鄂尔多斯盆地渭北隆起岐山－麟游地区中新生代构造热演化及地质响应——来自裂变径迹分析的证据

本文通过对渭北隆起西南缘岐山-麟游地区构造变形特征进行研究,结合磷灰石、锆石裂变径迹测试分析及热史模拟,探讨了研究区中新生代构造热演化过程及地质响应。结果表明,燕山运动对研究区影响最大,使得研究区发生大规模构造变形及抬升,研究区中生代以来至少包括三次构造抬升:晚侏罗-早白垩世早期(138~128Ma)、早白垩世末以来,主要是晚白垩世(86~69Ma)和始新世(50~40Ma)。AFT年龄的空间分布暗示了研究区抬升冷却具有南早北晚、后期整体抬升的特点。热史模拟结果表明研究区南部在158Ma达到最大古地温,158~130Ma,样品快速抬升至部分退火带,130~40Ma为缓慢抬升,40Ma以来抬升速率明显加快。研究区中新生代构造热演化过程与相邻构造单元的相互作用具有密切的联系,晚侏罗世构造抬升与秦-祁造山带此时进入强烈多旋回陆内造山过程相对应,早白垩世稳定沉降期是鄂尔多斯盆地油气成熟的关键时期,晚白垩世以来的构造抬升与秦岭造山带抬升具有一致性,始新世以来的快速隆升,与渭河盆地北缘翘倾作用有关。

The Meso cenozoic Tectonic Thermal Evolution of the Qishan Linyou Areas in Weibei Uplift of Ordos Basin and Its Response in Geology:Evidence from Fission track Analysis

Based on the study of tectonic deformation features in the Qishan Linyou areas in the southwest of Weibei uplift, and combined with fission track analysis as well as thermal evolution simulation, this paper discussed the Meso cenozoic tectonic dynamic thermal evolution and its response in geology. The results show that Yanshan movements were associated with largest impact on tectonic deformation in the study area, and there may be three times of uplift process, which occurred in the end of Jurassic to Early Cretaceous (138~128Ma), Late Cretaceous (86~69Ma) and Eocene (50~40Ma). The spatial distribution of AFT ages suggests that the time of uplift and cooling in the study area is characteristic of early in than in north, was the overall uplift taking place later. The results of the thermal evolution simulation indicate that the southern areas reached largest in palaeogeotherm in 158Ma, and had experienced rapid uplift during the period from 158 to 130 Ma, slow uplift between 130 and 40 Ma, and further rapid uplift after 40 Ma. Corresponding, the Meso cenozoic tectonic thermal evolution in the study areas remained a close contact on adjacent units. The uplift in Late Jurassic tectonic should be relative to the process that the Qin Qi orogen entered a strong multi cycle intracontinental orogenic period. The early Cretaceous stable subsidence stage was the key period to mature oil and gas in Ordos Basin. The tectonic uplift in the late Cretaceous was consistent with Qinling orogenic belt. The rapid uplift in Eocene was caused by the tilting effect of the northern margin, which was associated with the formation of Weihe Basin.