Studies in Event Stratigraphy; Impacts Volcanism & Mass Extinctions

地球历史的大部分是由气候和生命逐渐变化主导的很长的时间间隔组成的。这些平静的间隔偶尔会被快速变化的短暂插曲所打断。事件地层学是对这些地质上短暂而有趣的时期的研究，在这些时期里，发生了迅速的、有时甚至是剧烈的变化。沉积记录的事件地层学方法是多学科的，涉及各种实验室程序和仔细的野外地层学研究。利用这种方法，我们以前在白垩纪-第三纪和始新世-渐新世边界发现了Ir异常，导致了撞击假说的提出，并引起了人们对稀有事件在地球历史上的重要性的极大兴趣和研究。利用我们课题组开发的一种新的分析技术，我们能够将这种方法扩展到中生代和新生代的其余部分，并在中新世中期发现了一个新的Ir异常。我们将做以下工作：(1)系统地寻找新的Ir层位的地层记录；(2)解决关于白垩纪-第三纪玛斯灭绝原因的冲击与火山作用的争论；(3)研究始新世-渐新世边界，以解决Ir峰、玻璃陨石和灭绝层位之间的差异。

Most of Earth history consists of long intervals of time dominated by gradual changes in climate and life. These quiet intervals are occasionally punctuated by brief episodes of rapid change. Event stratigraphy is the study of these geologically brief and interesting periods of time in which rapid and sometimes violent changes have occurred. The event stratigraphy approach to the sedimentary record is multi-disciplinary, and involves a variety of laboratory procedures in conjunction with careful field stratigraphic studies. Using this approach, we previously discovered iridium anomalies at the Cretaceous-Tertiary and Eocene-Oligocene boundaries, leading to the formulation of the impact hypothesis and generating a great deal of interest and research on the importance of rare events in Earth history. Using a new analytical technique for rapid iridium measurements developed by our research group, we are in a position to extend this approach to the rest of the Mesozoic and Cenozoic, and have already found a new iridium anomaly in the middle Miocene. We will do the following: (1) a systematic search of the stratigraphic record for new iridium horizons, (2) resolve of the impact vs. volcanism debate over the cause of the Cretaceous- Tertiary mas extinction, and (3) study of the Eocene-Oligocene boundary to resolve discrepancies between iridium peaks, tektites and extinction horizons.