近日，中国科学院地质与地球物理研究所王学良与合作者，报道了短期气候驱动泥沙沉积对构造控制冲积河道切割的影响。该研究于2023年10月30日发表于国际一流学术期刊《地质学》杂志上。

研究人员通过对晚更新世（ca. 135 ka)西藏东南部流域的河流阶地及相关河道进行地质绘图和年代测定，测定河道水力几何形状，计算河道陡度指数和切割速率，提供了西藏东南部 流域的野外实地数据。对数据的分析表明，气候作用力是该流域沉积物产生和向河流输送的主要驱动力。新的加积事件改变了冲积河谷和河道的几何形状，并与构造隆升一起影响了流域内河道的切割速率。

研究人员提出了一个概念模型，将气候变化引起的构造隆升驱动的切口联系起来，该模型在研究流域内和其他地区都是有效的。研究结果强调，气候驱动的河道淤积导致的切口深度的减少，在短时间尺度上是显著的( 10²-10⁵ yr )，其累积效应为在长时间尺度上形成“萨德勒效应”(>10⁶ yr)。

据研究人员介绍，关于河流切割速率与时间(“萨德勒效应”)之间关系的争论仍在继续，阻碍了通过切割速率来推断构造和气候过程的研究。在 10²-10⁵ yr 的时间范围内，探讨构造和气候之间的耦合在控制冲击河道几何形状和切割速率方面的作用，缺乏详细的实地证据。

附：英文原文

Title: Effect of short-term, climate-driven sediment deposition on tectonically controlled alluvial channel incision

Author: Xueliang Wang, John J. Clague, Paolo Frattini, Shengwen Qi, Hengxing Lan, Wen Zhang, Lihui Li, Juanjuan Sun, Giovanni Battista Crosta

Issue&Volume: 2023-10-30

Abstract: Debate about relations between rates of fluvial incision and time (the “Sadler effect”) continues, impeding the use of incision rates to infer tectonic and climatic processes. There is a dearth of detailed field evidence that can be used to explore the coupling between tectonics and climate in controlling alluvial channel geometry and incision rates over time scales of 10²-10⁵ yr. We present field data from the Rumei watershed of southeast Tibet, which we obtained by mapping and dating late Pleistocene (ca. 135 ka) fluvial terraces and related channels, measuring channel hydraulic geometry, and calculating channel steepness indexes and incision rates. The evidence indicates that climate forcing is the main driver of sediment production and delivery to streams in the watershed. New aggradation events altered alluvial valley and channel geometry and, coupled with tectonic uplift, affected the rate of channel incision in the catchment. We propose a conceptual model (see pdf for equation) that links uplift-driven incision (see pdf for equation) induced by climate change, which is valid in catchments and other areas. We conclude that the reduction in incision depth caused by climate-driven channel aggradation is significant on short time scales (10²-10⁵ yr), and its cumulative effect contributes to the “Sadler effect” on long time scales (>10⁶ yr).

DOI: 10.1130/G51671.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51671.1/628885/Effect-of-short-term-climate-driven-sediment