Robert G.
影响因子：
5.8
作者：
Jin, Zhangdong;West, A. Joshua;Wang, Xulong
通讯作者：
Wang, Xulong
台湾宇宙成因 10 Be(流星)/ 9 Be比率测量剥蚀率上限
DOI：
10.1029/2021jf006221
发表时间：
2021
期刊：
Journal of Geophysical Research: Earth Surface
影响因子：
--
作者：
Kai Deng;Hella Wittmann;Shouye Yang;Friedhelm Blanckenburg
通讯作者：
Friedhelm Blanckenburg