Collaborative Research: The Late Ordovician Extinction and Concurrent Perturbations of Global Earth Systems: Paleontological, Sedimentologic, and Geochemical Records...

可爱的9628167 最近在内华达州罗伯茨山脉的维尼尼组露头中发现了一个特殊的上奥陶统-下志留统地层剖面。 这是世界上已知的唯一一个可以进行调查的地区，将碳酸盐变化与生物排斥和再辐射与海平面变化联系起来。 此外，古生物学、沉积学和地球化学记录的深海，较低的斜坡到大陆上升沉积相的维尼尼组可以比较密切的同时代地层序列在哥本哈根峡谷在监测范围的内华达州，代表一个更浅，外陆架边缘沉积环境。 该项目标志着第一次可以使用广泛而多样的地层记录直接比较同一沉积盆地内差异很大的晚奥陶世相。 它提供了一个机会来解决的问题，是否波动的生物生产力和潜在的变化，在大气中pCO 2的开始和结束的晚奥陶纪冰川期。 这对一个多元化的科学团队来说是一个探索全球地球系统基本关系的绝佳机会。 由于维尼尼溪部分有一个厚厚的覆盖层，一个沟槽将挖掘通过该部分的推土机。 然后，一组科学家和学生将记录，描述，研究和采样100米的部分床床。 各种合作伙伴，顾问和学生将采样笔石，牙形刺，有机壁微体化石，岩性，稳定同位素和古地磁。 哥本哈根峡谷部分有很好的地表暴露，但不太丰富。 它的一部分已经被很好地采样为化石，但更多发现的潜力将被追求。 此外，该部分将被彻底的样品进行稳定同位素分析。结果将允许13 C的漂移的笔石，conondonts，和有机壁微体化石的生物地层学和不同的沉积学记录的海平面变化，代表了冈瓦纳冰川的盈亏的直接expansion。 精确测定维尼尼河和哥本哈根峡谷部分之间的古生物学、沉积学和地球化学信号的时间关系，以及与全球其他地区之间的时间关系，应能为晚奥陶世期间全球气候、海洋学和生物扰动之间的因果关系提供明确的见解。

Sweet 9628167 An exceptional Upper Ordovician-Lower Silurian stratigraphic section was recently discovered in outcrops of the Vinini Formation in the Roberts Mountains of Nevada. It is the only section known anywhere in the world where an investigation can be carried out that relates carbonate 13 changes to biotic extinctions and re-radiations to sea-level changes. In addition, the paleontological, sedimentological, and geochemical records of the deep-marine, lower slope to continental rise depositional facies of the Vinini Formation can be compared closely to those of a coeval stratigraphic succession at Copenhagen Canyon in the Monitor Range of Nevada that represents a much shallower, outer shelf to shelf margin depositional setting. This project marks the first time that very different Late Ordovician facies within the same depositional basin may be directly compared using extensive and diverse stratigraphic records. It provides the opportunity to address the question of whether or not fluctuations in biological productivity and potential changes in atmospheric pCO2 coincided with the beginning and end of the Late Ordovician glaciation interval. It is a remarkable opportunity for a diverse scientific team to explore fundamental relationships in global earth systems. Because the Vinini Creek section has a thick cover of scree, a trench will be excavaed through the section by bulldozer. Then a team of scientists and students will log, describe, study, and sample 100 meters of section bed by bed. Various co-P.I.s, consultants, and students will sample for graptolites, conodonts, organic-walled microfossils, lithologies, stable isotopes, and paleomagnetism. The Copenhagen Canyon section has excellent surface exposures, but is mush less fossiliferous. Parts of it have been well sampled for fossils, but the potential for additional discoveries will be pursued. In addition, the section will be thoroughly samples for stable isotope analysis. Results will allow for the direct correla tion of 13C excursions to the biostratigraphies of graptolites, conondonts, and organic-walled microfossils and to distinct sedimentological records of sea-level changes that represent the waxing and waning of Gondwanan glaciation. Precise determination of the temporal relationships of paleontological, sedimentological, and geochemical signals between the Vinini Creek and Copenhagen Canyon sections and to others worldwide should provide definitive insights on causal relationships between profound global climatic, oceanographic, and biotic perturbations during the Late Ordovician.