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 .doc

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QI Kai 1)，REN ZhanLi 1,2)，CAO ZhanPeng 1) ，YANG Peng 1) ，DENG YaRen 1) ，MA WenQiang Department of Geology, Northwest University, Xi’an 710069, China； 2 State Key Laboratory of Continental Dynamics, Northwest University, Xi’an 710069, China Abstract Based on the study of tectonic deformation features in 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 are associated with largest impact on tectonic deformation in the study area, and there may be three times of uplift process at least which occurred in the end of Jurassic to Early Cretaceous (138-128Ma), Late Cretaceous (86-69Ma) and Eocene (50- 40Ma). The results of the thermal evolution simulation indicated that the southern areas were located at largest palaeogeothermal in158Ma, it 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. In corresponding, the Meso-cenozoic tectonic -dynamic thermal evolution in study areas remain a close contact on adjacent units. Key words: tectonic deformation；fission -track analysis；thermal evolution simulation； Qishan - Linyou；Weibei uplift；Ordos Basin 渭北隆起是鄂尔多斯盆地南部一级构造单元，在大地构造位置上，它处于构造活动带（秦岭造山带与稳定地块鄂尔多斯地块的过渡地带构造位置独特盆山 因此，本文在野外实际考察及前人资料研究的基础上，通过研究岐山-麟游地区中生代构造变形特征，结合野外露头样品的裂变径迹测试分析，运用构造热年代学的方法，详细探讨了研究区中新生代构造抬升期次、构造热演化过程及其地质响应，取得了新的认识。 1.研究区地质概况 岐山-麟游地区位于渭北隆起西南缘麟游-永寿逆冲带，该带以草碧山－老龙山－圣人桥断层为北界，以渭河盆地北缘断层为南界，整体呈一三角形区域（图1b、c），其与渭北隆起具有统一的结晶基底，由南向北，出露的地层依次变新，主要有：中上元古界、寒武系、奥陶系、、下石炭统及上白垩统缺失在1~100 Ma的时间内℃~125℃，锆石的封闭温度范围为210℃~240℃（Naeser N D et al.，1989；Gallagher K et al.，1998；Donelick R A et al.，2005），通过测量矿物中 238U 自发裂变和 235U 诱发裂变的密度，采用 Zeta 常数法可以获得矿物裂变径迹年龄。年代测定与磷灰石的退火特性相结合，就可以很好地解释盆地的抬升冷却过程及热演