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

正在进行的地层学和古生物学方面的地理信息学倡议的最终产品将是在线电子地层记录。它面临三个挑战：汇编足够的数据，整合多个数据库，维护能够将所有本地数据记录汇集成地质时间轴的工具。第三个挑战是对化石记录进行测序，我们建议解决它所面临的三个障碍：（1）由于栖息地和繁殖的影响，同一年龄的化石生物可能会有所不同;（2）非常大的数据集必须以较小的片段进行测序，并将结果无缝拼接在一起;（3）需要更有效地利用越来越多的有日期和指纹的灰烬层。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，提出了这些相同的问题。奥陶纪和志留纪跨越了近1亿年的早古生代时间，传统上被笔石和牙形石细分-这两个化石分支具有不同的生态和地理特征，限制了它们在很大程度上相互排斥的领域的使用。（晚奥陶世）北美东部的地质环境正是建立和测试时间序列的挑战性地质环境，我们设想的方法。莫霍基阶地层在该地区广泛暴露，并产生了丰富的化石记录，包括不同的，但有点地方性的牙形石动物群。该震陷层序沿着阿巴拉契亚边缘被塔科尼前陆盆地的深水沉积物所包围。这些地层包含一套洲际分布的笔石动物群，但很少描述牙形石组合。许多蚀变火山灰沉积物（钾镁矾）通过一组沿着盆地内部边缘的过渡相将这些相联系起来。尽管有这些优点，但普遍存在的短剖面、结构复杂性和动物群的相限制，阻碍了古陆和盆地序列之间精确可靠的相关性，从而限制了我们比较它们的古陆动物群和构造历史的能力。我们建议联合收割机（1）地球化学指纹对北美东部11个地区的莫霍基期牙形刺和笔石进行了再研究，全球奥陶纪牙形石和笔石化石记录的计算机辅助测序。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，改进生物相信息在化石记录时间序列中的应用。我们将重点关注步骤1和步骤2，特别是牙形石和含笔石的序列，其中含有钾霞石，特别是在牙形刺和笔石紧密共生的地区。我们在一个时间间隔内的工作结果仍然很麻烦，尽管有广泛的时间地层学信息将对局部和全球地层学的基本问题产生影响。在这项研究的过程中，我们将测试现有的替代相关模型中，上奥陶统的中部和东部北美。研究结果将为研究奥陶纪和志留纪动物群的更替和多样性变化提供改进的年龄标定依据。更广泛的影响：我们开发的数据和工具将立即通过CHRONOS项目共享，并将调查CHRONOS未解决的技术解决方案，以确定事件的序列。该项目符合EARTHTIME的目标，即交叉培训地层学家和地质年代学家，以开发高精度的时间尺度。我们将培养两名博士生（一名博士生）和三名本科生。我们将整合四个机构的努力，其中两个具有很大的知名度招生（UCR，UALR），在一个新的合作，将促进所有的学生和PI在每个机构的互动。本科生将作为PI和研究生的现场和实验室助理参加，并将作为高级研究项目获得项目的部分内容。每个学生将在专业会议上介绍研究的各个方面。该项目还将包括一名经济学校教师，他将在夏季与PI Leslie一起工作，作为阿肯色州教育计划的一部分。教师将根据他们的经验开发课堂项目。该项目通过加强中学教师的知识基础和科学课程来提高未来几代学生的能力。

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.