滇西临沧花岗岩基新生代剥蚀冷却的裂变径迹证据

为揭示临沧花岗岩基的剥蚀冷却历史，探讨印藏碰撞对滇西的影响，对6块临沧花岗岩基样品进行锆石和磷灰石裂变径迹测定，并利用模拟退火法对其中5块样品的磷灰石裂变径迹数据进行非线性热史反演，估算了不同时期的剥蚀量和抬升量. 结果表明，岩基自印藏陆陆碰撞以来经历了两期冷却事件，早期冷却速率仅5～10 ℃/Ma，晚期冷却速率明显增高，特别是近3 Ma以来的冷却速率达到16～20 ℃/Ma；两期总剥蚀厚度可达3300～3500 m. 分析表明冷却事件与印藏碰撞关系密切，早期冷却是在印藏碰撞影响下，临沧岩基卷入逆冲推覆运动而遭遇抬升、剥蚀的结果；晚期冷却则是上新世以来，特别是3Ma以来岩基经受整体的强烈抬升、剥蚀的结果，该期构造抬升量约为672～1263 m；裂变径迹资料还揭示印藏碰撞先影响南部岩体，随后才波及到岩基中北段.

Cenozoic cooling history of Lincang granitoid batholith, western Yunnan: Evidence from fission track data

To evaluate the history of denudation and cooling of the Lincang granitioid batholith, and investigate the effect of the collision between India and Asia on western Yunnan, zircon and apatite fission track data were obtained on 6 samples from the batholith, and 5 groups of which were used to reveal their temperature time paths with a nonlinear inversion model, which employs 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 ℃/Ma，while the cooling rate of the later stage is much larger than that of the early one, especially the rate is up to 16～20 ℃/Ma since 3 Ma B. P.; The total denudation of the two cooling stages is about 3300～3500 m. 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, since Pliocena especially since 3 Ma B.P., and the amount of tectonic uplift during this stage is about 672～1263 m. 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.