Collaborative Research: Investigating Mesozoic Deformation in the Pamir: Implications for Crustal Thickening in the Pamir and the Evolution of the Tibetan Orogen

合作研究：帕米尔中生代变形研究：帕米尔地壳增厚和青藏造山带演化的意义

• 批准号: 1450917
• 负责人: Barbara Carrapa
• 金额: $ 33.22万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-01 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1450917&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Mesozoic; Deformation; Collaborative; Research; Investigating; Mesozoic; Deformation

The objective of this proposal is to understand the timing and magnitude of Mesozoic crustal shortening that has occurred within the Central and Southern Pamir region as the western end of the Himalayan-Tibetan orogenic belt. The Himalayan-Tibetan orogen is the classic example of a mountain belt that has formed by continent-continent collision due to the convergence of the Indian and Eurasian tectonic plates. Conventional geologic understanding suggest that most of the uplift is occurred during the Cenozoic. In contrast, the principal investigators hypothesize that much of the crustal shortening and thickening recorded by rocks in this area occurred during Late Jurassic to middle Cretaceous time. To test this hypothesis, the PIs will conduct a multidisciplinary investigation that will involve geologic and structural mapping, stratigraphic analysis, geochronologic and and thermochronologic dating. The results of this project will provide new insights in to the understanding of the tectonic evolution of the Pamir region of the Himalayan-Tibetan orogenic belt. In addition to the scientific goals of the research, the project is contributing to the training of graduate and undergraduate students in cutting-edge research in the geosciences, an important STEM discipline. The project will contribute to the broadening of participation of underrepresented groups in the geosciences, which is an important societal outcome. The project will facilitate international collaboration between researchers at U.S., Italy, and Tajikistan, and will build important institutional collaborations between two U.S. universities. The project will include outreach efforts that include lectures and workshops on the Geology of the Pamir for students at the University of Dushanbe in order to promote geoscience education and science literacy in this developing country. The outcomes of the research will be published in peer-reviewed scientific literature and presentations at professional society meetings; isotopic and geochemical data will be archived in web-based community databases.Over the last decade, increased evidence has shown that much of the crustal shortening and thickening in the Tibetan plateau is Cretaceous in age, pre-dating the Cenozoic collision between India and Asia. However, it is still unclear how laterally extensive, or spatially variable, pre-Cenozoic shortening and thickening is across the entire orogen. This study will provide important information on the timing and magnitude of crustal shortening over a broad region of the western portion of the Tibetan orogen and address important questions regarding the along-strike continuity of pre-Cenozoic deformation in the Tibetan orogen. Further, while significant Cenozoic crustal thickening in the Pamir has been documented in Miocene to Recent gneiss domes, early calculations of the magnitude of upper crustal shortening have been shown to be significantly overestimated, raising important questions regarding the mechanism of Cenozoic crustal thickening (i.e. underthrusting vs. pure shear thickening). The results of this will also provide new information in understanding the mechanisms of crustal thickening in the Pamir region. The specific goal of this study involves testing the hypothesis that much of the crustal shortening and thickening in the Central and Southern Pamir is Mesozoic in age (rather than Cenozoic, as previously interpreted) and represents the along-strike continuation of extensive Late Jurassic-middle Cretaceous crustal shortening and thickening documented in Tibet. The project will include detailed geologic mapping and structural analysis to evaluate crustal shortening in the Pamir; stratigraphic analyses of coarse terrigenous deposits found throughout the region to evaluate whether the deposits are syntectonic with regional shortening structures; geochronologic (detrital U-Pb zircon) and thermochronologic (detrital muscovite 40Ar/39Ar dating, and detrital AFT/AHe double dating) analyses of coarse terrigenous deposits to determine the age of deposition in order to evaluate timing of regional shortening; thermochronologic analyses of basement terranes involved in regional shortening to evaluate timing of shortening related exhumation.

该提议的目的是了解中部和南部帕米尔地区中发生的中生代地壳缩短的时机和幅度，作为喜马拉雅帝国造山带的西端。喜马拉雅 - 藏基造山基因是由于印度和欧亚构造板的收敛而由大陆大陆碰撞形成的山带的经典例子。常规的地质理解表明，大部分隆升发生在新生代期间。相比之下，首席研究人员假设该地区岩石记录的大部分地壳缩短和增厚发生在侏罗纪晚期至白垩纪时间。为了检验这一假设，PI将进行多学科研究，该研究将涉及地质和结构映射，地层分析，地质学和热量计划约会。该项目的结果将为理解喜马拉雅 - 藏族造影带的帕米尔地区的构造进化提供新的见解。除了研究的科学目标外，该项目还为研究生和本科生的培训做出了贡献，这是一个重要的STEM学科。该项目将有助于扩大代表性不足的团体参与地球科学的参与，这是一个重要的社会结果。该项目将促进美国，意大利和塔吉克斯坦研究人员之间的国际合作，并将在两所美国大学之间建立重要的机构合作。该项目将包括宣传工作，包括关于杜尚大学学生PAMIR的地质学讲座和讲习班，以促进这个发展中国家的地球科学教育和科学素养。这项研究的结果将在同行评审的科学文献和专业社会会议上发表；同位素和地球化学数据将在基于Web的社区数据库中存档。在过去的十年中，越来越多的证据表明，藏族高原的大部分缩短和增厚的年龄都是白垩纪的，可以预先约会印度和亚洲之间的新生代碰撞。但是，整个造山机中仍不清楚如何在整个造山造成的横向广泛或空间变化。这项研究将提供有关藏族造基因西部广泛区域的地壳缩短的时机和幅度的重要信息，并解决了有关藏族造基因造基因生成的及时变形的重要问题。此外，尽管已在中新世到最近的片麻岩圆顶已记录了Pamir的明显的新生代地壳增厚，但已证明对上层地壳缩短的大小的早期计算被证明被显着高估了，这引发了有关培育酸壳增厚的机制的重要问题（即，纯净的纯净粉状切成薄片纯皮纯皮增厚）。结果还将提供新的信息，以了解帕米尔地区的地壳增厚的机理。这项研究的具体目标涉及测试以下假设：中部和南部帕米尔的大部分酥皮缩短和增厚的年龄是中生代（如先前解释的），代表了大侏罗纪晚期侏罗纪晚期的白垩纪甲壳虫折叠术和藏在藏藏的沿袭。该项目将包括详细的地质映射和结构分析，以评估Pamir中的地壳缩短； 在整个地区发现了整个地区的粗田沉积物的地层分析，以评估沉积物是否具有区域缩短结构的构造。 对粗陆质沉积物的分析（碎屑肌科植物40AR/39AR日期和碎屑后的AHE双重约会）分析，以评估法规换向的偏移时；与区域缩短有关的基底地层的热相导分析，以评估相关挖掘的缩短时间。