Role of extraction faulting and out-of-sequence thrusting in collisional orogeny - the base of the Dent Blanche Nappe in the Alps as an example

逆冲断层和正断层的低角度构造接触对碰撞造山带的构造和高压变质岩的折返起着关键作用。以前的工作结果表明，一个主要的低角度构造接触在西阿尔卑斯山（Combin断层），超高压变质岩覆盖的低压，代表提取故障，形成的断层与相反的剪切方向时，插入体积的岩石提取在一个向下的方向。Combin断层被阿尔卑斯山最突出的逆冲断层之一Dent Blanche基底逆冲断层（DBBT）覆盖，沿着大陆基底岩石侵位在海洋岩石上。我们假设，这个序列外的逆冲断层的形成是密切相关的提取process.The DBBT在阿尔卑斯造山带的作用是不清楚的，由于相互矛盾的意见和解释，其运动学和Dent布兰奇推覆体的古地理位置。我们将结合构造野外工作、显微构造和结构分析以及岩石学和地质年代学方法对其进行研究。这项研究将进一步了解构造过程，使高压岩石被挖出，并控制在大陆碰撞过程中的大规模剪切带的形成和复活。结合岩石学和地质年代学资料，我们将能够推断出早期大陆碰撞期间构造过程的全面观点。

Low-angle tectonic contacts, both thrusts and normal faults, play a key role in the tectonics of collisional mountain belts and in the exhumation of high-pressure metamorphic rocks. Results of previous work suggest that a major low-angle tectonic contact in the western Alps (Combin Fault), where ultrahigh-pressure metamorphic rocks are overlain by lower-pressure ones, represents an extraction fault, formed by the coalescence of faults with opposite shear sense when the intervening volume of rocks was extracted in a downward direction. The Combin Fault is overlain by one of the most prominent thrust faults of the Alps, the Dent Blanche Basal Thrust (DBBT), along which continental basement rocks where emplaced on oceanic rocks. We hypothesize that the formation of this out-of-sequence thrust is closely related to the extraction process.The role of the DBBT in the Alpine orogeny is not clear due to conflicting observations and interpretations regarding its kinematics and the paleogeographical position of the Dent Blanche nappe. We will study it by a combination of structural field work, microstructural and textural analyses, as well as petrological and geochronological methods. This research will further the understanding of the tectonic processes that allow high-pressure rocks to be exhumed and that control the formation and reactivation of large-scale shear zones during continental collision. In combination with petrological and geochronological data we will be able to deduce a comprehensive view of the tectonic processes during early continent collision.