Tajik Basin and Southwestern Tian Shan, Northwestern India-Asia Collision Zone: Timing of Basin Inversion and Associated Deformation-Field Evolution

塔吉克盆地和天山西南部构成了印度-亚洲碰撞带的西北端。可能是渐新世-新近纪盆地反转形成了顶部至西北偏西的薄皮塔吉克冲断褶皱带，其轮廓为向西凸起的褶皱列，下方为侏罗纪的褶皱。西南天山构成厚皮前陆支墩。塔吉克逆冲褶皱带形成一个不对称（旋转）挤压-滑动-扩张推覆体，连接帕米尔高原地壳塌陷和塔吉克盆地坳陷缩短。在本课题组研究的基础上，首先，通过区域“古应力”研究，全面了解塔吉克盆地反转过程中的变形演化。其结果将是建立一个详细的相对变形场的演变，从早期，旋转的结构组构到晚期，未旋转或旋转很少的;后者应该近似/匹配今天的变形场。第二，我们将补充现有的热年代学数据库，通过使用磷灰石裂变径迹和（U-Th）/He方法测定其他样品的年代。有了这些数据，我们将得到一个完整的，区域覆盖的年龄解释的时间演化的塔吉克盆地反转。第三，我们的目标是使用U-Pb方解石地质年代学的塔吉克冲断褶皱带的变形历史，把限制断层运动和张裂隙的形成。重要的是，我们将利用详细的分析前，同，和后折叠阶段的变形和日期的断层和裂缝有关，这种相对的演变。此外，我们还将选择方解石断层，表明早期和晚期阶段的垂直轴旋转的断层集。预期的结果是在全盆地范围内建立反转的开始，并了解盆地各部分随后的序列外再活化。

The Tajik basin and southwestern Tian Shan constitute the North-western tip of the India-Asia collision zone. Likely Oligocene-Neogene basin inversion formed the top-to-WNW, thin-skinned Tajik thrust-fold belt, outlined by westward convex fold trains, and underlain by a décollement in Jurassic evaporites. The southwestern Tian Shan constitutes the thick-skinned foreland buttress. The Tajik thrust-fold belt forms an asymmetric (rotational) extruding-gliding-spreading nappe, connecting Pamir-plateau crustal collapse with shortening in the Tajik-basin depression. Building on studies by my group, firstly we will develop a full understanding of the evolution of deformation during the inversion of the Tajik basin via a regional "paleostress" study. The outcome will be the establishment of a detailed relative deformation-field evolution, from early, rotated structural fabrics to late, un- or little-rotated ones; the latter should approximate/match today’s deformation field. Second, we will complement the existing thermochronologic database by dating additional samples using the apatite fission-track and (U-Th)/He methods. With this data, we will get a full, regional coverage of ages to interpret the time evolution of the inversion of the Tajik basin. Third, we aim to date the deformation history of the Tajik thrust-fold belt using U-Pb calcite geochronology, placing constraints on fault movements and tension-gash formation. Importantly, we will make use of the detailed analysis of the pre-, syn-, and post-folding stages of deformation and date faults and gashes related to this relative evolution. In addition, we will also select calcite from faults that indicate early and late stages in vertical axis rotation of fault-sets. The expected outcome is a basin-wide establishment of the onset of inversion and an understanding of the subsequent out-of-sequence reactivation in various parts of the basin.