Antarctica within Rodinia: Testing the Laurentia Connection

摘要本研究评估了东南极洲科茨陆块是否是新元古代罗迪尼亚超大陆内横跨造山带连接喀拉哈里和南劳伦西亚的构造示踪物。一条泛非洲（~600 Ma）缝合线将科茨陆块与莫森克拉通分开，表明该地块具有独立的前泛非洲历史。来自科茨地基岩微小露头的现有数据为古地理提供了关键线索，表明劳伦西亚与卡拉哈里穿过格伦维尔-纳马夸/纳塔尔-莫德造山带碰撞。科茨地块只有三组小的基岩暴露，两组形成nunatak，第三组出现在悬崖表面。这两个榴辉体包括与约1.1 Ga Keweenawan、中大陆裂谷、Laurentia及其西南延伸区同时期的花砾岩和流纹岩。此外，Coats Land和Keweenawan岩石的Pb同位素相同，古地磁数据广泛支持Coats Land地块位于现今Laurentian克拉通南缘附近。悬崖表面暴露的变质岩在岩性上与德克萨斯州埃尔帕索的基底岩相似。拟议的研究将进一步对先前从Coats Land收集的标本进行地球化学和地质年代学研究，并对德克萨斯州埃尔帕索附近收集的新的和现有的岩石样本进行详细比较。分析包括锆石U-Pb定年和Hf、O同位素分析，全岩地球化学分析和Pb、Sm-Nd、Rb-Sr同位素分析。这项研究将最大限度地利用南极这一极其偏远地区的现有材料来检验这一假设。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成熟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。研究人员将为JSP重建Rodinia提供现场和实验室研讨会，并将在GeoFORCE 12年级暑期学院期间与高中生进行研究。摘要本研究评估了东南极洲的科茨陆块是否是在古罗迪尼亚超大陆形成过程中，两大陆在约1ga碰撞和随后的分裂过程中转移到南部非洲（喀拉哈里）的一块祖先北美（劳伦西亚）。科茨陆块与邻近的南极洲莫森克拉通（Mawson克拉通）之间有~600 Ma的大陆缝合线，表明科茨陆块在600 Ma之前具有独立的历史。来自科茨地基岩微小露头的现有数据为古地理提供了关键线索，表明劳伦西亚与喀拉哈里相撞。科茨地块只有三组小的基岩暴露，两组形成nunatak，第三组出现在悬崖表面。这两个榴辉体包括与约1.1 Ga Keweenawan、中大陆裂谷、Laurentia及其西南延伸区同时期的花砾岩和流纹岩。此外，Coats Land和Keweenawan岩石的Pb同位素相同，古地磁数据广泛支持Coats Land地块位于现今Laurentian克拉通南缘附近。悬崖表面暴露的变质岩在岩性上与德克萨斯州埃尔帕索的基底岩相似。拟议的研究将进一步对先前从Coats Land收集的标本进行地球化学和地质年代学研究，并对德克萨斯州埃尔帕索附近收集的新的和现有的岩石样本进行详细比较。分析包括锆石U-Pb定年和Hf、O同位素分析，全岩地球化学分析和Pb、Sm-Nd、Rb-Sr同位素分析。这项研究将最大限度地利用南极这一极其偏远地区的现有材料来检验这一假设。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成熟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。研究人员将为JSP重建Rodinia提供现场和实验室研讨会，并将在GeoFORCE 12年级暑期学院期间与高中生进行研究。该奖项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。

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.