RUI: Magnetostratigraphy of the Eocene-Oligocene Transition in Tran-Pecos Texas

RUI：德克萨斯州 Tran-Pecos 始新世-渐新世过渡的磁性地层学

• 批准号: 9117819
• 负责人: Donald Prothero
• 金额: $ 6.06万
• 依托单位: Occidental College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-12-01 至 1994-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9117819&HistoricalAwards=false
• 关键词: RUI; Magnetostratigraphy; Eocene; Oligocene; Transition

The Eocene-Oligocene transition (about 42 to 30 million years ago) was the most significant episode of climatic change and mass extinction since the demise of the dinosaurs. The extinctions during this transition have been attributed to many causes, including meteorite or cometary impacts, volcanism, and climatic cooling due to Antarctic glaciation and oceanographic changes. Recent research has shown that the most dramatic changes occur between the middle and late Eocene. The Trans-Pecos region of Texas is the only place in North America where this change is recorded by superposed mammalian faunas datable by both radiometrics and magnetostratigraphy. There is no place in North American the contains interfingering marine/non-marine sequence of this age, so this area is the key to unlocking the details of the Uintan-Duchesnean-Chadronian transition in land mammals. The Trans-Pecos rocks contain a number of well studied faunas of middle Eocene (Uintan) and late Eocene (Duchesnean and Chadronian) age. Although preliminary paleomagnetic studies have been on some these rocks, many of the key fossil localities, and most of the Uintan and Chadronian parts of the section, have never been sampled. This project will collect and analyzed paleomagnetic samples from most of the key localities, and provide new 40Ar/39Ar dates to improve the geochronology. It will then be possible to correlate Uintan, Duchesnean, and Chadronian faunas from all over western North America to the magnetic polarity timescale. Episodes of extinction and faunal change can then be examined in greater detail, and correlated more precisely with the global record of climatic and biotic change during the Eocene-Oligocene transition.

始新世-渐新世过渡期（约4200万年至3000万年） 前）是气候变化和质量的最重要的插曲 自恐龙灭绝以来， 物种灭绝 在这一转变过程中，有许多原因， 包括陨石或彗星撞击、火山活动和气候变化。 由于南极冰川作用和海洋变化而变冷。 最近的研究表明，最引人注目的变化发生在 在始新世中晚期之间 外佩科斯地区 德克萨斯州是北美唯一一个发生这种变化的地方 记录的哺乳动物区系， 放射性测量学和磁性地层学。 北方没有地方 美国的包含交错的海洋/非海洋序列 这个年龄，所以这个区域是解开细节的关键。 陆栖哺乳动物的Uintan-Duchesnean-Chadronian转变。 外佩科斯岩石包含了许多研究良好的动物群 始新世中期（Uintan）和始新世晚期（Duchesnean和 Chadronian）age. 尽管初步的古地磁研究 在这些岩石上，许多关键的化石地点， 大部分的Uintan和Chadronian部分的部分，从来没有 被抽样。 本项目将收集和分析古地磁 样品来自大多数关键地点，并提供新的40 Ar/39 Ar 以改进地质年代学。 这样就有可能 将世界各地的尤因坦、杜切斯和查德隆动物群联系起来 与磁极性时间尺度相对应。 集 灭绝和动物群变化的研究可以在更大的 细节，并与全球记录更精确地相关， 始新世-渐新世过渡期的气候和生物变化。