Collaborative Research: Filling the Triassic geochronologic gap: A continuous cored record of continental environmental change in western North America

合作研究：填补三叠纪地质年代学空白：北美西部大陆环境变化的连续岩心记录。罗格斯大学的丹尼斯·肯特，伯克利地质年代学实验室的罗兰·蒙迪尔，耳朵-0958723摘要三叠纪期间发生了两次有史以来最大规模的物种大灭绝，见证了现代生物群中大多数元素的进化，以及恐龙时代的到来。科罗拉多高原是这一时期陆地上生物和环境变化最丰富的档案之一，尽管经过了100多年的研究，它的时间校准仍然很差，在全球其他地区的记录中也记录得很差。为了提供所需的数据，我们将在美国亚利桑那州石化森林国家公园（PFNP）的几乎整个三叠纪时代剖面（Chinle和Moenkopi地层）连续钻取一个~500米的岩心，这是地球上最著名和研究最好的三叠纪大陆序列之一。为了在可靠的定量和可导出的时间尺度上记录这一惊人的记录，需要连续采样（岩心），这在露头中被证明是不切实际的。石化森林岩心将提供定量可靠的参考剖面，其中磁地层、地质年代学、环境和古生物学数据将被登记到具有明确叠加的共同厚度尺度，并将提供原始的未风化样品。有了这样一个参考部分，PFNP和周边地区的大量露头数据就可以整合到全球框架中。井眼将从垂直方向偏离30°，以提供岩心-层理方向交叉点作为方位导向；此外，岩心的方向将通过全岩心扫描、罗盘定向声学和光学电视图像以及倾角测量来记录到井壁上。岩心定向将有助于恢复高分辨率磁极性地层学，以便与富含化石的露头剖面进行对比。该极性序列将由一系列从岩心离散层位获得的高精度U-Pb锆石日期进行校准，并将为填补晚三叠世全球陆地和海洋时间尺度的地质年代学空白提供关键数据。PFNP岩心的年龄校正年代学将用于解决早中生代生物和环境变化的主要问题。这些问题包括晚三叠世的海洋和大陆生物更替事件是否耦合；是晚三叠世与巨大的摩尼瓦根撞击同步发生的陆地上规模最大的动物更替事件；nsf资助的Newark盆地天文校准时间尺度是否与Chinle组高精度U-Pb锆石年龄数据一致？纽瓦克盆地湖泊记录的周期性气候变化是否以米兰科维奇气候变化为节奏？除了核心所产生的科学以及它与当地和全球环境和生物框架的整合之外，该项目还将有一个主要的教育和推广组成部分。石化森林国家公园是一个主要的旅游目的地，平均每年有60万游客。我们计划利用这一巨大的资源，为公园开发一个关于核心项目及其重要科学成果的永久性展览。在实际的取心活动中，我们将涉及许多学生团体，包括新墨西哥大学/盖洛普大学的美洲原住民地球科学专业学生和盖洛普地区的K-12学生。此外，我们将在公园赞助多个工作坊，并向公众开放，让他们参与。该项目涉及来自不同机构的6个共同项目人员，将持续24个月，目的是提供基本地层、测井、磁极和地质年代学数据的初步概要，供国际科学界用于进一步研究和与其他研究相结合，并提供一个主要平台，以便进行外联和更好地了解现代世界是如何形成的。

Collaborative Research: Filling the Triassic Geochronologic Gap: A Continuous Cored Record of Continental Environmental Change in Western North America.Paul Olsen, Lamont-Dougherty, EAR-0958976George Gehrels, University of Arizona, EAR-0959107Randall Irmis, University of Utah, Ear-0958915Dennis Kent, Rutgers University, EAR-0958859Roland Mundil, Berkeley Geochronology Laboratory, EAR-0958723ABSTRACTThe Triassic Period was punctuated by two of the largest mass-extinctions of all time and witnessed the evolution of most elements of the modern biota, as well as the advent of the age of the dinosaurs. One of the richest archives of the biotic and environmental changes on land for this period is on the Colorado Plateau, which despite over 100 years of study still remains poorly calibrated in time and poorly registered to the rest of the global record. To provide this desiderata, we will drill a continuous a ~500 m core through nearly the entire Triassic age section (Chinle and Moenkopi formations) at Petrified Forest National Park (PFNP), Arizona, USA, one of the most famous and best studied successions of the continental Triassic on Earth. A continuous sampling (core) is needed to place this spectacular record in a reliable quantitative and exportable time scale, which has proved impractical in outcrop. The Petrified Forest core will provide a quantitatively sound reference section in which magnetostratigraphic, geochronologic, environmental, and paleontologic data are registered to a common thickness scale with unambiguous superposition and will provide pristine unweathered samples. With such a reference section in hand the entire voluminous assemblage of outcrop data from the PFNP and the surrounding region can be integrated into the global framework. The hole will be deviated 30° from vertical to provide core-bedding orientation intersections for an azimuthal guide; additionally, the orientation of the core will be registered to the hole wall using whole-core-scans and compass-oriented acoustic and optical televiewer images and dipmeter surveys. Core orientation will facilitate the recovery of a high-resolution magnetic polarity stratigraphy for correlation to the fossil-rich outcrop sections. The polarity sequence will be calibrated by a series of high-precision U-Pb zircon dates obtained from discrete levels in the core, and will provide critical data to fill the geochronologic gap in global terrestrial and marine time scales for the Late Triassic. The age-calibrated chronostratigraphy of the PFNP core will be used to address major issues of early Mesozoic biotic and environmental change. These include whether marine and continental biotic turnover events in the Late Triassic were coupled; was the largest magnitude faunal turnover event on land during the Late Triassic synchronous with the giant Manicouagan impact; Is the NSF-funded Newark basin astronomically-calibrated time scale consistent with high precision U-Pb zircon age data from the Chinle Formation; and was the cyclical climate change recorded in the Newark basin lacustrine record paced by Milankovitch climate change? In addition to the science generated by the core and its integration into the local and global environmental and biotic framework, the project will have a major education and outreach component. The Petrified Forest National Park is a major tourist destination, averaging 600,000 visitors a year. We plan to leverage this huge resource by developing a permanent exhibit on the coring project and its important scientific results for the park. We will involve numerous student groups during the actual coring activities, including Native American geoscience concentrators at The University of New Mexico/Gallup and K-12 students from throughout the Gallup area. In addition, we will sponsor several workshops at the Park and will reach out to the general public for their participation. The project involves six co-PIs from different institutions and will last 24 months and is intended to provide an initial synopsis of basic stratigraphic, logging, magnetic polarity, and geochronologic data for utilization by the international scientific community for further research and integration with other studies, as well as a major platform for outreach, and a better understanding of how the modern world came to be.