Biostratigraphic and paleogeographic utility of Cambrian-Ordovician trilobite faunas in Alaska

北美的古地理地图描绘了我们的大陆在地球历史上某些时期的出现，地质学家利用这些地图来勘探化石燃料和其他重要的社会资源，气候专家利用这些地图来更深入地了解我们的星球在“深时间”时的状况。地球科学家研究构造板块的行为以及形成地球表面的衍生过程。但是，在寒武纪和奥陶纪（一个温室气候时期），构建这样的地图的数据，对于大陆的北半部和北极地区来说，是极其稀少的。本项目将通过对阿拉斯加北部北极阿拉斯加Terrane （AAT）和阿拉斯加东部育空稳定块（YSB）寒武-奥陶系三叶虫（已灭绝的海洋节肢动物）的详细研究来改善这一状况。它将利用美国和加拿大地质调查局的地质学家在过去一个世纪里收集的大量化石，并辅以在阿拉斯加几个关键地区收集的新材料。AAT的目标是通过比较其北坡地下（NST）新发现的动物群与先前在阿拉斯加西部苏厄德地下（ST）报道的三叶虫，来验证NST中厚石灰岩序列沉积在北美东北部（现代坐标）某处的假设，而ST起源于西伯利亚或其附近。在YSB中，对琼斯岭石灰岩中岩石和化石的全面记录将完善与其他地区同年龄岩石的对比。对于许多要研究的地平线来说，琼斯岭的数据将是第一次从整个非洲大陆北半部获得信息。通过保存在北美西北角附近的厚厚的（约450米）石灰石堆进行精确的时间控制，将有助于测试在大陆另一边的美国和加拿大南部的广大地区记录的许多事件的整个大陆（也许是全球）范围的说法。这些变化包括（除其他外）：1)海平面的显著上升和下降；2)寒武纪晚期边界灭绝后，台地范围内的微生物礁发育受到抑制。拟议项目的科学成果将通过提高对北极地区的认识而造福社会，北极地区拥有丰富的重要资源，但就我们对其构造历史的基本方面的理解而言，仍然是一个前沿。地质学本科专业学生和地球与空间科学教育专业学生作为初级合作者广泛参与该项目，将培养一批具有非凡洞察力的专业地球科学家骨干，以及能够以实际从事科学工作的人的热情和知识教授科学的中学教师。

Biostratigraphic and paleogeographic utility of Cambrian-Ordoviciantrilobite faunas in Alaskaby John Taylor, Indiana University of PennsylvaniaEAR-1325333ABSTRACTPaleogeographic maps of North America, which depict our continent as it appeared at certain times in Earth history, are utilized by geologists exploring for fossil fuels and other critical societal resources, climate specialists seeking greater insight to conditions that prevailed on our planet in 'deep time', and geoscientists investigating the behavior of tectonic plates and derivative processes that shape the surface of our planet. But the data for constructing such maps for the Cambrian and Ordovician Periods, a time of greenhouse climate, are exceedingly sparse for the northern half of the continent, and the Arctic regions in general. This project will improve that situation through detailed study of Cambrian-Ordovician trilobite (extinct marine arthropod) faunas)from the Arctic Alaska Terrane (AAT) of northern Alaska, and the Yukon Stable Block (YSB) of eastern Alaska. It will utilize large fossil collections archived by geologists of the U.S. and Canadian Geological Surveys over the past century, supplemented by new material collected in several key areas in Alaska. The goal for the AAT is to test, by comparing newly discovered faunas from its North Slope Subterrane (NST) with trilobites previously reported from the Seward Terrane (ST) in western Alaska, the hypothesis that the thick limestone succession in the NST was deposited somewhere in northeastern (modern coordinates) North America, whereas the ST originated in or near Siberia. In the YSB, thorough documentation of rocks and fossils in the Jones Ridge Limestone will refine correlation with rocks of the same age in other regions. For many of the horizons targeted for study, the data from Jones Ridge will be the first information acquired from the entire northern half of the continent. The refined time control through this thick (ca. 450m) stack of limestone preserved near the northwestern corner of North America will serve to test the claim of continent wide (and perhaps global) extent for numerous events documented across broad areas in the U.S. and southern Canada, on the opposite side of the continent. These include (among others), 1) a number of significant rises and falls in sea level and 2) episodes of platform-wide suppression of microbial reef development in the aftermath stage boundary extinctions in the late Cambrian. The scientific results of the proposed project will benefit society by advancing knowledge of the Arctic region, an area rich in vital resources but still a frontier with respect to our understanding of even basic aspects of its tectonic history. Extensive involvement of undergraduate Geology majors and Earth and Space Science Education majors as junior collaborators in the project will produce a cadre of professional geoscientists with exceptional insight and secondary school teachers able to teach science with the enthusiasm and knowledge of someone who has actually done science.