Collaborative Research: Integrated Tectonic and Paleomagnetic Study of the Early Cenozoic Rotation and Extrusion of Asian Crust Around the Eastern Himalayan Syntaxis

合作研究：东喜马拉雅构造系亚洲地壳早新生代旋转和挤压的构造和古地磁综合研究

• 批准号: 0537604
• 负责人: John Geissman
• 金额: --
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-15 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0537604&HistoricalAwards=false
• 关键词: Collaborative; Research; Integrated; Tectonic; Paleomagnetic

A research team from the University of New Mexico and Massachusetts Institute of Technology is investigating the processes by which continental lithosphere is deformed to form syntaxes, regions within orogenic belts where there is a pronounced change in the orientation of structural fabrics over a short distance, in the actively deforming region around the Eastern Himalayan syntaxis. Previous work on the upper Jurassic to lower Tertiary redbeds in the Lanping Simao fold belt of western Yunnan indicates that the process of early Cenozoic extrusion of southeast Asia is complicated and heterogeneous. Specifically, clockwise vertical axis rotation of parts of the crust have been as large as 120 degrees in the western part of the Lanping Simao fold belt, whereas the eastern part remains apparently unrotated. It is inferred that the two parts of the belt are separated by a previously unrecognized shear zone that played a major role in the extrusion process. These results suggest that the prevailing paradigm for extrusion at the eastern Himalayan syntaxis and other syntaxial areas, involving translation of discrete blocks that remain internally undeformed, is inconsistent with several observations. Similar complexities probably exist for other parts, namely to the west of the Lanping-Simao belt, of the extruded Indochina crustal fragments. This project extends paleomagnetic and tectonic studies into other regions of the extruded Indochina crustal fragment to define in more extensive detail the deformation, including translation and rotation, of crustal fragments around the eastern Himalayan syntaxis. The primary focus is on: (1) the Baoshan tectonic element in far southwest Yunnan province, where lower Tertiary strata are exposed close to important structures; (2) northwest Vietnam, where the southernmost part of the Lanping Simao fold belt is exposed; (3) the Qiangtiang elements in eastern Tibet, where Cretaceous/ Paleogene rock, as the northward continuation of the Lanping-Simao belt are exposed (4) selected parts of the Chuxiong basin, northeast of the Red River Fault system; and (5) the Chengling-Mengliang and Linchang elements, immediately west of the Lanping-Simao belt, where Jurassic red beds are well-exposed. This project will better define the regional extent of parts of Southeast Asia that have experienced large magnitude crustal rotations and integrate this information with observations to better understand how the entire top down to bottom up Asian lithosphere has deformed during India's collision. The study area, as well as the entire Himalayan region as part of a broad collisional belt stretching from the Iberian Peninsula to the tip of Southeast Asia, has been the subject of considerable geological interest for decades and the genesis of the great syntaxial regions remains a first-order controversy in tectonics. This project will provide important insight into the processes by which these large structures form. Undergraduate and graduate students are gaining valuable experience in the laboratory and field components of this study. Importantly, they and their mentors benefit from close collaborations with scientists from People's Republic of China and Vietnam.

新墨西哥大学和马萨诸塞州理工学院的一个研究团队正在调查岩石圈形成大陆岩石圈形成语法，造型腰带内部的区域的过程，在短距离内，在短距离内的结构织物方向发生了明显变化，在easperty the Easterty the Espertern the Espertern the Espertern the Espertern ternemalayan ternemalayan synalayan synataxis syntaxis synataxs synataxis synataxis。西云南的Lanping Simao折叠带上的侏罗纪上侏罗纪的先前工作表明，东南亚的早期新生代挤压过程是复杂且异质性的。具体而言，在Lanping Simao Fold Belt的西部，地壳部分的顺时针垂直轴旋转量高达120度，而东部显然仍然没有坐着。可以推断，皮带的两个部分是通过先前未认识到的剪切区分开的，该剪切带在挤出过程中起着重要作用。这些结果表明，在喜马拉雅东部语法和其他语法区域中，挤压的典范范围涉及在内部尚未呈现的离散块的翻译，这与几个观察结果不一致。其他部位可能存在类似的复杂性，即挤压的印度近地壳碎片的Lanping-Simao带的西部。该项目将古磁性和构造研究扩展到挤出的印度支那地壳碎片的其他区域，以更广泛的细节定义了东部喜马拉雅语构成周围地壳碎片的变形，包括翻译和旋转。主要重点是：（1）远西南云南省的Baoshan构造元素，下层三级地层接近重要结构； （2）西北越南，野生式Simao折叠带的最南端暴露在那里； （3）西藏东部的Qiangtiang元素，白垩纪/古生岩，随着Lanping-Simao带的向北延续，暴露了（4）红河断层系统东北部Chuxiong盆地的选定部分； （5）Chengling-Mengliang和Linchang元素，位于Lanping-Simao Belt以西，侏罗纪红床暴露得很好。该项目将更好地定义东南亚部分地区的区域范围，这些区域经历了大量的地壳旋转，并将这些信息与观察结果相结合，以更好地了解整个在印度碰撞期间的上下底部到底上的底层到底上的底层变形。研究区域以及整个喜马拉雅地区，作为从伊比利亚半岛延伸到东南亚尖端的广阔碰撞带的一部分，数十年来一直具有相当大的地质兴趣，并且大义大态地区的起源仍然是构造中的一阶争议。该项目将为这些大型结构形成的过程提供重要的见解。本科生和研究生在这项研究的实验室和现场成分中获得了宝贵的经验。重要的是，他们和他们的导师受益于与中华人民共和国和越南科学家的密切合作。