Coordination between deformation, precipitation, and erosion during orogenic growth

Abstract Crustal thickening associated with orogenic growth increases topography, causing the orographic enhancement of precipitation, which in turn facilitates local erosion and possibly intensifies the localization of deformation. How these three processes—deformation, precipitation, and erosion—coordinate during orogenic growth remains unknown, and whether tectonics or climate controls erosion in active orogens is much debated. Here, we present a new numerical model where tectonics, surface processes, and orographic precipitation are tightly coupled. We show that rock uplift rates and precipitation rates correlate well with erosion rates for the formation of orogenic plateaus with high correlation coefficients of ~0.9 between rock uplift and erosion rates, and ~0.8 between precipitation and erosion rates. We propose that three processes take place successively as a consequence of the lateral orogenic growth, and demonstrate a cyclicity of correlation evolution among uplift, precipitation, and erosion rates through the development of new faults propagating outward. These results shed new insights into the relative tectonic or climatic control on erosion in active orogens (e.g., the Himalayas, the Central Andes, and the Southern Alps of New Zealand), and reconcile several conflicting data and interpretations in the Himalayas, which depend on the stage of maturity of the newest fault and the relative locations to old faults.