Rates of Thermal and Structural Processes in an Oblique Orogen

斜造山带的热和构造过程速率

• 批准号: 0106667
• 负责人: Donna Whitney
• 金额: $ 20.97万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-15 至 2005-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106667&HistoricalAwards=false
• 关键词: Rates; Thermal; Structural; Processes; Oblique

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.

0106667 Whitney在高度倾斜（扭转）构造环境中的地壳增厚和折返，在喜马拉雅山、阿尔卑斯山、北美科迪勒拉山和其他山系的大部分地区都是典型的，但倾斜运动对造山带中深部地壳水平的热效应和结构效应知之甚少。简单的热模型预测，倾斜区将经历长期的加热和延迟相对于更多的迎面收敛区。 未解决的问题有关这个模型及其应用造山带包括：什么是倾斜变形过程中的热和结构过程的速率和风格在不同的地壳水平？ 在斜向变形带中，从中地壳到上地壳，变形的类型和时间是如何变化的？阿尔卑斯-喜马拉雅造山带的安纳托利亚段既有斜向变形带，也有迎头变形带，它们记录了地壳变形与变质作用的相互作用。 在安纳托利亚中部，中地壳岩石在一个广阔的剪切带中，在平移挤压和平移拉伸过程中因伸展而被掀顶，上地壳盖保存在邻近的沉积盆地中。 位于安纳托利亚中部的Nigde核杂岩提供了一个进入高度倾斜造山系统中地壳的窗口，并允许在倾斜运动期间重建上20公里大陆地壳的构造和热历史。作为斜向造山带热演化和构造演化研究的一部分，通过野外调查确定变质相背景下岩石类型和构造的分布，并采集样品进行运动学和同位素分析，通过构造和运动学研究重建中上地壳不同层次的变形历史，通过构造和运动学研究重建地壳的变形历史，通过构造和运动学研究重建地壳的变形历史。高温地质年代学（U-Pb）和热年代学（40 Ar-39 Ar;裂变径迹），以确定不同地壳层次的变质作用高峰和冷却历史的时间。这些数据用于确定变质作用的持续时间，岩浆，变质和构造事件的时间，并推断折返率/机制。