Structural, metamorphic, and thermal evolution of the Brooks Range (Alaska) metamorphic belts: implications for formation-exhumation of high-pressure rocks and Arctic tectonic evol

布鲁克斯山脉（阿拉斯加）变质带的结构、变质和热演化：对高压岩石形成折返和北极构造演化的影响

• 批准号: 2019525
• 负责人: James Vogl
• 金额: $ 22万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2019525&HistoricalAwards=false
• 关键词: Structural; metamorphic; thermal; evolution; Brooks

With a length of over 600 km, the Schist belt in the Brooks Range of northern Alaska is one of the largest high-pressure metamorphic terranes in the world and shares many characteristics with other high-/ultra-high- metamorphic rocks around the world. This study is focused on documenting the deformational, metamorphic, and thermal histories of the Schist belt and adjacent lower pressure metamorphic rocks to test hypotheses related to two groups of questions. (1) How are high-pressure rocks exhumed to the Earth’s surface? Buoyant continental lithospheric plates may be pulled into subduction zones by sinking of the attached dense oceanic lithosphere at subduction zones, providing a simple explanation for deep tectonic burial and associated high-pressure metamorphism in continental rocks. However, the processes by which these high-pressure rocks are brought back up to the earth’s surface remain poorly understood. (2) The Brooks Range, the rest of the northern Alaska, and Chukotka are widely believed to have rotated about 66° anti-clockwise away from the Canadian Arctic Islands during formation of the Canada Basin (Arctic Ocean). It remains unclear as to what geologic events (e.g., continental subduction and high-pressure metamorphism, collision, extension, basin formation), if any, in the Brooks Range are dynamically linked to rotational basin opening. Furthermore, it is unclear as to how this geometrical style of basin opening is accommodated along the strike of the of the ca. 3000 km long continental land mass from northeastern Alaska to Chukotka. This project will provide financial support and training of a Ph.D. student, a M.Sc. student, and multiple undergraduates in STEM fields, potentially including women and underrepresented groups. The students will gain experience in field mapping, as well as a variety of analytical laboratory techniques in facilities with experts at two universities. Graduate students will be involved in outreach through creation of teaching materials focused on Arctic geology that will be distributed to Alaska schools through collaboration with the Alaska Division of Geological & Geophysical Surveys. Through an increased understanding of Arctic geology, this study will provide an improved framework for economic development of resources as the Arctic region opens for exploration in the coming decade.Jurassic(?)-Cretaceous convergence between a passive margin and the oceanic Angayucham terrane produced the Brooks Range orogen (northern Alaska), which includes a fold-thrust belt and two metamorphic belts: the blueschist/eclogite Schist belt and the high-pressure greenschist Central belt. However, many key aspects of the structural, metamorphic, and thermal histories are lacking for these metamorphic belts, resulting in diverse models for exhumation of the high-pressure rocks, and the tectonic evolution of both the Brooks Range and greater Arctic region. In this study we will use field and analytical techniques to document the structural, metamorphic, and thermal evolution of both belts to test models in three interrelated categories. (1) The researchers will test models for the highly debated relationships regarding the timing and geodynamic significance of normal-sense structures on the south flank of the Brooks Range, and the tectonic setting of flanking basins. The work will place kinematic and age constraints on tectono-thermal events, particularly in during the Aptian-Albian, a key time of important change in north Alaska and the adjacent Arctic realm. (2) The researchers will test models for the formation and exhumation of high-pressure rocks, with a focus on the role of buoyancy-driven exhumation models. (3) The Brooks Range and the rest of the Arctic Alaska – Chukotka microplate is believed to have rotated about 66° anti-clockwise away from the Canadian Arctic Islands, resulting in the formation of the Canada Basin. It remains unclear as to what events (e.g., continental subduction and high-P metamorphism, collision, extension, basin formation), if any, in the Brooks Range are dynamically linked to basin opening. Furthermore, there is debate regarding how this geologically unprecedented geometrical basin opening is accommodated along the strike of the of the ca. 3000-km-long continental land mass of the Arctic Alaska – Chukotka microplate. Improved timing constraints for Brooks Range tectonic events will address these issues and test specific models.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.

在阿拉斯加北部的布鲁克斯山脉中，片岩腰带的长度超过600公里，是世界上最大的高压变质台之一，并且在世界各地具有许多高/超高的金属型岩石。这项研究的重点是记录片岩带和相邻的下压力岩石的变形，变质和热历史，以测试与两组问题相关的假设。 （1）如何将高压岩石挖掘到地球表面？浮力连续岩石圈板可以通过在俯冲带上的附着的致密岩石圈下沉到俯冲带中，从而为连续岩石中的深层构造埋葬和相关的高压变质提供了一个简单的解释。但是，这些高压岩石被带回地球表面的过程仍然很差。 （2）布鲁克斯山脉，阿拉斯加北部和丘科特卡的其余部分被广泛认为在加拿大盆地（北极海洋）的形成期间，距加拿大北极岛（Canadian Arctic Islands）旋转了约66°的逆时针方向。目前尚不清楚地质事件（例如，连续的俯冲和高压变质，碰撞，延伸，盆地形成）（如果有的话）在布鲁克斯范围内与旋转盆地开放动态相关。此外，尚不清楚如何在CA的罢工中容纳这种几何风格的盆地开口风格。从阿拉斯加东北部到Chukotka的3000公里长的连续土地。该项目将提供博士学位的财政支持和培训。学生，硕士学生和STEM领域的多个本科生，可能包括妇女和代表性不足的群体。学生将获得现场映射的经验，以及两所大学专家的设施中的各种分析实验室技术。研究生将通过创建专注于北极地质的教材来参与外展活动，该教学将通过与阿拉斯加地质与地球物理调查部合作分发给阿拉斯加学校。通过对北极地质学的越来越多的了解，这项研究将为资源的经济发展提供改进的框架，随着北极地区在未来十年的探索开放。片岩带和高压绿党中央带。然而，这些变质带缺乏结构，变质和热历史的许多关键方面，从而导致了潜水员模型的高压岩石，以及布鲁克斯范围和更大北极区域的构造演化。在这项研究中，我们将使用现场和分析技术来记录两种皮带的结构，变质和热演化，以在三个相互关联的类别中测试模型。 （1）研究人员将测试有关正常义结构在Brooks范围的南侧的正常义结构的时机和地球动力学意义的高度争论关系，以及低音侧翼的构造设置。这项工作将对构造构造 - 热事件（尤其是在Aptian-Albian，北阿拉斯加北部和邻近的北极领域都有重要变化的关键时期，都会对运动和年龄限制。 （2）研究人员将测试模型的高压岩石的形成和挖掘，重点是浮力驱动的挖掘模型的作用。 （3）布鲁克斯范围和北极阿拉斯加的其余部分 - 丘科特卡微板岩据信已旋转约66°逆时针方向，远离加拿大北极群岛，导致形成了加拿大盆地。目前尚不清楚哪些事件（例如，连续的俯冲和高-P变质，碰撞，延伸，盆地形成），如果有的话，在布鲁克斯范围内的任何事件都与盆地开口动态相关。此外，关于这种地质前所未有的几何盆地开口如何在CA的罢工中容纳了这种地质前所未有的几何盆地开口。北极阿拉斯加 - 丘科特卡微板的3000公里长的连续土地质量。 Brooks范围构造事件的改进的正时限制将解决这些问题并测试特定的模型。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，认为通过评估被认为是宝贵的支持。