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

上三叠统地体动物群及其在科迪勒伦地区古地理比较中的应用乔治·斯坦利，罗伯特·布洛吉特·埃里克森，蒙大拿大学摘要该项目将结合野外工作、实验室和博物馆收藏品研究，在晚三叠世的关键时期评估无脊椎动物动物群。它试图记录来自阿拉斯加、加拿大西部、内华达州和墨西哥的各种热带到亚热带的壳类化石的分类组成、古生态和古地理意义，并与世界其他地区的同时代化石进行比较，如西欧和前特提斯的部分地区。待研究的化石有珊瑚、海绵、水生动物、有关节腕足动物、双壳类和足足类。它们种类繁多，分布广泛，但对物种分类学知之甚少。这项研究将评估分类学和古生态联系。在三叠纪时期，这些无脊椎动物群中的一些生活在北美的西海岸，但其他许多生活在火山岛上，现在被认为是流离失所的地体。将从中提取动物群的地体包括Wrangellia的阿拉斯加部分和Farewell地体，以及丘利特纳、沃洛瓦、亚历山大和Junco地体。在三叠纪时期，这些地体位于克拉通西海岸以外的不明距离处，它们的动物群提供了无与伦比的机会来测试和更好地解析古地理，特别是研究一些关键地体之间的古地理亲缘关系和关系，如Wrangellia和Alexander Terrane。许多地体代表活跃的岛弧，在火山活动停止期间和之后，这些岛弧下沉，并被沉积沉积所取代，从而促进了丰富的无脊椎动物海洋组合。一些待研究的化石出现在厚厚的碳酸盐沉积中，甚至出现在珊瑚礁组合中。这些生物曾经在热带到亚热带的古代太平洋的某个地方发展起来。由于许多被提议研究的生物组合是硅化的，化石将被蚀刻在稀酸中，这有望释放大量化石用于研究。对这些硅化动物群的分类研究将提供大量新的重要数据。预计该项目还将受益于与一些外部专家的合作。将采用统计古生物地理学方法，该项目还将受益于为许多三叠纪分类群开发一个电子古生物数据库。这一古生物学项目有望为全面的古生物地理综合提供必要的数据，并为检验地体关系的某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.