天山分段性的地球物理学分析

GEOPHYSICAL EVIDENCE FOR SEGMENTATION OF THE TIANSHAN

天山造山带纵向延绵 30 0 0多km ,其主要部分在国外。文中根据横跨天山的卡拉库姆—新都库什天然地震剖面、沙雅—布尔津综合地球物理剖面、库尔勒—吉木萨尔综合地球物理剖面以及可可托海—阿克塞剖面的探测研究结果 ,综合分析天山造山带的岩石圈结构、构造分段以及不同段盆山耦合特点的差异特征。卡拉库姆—新都库什天然地震剖面揭示了费尔干纳盆地由北向南插入到南天山之下约 2 0 0km深处 ;沙雅—布尔津综合地球物理剖面表明塔里木盆地向天山造山带“层间插入与俯冲消减” ,俯冲的最大深度约 180km ,而准噶尔盆地与天山造山带主要以走滑接触为主 ;库尔勒—吉木萨尔综合地球物理剖面又得出塔里木盆地与准噶尔盆地同时向天山造山带对冲的结论 ,俯冲的深度约 16 0km ;可可托海—阿克塞剖面位于天山造山带的东端 ,探测结果没有发现明显的岩石圈规模俯冲现象。这些资料对于天山造山带的分段性及盆山耦合类型的差别研究提供了岩石圈尺度的深部依据。

The Tianshan extends more than 3 000 km with its main part beyond the border of China.This paper analyzes the lithospheric structure, tectonic segmentation and different features of each section of the Tianshan using the data of the Karakorum-Ferghana earthquake profile, Xayar-Burjing comprehensive geophysical profile, Korla-Jimsar comprehensive profile and Koktokay-Aksay profile, which cross the Tianshan. The Karakorum-Ferghana profile indicates that the Ferghana block underthrusts beneath the southern Tianshan to about 200 km depth. The Xayar-Burjing profile shows that the Tarim block intrudes into the crust and subducts to the Tianshan at the depth of about 180 km, while the Junggar basin contacts the Tianshan by strike sliding. The Korla-Jimsar profile reveals that both the Tarim block and the Junggar block subduct to the Tianshan jointly. The Kktokai-Aksa profile, located at the eastern end of the Tianshan, shows no evidence of obvious subduction. All of the evidence allows us to make a further analysis to the segmentation of the Tianshan and to the differences between varied modes of basin-range coupling with deep images of structures on a lithospheric scale.