Defect-controlled Ar40 diffusion-domain structure of white micas from high-resolution

Cenozoic kinematics of the Wenchuan-Maoxian fault implies crustal stacking rather than channel flow extrusion at the eastern margin of Tibetan plateau (Longmen Shan)

“…Our interpretation is that the micas with Xcel > 0.3 are porphyroclasts inherited from an early event (≥ 600 Ma) while the younger age of the Xcel < 0.2 micas record a younger fluid-rock interaction event responsible for the growth of secondary white micas and chlorite between 250 and 350 °C during top to the east deformation. That temperature is lower than the closure temperature of white micas for the K/Ar system of 400-445 °C (Harrison et al, 2009) and recently revised theoretical and empirical estimates (Nteme et al, 2022(Nteme et al, , 2023 implying that the 15.4 ± 0.2 Ma (middle Miocene) age correspond to white mica crystallization, not cooling.…”