EAR-PF:Constraining the burial and unroofing history of the Rae craton, Baffin Island, from multiple low temperature thermochronometers and secondary Fe-oxide (U-Th)/He dating

Alexis K. Ault博士获得美国国家科学基金会地球科学博士后奖学金，在亚利桑那大学开展研究和教育计划。本文研究了克拉通对近场板块边界活动的地表响应，包括变形、高地形地区的沉积、前陆盆地发育、弯曲隆起和与挖掘相关的流体循环。本文的研究重点是加拿大巴芬岛的Rae克拉通，这是一个独特的克拉通地区，因为它在显生宙期间靠近板块边界，旨在通过一套热时计，包括磷灰石(U-Th)/He、磷灰石裂变径迹和锆石(U-Th)/He测年，来限制克拉通埋藏和拆顶的规模和模式。流体流动和与岩石挖掘相关的二次成矿作用将通过赤铁矿(U-Th)/He定年进行测定。该建议的创新之处在于，将古地磁数据与赤铁矿定年相结合，为评估美国西部两项试点研究中的铁氧化物数据和潜在的“双重日期”流体流动事件提供了背景。在将该技术应用于巴芬岛等其他环境之前，必须准确解释和理解赤铁矿(U-Th)/He日期的意义。长期以来被认为不受构造运动影响的克拉通区域或大陆的核心如何以及为什么会被重新激活，这些过程在克拉通表面演化中的特征仍然是大陆动力学中悬而未决的问题。这一研究结果将对地质年代学和构造学界有重要意义。重建Rae克拉通过去沉积的沉积岩的范围和厚度以及埋藏温度的量化将有助于冰川学家和地貌学家探索Laurentide冰盖动力学对巴芬岛景观的影响，但也将为了解加拿大北极地区的区域油气藏潜力提供关键信息。赤铁矿(U-Th)/He定年技术的发展和成功应用，将对活动构造界和经济地质界的人们有很大的帮助。与这项研究相关的教育活动包括指导亚利桑那大学的本科生和研究生，并共同教授一个关于新的赤铁矿(U-Th)/He测年技术的方法和应用的暑期强化学生研讨会。

Dr. Alexis K. Ault has been granted an NSF Earth Sciences Postdoctoral Fellowship to carry out research and an education plan at the University of Arizona. This research investigates the surface response of cratons to near-field plate boundary activity including deformation, sedimentation from regions of high topography, foreland basin development, flexural uplift, and exhumation-related fluid-circulation. The proposed research focuses on the Rae craton, exposed on Baffin Island, Canada, a unique cratonic locality given its proximity to plate boundaries throughout the Phanerozoic, and aims to constrain the magnitudes and patterns of cratonic burial and unroofing with a suite of thermochronometers including apatite (U-Th)/He, apatite fission-track, and zircon (U-Th)/He dating. Fluid flow and secondary mineralization associated with rock exhumation, will be dated via hematite (U-Th)/He dating. An innovative aspect of this proposal is the coupling of paleomagnetic data with the hematite dating to provide a backdrop to evaluate Fe-oxide data and potentially "double-date" fluid flow events in two Western U.S. pilot studies. Accurate interpretation and understanding of the significance of hematite (U-Th)/He dates is necessary before application of the technique to other settings like Baffin Island.How and why cratonic regions, or the cores of continents long considered to be immune to tectonism, are reactivated and the signatures of such processes on the surface evolution of cratons remain outstanding questions in continental dynamics. The results of this research will be of interest to the geochronology and tectonics communities. Reconstruction of the past extent and thickness of sedimentary rocks deposited across the Rae craton and quantification of burial temperatures will aid glaciologists and geomorphologists exploring the impact of Laurentide ice sheet dynamics on the Baffin Island landscape, but will also provide critical information for understanding regional hydrocarbon reservoir potential in the Canadian Arctic. The development and successful application of the hematite (U-Th)/He dating technique to constrain near-surface fluid flow will benefit those in the active tectonics and economic geology communities. Education activities associated with this research include mentoring University of Arizona undergraduate and graduate students and co-teaching an intensive summer student workshop on the method and application of the new hematite (U-Th)/He dating technique.