The thick Cenozoic strata in the Tianshan piedmont depression have recorded not only the thermal history of deposit zone,but also the uplifting history of the mountain.We conducted Apatite Fission Track (AFT) research on a large number of samples along 3 chosen geological profiles and simulated their AFT thermal histories.Compared with the former studies,the sampling location of this study is closer to the foreland area,i.e.,the sampling strata are much younger.We try to reconstruct the differential history of range growth from the Pliocene to present.The result suggests that samples from the East Qiulitage section record that the Mid-Tianshan,the South Tianshan and the East Qiulitage anticline experienced an uplift event at 55 ～65Ma,20 ～25Ma,5Ma,respectively.At the meanwhile,samples from the Manas section record 3 tectonic uplift events in the North Tianshan which happened at 55 ～65Ma,20 ～ 25Ma and 5Ma,respectively.The uplift event started at 5Ma is the initiative point of folding and uplifting of the Manas anticline in the Urumqi piedmont depression.The combination of different AFT research results in Tianshan zone reveals that the Tianshan Mountains have three tectonic uplift phases from 150Ma to present.The whole Tianshan Mountains commenced uplifted evenly in the Mesozoic (150 ～125Ma).From Late Mesozoic-Early Cenozoic (100 ～ 50Ma),the starting-time of uplift in the North Tianshan is much earlier than that in the South Tianshan.The characteristics of the tectonics in the Late Cenozoic are the propagation to the foreland of the Tianshan Mountains and the smaller gap of uplift time between the South Tianshan and the North Tianshan.Despite the Tianshan Mountains underwent differential uplift on the north-south direction,the denudation rates of source zones are much the same since the Mesozoic-Cenozoic to the present.So there is no causal relationship between starting-time and the amount of uplift.The fact that different blocks have different tectonic evolution histories suggests that the tectonic should be treated as a process when it occurs in a large area.During the spreading process of deformation,there is a certain lag in space and time.%堆积于天山山前坳陷内部的巨厚新生代地层不仅记录所在沉积区的热历史信息,还记录了物源区的信息.本文选择天山南北两侧山前坳陷中3条地质剖面进行了大量的磷灰石裂变径迹测试和部分样品的热历史模拟分析,来揭示上新世以来天山在南北方向上隆升过程的差异性.采样剖面的选取较前人更加靠近前陆盆地方向,样品所在地层年代更新.结果显示,东秋里塔格背斜剖面中的样品记录了中天山、南天山和背斜区分别在55 ～ 65Ma、20 ～ 25Ma和5Ma经历了构造隆升.玛纳斯背斜剖面中的样品记录了北天山的三次构造隆升事件分别发生于55 ～ 65Ma、20～25Ma和5Ma,其中距今5Ma为玛纳斯背斜带起始隆升的时代.结合前人在相同区域的研究成果,分析得出天山的不同部分经历了不同的构造演化历史,自150Ma以来经历了三期差异性隆升.中生代时期(150～ 125Ma)表现为山体整体抬升,中生代晚期-新生代早期(100～50Ma)北天山明显早于南天山开始构造隆升,新生代以来(～ 50Ma)的构造运动以向前陆盆地方向扩展为特征,而隆升起始时间南北差异变小.虽然在南北方向上天山山体隆起时间上存在明显的差异,但是中新生代以来山体物源区的剥蚀速率大体相同.因此,隆升起始时间与隆升量之间并不存在必然的定量关系.天山的不同块体具有不同的构造演化历史的事实提示在研究大范围构造隆升作用时,应将构造作用作为一个过程来对待.变形在传递的过程中,在时间和空间上存在一定的滞后现象.
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