新疆库车黑英山地区晚新生代构造运动及其对砂岩型铀矿成矿的控制作用初析

Late Cenozoic tectonic movement in the Keyir Mountain area,Kuqa,Xinjiang,and its controls on sandstone-type uranium deposits

黑英山位于塔里木盆地库车—拜城坳陷的北缘,是砂岩型铀矿成矿的有利区域。野外地质调查结合遥感图像解译分析,揭示出本区既发育有EW走向的褶皱构造和逆冲断层,同时也发现了EW走向的正断层和半地堑构造;根据区域地层对比和不整合面的发育,确定逆冲断层和褶皱形成于新近纪末至第四纪早期,EW正断层和半地堑构造形成于中更新世之后,进而复原了黑英山地区晚新生代的构造演化过程,推测本区新近纪至第四纪早期属于NS向的挤压构造环境,晚更新世至今出现局部拉张环境。结合砂岩型铀矿成矿条件分析,认为黑英山北单斜带隆起区为成矿的有利区域,为目前找矿的首选地段。

The Keyir Mountain area, located at the northern edge of the Kuqa-Baicheng depression of the Tarim Basin, is one of the favorable areas for the formation of sandstone-type uranium deposits in NW China. Field geological survey and interpretation of remote-sensing images have revealed that not only E-W-trending thrust faults and folds but also E-W-trending normal faults and a half-graben are developed in the study area. Stratigraphic correlation and development of unconformities indicate that these thrust faults and folds formed during the terminal Neogene to Early Quaternary, and E-W-trending normal faults and the half-graben formed later than the Middle Pleistocene. Therefore, the Late Cenozoic tectonic evolution process of the Keyir Mountain area is reconstructed. It is inferred that a regional N-S compressional environment occurred in the Neogene to early Pleistocene, while a local extensional environment from the late Pleistocene to present time. According to the above-mentioned study, combined with an analysis of the mineralization conditions for sandstone-type uranium deposits, the authors suggest that the uplifting segments of the a monoclinal zone in the northern part of the Keyir Mountain area are favorable areas for the formation of sandstone-type uranium deposits and should be firstly explored.