Geologic and Paleomagnetic Study of the Basal Belt Supergroup, Little Belt Mountains, Montana: Testing the Siberian Connection to Rodinia

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。大量时间的流逝模糊了地球的构造历史，就像它模糊了人类历史一样。古代大陆的构造联系引起了社会的极大兴趣，因为它们控制着能源和矿产资源分布等关键方面。地质学家提出，假设的超大陆罗迪尼亚的构造分裂将西伯利亚和北美分开，并引发了重大的地质事件，包括全球冰河时代、海平面变化以及动物生命的起源和扩散。该项目将测试蒙大拿州中部古代沉积岩的磁记忆，以便与西伯利亚类似沉积物的先前结果进行比较，以评估这些现在遥远的大陆是否在大约15亿年前是一个单一超大陆的邻近部分。如果是这样，当它们利用岩石的磁记忆通过时间恢复时，它们应该会聚在一个共同的磁极位置上。除了揭示大陆之间的古代联系外，这项研究的结果还将提高我们对古代磁场的性质和历史的基本认识。地球科学家提出了假设的前寒武纪超大陆罗丁尼亚的几种构造。研究人员将通过从蒙大拿州中部小带山脉的基带超群的未受干扰的沉积岩中得出16 - 15亿年前北美古人类极点的位置来评估这些模型。这些结果将与之前在西伯利亚克拉通上相似和相关地层中得到的pi古地磁位置进行比较，以测试北美和西伯利亚在Rodinia内的相对位置。地质学家普遍认为，早在罗丁尼亚形成之前，西伯利亚和北美就已经是一个大大陆的相邻部分，只是在罗丁尼亚分裂后才分开。本项目古地磁模拟的成功将填补北美视极漂移路径的关键时间空白。PI将收集定向样品作为正在进行的合作的一部分，该小组将使用消磁方法在领先的国际实验室分析样品。目的是将结果与已经从西伯利亚样本中获得的结果进行比较。使用相同的实验室、技术和人员来分析蒙大拿州的样本将产生与西伯利亚结果直接可比的数据，并确保模型漫游路径的准确性。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The passing of enormous amounts of time obscures Earths tectonic history much as it does human history. The ancient tectonic connections of continents are of great interest to society because they control critical aspects of, for example, the distribution of energy and mineral resources. Geologists have proposed that the tectonic breakup of the hypothetical supercontinent, Rodinia, separated Siberia and North America and triggered significant geologic events, including global ice-ages, sea-level changes, and the origin and dispersal of animal life. This project will test the magnetic memory of ancient sedimentary rock formations in central Montana for comparison with previous results from similar sediments in Siberia to evaluate whether these now distant landmasses were adjacent parts of a single supercontinent about 1.5 billion years ago. If so, they should converge on a common magnetic pole position when they are restored through time using the magnetic memory of the rocks. In addition to revealing the ancient connections of the continents, results from this study will improve our basic understanding of the nature and history of the ancient magnetic field. Geoscientists have proposed several configurations for the hypothetical Precambrian supercontinent Rodinia. The investigators will evaluate these models by deriving North American paleopole positions for the interval 1.6-1.5 billion years ago from undisturbed sedimentary rocks of the basal Belt Supergroup in the Little Belt Mountains of central Montana. The results will be compared with previous paleomagnetic positions that the PIs derived from similar and correlative strata on the Siberian craton, to test the relative locations of North America and Siberia within Rodinia. Geologists generally consider that Siberia and North America were already adjacent parts of a single large continent well before Rodinia formed, and became separated only when Rodinia broke apart. Successful paleomagnetic modeling in this project will fill in a critical time gap for the North American apparent polar wander path. The PI will collect oriented samples as part of ongoing collaborations and the group will use demagnetization methods to analyze the samples at leading international laboratories. The goal is to compare the results with those already obtained from Siberian samples. Using the same lab, techniques, and personnel to analyze the Montana samples will yield data directly comparable with the Siberian results, and ensure the veracity of the model wander paths.