准噶尔盆地南缘中生代正反转构造分析

Mesozoic inverted structure analysis of the southern margin of the Junggar Basin

本文以地质露头、钻井和测井资料为约束,运用断层相关褶皱理论解释了新处理的准噶尔盆地南缘94条工业地震反射剖面,并通过数值模拟实验以及平衡剖面恢复技术,合理地再现了准噶尔盆地南缘第一排褶皱冲断带中生代构造演化的运动学过程。研究结果表明准噶尔盆地南缘中三叠世—中侏罗世为拉张环境,喀拉扎正断层、昌吉正断层发育,并控制中-上三叠统一中-下侏罗统沉积;中-晚侏罗世转变为挤压环境,早期正断裂发生反转,同时控制第一排背斜带的齐古逆断裂开始发育,齐古背斜、昌吉背斜雏形形成;上新世(N_2)再次发生强烈挤压,齐古背斜、昌吉背斜和喀拉扎背斜最终定型。

The dynamic of the first-order fold-thrust belts were modeled by the combination of the numerical modeling and balanced cross-section techniques, with the constraints from the outcrop, well drilling and logging data. Moreover, 94 seismic sections collected from southern margin of the Junggar Basin were analyzed with the fault-related fold theory. The results indicate that the Junggar Basin showing extensional conditions with the development of the Kalazha and Changji normal faults from the Middle Triassic to Middle Jurassic. This tectonic frame was in charge of the sedimentary characteristics; the switch of the stress field from the extension to compression occurred in the Middle-Late Jurassic. As a result of this switch, normal faults developed earlier reversed to reverse fault （Qigu fault ）and controlled the initial development of the first-order anticlines. Meanwhile, the initial from of the Qigu and Changji anticlines developed; The Qigu, Changji and Kalazha anticlines finally shaped with the strong compression.