Cenozoic Cooling History of Lincang Granitoid Batholith in Western Yunnan: Evidence from Fission Track Data

Abstract

AbstractTo evaluate the history of denudation and cooling of the Lincang Granitoid Batholith, and investigate the effect of the collision between India and Asia on Western Yunnan, zircon and apatite fission tracks were measured on 6 samples from the Batholith, and of which 5 groups were used to reveal their temperature‐time paths with a nonlinear inverse model, employing a simulated annealing algorithm. Based on the temperature‐time paths, the amount of denudation and uplift was estimated. The results indicate that since the continent‐continent collision of the Indian plate and Asian plate, the batholith has undergone two cooling stages, the cooling rate of the early stage is only 5~10°C/Ma, while the cooling rate of the later stage is far larger than the early one, especially the rate since 3Ma is up to 16~20°C/Ma. The total denudation of the two cooling stages is about 3300~3500m. The analyses also show that the two cooling events are closely related with the collision of India and Asia. The early cooling event is the result from the denudation of the batholith which was involved into thrust‐nappe tectonics driven by the middle Eocene‐Oligocene India‐Asia collision, while the later one is the result from the quick whole uplift and erosion of the batholith, especially since 3Ma, and the amount of tectonic uplift during this stage is about 672~1263m. The fission track data also indicate that the southern part of the batholith was affected by the collision event earlier than the middle and northern parts.