金川铜镍矿床成矿后的抬升破坏:来自热年代学的证据

Uplift destruction after mineralization in Jinchuan copper-nickel deposit:evidences from thermochronology

以热年代学原理为指导,在以往成岩成矿年龄的基础上,结合矿区内裂变径迹测试结果,认为金川矿床经历了初期的急速抬升冷却、中期（827 Ma±766 Ma±乃至403 Ma）、晚期（308 Ma）和中、新生代的快速折返冷却过程,也遭受了1 508～ 827 Ma、403 ～ 308 Ma两次增温改造事件;而同一样品中相似的磷灰石和锆石裂变径迹年龄表明金川矿区至少在晚白垩纪早期经历了极速的抬升冷却、剥蚀事件.F8断裂西侧的抬升明显慢于其东侧,体现出矿区内抬升速率的差异性,这对找矿预测具有借鉴意义.

Based on thermochronological principle as a guide,this study uses the published rock-and oreforming ages of the deposits,linked with fission-track results of apatites and zircons from the mining area.It is considered that the Jinchuan copper-nickel deposit underwent rapid uplift and cooling during the initial stage,a rapid cooling and exhumation processes during 827 ～766 Ma （even to 403 Ma）,exhumation-uplift in the late stage （308 Ma） and the Mesozoic-Cenozoic.It also suffered two time heating and transforming events during 1 508 ～ 827 Ma and 403 ～ 308 Ma in turn.Similar fission-track ages of apatite and zircon in the same sample indicate that the Jinchuan mine at least experienced uplift-cooling at high speed of erosion events in the early Late Cretaceous.The uplift in western side of the fanlt F8 was significantly slower than that in eastern side,suggesting the difference of the uplift rate,which is beneficial for prospecting prediction.