Collaborative Research: Age, Petrology, and Tectonic Setting of Purported Taconic-aged plutons, Ashland-Wedowee-Emuckfaw Belt, Southern Appalachians

哥伦布州立大学和佛罗里达大学的研究人员之间的这个合作项目旨在解决在阿巴拉契亚山脉最南端的阿拉巴马州的ashland - wedowe - emuckfaw带（东蓝岭）的一些变质花岗岩的构造起源和年龄的相互矛盾的解释。Elkahatchee石英闪长岩、Zana片麻岩和Kowaliga片麻岩通常被认为是与Taconic造山运动相关的最新寒武纪-中奥陶统岩浆活动的产物，一些工作者认为它们是位于北美俯冲边缘上的Taconic岛或周劳伦弧的一部分。然而，来自Elkahatchee的主要石英闪长岩成分的SHRIMP-RG结果表明，上泥盆世的侵位年龄有大量的异种晶体继承的证据，这可能使20多年前完成的初始整体岩石和多颗粒分析变得复杂。Elkahatchee可能存在重要的阿卡迪亚期岩浆成分，这使人们对其与Taconic弧的联系产生了疑问；这个问题只能通过对该岩基的各种岩性进行详细的同位素分析来解决。此外，由于Zana和Kowaliga片麻岩的年代测定方法与Elkahatchee片麻岩的最新寒武纪年代测定方法相同，因此将这些岩体归因于奥陶系造山作用也值得怀疑。这些岩体的空间分辨U-Pb分析将为研究锆石成分的Lu-Hf系统提供最佳的时间背景，并将使我们能够约束母岩浆的岩石构造演化。该项目的研究结果将对北美边缘的构造演化和阿巴拉契亚山脉古生代的发育提供新的线索。重要的是，它将为有关南阿巴拉契亚造山运动演化的基本问题提供新的限制，因为它关系到在Iapetus和Rheic海洋关闭期间沿北美东部边缘俯冲的连续性和性质。这些结果也将有助于人们更好地了解重要的深部元素在南阿巴拉契亚山脉演化中的作用，这将有利于该地区许多机构的本科生和研究生教学。这些大学的学生和教师的专业知识和机会的整合将对培养专业的地球科学家产生重大影响，他们对发展强大的国家STEM劳动力至关重要，并将通过本科院校研究计划（RUI）为主要的本科院校的教师研究计划提供宝贵的支持。最后，本项目将通过参与地质研究项目，为一批地质学本科生提供宝贵的经验（从实地到分析），极大地提高他们的本科教育水平，促进国家的发展。it’s STEM劳动力。

This collaborative project between investigators at Columbus State University and the University of Florida aims to resolve conflicting interpretations of the tectonic origin and age of a number of metamorphosed granitoids in the Ashland-Wedowee-Emuckfaw belt (Eastern Blue Ridge) province of Alabama in the southernmost Appalachians. Traditionally attributed to latest Cambrian-Middle Ordovician magmatism associated with the Taconic orogeny, the Elkahatchee Quartz Diorite, Zana Gneiss, and Kowaliga Gneiss have been considered by some workers to be part of an obducted Taconic island or peri-Laurentian arc emplaced atop the subducting margin of North America. SHRIMP-RG results from the dominant quartz diorite component of the Elkahatchee, however, suggest an Upper Devonian emplacement age with considerable evidence for abundant xenocrystic inheritance which may have complicated the initial whole rock and multi-grain analyses completed over two decades ago. The potential for significant Acadian-aged magmatic components in the Elkahatchee calls into question its association with a Taconic arc; a question which can only be addressed by detailed isotopic analysis of the various lithologies typically assigned to this batholith. Furthermore, since both the Zana and Kowaliga gneisses were assigned ages using some of the same techniques as those used to assign a latest Cambrian age to the Elkahatchee, attribution of these plutons to Ordovician orogenesis is also suspect. Spatially resolved U-Pb analysis of these plutons will provide the best temporal context for examining the Lu-Hf systematics of zircon components and, in combination, will allow us to constrain the petrotectonic evolution of parental magma(s).Results from this project will shed new light on the tectonic evolution of the North American margin and the development of the Appalachian Mountains through the Paleozoic. Significantly, it will provide new constraints on fundamental questions regarding evolution of the southern Appalachian orogeny because of its bearing on the continuity and nature of subduction along the eastern margin of North America during the closure of the Iapetus and Rheic oceans. These results will also afford an improved understanding of the role of important plutonic elements in the evolution of the southern Appalachians, which will be of advantage to many institutions in the region for undergraduate and graduate instruction. Integration of student and faculty expertise and opportunities at these universities will have a significant impact on training professional geoscientists, who are critical to developing a strong national STEM workforce, and will provide valuable support for a faculty research program at a predominantly undergraduate institution through the Research in Undergraduate Institutions program (RUI). Finally, this project will afford a group of geology undergraduates an invaluable experience (from field to analytical) through participation in a geological research program, greatly enhancing their undergraduate education and enhancing the nation?s STEM workforce.