准噶尔盆地周缘山脉抬升-剥露过程的FT证据

Apatite fission track evidence for uplifting-exhumation processes of mountains surrounding the Junggar basin.

本文主要通过磷灰石裂变径迹测年结果结合温度-时间热模拟反演的研究,探讨准噶尔盆地周缘造山带的抬升-剥露作用过程及其差异性特征。研究结果表明,准噶尔周缘造山带自晚三叠世至新近纪至少经历三次大的抬升-剥露事件,结合样品位置分析,推测准噶尔盆地周缘造山带的抬升-剥露作用具有明显不均一特征。始于晚三叠-早侏罗世的山脉抬升作用范围有限,仅局限于准噶尔东北缘;但是,发生在中-晚白垩世(～115～95Ma)的这期构造抬升作用在盆地周缘的所有山系都有记录;古近纪早期(～60～50Ma)在准噶尔盆地北缘有一期隆升事件,但该事件也仅仅局限于盆地北缘;新近纪～25Ma 以来发生在巴里坤(博格达山)的局部抬升冷却事件,仅仅局限于天山北缘,而此时准噶尔盆地的东西两侧山脉可能相对稳定,推测该期抬升事件应是印-亚碰撞的远程效应在天山地区的构造表现。

Apatite Fission track dating and thermal history modeling have been carried out from 12 granite samples collected from mountains surrounding the Junggar Basin to investigate the uplifting-exhumation processes of mountains. Analyses results reveal significant discrepancy in patterns of uplifting-exhumation processes among the Tianshan, East and West Junggar mountains. Combined with samples locations, it was suggested that there probably have been at least three phases of cooling events throughout surrounding mountains of Junggar Basin since Late Triassic. The event initiated during the Late Triassic to early Jurassic was simply limited to the East Junggar mountain, and the Middle-late Cretaceous （ - 115 -95 Ma） cooling event, however, had been demonstrated by roughly all samples all over the surrounding mountains. During the early Paleocene （ -60 -50Ma ） northern Junggar mountains had been predominantly uplifted and exhumed. The Neocene （ since - 25Ma） cooling event was only recorded by samples collected from southeastern Junggar basin （ Bogeda mountains） , probably due to the far-field effect of the Indo-Eurasian collision, suggesting that the east and west Junggar mountains have been staying relative stable during this time period.