The 2.67 Ga Orogeny in the Teton and Wind RIver Ranges: One of the Oldest Himalayan Orogenies on Earth

怀俄明州西部的片麻岩提供了2.68 - 2.67 Ga.岩石学、构造学和变质作用记录，最好解释为现代板块构造的产物。 重要特征包括风河山脉和提顿山脉可能存在岩浆弧; 2678 Ma时在猫头鹰溪山脉和风河山脉东部可能存在以同时代拉斑玄武岩岩墙群为标志的弧后盆地;风河山脉存在一个主要的地壳规模的SW至W向逆冲断层;提顿山脉可能存在增生棱柱或弧前盆地;以及北美最古老的高压变质岩标志着提顿山脉可能发生大陆-大陆碰撞的记录。这项研究是一个详细的岩石学，结构，地球化学和地质年代学研究在北方提顿山脉，以评估是否基底岩石记录现代风格的板块构造。该研究包括结合热压法确定高压片麻岩的压力-温度路径，地质测绘确定高压片麻岩与北方提顿山脉其他岩石之间的结构关系。同位素分析被用来确定的年龄的关键深成单元的片麻岩的提顿范围，限制的时间的高压岩石减压，更精确地确定逆冲在风河范围的年龄。此外，还将使用新锆石和锶同位素分析来确定提顿片麻岩中变质沉积岩的物源以及侵入它们的花岗岩类的可能来源。该项目的意义在于解决现代板块构造何时开始的问题，这是地球历史上的一个主要问题。 地球在太古代（25亿年前）更热。 由于构造板块的运动是热量从地球消散的一种方式，许多地质学家认为，一个更热的地球应该有一个与我们今天看到的不同的构造风格。 怀俄明州西北部的26.7亿年前的岩石可能保存了太古代现代风格板块构造的最佳记录之一。因此，这项研究可能是了解北美地质构造和构造演化的关键。 该项目支持博士教育。学生和贡献的本科生的培养。研究结果将有助于了解大提顿国家公园的地质情况。

The gneisses in western Wyoming Province provide a 2.68 - 2.67 Ga. petrologic, structural, and metamorphic record that is best explained as being a product of modern style plate tectonics. Important features include the presence of a possible magmatic arc in the Wind River and Teton ranges; the presence of a possible back-arc basin marked by coeval tholeiitic dike swarms in the Owl Creek Mountains and the eastern Wind River Range at 2678 Ma; a major crustal-scale SW- to W-directed thrust in the Wind River Range; a possible accretionary prism or fore-arc basin in the Teton Range; and a record of possible continent-continent collision in the Teton Range marked by the oldest high-pressure metamorphic rocks in North America. This research is a detailed petrologic, structural, geochemical and geochronologic study in the Northern Teton Range to evaluate whether the basement rocks record modern style plate tectonics. The research involves a combination of thermobarometry to determine the Pressure-Temperature path of the high-pressure gneisses, geologic mapping to determine the structural relations between the high-pressure gneisses and other rocks in the northern Teton Range. Isotopic analyses are being used to determine the age of key plutonic units in the gneisses of the Teton Range, constrain the timing of the decompression of the HP rocks, and more precisely determine the age of thrusting in the Wind River Range. In addition, Neodymium and Strontium isotopic analyses will be used to determine the provenance of metasedimentary rocks in the Teton gneisses and the possible sources of the granitoids that intrude them. The significance of the project lies in addressing the question of when modern-style plate tectonics began, which is a major problem in Earth history. The Earth was much hotter in Archean time (before 2.5 billion years ago). Since the movement of tectonic plates is one way that heat is dissipated from the Earth, many geologists maintain that a hotter Earth should have had a different the tectonic style from what we see today. The 2.67 billion year old rocks in northwestern Wyoming may preserve one of the best records of modern-style plate tectonics in the Archean. Therefore, this study may be a key to understanding the geologic construction of North America and the evolution of tectonics in general. The project is supporting the education of a Ph.D. student and contributing to the training of undergraduate students. Results of the research will contribute to the understanding of the geology of the Grand Teton National Park.