A Method for Reconstructing Denudation Histories From Big Global Thermochronologic Data, Tested on the Dabie Orogen, Eastern China

Abstract

Denudation histories are of great significance for constraining landscape evolution and underlying tectonic and climatic drivers. Rock exhumation toward the Earth's surface by denudation results in cooling of rocks, as recorded by mineral thermochronometers. Decades of global thermochronologic studies have produced a large database of rock temperature history models, which have been used as indices for denudation. However, quantitative conversion of the data set into denudation histories remains lacking. This study presents a new method for inverting rock cooling paths to produce denudation histories. The method solves the 1-D thermal advection-conduction equation and uses a Bayesian method for searching the denudation rate and geothermal parameter space. In addition to thermochronometric data used by other methods, inputs also include geothermal and geological constraints. We applied the method to explore the post-orogenic denudation history of the Paleozoic–early Mesozoic Dabie orogen using a compilation of published and new rock cooling histories (n = 158). The results show episodic differential Cretaceous (145-110 Ma) and regional Late Cenozoic (10-0 Ma) phases of denudation. Relatively high rates of Cretaceous denudation, which locally continued to the early Cenozoic, occurred along major normal faults in response to the retreat of westward subduction of the Paleo-Pacific plate. Enhanced regional late Cenozoic denudation coincides with coeval intensification of the East Asian monsoon. The method demonstrated here will be useful for utilizing the big global thermochronologic data for quantifying spatiotemporal changes in denudation, to advance our understanding of the interactions among tectonics, climate, landscape evolution and preservation of ore deposits.