阿尔金山北段阿克塞—当金山口一带新生代山体抬升和剥蚀的裂变径迹证据

阿尔金山北段阿克塞—当金山口一带的裂变径迹测年证据表明,该地区于9～7 Ma以来发生过快速抬升和剥蚀,并且一直持续形成了现今所见的阿尔金山。新生代以来至少经历了三次抬升:早期43.6～24.3Ma、中期19.6～13.6 Ma、晚期9～7 Ma。抬升速率先缓慢、后相对快速,9～7 Ma以来的抬升速率为0.94 mm/a。晚期的构造拾升可能与阿尔金断裂带左行走滑活动有关,而与相邻的柴达木盆地北缘地区的构造抬升并不一致。

Fission-track Evidence for the Cenozoic Uplift and Erosion of the Northern Segment of the Altyn Tagh Fault Zone at the Aksay-Dangjin Pass

Fission-track analysis indicates that the uplifting process of the northern segment of Altyn Tagh fault zone at the Aksay-Dangjin Pass since the Cenozoic can be divided roughly into three stages,43. 6~24. 3Ma,19. 6-13. 6 Ma and 9~7 Ma BP. The tectonic uplift of the Altyn Tagh fault zone related to the sinistral strike-slip movement in the Cenozoic occurred during 19. 6 -13. 6 Ma,and the uplift became rapid in 9~7 Ma BP, thus forming the Altun Mountains. The uplift was initiated in the early -middle Cenozoic (43. 6~24. 3 Ma) at a rate of 0. 227 mm/a;the second uplift occurred in the middle Cenozoic (19. 6~13. 6 Ma) at a rate of 0. 35 mm/a; and the third took place in the late Cenozoic (9-7 Ma)at an average rate of 0. 94 mm/a. The middle-late Cenozoic activation model shows that the fault zone appears to have undergone uplifting and sinistral strike-slip movement during 19. 6~13. 6 Ma; later it had sinistral strike-slip and thrust characters, giving rise to pull-apart basins after 9-7 Ma. The fission-track age of apatite from the eastern part of the Altyn Tagh fault zone is older than 30 Ma and that of apatite from the northern margin of the Qaidam Basin is 43. 6-24. 3 Ma, dif- ferent from the apatite fission-track ages of the Altyn Tagh fault zone. The age data of the samples taken from the Altyn Tagh fault zone on the northern margin of the Qaidam Basin indicate that the sinistral strike-slip movement along the fault zone seems not to have affected the uplifting of the northern margin of the Qaidam Basin. The middle-late Cenozoic tectonic uplift and sinistral strike-slip movement of the Altyn Tagh fault zone were related to the collision between thelndian and Eurasian plates and the tectonic uplift of Qinghai-Tibet Plateau.