Carr Julia C, DiBiase Roman A, Yeh En-Chao, Fisher Donald M, Kirby Eric
Department of Geosciences, Penn State University, State College, PA 16802, USA.
Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA.
Sci Adv. 2023 Nov 17;9(46):eadg6794. doi: 10.1126/sciadv.adg6794. Epub 2023 Nov 15.
Feedbacks between surface and deep Earth processes in collisional mountain belts depend on how erosion and topographic relief vary in space and time. One outstanding unknown lies in how rock strength influences bedrock river morphology and thus mountain relief. Here, we quantify boulder cover and channel morphology using uncrewed aerial vehicle surveys along 30 kilometers of bedrock-bound river corridors throughout the Taiwan Central Range where regional gradients in rock properties relate to tectonic history. We find that boulder size systematically increases with increasing metamorphic grade and depth of exhumation. Boulder size correlates with reach-scale channel steepness but does not explain observations of highly variable channel width. Transport thresholds indicate that rivers are adjusted to mobilize boulders and are well in excess of the threshold to transport gravel and cobbles, as previously assumed. The linkage between metamorphic history, boulder size, and channel steepness reveals how rock properties can influence feedbacks between tectonics and topography throughout the life span of a mountain range.
碰撞造山带中地表与深部地球过程之间的反馈取决于侵蚀作用和地形起伏如何随时间和空间变化。一个悬而未决的问题在于岩石强度如何影响基岩河道形态进而影响山脉地形起伏。在此，我们利用无人机测量，沿着台湾中央山脉30公里长的基岩束缚河道走廊量化巨石覆盖度和河道形态，该区域岩石性质的梯度与构造历史相关。我们发现，巨石尺寸随着变质程度和剥露深度的增加而系统性增大。巨石尺寸与河段尺度的河道比降相关，但无法解释河道宽度高度变化的观测结果。输移阈值表明，河流经过调整可搬运巨石，且远超此前假设的搬运砾石和卵石的阈值。变质历史、巨石尺寸和河道比降之间的联系揭示了岩石性质如何在山脉的整个生命周期中影响构造与地形之间的反馈。
