Paleontology, Sedimentology, and Isotopic Geochemistry of the Middle Proterozoic Bangemall Group, Western Australia

在过去的世纪，大多数古生物学研究 集中在过去550年沉积的沉积岩上 百万年。 然而，现在很清楚，这一明显的 记录的动植物文件只有最新的15%， 地球生命的历史 早期（前动物）生物学 记录写在微生物的化石中，以及 微生物活性的化学痕迹 沉积岩 晚元古代岩石（900-550 100万年）包含丰富的化石记录，包括各种 浮游藻类和海藻，以及许多种类的细菌。 化石表明这是一个快速进化的时期 变化 化学和地质数据进一步表明， 晚元古代地球的特征是 气候、构造、大气化学和 重要的生物学元素。 相比之下， 元古宙年龄（2500-1800万年）反映了一个非常 一个完全由细菌组成的生物群 在不受气候影响的环境中茁壮成长， 晚元古代的地球化学变化。 理解从早期的 元古代地球到晚元古代行星显然必须 位于中元古代（1800- 9亿年）。 将进行仔细的实地和实验室研究， 进行了1400-1300万年的Bangemall集团， 西澳大利亚--一套岩石特别适合 产生关于生物和环境的重要信息 在此期间的变化。 实地测量厚度， 这些岩石的成分和特征将是 这将有助于确定年龄和环境。 岩石的关系。 在该基质中采集的样本 将检查其微化石含量，岩石结构和 蚀变历史和地球化学（特别是 碳和锶的同位素， 这些岩石）。 其结果将是一个多学科的数据集， 提供对中元古代生物学的重要见解， 环境. 这些数据对于努力 了解生命的早期进化以及生物学和地球 随着时间的推移，地表环境相互影响， 创造了现代世界。 虽然这项研究是基本的， 在自然界中，它在矿物和石油中有重要的应用 元古宙岩石勘探 化石的记录和 地球化学标志物分布将提高我们的能力， 对比元古代岩石， 地质勘探 更好地了解地球 环境历史将进一步限制 层控富矿勘查模式 被锁在元古代的沉积岩中

For the past century, most paleontological research has concentrated on sedimentary rocks deposited over the past 550 million years. It is now clear, however, that this conspicuous record of animals and plants documents only the latest 15% of the history of life on Earth. The earlier (pre-animal) biological record is written in the fossils of microorganisms, as well as in the chemical traces of microbial activity contained in sedimentary rocks. Rocks of Late Proterozoic age (900-550 million years) contain a rich fossil record that includes diverse planktonic algae and seaweeds, as well as bacteria of many kinds. The fossils indicate that this was a period of rapid evolutionary change. Chemical and geological data further suggest that the Late Proterozoic Earth was characterized by major changes in climate, tectonics, atmospheric chemistry, and the cycling of biologically important elements. In contrast, rocks of Early Proterozoic age (2500-1800 million years) reflect a very different world -- one in which an exclusively bacterial biota thrived in environments unaffected by the kinds of climatic and biogeochemical variability seen in the Late Proterozoic era. The key to understanding the transition from the Early Proterozoic Earth to the Late Proterozoic planet clearly must lie in rocks deposited during Middle Proterozoic times (1800- 900 million years). Careful field and laboratory studies will be conducted of the 1400-1300 million year of Bangemall Group, Western Australia -- a suite of rocks especially well suited to yield critical information on biological and environmental change during this period. Field measurements of the thickness, composition, and characteristic features of these rocks will be made; this will permit determination of the age and environmental relationships of the rocks. Samples collected within this matrix will be examined for their microfossil content, rock fabric and alteration history, and geochemistry (especially the ratios of the isotopes of carbon and strontium contained in certain of these rocks). The result will be a multidisciplinary data set that will provide critical insights into Middle Proterozoic biology and environments. Such data are of great importance in efforts to understand life's early evolution and how biology and Earth surface environments have influenced each other through time to produce the modern world. Although this research is basic in nature, it has important applications to mineral and petroleum exploration in Proterozoic rocks. Documentation of fossil and geochemical marker distributions will improve our ability to correlate Proterozoic rocks, the important first step in geological prospecting. A better understanding of Earth's environmental history will additionally serve to constrain patterns of exploration for the rich deposits of stratabound ores locked in Proterozoic sedimentary rocks.