Antarctica within Rodinia: Testing the Laurentia Connection

技术摘要本研究评估是否小科茨土地地壳块东南极洲是一个构造示踪剂连接喀拉哈里和南部劳伦蒂亚在新元古代超大陆Rodinia跨越造山带。泛非缝合线（~600 Ma）将小科茨地块与主莫森地块分开，表明该地壳地块具有独立的前泛非历史。从科茨地微小的基岩露头中获得的现有数据为古地理学提供了关键线索，表明劳伦蒂亚与卡拉哈里穿过格伦维尔-纳马夸/纳塔尔-莫德造山带相撞。 科茨地地块只有三个小的基岩暴露组，两个形成冰原岛峰，第三个出现在悬崖面。这两个冰原岛峰由与该火山同生的花岗斑岩和流纹岩组成。1.1 Ga Keweenawan，中大陆裂谷，劳伦蒂亚火山岩及其在德克萨斯州埃尔帕索的西南延伸。此外，科茨地和Keweenawan岩石的铅同位素是相同的，和古地磁数据广泛支持科茨地块已位于毗邻目前的劳伦克拉通南缘。从岩石学上看，悬崖面暴露的变质岩类似于德克萨斯州埃尔帕索的基底岩石。拟议的研究将进一步对先前从科茨地收集的标本进行现有的地球化学和地质年代学研究，并对在德克萨斯州埃尔帕索附近收集的新的和现有的岩石样品进行详细的比较。分析包括锆石U-Pb定年和Hf、O同位素分析，全岩地球化学和Pb、Sm-Nd、Rb-Sr同位素分析。这项研究将最大限度地利用南极洲这一极其偏远地区的现有材料来验证这一假设。研究人员将与德克萨斯大学奥斯汀分校杰克逊地球科学学院的两个完善的教育推广项目合作。本科研究助理将从杰克逊学者计划（JSP）招募。研究人员将提供一个基于现场和实验室的研讨会，为JSP重建Rodinia，并将在GeoFORCE 12年级暑期学院与高中生进行研究。非技术摘要本研究评估了东南极洲的小科茨地地壳块体是否是在Rodinia古超大陆形成过程中，两个大陆在~ 1Ga碰撞和随后的分裂过程中转移到南部非洲（Kalahari）的一块祖先北美（Laurentia）。科茨地与相邻的南极洲莫森岛被约600 Ma的大陆缝合线隔开，表明科茨地在600 Ma之前有独立的历史。从科茨地微小的基岩露头中获得的现有数据为古地理学提供了关键线索，表明劳伦蒂亚与卡拉哈里相撞。科茨地地块只有三个小的基岩暴露组，两个形成冰原岛峰，第三个出现在悬崖面。这两个冰原岛峰由与该火山同生的花岗斑岩和流纹岩组成。1.1 Ga Keweenawan，中大陆裂谷，劳伦蒂亚火山岩及其在德克萨斯州埃尔帕索的西南延伸。此外，科茨地和Keweenawan岩石的铅同位素是相同的，和古地磁数据广泛支持科茨地块已位于毗邻目前的劳伦克拉通南缘。从岩石学上看，悬崖面暴露的变质岩类似于德克萨斯州埃尔帕索的基底岩石。拟议的研究将进一步对先前从科茨地收集的标本进行现有的地球化学和地质年代学研究，并对在德克萨斯州埃尔帕索附近收集的新的和现有的岩石样品进行详细的比较。分析包括锆石U-Pb定年和Hf、O同位素分析，全岩地球化学和Pb、Sm-Nd、Rb-Sr同位素分析。这项研究将最大限度地利用南极洲这一极其偏远地区的现有材料来验证这一假设。研究人员将与德克萨斯大学奥斯汀分校杰克逊地球科学学院的两个完善的教育推广项目合作。本科研究助理将从杰克逊学者计划（JSP）招募。研究人员将提供一个现场和实验室为基础的研讨会重建Rodinia的JSP，并将进行研究与高中学生在GeoFORCE 12年级暑期学院。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Technical AbstractThis research evaluates whether the small Coats Land crustal block of East Antarctica is a tectonic tracer linking Kalahari and southern Laurentia within the Neoproterozoic supercontinent of Rodinia across an orogenic suture. A Pan-African (~600 Ma) suture separates the small Coats Land block from the main Mawson Craton indicating that this crustal block had an independent pre-Pan-African history. Existing data from the miniscule outcrops of bedrock in Coats Land provide critical clues to that paleogeography, suggesting that Laurentia collided with Kalahari across the Grenville-Namaqua/Natal-Maud orogen. The Coats Land block has only three small groups of bedrock exposures, two form nunataks and the third occurs in a cliff face. The two nunataks comprise granophyre and rhyolite contemporaneous with the ca. 1.1 Ga Keweenawan, mid-continent rift, volcanics of Laurentia and its proposed southwestern extension in El Paso, TX. Moreover, the Pb isotopes of the Coats Land and Keweenawan rocks are identical, and paleomagnetic data are broadly supportive of the Coats Land block having been located adjacent to the present southern margin of the Laurentian craton. Metamorphic rocks from the cliff face exposure lithologically resemble basement rocks of the El Paso, TX. The proposed research will further existing geochemical and geochronologic studies of specimens previously collected from Coats Land and new and existing samples of rocks collected near El Paso, Texas for detailed comparison. Analyses include zircon U-Pb dating and Hf and O isotope analysis, and whole rock geochemistry and Pb, Sm-Nd and Rb-Sr isotope analysis. This research will make maximum use of existing material from this extremely remote part of Antarctica to test this hypothesis. Researchers will collaborate with 2 well-established education-outreach programs in the Jackson School of Geosciences at The University of Texas at Austin. Undergraduate research assistants will be recruited from the Jackson Scholars Program (JSP). Researchers will provide a field- and lab-based seminar on reconstructing Rodinia for the JSP and will conduct research with high school students during GeoFORCE 12th grade summer academy. Non-technical AbstractThis research evaluates whether the small Coats Land crustal block of East Antarctica is a piece of ancestral North America (Laurentia) that was transferred to southern Africa (Kalahari) during ~ 1 Ga collision, and subsequent breakup, of the two continents during the formation of the ancient supercontinent of Rodinia. Coats Land is separated from the adjacent Mawson Craton of Antarctica by ~600 Ma continental sutures indicating that Coats Land had an independent history prior to 600 Ma. Existing data from the miniscule outcrops of bedrock in Coats Land provide critical clues to that paleogeography, suggesting that Laurentia collided with Kalahari. The Coats Land block has only three small groups of bedrock exposures, two form nunataks and the third occurs in a cliff face. The two nunataks comprise granophyre and rhyolite contemporaneous with the ca. 1.1 Ga Keweenawan, mid-continent rift, volcanics of Laurentia and its proposed southwestern extension in El Paso, TX. Moreover, the Pb isotopes of the Coats Land and Keweenawan rocks are identical, and paleomagnetic data are broadly supportive of the Coats Land block having been located adjacent to the present southern margin of the Laurentian craton. Metamorphic rocks from the cliff face exposure lithologically resemble basement rocks of the El Paso, TX. The proposed research will further existing geochemical and geochronologic studies of specimens previously collected from Coats Land and new and existing samples of rocks collected near El Paso, Texas for detailed comparison. Analyses include zircon U-Pb dating and Hf and O isotope analysis, and whole rock geochemistry and Pb, Sm-Nd and Rb-Sr isotope analysis. This research will make maximum use of existing material from this extremely remote part of Antarctica to test this hypothesis. Researchers will collaborate with 2 well-established education-outreach programs in the Jackson School of Geosciences at The University of Texas at Austin. Undergraduate research assistants will be recruited from the Jackson Scholars Program (JSP). Researchers will provide a field- and lab-based seminar on reconstructing Rodinia for the JSP and will conduct research with high school students during GeoFORCE 12th grade summer academy.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.