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

西澳大利亚中元古界 Bangemall 群​​的古生物学、沉积学和同位素地球化学

• 批准号: 8817662
• 负责人: Andrew Knoll
• 金额: $ 11万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-01-15 至 1991-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8817662&HistoricalAwards=false
• 关键词: Paleontology; Sedimentology; Isotopic; Geochemistry; Middle; Paleontology; Sedimentology; Isotopic; Geochemistry; Middle

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.

在过去的一个世纪中，大多数古生物学研究集中在过去5.5亿年中沉积的沉积岩上。 然而，现在很明显，这种动物和植物的显着记录仅记录了地球上生命史的最新15％。 较早的（动物前）生物记录写在微生物的化石以及沉积岩中包含的微生物活性的化学痕迹中。 植物学时代晚期的岩石（900-5.550亿年）包含丰富的化石记录，其中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变化的时期。 化学和地质数据进一步表明，晚期的植物大地的特征是气候，构造学，大气化学和生物学上重要元素的循环的重大变化。 相比之下，早期植物年龄（2500-8亿年）的岩石反映了一个截然不同的世界 - 在这种世界中，一个独家的细菌性生物群在不受晚期protererogic时代的气候和生物地球化学变异性影响的环境中繁荣发展。 理解从早期的properoroic地球向晚期植物学星球的过渡显然必须位于中学中期（1800-9亿年）中沉积的岩石中。 仔细的现场和实验室研究将对西澳大利亚州Bangemall Group 1400 - 1.3亿年 - 一套非常适合在此期间产生有关生物和环境变化的关键信息的岩石套件。 将对这些岩石的厚度，成分和特征特征进行现场测量；这将允许确定岩石的年龄和环境关系。 将检查该基质中收集的样品，以了解其微化石含量，岩石织物和改变历史以及地球化学（尤其是在某些岩石中包含的碳和锶的比率）。 结果将是一个多学科数据集，该数据集将为中部植物生物学和环境提供关键的见解。 这种数据在了解生活的早期进化以及生物学和地面环境如何互相影响的努力方面非常重要。 尽管这项研究本质上是基本的，但它在植物岩石中对矿物和石油勘探具有重要的应用。 化石和地球化学标记分布的文献将提高我们将植物岩石相关的能力，这是地质勘探的重要第一步。 对地球环境历史的更好理解还将有助于限制落在植物学沉积岩中的地层矿石的丰富沉积物的勘探模式。