Resolving Mesoproterozoic supercontinent configuration with an integrated multi-tool approach to sedimentary provenance analysis

超大陆周期包括地球各大洲周期性地组合成一个单一的超大陆，然后分裂和分散。存在重大地质限制的最古老的超级大陆之一是哥伦比亚(也被称为努纳)，它被认为是大约15亿年前组装而成的。15亿至14亿年前在北美西部沉积的沉积物中含有缺乏已知北美来源的矿物，因此表明另一个大陆在哥伦比亚境内与北美西部毗邻。然而，这块大陆的身份以及在约15亿年前和约10亿年前下一个超级大陆(称为罗迪尼亚)的形成之间发生的任何重新安排的程度仍然存在争议。已经提出的模型是将澳大利亚北部、澳大利亚南部和/或南极洲东部与北美西部毗邻。这项研究将通过详细分析蒙大拿州、爱达荷州和亚利桑那州古代沉积岩中矿物的年龄和成分，并与澳大利亚和南极洲的潜在来源进行比较，来检验这些不同的模型。对从南极洲采集的古代沉积岩中的矿物进行的可比分析将提供进一步的限制。这个项目将支持马萨诸塞大学洛厄尔分校的研究生和本科生的研究，为冰川国家公园内和周围的学生开发一门新的夏季野外地质学和生态学课程(冰川国家公园是该项目感兴趣的岩石的关键地点)，将辅助研究纳入该大学的其他本科课程，以及与爱达荷州、亚利桑那州、华盛顿州、德克萨斯州和明尼苏达州的科学家合作。该项目的目标是测试与中元古代超级大陆哥伦比亚中北美西部相连的大陆块体的身份和位置。这项研究将集中于北美西部中元古代沉积岩的来源，特别是蒙大拿州/爱达荷州的带状超群和亚利桑那州类似年代的岩石。这些沉积层序以前被认为具有非北美的输入，通过传统的碎屑锆石测年。这项工作将使用一种创新的综合方法来确定来源，方法是同时对碎屑锆石、独居石和金红石进行U-Pb测年和微量元素指纹分析，并分别对碎屑锆石和长石进行Hf和普通铅同位素表征。结果将与北澳大利亚克拉通、南澳大利亚克拉通和东南极克拉通的潜在源岩进行比较。之前从南极洲东部采集的沉积样品也将包括在这项研究中，以扩大对该冰盖大陆前寒武纪基底地质的了解。这项裁决反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The supercontinent cycle involves the periodic assembly of the Earth’s continents into a single supercontinent followed by breakup and dispersal. One of the oldest supercontinents for which significant geologic constraints exist is Columbia (also referred to as Nuna), which is thought to have been assembled by about 1.5 billion years ago. Sediments deposited between ~1.5 and 1.4 billion years ago in western North America include minerals that lack known North American sources and thus suggest that another continent was adjacent to western North America within Columbia. However, the identity of this continent and the extent to which any rearrangement occurred between ~1.5 billion years ago and the formation of the next supercontinent (called Rodinia) at ~1.0 billion years ago remains debated. Models have been proposed that place either northern Australia, southern Australia, and/or eastern Antarctica adjacent to western North America. This research will test these different models through detailed analyses of the ages and compositions of minerals within ancient sedimentary rocks in Montana, Idaho, and Arizona and comparison with potential sources in Australia and Antarctica. Further constraints will be provided from comparable analyses of minerals in ancient sedimentary rocks collected from Antarctica. This project will support graduate and undergraduate student research at the University of Massachusetts Lowell (UML), the development of a new summer field geology and ecology course for UML students held in and around Glacier National Park (which is a key locality for the rocks of interest in this project), incorporation of supported research into other undergraduate courses at UML, and collaborations with scientists in Idaho, Arizona, Washington, Texas, and Minnesota.The goal of this project is to test models for the identity and positions of continental blocks that were connected to western North America in the Mesoproterozoic supercontinent Columbia. The study will focus on the provenance of Mesoproterozoic sedimentary rocks in western North America, particularly the Belt Supergroup in Montana/Idaho and similarly aged rocks in Arizona. These sedimentary sequences have previously been recognized as having non-North American input via conventional detrital zircon dating. This work will use an innovative and integrative approach to determining provenance by way of simultaneous U-Pb dating and trace element fingerprinting of detrital zircon, monazite, and rutile, along with Hf and common Pb isotope characterization of detrital zircon and feldspar, respectively. Results will be compared to potential source rocks in the North Australian craton, South Australia craton, and East Antarctic craton. Previously collected sedimentary samples from East Antarctica will also be included in this study in order to expand knowledge of the Precambrian basement geology of that ice-covered continent.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.