Collaborative Research: Resolving Conflicting Thermobarometry and Stratigraphy in the Tethyan Himalaya: is Non-Lithostatic Pressure During Orogenesis Preserved at Crustal Scales?

合作研究：解决特提斯喜马拉雅地区温压测量和地层学的冲突：造山作用期间的非岩石静压是否保留在地壳尺度？

• 批准号: 2210075
• 负责人: Peter Haproff
• 金额: $ 21.24万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2210075&HistoricalAwards=false
• 关键词: Collaborative; Research; Resolving; Conflicting; Thermobarometry

Metamorphic rocks exposed in mountain belts record crustal burial and heating during mountain building. The metamorphic pressures recorded by exhumed rocks are commonly assumed to reflect their burial depth. Such pressures are in turn used to reconstruct the evolution of mountain belts and refine our knowledge of fundamental plate-tectonic processes. However, recent studies suggest that some rocks record pressures that do not reflect their true burial depths (i.e., “non-lithostatic pressure”), thus potentially complicating our understanding of mountain building events. The Tethyan Himalaya in northwestern India is a unique location to test the controversial concept of non-lithostatic pressure because previous structural, sedimentological, and paleontological observations regarding burial depths conflict with recorded metamorphic pressures. The preservation of non-lithostatic pressure in the Tethyan Himalaya will be tested via an integrated field and laboratory study to reveal the geometric, temperature, and pressure relationships and assess the viability of non-lithostatic pressure conditions recorded in the Himalayan orogen. This project serves national interests by: (1) making fundamental advances in science through testing and challenging the “lithostatic pressure” paradigm in the Earth Sciences; (2) training graduate and undergraduate students in STEM; (3) supporting three early-career faculty to establish globally competitive research programs; (4) international collaboration with researchers and institutions; and (5) development of a publicly accessible field-trip guide that will explore the geology of the Himalaya of northwestern India and focus on how scientific interpretations evolve with new observations. Whether pressures recorded by metamorphic rocks accurately reflect burial depths or can represent non-lithostatic pressure conditions—so called tectonic overpressure—is controversial. Numerical models and theory suggest that non-lithostatic pressure conditions are possible, and even likely in several tectonic settings, but direct, unambiguous observations of this phenomenon are rare. The research team has identified a unique study site in the western Himalaya where decades of sedimentological investigations of the Tethyan stratigraphic section are inconsistent with metamorphic pressure estimates from basal strata that imply ~28+ km burial. Existing kinematic models from field studies do not suggest such burial depths of the section, and thus the discrepancy between pressure estimates and palinspastic reconstructions requires more systematic investigation. The researchers hypothesize that metamorphic pressures from the basal Tethyan strata reflect non-lithostatic pressure conditions at the regional scale (10’s of km). This will be tested via a systematic research plan involving geologic mapping, quantitative microstructural analysis, metamorphic thermobarometry and petrochronology, detrital zircon geochronology, and low-temperature thermochronology. Whether or not non-lithostatic pressure is preserved in the geological record, and the length-scales over which it is preserved, has been identified by the geoscience community as an important research goal in the field of tectonics. Empirical support of regional-scale, non-lithostatic pressures would require a paradigm shift in metamorphic petrology and tectonics, with profound implications for understanding the evolution of fault zones, orogens, and plate-scale dynamics. If the research finds that non-lithostatic pressure is not required to explain the geological discrepancies in the western Tethyan Himalaya, this study will still provide important geologic relationships to evaluate and advance models of Himalayan tectonics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在山带中暴露的变质岩石记录了地​​壳埋葬和山地建筑期间的供暖。通常认为被挖掘出的岩石记录的变质压力反映了它们的埋葬深度。这种压力又被用来重建山带的演变，并完善我们对基本板岩过程的了解。但是，最近的研究表明，一些岩石记录的压力并不能反映其真正的埋葬深度（即“非静态压力”），从而有可能使我们对山区建筑事件的理解变得复杂。印度西北部的Tethyan喜马拉雅山是测试非静态压力概念的独特地点，因为关于埋葬深度与记录的变质压力冲突的先前结构，沉积学和古生物学观察结果。 Tethyan喜马拉雅山中非静态压力的保存将通过综合现场和实验室研究进行测试，以揭示喜马拉雅骨基因中记录的非静态压力条件的几何，温度和压力关系以及评估的生存能力。该项目通过：（1）通过测试和挑战地球科学的“岩性压力”范式来实现科学的基本进步； （2）STEM的培训毕业生和本科生； （3）支持三个早期职业教师建立全球竞争性的研究计划； （4）与研究人员和机构的国际合作； （5）开发一项公开访问的现场旅行指南，该指南将探讨印度西北部喜马拉雅山的地质，并着重于科学解释如何随着新观察的发展而发展。是由变质岩石记录的压力准确地反映了埋葬的深度还是可以代表非静态压力条件（因此称为构造过压）是有争议的。数值模型和理论表明，非静态压力条件是可能的，甚至可能在几个构造环境中，但对此现象的直接，明确的观察很少见。研究小组已经确定了在喜马拉雅西部的一个独特的研究地点，其中数十年的Tethyan地层阶层的沉积学研究与巴萨尔地层的变质压力估计不一致，这意味着埋葬〜28+ km。现有的现有运动学模型并不建议本节的埋葬深度，因此压力估计和壁画重建之间的差异需要更多的系统投资。研究人员假设基本Tethyan地层的变质压力反映了区域尺度上的非静压压力条件（10 km）。这将通过系统的研究计划进行测试，涉及地质图，定量微观结构分析，变质热量学和石化学，碎屑锆石地球人工学和低温热量学。地质记录中是否保留了非静态压力，以及保留其所在的长度尺度，被地球科学界确定​​为构造领域的重要研究目标。区域尺度，非静态压力的经验支持将需要变质岩石学和构造学的范式转移，对理解断层区域，Orogens和板尺度动力学的演变产生了深远的影响。如果研究发现不需要非静态压力来解释西部Tethyan喜马拉雅山的地质差异，那么这项研究仍将提供重要的地质关系来评估和提高喜马拉雅构造的模型。该奖项奖反映了NSF的法定任务，并通过使用基金会的智能范围来评估支持，并通过评估了基金会的范围和广泛的影响。

项目成果

Cenozoic kinematic histories of the Tidding and Lohit thrusts in the northern Indo-Burma Ranges: Implications for crustal thickening and exhumation of Gangdese lower arc crust along the Indus-Yarlung suture zone

印缅山脉北部蒂丁和洛希特逆冲断层的新生代运动史：印度河-雅鲁藏布江缝合带冈底斯下弧地壳增厚和折返的意义

• DOI: 10.1130/b36323.1
• 发表时间: 2022
• 期刊: GSA Bulletin
• 作者: Haproff, Peter J.;Levy, Drew A.;Zuza, Andrew V.;Hooker, Julian D.;Heizler, Matthew T.;Stockli, Daniel F.;Braza, Mary
• 通讯作者: Braza, Mary

Tectonic setting of metamorphism and exhumation of eclogite-facies rocks in the South Beishan orogen, northwestern China

北山南造山带榴辉岩相岩石变质作用与折返作用的构造背景

• DOI: 10.1130/ges02548.1
• 发表时间: 2022
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Li, Jie;Wu, Chen;Chen, Xuanhua;Yin, An;Zuza, Andrew V.;Haproff, Peter J.;Chen, Yanfei;Wang, Luojuan;Shao, Zhaogang
• 通讯作者: Shao, Zhaogang