Climate control on silicate weathering and physical erosion rates in youngorogenic belts: Case study along a runoff gradient in Pacific andAmazonian Andean basins based on SNO-HYBAM Monitoring Programdata

Abstract

International audienceAt the global scale and on geological time scales, mechanical erosion and chemical weathering budgets are linked.Together, these processes contribute to the formation and the degradation of the Earth’s critical zone and to thebiogeochemical cycles of elements. In young orogenic belts, climate and tectonic subsidence control together therate of these matter balance budget and their relationships. The climate gradient observed along the Andean basinin both the Pacific and the Atlantic slopes offers the opportunity to explore the role of the climate variability onthe erosion and weathering budgets and on their reciprocal relationships.Based on the SNO-HYBAM Monitoring Program database (Geodynamical, hydrological and Biogeochemi-cal control of erosion/weathering and material transport in the Amazon, Orinoco and Congo basins), we explorethe relationship between climate, the lithology, silicate weathering rates and physical erosion rates along a runoffgradient in Andean basins of the Amazon River (13 gauging stations) and Pacific drainage rivers (5 gaugingstations).No homogenous relationship between erosion rates (E) and chemical weathering rate (W) is observed overthe monitored basins. Only the volcanic basins respond to a global relationship defined in the literature whilethe other basins budget may depend on anthropogenic interferences on erosion/sedimentation budget, a lithologydependence of the W-E relationship parameters or/and on the existence of a threshold in this relationship.The results presented here contribute to better understanding the role of mountains belt formation in thebiogeochemical cycles and in particular in the long-term carbon cycle.Your presentation type preference