构造地貌学：构造-气候-地表过程相互作用的交叉研究

Tectonic geomorphology: An interdisciplinary study of the interaction among tectonic climatic and surface processes

构造地貌学是发展迅速的新兴交叉学科.与传统地貌学不同,构造地貌学是一种定量地貌学,强调对地貌过程的定量描述,其核心概念是构造-气候-地表过程相互作用,聚焦于以量化的方式具体阐述构造活跃造山带地区气候、地形、水文、物理和化学剥蚀、沉积以及岩石变形之间的相互作用.本文首先阐释构造地貌学的主要科学问题与核心概念,即构造、气候和地表过程之间的相互作用.随后简要介绍构造地貌学的主要研究方法和手段,特别是对学科发展起到重要推动作用的测年手段(如宇宙成因核素和低温热年代学)和空间探测技术手段(如LiDAR).基于近年来构造地貌学的研究实例,梳理了构造-气候-地表过程相互作用的研究中获得的一些重要认知,这些研究实例涵盖的时空尺度巨大:时间跨度从数小时到百万年,空间跨度从单个断裂到整个造山带.这些跨度广泛的研究对理解造山带的地形演化具有重大的启示意义.最后,简要总结了构造地貌学的前沿问题.

Tectonic geomorphology is a fast-developing interdisciplinary research field. Different from traditional geomorphology, tectonic geomorphology strongly shifts to quantify the geomorphic processes. The central tenet in tectonic geomorphology is to clarify the interactions among tectonic, climatic, and surface processes, and to provide quantitative descriptions of climate, topography, hydrology, physical and chemical erosion, deposition and rock deformation and their relationships in tectonically active settings. In this review, we first introduce major scientific questions and central concepts, the techniques and methods com- monly used in this field, especially the major game-changing dating techniques （e.g., cosmogenic nuclide dating and low-temperature thermochronology） and remote sensing or surveying methods （e.g., LiDAR）. Then we present some case studies in the past three decades showing lines of evidence that the interaction among tectonic, climatic, and surface processes can occur in a wide range of temporal and spatial scales, ranging from hours to million-year in time, and from single fault to orogenic belt in space. We also synthesize important progresses in this field toward a better understanding of the topographic evolution of orogenic belts： （1） Tectonic, climatic and surface processes collaborate to shape the land- scape such that tectonic activities alone do not necessarily lead to topographic growth. For instance, when erosion and tectonic accretion are in equilibrium, topographic steady state is reached, with no surface uplifting despite on-going tectonic activity. （2） Sedimentary records in range-front basins, such as the increase of deposition rate, or the occurrence of conglomerates, were often used as proxies of tectonic uplift of mountain ranges in early studies. However, sedimentary sequence should be a collective product of tectonic, climatic, and surface processes. These commonly-used proxies for tectonic activity can also be due to climate changes, instead. （3） Tectonics plays a key and leading role in the coupling of tectonic-climatic-surface process; climatic and surface processes influence but do not drive tectonics. （4） Isostatic re- sponse to erosion will lead to the rebound of mountain peaks, but the overall effect of erosion is to lower the mean elevation. Thus, uplift due to isostatic rebound is a secondary component of tectonics. Lastly, we outline in brief a list of outstanding scientific questions remaining to be answered in the field.