作　　者： ; ; ; ; ;

机构地区： 中国科学院广州地球化学研究所边缘海地质重点实验室

出　　处： 《岩石学报》 2006年第2期465-479,共15页

摘　　要： 为利用热年代学方法重建临沧花岗岩基的冷却历史,测定了6块花岗岩样品的锆石U-Pb年龄、黑云母Rb-Sr等时线年龄、黑云母和钾长石的^(40)Ar/^(39)Ar年龄以及锆石和磷灰石的裂变径迹数据。分析表明,自结晶以来,岩基主体经历了较复杂的热演化,在两个基本阶段即早期快速冷却阶段和晚期缓慢冷却阶段上叠加了短周期的热扰动,从中—晚三叠世到早侏罗世末,冷却速率可以达到6℃～13℃/Ma,中侏罗世冷却缓慢,晚侏罗世到早白垩世早期,岩基快速冷却,平均速率达到5℃/Ma,早白垩世晚期到喜山运动前,为缓慢冷却阶段,平均速率仅为0．5℃/Ma,喜山运动后,受印藏碰撞的影响,岩基经历了两期冷却事件,早期冷却速率为5℃～10℃/Ma,晚期即5Ma以来冷却速率明显增大,特别是近3Ma以来的冷却速率达到16℃～20℃/Ma；早白垩世侵入的岩体(如样品S57),在侵入后快速冷却,晚白垩世以后与岩基主体同步冷却；宕基东倒糜棱岩带不是形成于150Ma,而可能是早期陆陆碰撞造山时推覆冲断的产物；自晚白垩世以来,岩基地区的总剥蚀厚度可达5000m左右,其中印藏碰撞引起的剥蚀可达3500m左右。 Multi-system geochronology, including zircon U-Pb dating, biotite Rb-Sr isochron dating, biotite and K-feldspar ^40Ar/^39Ar dating, zircon and apatite fission track data, was used to unravel the cooling histories of 6 granite samples from the Lincang Granitioid Batholith with thermochronology technique. Analyses shows that, the main part of the batholith has undergone a complex thermal history since its intrusion, and short term thermal events were overprinted on the basic cooling history which consists of the early quick cooling stage and the later slow cooling stage. During the Middle and Late Triassic, and the end of the Early Jurassic, the average cooling rate is up to 6°C - 13°C/Ma, which was followed by a slow cooling stage of the Middle Jurassic. During the Late Jurassic and the early stage of the Early Cretaceous, there was a quick cooling stage with an average rate of 5°C/Ma ,which was followed by a slow cooling stage with a cooling rate of about 0.5°C/Ma, from the late stage of the Early Cretaceous to the beginning of the continent-continent collision of India plate and Asia plate which happens at the Late Eocene. Since the collision, the batholith has undergone two cooling stages, the cooling rate of the early stage is about 5°C - 10°C/Ma,while the cooling rate of the later stage is far larger than the early one, especially the rate since 3 Ma is up to 16°C - 20°C/Ma; The intrusion, happened in the Early Cretaceous （for example, Sample S57 ）, which cooled quickly immediately after intrusion, cooled slowly together with the main part of the batholith since the Late Cretaceous ; The mylonite zone, lying on the eastern side of the batholith, was generated much earlier than its biotite ^40Ar/39Ar age, 150Ma,and maybe was generated during the thrust and nappe stage due to the collision between the Baoshan Block and the Lanping-Simao Block. Since the Late Cretaceous, the denudation is about 5000m, and 3500m of which is the result of the collision of the India plate and the Asia plate.

关 键 词： 云南 临沧岩基 热演化 封闭温度 糜棱岩 同位素年龄 裂变径迹

领　　域： [天文地球] [天文地球]