Detrital Mineral Thermochronology of the Indus Molasse, Northwestern Indian Himalaya

印度西北部喜马拉雅地区印度河磨拉石的碎屑矿物热年代学

• 批准号: 0642731
• 负责人: Kip Hodges
• 金额: $ 23.34万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2011-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0642731&HistoricalAwards=false
• 关键词: Detrital; Mineral; Thermochronology; Indus; Molasse

This project will use detrital mineral thermochronology to greatly improve our understanding of the age range, depositional history, and thermal evolution of an important sedimentary succession that constrains the timing of the continent-continent collision between Eurasia and India. Continental sediments of the Indus Group of northwest India provide a critical constraint on the age of the collisional event. The generally accepted beginning of deposition of the Indus molasse in Lutetian-Ypresian time is not explicitly supported by paleontological or geochronological data. Other than the fact that most of the molasse must be younger than Ypresian limestones, age-diagnostic fossils or volcanic horizons have not been identified throughout most of the section, and the stratigraphic position of the only well-documented fossil assemblage from the Indus Group (Upper Oligocene ostracods) is debatable. There are no firm constraints on the ages of any deposits in this important sequence. The principal tools of this work will be laser fusion 40Ar/39Ar biotite thermochronology and both laser heating and laser ablation (U-Th)/He zircon thermochronology. The first method capitalizes on the wide distribution of biotite in Indus Group sandstones and on the fact that post-depositional metamorphism of the sequence was at a low enough temperature to eliminate the possibility of thermal resetting of the 40Ar/39Ar biotite chronometer. Thus, the youngest detrital biotites in each sample provide an upper boundary of the sample's depositional age. The (UTh)/He zircon chronometer, on the other hand, has a closure temperature range low enough that it should have been reset by post-depositional metamorphism in the highest-grade portions of the Indus Group sequence. The zircon ages from these parts of the sequence will provide a lower boundary on depositional ages of all parts of the sequence, since the entire depositional basin experienced epizonal-anchizonal metamorphism at that time. In addition to these important brackets on the age of sedimentation, the results of this study will provide better insights into the provenance of Indus Group sediments, the likely developmental age of the modern Indus River drainage system, and the age of regionally important deformation that accompanied epizonal-anchizonal metamorphism.Broader ImpactsThe project will involve both graduate-level and undergraduate-level education through research participation. A female graduate student will make this research the principal focus of her Ph.D. dissertation. With regard to research and education infrastructure, the proposed work reinforces international research relationships among Arizona State and foreign research institutions in India and the United Kingdom.

该项目将利用碎屑矿物热力学来大大提高我们对年龄范围，沉积历史和重要沉积继承的热演化的理解，从而限制了欧亚大陆与印度之间大陆碰撞的时机。印度西北部印度河集团的大陆沉积物对碰撞事件的年龄提供了关键的限制。印度摩拉斯在卢特蒂安·伊普雷斯时代的沉积开始普遍接受的开始，并未得到古生物学或地球学数据的明确支持。除了大多数莫拉斯必须比Ypresian石灰石还年轻，在整个部分中尚未确定年龄诊断的化石或火山层，并且唯一来自印度企业集团（上寡新洲ostracods）的唯一有据可查的化石组合的地层位置尚未确定。在这个重要序列中，对任何沉积物的年龄没有任何牢固的限制。这项工作的主要工具将是激光融合40AR/39AR BIOTITE热团体学以及激光加热和激光消融（U-TH）/HE锆石热量体。第一种方法利用了印度河组砂岩中生物岩的广泛分布，以及该序列的沉积后变质性在足够低的温度下，以消除40AR/39AR Biotite biotite Chronometer的热重置的可能性。因此，每个样品中最年轻的碎屑生物岩提供了样品沉积年龄的上限。另一方面，（UTH）/He锆石精彩仪的闭合温度范围足够低，以至于在印度河组序列的最高级别部分中应该通过沉积后变质重置。序列的这些部分的锆石年龄将在序列的所有部分的沉积年龄上提供下边界，因为当时的整个沉积盆地经历了epizonal-pandizonal morthorlist。除了这些关于沉积时代的重要括号外，这项研究的结果还将提供更好的见解，以了解印度河集团沉积物的出处，现代印度河河排水系统的可能发育时代以及区域重要变形的时代，伴随Epizonal-pandizonal-panizonal metamorphism术的研究将涉及研究的参与者和小学的研究，并且均参与了研究生。一名女研究生将把这项研究作为博士学位的主要重点。论文。关于研究和教育基础设施，拟议的工作加强了印度和英国的亚利桑那州和外国研究机构之间的国际研究关系。