The Alamo Event: Widespread Devonian Breccia of Probable Cataclysmic Origin, Southeastern Nevada

一个神秘的石灰岩角砾岩在吉尔梅特组， 将对内华达州东南部进行调查。 吉尔梅特形成 跨越了晚泥盆世弗拉斯期-法门期的阶段界线。 的 在至少5000平方英里的范围内， 并且已知厚度范围为25至435英尺;其 包括100立方英里或更大的体积。 角砾岩似乎是一个单一的碳酸盐沉积层 不是构造作用的、成岩作用的或溶液衍生的。 它有一个 尖锐，擦洗基地，并包含hapazardous定向， 向上变细的岩性不均匀碎屑。 一些碎屑 最长可达50英尺或更长。 角砾岩产于 一个浅水海洋环境，基于 上覆层和下伏层。 它表明是灾难性的起源， 可能与撞击地球的外星物体有关 角砾岩及其意义将通过以下方式进行研究： 上覆和下伏地层分析， 其古地理环境;其内部特征 确定物源、搬运和沉积的性质 机制，并测试单事件假设;缩小其 通过更紧密的生物地层分带确定年代; 与可能的外星起源的联系，例如，震惊 石英、地球化学异常等。

An enigmatic limestone breccia in the Guilmette Formation of southeastern Nevada will be investigated. The Guilmette Formation spans the Late Devonian Frasnian-Famennian stage boundary. The breccia is exposed in seven ranges over at least 5000 square miles and has known thicknesses ranging from 25 to 435 feet; it encompasses a volume of 100 cubic miles or more. The breccia appears to be a single sedimentary carbonate bed not tectonically, diagenetically, or solution-derived. It has a sharp, scoured base, and contains haphazardly oriented, lithologically heterogeneous clasts that fine-upward. Some clasts reach 50 feet or more in longest dimension. The breccia occurs in a shallow-water marine setting, based on characteristics of overlying and underlying beds. It suggests catastrophic origin, perhaps related to an extraterrestrial object impacting Earth. The breccia and its significance will be investigated through: stratigraphic analysis of overlying and underlying beds to refine its paleogeographic setting; characterization of its internal properties to determine provenance, transporting and depositing mechanisms, and to test the single-event hypothesis; narrowing its age designation through closer biostratigraphic zonation; searching for links to possible extraterrestrial genesis, e.g., shocked quartz, geochemical anomalies, etc.