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

Abstract

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 commonly 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 landscape 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 response 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.