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

通过沉积物源分析的综合多工具方法解析中元古代超大陆构造

• 批准号: 1951905
• 负责人: Richard Gaschnig
• 金额: $ 22.97万
• 依托单位: University of Massachusetts Lowell
• 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: 2020-05-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1951905&HistoricalAwards=false
• 关键词: Resolving; Mesoproterozoic; supercontinent; configuration; integrated

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.

超大陆周期包括地球各大陆周期性地聚集成一个单一的超大陆，然后分裂和分散。 最古老的超级大陆之一是哥伦比亚（也称为努纳），它被认为是在大约15亿年前组装起来的。 北美西部约15亿至14亿年前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内与北美西部相邻。 然而，这个大陆的身份以及在大约15亿年前和大约10亿年前下一个超大陆（称为Rodinia）形成之间发生的任何重组的程度仍然存在争议。 已经提出了将澳大利亚北方、澳大利亚南部和/或南极洲东部与北美西部相邻的模型。 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，来测试这些不同的模型。 对从南极洲收集的古代沉积岩中的矿物进行比较分析，将提供进一步的限制。 该项目将支持马萨诸塞州洛厄尔大学（UML）的研究生和本科生的研究，在冰川国家公园及其周围地区为UML学生开发一门新的夏季野外地质学和生态学课程（这是本项目中感兴趣的岩石的关键地点），将支持的研究纳入UML的其他本科课程，并与亚利桑那州爱达荷州的科学家合作，华盛顿，得克萨斯州和明尼苏达州。该项目的目标是测试模型的身份和位置的大陆块，连接到北美西部的中元古代超大陆哥伦比亚。 这项研究将侧重于北美西部中元古代沉积岩的物源，特别是蒙大拿州/爱达荷州的带超群和亚利桑那州的类似年龄的岩石。 这些沉积序列以前被认为是通过传统的碎屑锆石测年的非北美输入。 本工作将采用一种创新的、综合的方法来确定物源，通过同时进行碎屑锆石、独居石和金红石的U-Pb定年和微量元素指纹，分别沿着碎屑锆石和长石的Hf和普通Pb同位素特征。 将结果与北澳大利亚克拉通、南澳克拉通和东南极克拉通的潜在烃源岩进行比较。 以前从东南极洲收集的沉积样品也将包括在这项研究中，以扩大对该冰雪覆盖大陆的前寒武纪基底地质的了解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。