Simplified modeling of the impact of lithospheric-scale geological processes on thermal histories and low-temperature thermochronometers

Abstract. Many geological processes influence or perturb the thermal state of the lithosphere. This presents a challenge for relating thermal history data modeled from thermochronometers such as apatite and zircon fission-track and (U-Th)/He dating to geological evolution, a primary goal of many thermochronology studies. Here we address this challenge by exploring the thermal and thermochronological evolution of tracked rock parcels in 1D models that simulate key lithospheric geological processes, including erosional exhumation, sedimentary burial and exhumation, dip-slip faulting and delamination of the lithospheric mantle. We compare results from common depth history scenarios in which the Moho either experiences exhumation/burial or remains at a fixed depth balanced by crustal flux and erosion. Results show that Moho depth changes have a significant effect on thermal histories and thermochronometers, though this is not often considered in thermal history studies. Further, our results show that the recorded response of thermal histories/thermochronometers in the upper crust and geological processes that disrupt the crustal thermal field may be disassociated in time, because of the time and length scales of different heat transfer mechanisms. For example, a delamination event produces younger thermochronometer ages than an identical crustal exhumation history without delamination, but younger ages do not record the timing of delamination.