Collaborative Research: Automated sequencing of the fossil record: improved methods and insights from Mohawkian (Ordovician) geochronology, tephrachronology and biostratigraphy.

地层学和古生物学方面正在进行的地理信息学举措的最终产品将是在线电子地层记录。它面临着三个挑战：汇编足够的数据，整合多个数据库，以及维护能够将所有当地数据记录汇集到一个地质时间表中的工具。第三个挑战是对化石记录进行测序，我们建议解决它面临的三个障碍：(1)由于生境和保护的影响，相同年龄的化石生物群可能会有所不同；(2)非常大的数据集必须被分成更小的片段进行排序，并将结果无缝地拼接在一起；(3)需要更有效地利用越来越多的过时的和有指纹的火山灰床。我们提出了一个可管理的地理和时间范围的案例研究，然而，它提出了同样的问题。奥陶纪和志留纪跨越了早古生代近1亿年的时间，传统上被笔石和牙形石细分-这两个化石支系具有不同的生态和保存特征，限制了它们的使用，主要是相互排斥的领域。北美东部的莫霍基(晚奥陶世)正是具有挑战性的地质环境类型，在其中建立和测试我们设想的时间序列和拼接方法。莫霍基地层在该地区被广泛暴露，并产生了丰富的化石记录，其中包括各种但有些特有的牙形刺动物群。沿阿巴拉契亚边缘，塔科尼亚前陆盆地较深的水沉积形成了表生陆架序列。这些地层包含一套陆间分布的笔石动物群，但很少描述牙形刺组合。众多蚀变火山灰沉积(K-膨润土)通过一套沿盆地内缘的过渡相将这些相联系在一起。尽管有这些优点，但动物群的短切面、构造复杂性和相局限性阻碍了克拉通和盆地序列之间精确而可靠的对比，从而限制了我们比较它们不同的动物群和构造史的能力。智力上的优点：我们建议将(1)莫霍基和辛辛那提早期K-膨润土的地球化学指纹(Tephrochronology)和Pu-Pb年代学与(2)北美东部11个地区的扁平莫霍基牙形刺和笔石重新研究相结合，(3)计算机辅助全球奥陶纪牙形刺和笔石化石记录的测序。这项工作将提供一个详细的时间和古生态框架，在此框架内，通过严格的定量技术，将生物相信息应用于化石记录的时间序列。我们将在步骤1和2中特别关注包含膨润石的牙形石和含笔石的序列，特别是在牙形石和笔石密切共生的区域。尽管存在广泛的时间地层信息，但我们在一段时间间隔内的工作结果将涉及当地和全球地层学的基本问题。在这项研究过程中，我们将检验北美中部和东部中上奥陶统现有的交替对比模式。这一结果将为研究奥陶系和志留系的动物群周转和多样性变化提供一个改进的、年龄校准的基础。最重要的是，这项工作将导致改进的时间尺度构建和验证技术的发展。广泛的影响：我们开发的数据和工具将立即通过时钟项目共享，并将调查时钟没有解决的技术解决方案，以对事件进行排序。该项目满足了EARTHTIME在开发高精度时间尺度方面的交叉培训地层学家和地质年代学家的目标。我们将培养两名博士生(一名副学士)和三名本科生。我们将整合四个机构的努力，其中两个机构招生人数较多(UCR、UALR)，形成一个新的合作关系，促进每个机构的所有学生和私人投资机构之间的互动。本科生将作为PIand的现场和实验室助理参与研究生，并将获得项目的部分作为高级研究项目。每个学生都将在专业会议上陈述研究的各个方面。该项目还将包括一名中学教师，作为阿肯色州STRIVE项目的一部分，他将在夏季与皮莱斯利一起工作。老师将根据他们的经验制定课堂项目。该项目通过增强中学教育教师的知识基础和科学课程来简化未来几代学生。

The end-product of ongoing geoinformatics initiatives in stratigraphy and paleontology will be an onlineelectronic stratigraphic record. It faces three challenges: to compile sufficient data, to integratemultiple databases, and to maintain tools that can assemble all the local data records into a geologic timeline. The third challenge amounts to sequencing the fossil record and we propose to address three of theobstacles it faces: (1) Fossil biotas of the same age may differ as a result of habitat and preservationeffects; (2) Very large data sets must be sequenced in smaller pieces and the results stitched seamlesslytogether; (3) Increasing numbers of dated and fingerprinted ash beds need to used more effectively. Wepropose a case study of manageable geographic and temporal extent that, nevertheless, raises these sameissues. The Ordovician and Silurian periods span almost 100 million years of early Paleozoic time and aretraditionally subdivided by graptolites and conodonts - two fossil clades with different ecological andpreservational traits that restrict their use to largely mutually exclusive domains.The Mohawkian (Late Ordovician) of eastern North America presents precisely the type ofchallenging geological environment in which to build and test the temporal sequencing and stitchingapproaches that we envision. Mohawkian strata are widely exposed in the region and yield a rich fossilrecord that includes diverse, but somewhat endemic, conodont faunas. The epicratonic succession isrimmed along the Appalachian margin by deeper water sediments of the Taconic foreland basin. Thesestrata contain a suite of inter-continentally distributed graptolite faunas, but few described conodontassemblages. Numerous altered volcanic ash deposits (K-bentonites) link these facies through a set oftransitional facies along the interior basin margin. Despite these advantages, the prevalence of shortsections, structural complexity, and facies limitation of the faunas impedes precise and reliable correlationbetween the cratonic and basinal successions, consequently limiting our ability to compare their disparatefaunas and tectonic histories.Intellectual Merit: We propose to combine (1) geochemical fingerprinting (tephrochronology) andU-Pb geochronology of K-bentonites from the Mohawkian and early Cincinnatian with (2) a restudy oflate Mohawkian conodonts and graptolites from eleven regions across eastern North America and (3)computer assisted sequencing of the global Ordovician conodont and graptolite fossil record. This workwill provide a detailed temporal and paleoecological framework within which to refine the application ofbiofacies information to the temporal sequencing of the fossil record via rigorous quantitative techniques.We will focus in steps 1 and 2 particularly on conodont and graptolite-bearing successions that contain Kbentonites,and especially on regions where conodonts and graptolites occur in close association.The results of our work in a time interval that remains troublesome in spite of a wide range of timestratigraphicinformation will bear upon fundamental questions in both local and global stratigraphy. Inthe course of this study we will test existing alternate correlation models for the mid Upper Ordovician ofcentral and eastern North America. The results will provide an improved, age-calibrated basis for studiesof faunal turnover and diversity change in the Ordovician and Silurian. Most importantly, the work willlead to the development of improved techniques for time scale construction and validation.Broader Impact: The data and tools we develop will be shared immediately through the CHRONOSproject and will investigate technological solutions that are not being addressed by CHRONOS tosequence events. The project meets the EARTHTIME goal of cross-training stratigraphers andgeochronologists in developing high precision time-scales. We will train two PhD students (one aminority), and three undergraduates. We will integrate the efforts of four institutions, two with largeminority enrolment (UCR, UALR), in a new collaboration that will facilitate the interaction of all thestudents and PIs at each institution. Undergraduates will participate as field and lab assistants for the PIsand for the graduate students, and will be given pieces of the project as senior research projects. Eachstudent will present aspects of the research at a professional meeting. The project will also include asecondary school teacher who will work alongside PI Leslie during the summer as part of the ArkansasSTRIVE program. The teacher will develop class projects based on their experiences. The project thusimpacts future generations of students by enhancing a secondary education teacher's knowledge base andscientific curriculum.