Late Cretaceous Activity Record of the Guangsan Fault-Insights from Zircon U-Pb and Apatite Fission-Track Thermochronology

The timing of fault activity is a concern for geologists. This study used zircon U-Pb and apatite fission-track dating of fault breccia to determine the upper and lower limits for the time of faulting. The Guangsan fault in South China was taken as an example, and zircon U-Pb and apatite fission-track thermochronology were applied to the surrounding rock and fault breccia. The surrounding rock and fault breccia demonstrated 74.9-91.8 Ma and 73.9-93.5 Ma zircon U-Pb dates, respectively, indicating that the breccia formed after 73.9 Ma. They also demonstrated 71.6 +/- 7.3 Ma and 85.9 +/- 8.2-65.5 +/- 6.5 Ma fission-track dates, implying that the fault breccia samples likely formed before similar to 70 Ma. Their thermal histories were highly consistent: both showed rapid cooling during 70-65 Ma and slow cooling during 65-0 Ma, implying that the fault was likely still active during 70-65 Ma, resulting in the rapid exhumation.

Automated summary

This study used different dating methods to determine the timing of fault activity, and the results indicate that the Guangsan fault was still active during the period of 70-65 million years ago, leading to rapid uplift.