Rates of Thermal and Structural Processes in an Oblique Orogen

高度倾斜(扭动)构造背景下的地壳增厚和折返是喜马拉雅山脉、阿尔卑斯山脉、北美科迪勒拉山脉和其他山脉大片地区的典型特征，但斜向运动对造山带中至深层地壳水平的热和构造影响鲜为人知。简单的热模型预测，与更多迎头收敛的区域相比，倾斜区域将经历更长的加热时间和延迟的揭顶。与这一模型及其在造山带中的应用有关的悬而未决的问题包括：在不同地壳水平的倾斜变形过程中，热过程和构造过程的速率和方式是什么？阿尔卑斯-喜马拉雅造山带的安纳托利亚段既有倾斜变形带，又有正向变形带，记录了地壳变形和变质作用的相互作用。在安纳托利亚中部，中地壳岩石在广泛的剪切带中因伸展作用而剥离，上地壳盖层保存在邻近的沉积盆地中。位于安纳托利亚中部的Nigde核杂岩提供了一扇窗口，可以看到高度倾斜造山系统的中地壳，并允许重建倾斜运动期间大陆地壳上部20公里的构造和热史。作为斜造山带热和构造演化的整体研究的一部分，关于扭动构造带的想法是用以下方法检验的：野外工作以确定变质相背景下的岩石类型和结构的分布，并收集样品进行运动学和同位素分析；结构和运动学研究以重建中上地壳不同级别的变形历史；高温地质年代学(U-Pb)和热年代学(40Ar-39Ar；裂变径迹)以确定不同地壳级别的峰值变质作用和冷却历史的时间。这些数据被用来确定变质作用的持续时间、岩浆、变质和构造事件的时间，并推断折返速率/机制。

0106667WhitneyCrustal thickening and exhumation in highly oblique (wrench) tectonic settings typify large regions of the Himalayas, Alps, North American Cordillera, and other mountain systems, but the thermal and structural effects of oblique motion on mid- to deep crustal levels of orogens are poorly known. Simple thermal models predict that oblique zones will experience prolonged heating and delayed unroofing relative to more head-on convergent zones. Unresolved questions related to this model and its application to orogens include: What are the rates and styles of thermal and structural processes during oblique deformation at different crustal levels? How does the style and timing of deformation change from the mid- to upper crust in zones of oblique deformation?The Anatolian segment of the Alpine-Himalayan orogen contains both obliquely deformed and head-on deformed zones that record the interplay between crustal deformation and metamorphism. In central Anatolia, mid-crustal rocks were unroofed by extension during transpression and transtension in a broad zone of shearing, with the upper crustal lid preserved in an adjacent sedimentary basin. The Nigde core complex in central Anatolia provides a window into the mid-crust of a highly oblique orogenic system and permits reconstruction of the tectonic and thermal history of the upper 20 km of continental crust during oblique motion. As part of the overall study of the thermal and structural evolution of oblique orogens, ideas about wrench tectonic zones are tested using the following methods: Fieldwork to determine the distribution of rock types and structures in the context of metamorphic facies, and to collect samples for kinematic and isotopic analyses; Structural and kinematic studies to reconstruct the deformation history of different levels of the mid- to upper crust; High-temperature geochronology (U-Pb) and thermochronology (40Ar-39Ar; fission track) to determine the timing of peak metamorphism and cooling histories of various crustal levels. These data are used to determine the duration of metamorphism, timing of magmatic, metamorphic, and tectonic events, and to infer exhumation rates/mechanisms.