Extension of the Newark Geomagnetic Polarity Reference Sequence to Address Problems of the Carnian and the Middle Triassic

根据纽瓦克盆地厚而连续的大陆记录，晚三叠世的地磁极性时间尺度（GPTS）是基于以湖相的帕塞伊克、洛克通和上斯托克顿组为代表的2600万年的旋回地层学，但基于河流相的下斯托克顿组的沉积速率外推，其中来自岩心孔的单一磁性地层记录尚未得到证实。在纽瓦克序列中对比三叠纪-侏罗纪界线似乎是可靠的，但在试图合并海洋生物地层和非海洋岩石地层记录时，主要基于孢粉学的诺里安-雷蒂安界线，特别是卡尼-诺里安界线的位置变得非常成问题。最近提出的海洋剖面中Carnian-Norian边界与纽瓦克层序的相关性将该边界置于斯托克顿组的中部，并意味着边界年龄为~228 Ma。这是明显的老比通常显示在地质年代尺度，虽然不排除现有的放射性年龄数据。如果得到证实，它将对我们理解区域和全球历史地质学产生重大影响，包括恐龙等主要陆地脊椎动物群体的进化时间和盘古大陆的裂谷。然而，海相和非海相层序的相关性强烈依赖于参考极性层序的可靠性，这需要针对下斯托克顿组所代表的时间进行验证和细化。我们提出了一种双管齐下的方法来解决海相卡尼期和更老地层与纽瓦克参考剖面之间相关性的模糊性：1）古地磁分析和测量出露的斯托克顿地层，以测试和扩展普林斯顿岩心孔中描绘的极性序列，并将该记录直接与天文校准的GPTS联系起来，Timesgadiouine组相关出露地层的古地磁分析与测量（阿尔加纳盆地，摩洛哥）进行旋回地层控制。成功完成了这2-一个为期一年的项目将扩大天文校准的GPTS，以涵盖超过3000万年的晚三叠世，并可能进入中三叠世。一个精确的地质时间尺度具有广泛的适用性，例如，它将提供一个难得的机会，在盘古大陆解体之前的一个重要而有趣的地质时间间隔内解决海洋和非海洋的相关性，在全球范围内关联重要的陆地脊椎动物区系组合，我们的工作包括与一位摩洛哥地质学家合作，摩洛哥国家石油公司ONAREP提供了大量实物后勤捐助，除了对项目本身不可或缺之外，还将在这一困难时期帮助在阿拉伯和美国机构之间建立桥梁。最后，我们将开发一个网站，其中将包括一个阿拉伯语版本，以便它可以被用作美国和摩洛哥团体的教育工具，并围绕着这两个地区（美国东部和摩洛哥）是姐妹地质和生物省份的概念，现在被海洋分开，但曾经是同一大片陆地的一部分，彼此直接相邻。美国本科生将参与该项目的几个阶段，他们将获得定量方法的宝贵经验，以及在美国接触阿拉伯科学家和文化。

ABSTRACTThe geomagnetic polarity time scale (GPTS) for the Late Triassic developed from the thick, continuous continental record from the Newark basin is based on cycle stratigraphy for 26 million years represented by the lacustrine Passaic, Lockatong and upper Stockton formations but on extrapolation of sedimentation rates for the fluvial lower Stockton Formation for which the single magnetostratigraphic record from a core hole has not been verified. Correlation of the Triassic-Jurassic boundary within the Newark succession seems secure but placements of the Norian-Rhaetian and especially the Carnian-Norian boundaries based largely on palynology have become highly problematical in attempts to merge the marine biostratigraphic and nonmarine lithostratigraphic records. Recently proposed correlations of the Carnian-Norian boundary in marine sections to the Newark sequence place this boundary in the middle of the Stockton Formation and would imply a boundary age of ~228 Ma. This is appreciably older than usually shown in geologic time scales although not precluded by available radiometric age data. If confirmed it would have major implications to our understanding of regional and global historical geology including the timing of evolution of major groups of land vertebrates like the dinosaurs and the rifting of Pangea. However, the correlation of the marine and nonmarine sequences depends strongly on the reliability of a reference polarity sequence, which needs to be validated and refined for the time represented by the lower Stockton Formation.We propose a two-pronged approach to resolving the ambiguities in the correlations between the marine Carnian and older strata and the Newark reference section: 1) paleomagnetic analysis and measurement of outcropping Stockton Formation to test and extend the polarity sequence delineated in the Princeton corehole and to link this record directly to the astronomically calibrated GPTS, and 2) paleomagnetic analysis and measurement of correlative outcropping strata of the Timesgadiouine Formation (Argana Basin, Morocco) for cycle stratigraphic control.Successful completion of this 2-year project will extend the astronomically calibrated GPTS to encompass more than 30 million years of the Late Triassic and possibly into the Middle Triassic. A precise geologic time scale has broad applicability and will, for example, provide a rare opportunity to resolve marine and nonmarine correlations over a significant and interesting interval of geologic time just prior to the breakup of Pangea, to correlate important land vertebrate faunal assemblages on a global scale, and to incorporate some of the few radiometric dates that are available for age control but which come from nonmarine sections.Our work includes collaboration with a Moroccan geologist and a significant in-kind logistical contribution from ONAREP, the Moroccan state oil company that in addition to being integral to the project itself will help build bridges between Arab and U.S. institutions during this difficult time. Finally, we will develop a web site that will include an Arabic version so that it can be used as an educational tool for both U.S. and Moroccan groups and revolve around the concept that the two areas (eastern U.S. and Morocco) are sister geological and biological provinces, now separated by an ocean, but were once part of the same vast land mass and directly adjacent to one another. U.S. undergraduates will be involved with several stages of this project in which they will get valuable experience in quantitative methods as well as exposure in the U.S. to Arab scientists and culture.