High-precision U-Pb zircon geochronology and intracontinental correlation of terrestrial ecosystems during the "zenith" of dinosaur diversity in the Late Campanian of North America

北美坎帕尼亚晚期恐龙多样性“顶峰”期间陆地生态系统的高精度U-Pb锆石年代学和陆内对比

• 批准号: 1424892
• 负责人: Jahandar Ramezani
• 金额: $ 25.46万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1424892&HistoricalAwards=false
• 关键词: precision; Pb; zircon; geochronology; intracontinental

High-precision U-Pb zircon geochronology and intracontinental correlation of terrestrial ecosystems during the 'zenith' of dinosaur diversity in the Late Campanian of North AmericaSamuel BowringEAR-1424892--MITABSTRACTNon-technical overview:A major question is whether global environmental change cause changes in biological evolution. The time period between 80 and 70 million years ago has been described as the ?zenith? of dinosaur diversity and western North America contains unparalleled exposures of rocks with abundant dinosaur fossils from this time period. We do not have a good understanding of what triggered this burst of evolutionary diversity but we do know that at the same time were profound, global-scale environmental changes, including an increase in global atmospheric temperatures and an abrupt rise in sea level. However some have argued that the apparent increase in diversity has more to do with preservation than evolution. To test whether global environmental changes or preferential preservation are responsible, we must be able to correlate rocks and fossils from southern Canada to the southwestern United States. This project will focus on high precision dating of volcanic rocks interlayered with fossil bearing rocks so that we determine the rates of evolution across more than 2000 km of latitude in western North America. This will allow us to in turn evaluate whether evidence for environmental change preserved in the rocks can be correlated with dinosaur evolution. Technical AbstractThis project will focus on developing an unparalleled chronostratigraphy for an approximately ten million year (80-70 Ma) interval across a 2000 km long corridor of Late Campanian (Cretaceous) strata preserved in the Western Interior Basin of western North America (Laramidia). This represents one of the most laterally extensive and fossiliferous continental successions in the world, and includes the famous Two Medicine-Judith River fauna/flora in Montana and Wyoming, the Dinosaur Park fauna/flora in Alberta, the Kaiparowits fauna/flora in Utah, the Kirtland-Fruitland fauna/flora in New Mexico and the Aguja fauna in Texas. The research team will use high-precision U-Pb zircon geochronology on volcanic ash beds to build age models for each area and allow detailed correlations and insight into evolutionary/preservation trends.The Western Interior Basin has been pivotal in the formation and assessment of many hypotheses relating to Late Cretaceous vertebrates, from physiology and behavior to biogeography and evolution. Recent discoveries from the southern Western Interior (i.e., Utah, New Mexico, Texas, Mexico) and the far north (Alaska) have revealed new Campanian-aged vertebrate faunas, highlighted by an array of previously unknown dinosaurs, other vertebrates and plants. Following more than a century of intense sampling and study, more is known about Campanian terrestrial vertebrates from Laramidia (western North America) than from any other continent-scale region of Mesozoic age. Thus, Campanian Laramidia represents arguably the best time and place to investigate major questions surrounding the tempo and mode of evolution among Mesozoic terrestrial vertebrates and associated ecosystem changes. A major hurdle to addressing questions of these types in ancient ecosystems is the ability to precisely and accurately constrain the depositional age of important fossil localities and to correlate floras and faunas through space. U-Pb zircon geochronology can be used to date ca 90 million year old volcanic ash beds to better than ± 20-30 thousand years. When multiple ash beds are dated in stratigraphic succession, age models can be constructed that allow resolution at millennial to decamillenial levels and thus high-precision correlation.The proposed project will focus on the following key faunas and floras: 1) the Two Medicine-Judith River formations in Montana and Wyoming; 2) the Dinosaur Park Formation in Alberta; 3) the Kaiparowits Formation in Utah; 4) the Fruitland-Kirtland formations in New Mexico; and the Aguja Formation in Texas. Together, these continental units and their floras and faunas have been interpreted as contemporaneous, and by developing a high precision chronostratigraphy, the research team will create an unparalleled opportunity for investigating the mode and tempo of evolution in a Mesozoic terrestrial ecosystem, with opportunities for investigating and testing concepts of latitudinally arrayed provinciality, turnover rates, diachroneity in evolutionary changes, predictions from molecular studies and the roles of eustasy, tectonics and climate as drivers of such changes. In addition, once completed, it will be possible to compare the record from Laramidia with those from South America and Asia.

北美晚坎帕纪恐龙多样性“顶峰”时期的高精度U-Pb锆石年代学和陆地生态系统的大陆内对比非技术概述：一个主要问题是全球环境变化是否导致了生物进化的变化。8000万到7000万年前这段时间被称为“天顶”。北美西部的恐龙多样性和丰富的恐龙化石在这一时期的岩石中有着无与伦比的暴露。我们不太清楚是什么引发了这种进化多样性的爆发，但我们知道，与此同时，全球范围的环境变化，包括全球大气温度的升高和海平面的突然上升，也产生了深远的影响。然而，一些人认为，多样性的明显增加更多的是保护，而不是进化。为了测试是全球环境变化还是优先保护的原因，我们必须能够将从加拿大南部到美国西南部的岩石和化石联系起来。该项目将重点关注火山岩与含化石岩石层间的高精度测年，以便我们确定北美西部超过2000公里纬度的进化速度。这将使我们反过来评估保存在岩石中的环境变化证据是否可以与恐龙进化相关联。技术摘要：该项目将重点研究北美西部内陆盆地（Laramidia）保存的2000公里长的晚坎帕尼亚（白垩纪）地层走廊，在大约1000万年（80-70 Ma）的时间间隔内建立一个无与伦比的年代地层学。这代表了世界上横向分布最广、化石最多的大陆演替之一，包括蒙大拿州和怀俄明州著名的双医学-朱迪思河动物群/植物群，阿尔伯塔省的恐龙公园动物群/植物群，犹他州的Kaiparowits动物群/植物群，新墨西哥州的kirkland - fruitland动物群和德克萨斯州的Aguja动物群。研究小组将利用火山灰床上的高精度U-Pb锆石年代学，为每个地区建立年龄模型，并对进化/保存趋势进行详细的关联和洞察。西部内陆盆地在许多关于晚白垩世脊椎动物的假说的形成和评估中起着关键作用，从生理学和行为学到生物地理学和进化。最近在西部内陆南部（即犹他州、新墨西哥州、德克萨斯州、墨西哥）和最北部（阿拉斯加）的发现，揭示了新的坎帕尼亚时代的脊椎动物动物群，突出的是一系列以前不为人知的恐龙、其他脊椎动物和植物。经过一个多世纪的密集采样和研究，我们对来自Laramidia（北美西部）的坎帕尼亚陆生脊椎动物的了解比来自任何其他中生代大陆尺度地区的了解都要多。因此，坎帕尼亚Laramidia可以说是研究中生代陆生脊椎动物进化的速度和模式以及相关生态系统变化等主要问题的最佳时间和地点。在古代生态系统中解决这类问题的一个主要障碍是精确和准确地限制重要化石地点的沉积时代的能力，以及通过空间将动植物联系起来的能力。U-Pb锆石年代学可用于测定约9000万年至±2 -3万年的火山灰床。当在地层演替中确定多个灰层的年代时，可以建立年龄模型，使分辨率达到千年至十千年的水平，从而实现高精度的相关性。拟议的项目将重点关注以下主要动植物群：1)蒙大拿州和怀俄明州的两个梅迪奇-朱迪思河构造；2)阿尔伯塔省的恐龙公园组；3)犹他州Kaiparowits组；4)新墨西哥州的Fruitland-Kirtland地层；以及德克萨斯州的阿古加地层。这些大陆单元和它们的动植物被解释为同时期的，通过发展高精度的年代地层学，研究小组将为研究中生代陆地生态系统的进化模式和速度创造一个无与伦比的机会，有机会调查和测试纬度排列的省级、周转率、进化变化的历时性等概念。来自分子研究的预测以及尤斯塔西、构造和气候作为这些变化的驱动因素的作用。此外，一旦完成，将有可能将拉腊米迪亚的记录与南美和亚洲的记录进行比较。

项目成果

Paleoenvironments, taphonomy, and stable isotopic content of the terrestrial, fossil-vertebrate–bearing sequence of the El Disecado Member, El Gallo Formation, Upper Cretaceous, Baja California, México

墨西哥下加利福尼亚州上白垩纪埃尔迪塞卡多段埃尔加洛组陆地化石脊椎动物序列的古环境、埋藏学和稳定同位素含量

• DOI: 10.1130/ges02207.1
• 发表时间: 2020
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Fastovsky, David E.;Montellano-Ballesteros, Marisol;Fricke, Henry C.;Ramezani, Jahandar;Tsukui, Kaori;Wilson, Gregory P.;Hall, Paul;Hernandez-Rivera, Rene;Alvarez, Geraldo
• 通讯作者: Alvarez, Geraldo