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天山造山带新生代剥露过程与构造演化历史一直是国内外地学界关注的热点.本文联合运用磷灰石裂变径迹(AFT)和(U-Th)/He(AHe)低温热年代学技术,重建了新疆天山巴仑台剖面基岩山体的热演化历史,分析了剥露速率的变化特征,结合前人研究成果进一步探讨了新生代天山地区剥露作用过程的基本特点.结果表明,巴仑台剖面磷灰石样品的裂变径迹年龄集中在40~60 Ma,(U-Th)/He年龄为10~40 Ma;裂变径迹时间-温度史模拟结果表明巴仑台地区中新世早期以来剥露作用明显增速,剥露速率由之前的<30 m Ma增大为>100 m Ma;基于AFT与AHe年龄,利用年龄-封闭温度法以及矿物对法计算得到的剥露速率也表明该地区新生代剥露作用自中新世早期开始加速,并且在晚中新世剥露作用进一步增强.本文所揭示的快速剥露过程也存在于天山造山带其他地区.从整个天山造山带来看,开始于中新世早期的快速剥露是新生代天山地区一次重要的剥露作用过程.
The Cenozoic exhumation process and tectonic evolution history of the Tianshan orogenic belt have always been the focus of attention in the field of geosciences both at home and abroad.This paper combined apatite fission track (AFT) and (U-Th) / He (AHe) Rebuilt the thermal evolution history of basement rocks in Baluntai section of Xinjiang Tianshan Mountains and analyzed the changing characteristics of peel rate and combined with the research results of predecessors to further explore the basic characteristics of peel exposure process in the Cenozoic Tianshan Mountains.The results show that, The fission track age of the apatite samples in the Taihang section is concentrated in the range of 40-60 Ma and the U-Th / He age ranged from 10-40 Ma. The fission track time-temperature history simulation results show that the fission track ages in the early stage of the Miocene Since the previous <30 m Ma increased to> 100 m Ma; based on the AFT and AHe age, the use of age - closed temperature method and the mineral method of calculation of the rate of exposure also shows that The Cenozoic exhumation in the area accelerated since the early Miocene and further enhanced in late Miocene exhumation.The rapid exhumation process disclosed in this paper also exists in other parts of the Tianshan orogenic belt, Look, started early in the Miocene Fast exhumation is an important process of exhumation new generation of Tianshan Mountains.