Upper Triassic Terrane Faunas and Their Use in Paleogeographic Comparisons within the Cordilleran Region

上三叠纪地体动物群及其在科迪勒拉地区古地理比较中的应用乔治·斯坦利、罗伯特·布洛杰特 EA​​R0229795蒙大拿大学摘要该项目将结合实地工作、实验室和博物馆藏品研究来评估晚三叠世关键时期的无脊椎动物群。它旨在记录来自阿拉斯加、加拿大西部、内华达州和墨西哥的各种热带至亚热带贝类化石的分类组成、古生态学和古地理意义，并与世界其他地区（例如西欧和前特提斯部分地区）的同时代化石进行比较。 待研究的化石包括珊瑚、海绵、水螅动物、有关节的腕足动物、双壳类和腹足类动物。这些物种丰富且分布广泛，但人们对物种分类知之甚少。该研究将评估分类学和古生态学关联。在三叠纪时期，其中一些无脊椎动物群栖息在北美西海岸，但许多其他动物群栖息在火山岛上，现在被视为流离失所的地体。将提取动物群的地体包括兰盖利亚的阿拉斯加部分和告别地体，以及 Chulitna、Wallowa、A​​lexander 和 Junco 地体。 在三叠纪时期，这些地体位于距克拉通西海岸不详的距离，其动物群为测试和更好地解析古地理提供了无与伦比的机会，特别是为了确定一些关键地体（如兰盖利亚和亚历山大地体）之间的古生物地理亲和力和关系。许多地体代表活跃的岛弧，在火山活动期间和之后，这些岛弧下沉并被沉积沉积所取代，从而培育了丰富的无脊椎动物海洋群落。一些待研究的化石产于厚的碳酸盐矿床甚至珊瑚礁组合中。这些生物曾经在古代太平洋的热带至亚热带纬度地区发育。由于许多用于研究的生物组合都已硅化，因此化石将在稀酸中蚀刻，预计将释放大量化石用于研究。对这些硅化动物群的分类学研究将提供大量新的重要数据。该项目预计还将受益于与许多外部专家的合作。 将采用统计古生物地理学方法，该项目还将受益于许多三叠纪类群的电子古生物学数据库的开发。该古生物学项目预计将为一般古生物地理综合提供必要的数据，并为测试地体关系的一些构造假设奠定基础。

Upper Triassic Terrane Faunas and Their Use in Paleogeographic Comparisons within the Cordilleran RegionGeorge Stanley, Robert Blodgett EAR0229795University of MontanaABSTRACTThis project will employ a combination of field work, laboratory, and museum collections research to assess invertebrate faunas during a critical time in the Late Triassic. It seeks to document the taxonomic composition, paleoecology and paleogeographic significance of various tropical to subtropical, shelly fossils from Alaska, western Canada, Nevada, and Mexico and to make comparisons with coeval fossils from other regions of the world, such as western Europe and parts of the former Tethys. Fossils to be studied are corals, sponges, hydrozoans, articulate brachiopods, bivalves and gasropods. These are abundant and widespread but little is known about the species taxonomy. The study will assess both taxonomy and paleoecological associations. During the Triassic time, some of these invertebrate faunas inhabited the western shores of North America but many others inhabited volcanic islands, now regarded as displaced terranes. The terranes from which faunas will be extracted, include the Alaskan portion of Wrangellia and the Farewell terrane, as well as Chulitna, Wallowa, Alexander and Junco terranes. In Triassic time, these terranes were located at unspecified distances off the western coast of the craton and their faunas provide unparalleled opportunities to test and better resolve the paleogeography, specifically to work out the paleobiogeographic affinities and relationships between some key terranes such as Wrangellia and the Alexander terrane. Many terranes represent active island arcs which, during and following cessation of volcanism, subsided and were replaced by sedimentary deposition, thus fostering rich invertebrate marine associations. Some of the fossils to be studied occur in thick carbonate deposits and even reefal associations. These organisms once developed at tropical to subtropical latitudes somewhere in the ancient Pacific ocean. Because many biotic assemblages proposed for study are silicified, fossils will be etched in dilute acids which are expected to free large numbers of fossils for study. Taxonomic study these silicified faunas will provide a wealth of new and important data. The project also is expected to benefit by collaboration with a number of outside specialists. Statistical paleobiogeographic methods will be employed and the project also will benefit from the development of an electronic paleontological database for many of the Triassic taxa. This paleontological project is expected to provide the necessary data for a general paleobiogeographic synthesis and to lay the foundation for testing some tectonic postulates for terrane relationships.