Interplay of tectonics and erosion controls the exhumation of the Tso-Morari Crystallines in the India–Asia collision zone

Abstract

Understanding the exhumation history of the gneissic domes in continental collision zones is vital for deciphering the orogen’s geodynamic evolution. This study uses the zircon and apatite fission track (ZFT and AFT) dataset and thermokinematic modeling constraints to understand the tectonic evolution of the Tso-Morari crystalline (TMC) dome exposed in Ladakh, NW India. The ZFT and AFT ages vary from ~36.9 to ~27.7 Ma and ~16.3 to ~7.5 Ma. The ZFT cooling ages show no systematic variation, while AFT ages become younger, from ~25.7 Ma to 7.5 Ma across the dome. ZFT ages suggest that doming has been inactive since ~35 Ma. Based on thermochronological results, the thermokinematic modeling suggests that the Ribil Zildat fault (RZF) and Karzog fault bounding the TMC dome, were activated in three phases. They first activated as normal faults between ~49.8–41.3 Ma and ~49.7–43.8 Ma, respectively. The second activation phase occurred between ~24.3–20.1 Ma for RZF as a normal fault and ~20.3–13.7 Ma for the Karzog fault as a thrust. The third activation phase was 12–10.9 Ma for RZF as a normal fault and ~12.1–9.8 Ma for the Karzog fault as a thrust. We propose that these faults’ second and third activation phases were due to the activation of the normal faults in the north Himalayan nappes.

Keywords

• Fission-track thermochronology
• Tso-Morari crystalline
• exhumation
• India-Asia collision