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

上三叠世地体动物群及其在科迪勒拉地区古地理比较中的应用蒙大拿大学乔治斯坦利，罗伯特布洛杰特EAR0229795摘要该项目将采用野外工作，实验室和博物馆收藏研究相结合的方式来评估晚三叠世关键时期的无脊椎动物群。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贝壳化石的分类组成、古生态学和古地理学意义，并与来自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、水螅虫、有节腕足动物、双壳类和气足类。这些是丰富和广泛的，但很少有人知道物种分类。这项研究将评估分类学和古生态学的联系。在三叠纪时期，这些无脊椎动物群中的一些居住在北美的西海岸，但许多其他人居住在火山岛，现在被认为是流离失所的珊瑚礁。将从中提取动物群的物种包括阿拉斯加部分的弗兰格利亚和告别鸟，以及丘利特纳、瓦洛瓦、亚历山大和Junco鸟。 在三叠纪时期，这些化石位于克拉通西海岸以外的未知距离处，它们的动物群为测试和更好地解决古地理问题提供了无与伦比的机会，特别是为确定一些关键化石（如弗兰格利亚和亚历山大化石）之间的古生物地理亲缘关系和关系提供了机会。许多珊瑚礁代表了活跃的岛弧，在火山活动停止期间和之后，这些岛弧下沉并被沉积物所取代，从而培育了丰富的无脊椎海洋生物群。一些待研究的化石出现在厚的碳酸盐沉积物中，甚至是珊瑚礁组合中。这些生物曾经在热带到亚热带纬度的古太平洋某处发展。由于许多建议研究的生物组合是硅化的，化石将在稀酸中蚀刻，这有望释放大量的化石用于研究。对这些硅化动物群的分类研究将提供丰富的新的重要资料。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建立的电子古生物学数据库。这一古生物学项目有望为一般的古生物地理综合提供必要的数据，并为检验某些构造假设的构造关系奠定基础。

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.