Deformation characteristics and Cenozoic exhumation of the Yao Shan complex evidenced by apatite fission track thermochronology

'Hie Yao Shan complex is located in the southern part of the Ailao Shan-Red River ( ASRR ) shear zone, i. e., the China part of the Yao Shan-Day Nui Con Voi massif. In order to reveal the low- Temperature thermal evolution and exhumation history of the Yao Shan complex in shallow cnjstal level, and to understand the exhumation history and tectonic evolution of the ASRR shear zone, this paper earned out macro- And micro-structural analysis, and apatite fission track analysis along two sections parallel and cross the long axis of the complex. Our results show that, as part of a linear dome, the complex has experienced multi-phase thermal evolution since Oligocene. The thermal history inversion of apatite indicates that the Yao Shan complex was uplifted to ca. 4. 3km below the earth' s surface at ∼30Ma. Subsequently, three stages of uplifting successively occurred, i. e. a first stage (30 ∼25Ma) of rapid cooling with cooling rates from 8 to 8. 9°/Myr, a second (25 ∼ 12. 5Ma) stage of slow cooling with cooling rates from 1. 5 to 1. 9° Myr, and a final stage of relatively rapid cooling with cooling rates from 3.4 to 4. l°/Myr. According to the distribution of apatite fission track ages ( AFT), the exhumation is a heterogeneous process. However, the exhumation is across the complex homogeneous with a regional overall uplift along the extension of the complex. On the regional scale, the AFT ages along the extension of the Yao Shan-Day Nui Con Voi become younger from southeast to northwest, indicating a diachronism of exhumation. Meanwhile, the exhumation is heterogeneous, similar to an undulatory exhumation pattern along the Yao Shan complex.