The Stable Isotope and Minor Element Geochemistry of Iron- Rich Chemical Sediments

以氧化铁（III）为主的化学沉积物是一种 丰富的游离氧与 在地表和许多近地表发现的液态水 地球的环境。 该实验室进行的研究 表明氧氢碳的稳定同位素比 在某些氧化铁中，含有古生物信息 温度、水源和有机物对水的贡献 与氧化铁沉淀有关的碳酸盐体系。 此外，地安岩中捕获的CO2丰度数据可能与 到矿物形成时的环境CO2分压。 普遍存在的磷酸铁（III）的氧同位素系统学 将研究氧化物对，以确定它们是否含有 古温度的信息。 从中获得的知识， 我们以前对氧化铁的研究将应用于 同位素、化学和伴随的岩相学研究 古生代的鲕状铁矿石，最近的细菌介导 氧化铁沉淀与晚前寒武纪条带状铁 形成（BIF）。 Fe（III）碳酸盐丰度和碳-13 晚奥陶世风化面的变化可以提供 了解环境CO2分压和有机物的作用 在这个古老的环境中。 氧、氢和碳 丰度和同位素数据， 从全球“温室”和“冰库”间隔的日期， 将获得古生界。 古代的热带温度 和水源将被比较的存款， 代表了这些假定的全球极端气候。 氧同位素 晚前寒武纪石英-赤铁矿BIF的测量应该 提供了对该存款沉积环境的了解。 本研究所要获得的古气候资料有： 这对于最终理解 全球构造和气候系统的类型， 形成了明显的热带大陆冰盖 晚奥陶世的前寒武纪或极地冰盖。

Chemical sediments dominated by iron(III) oxides are a manifestation of the unique combination of abundant free oxygen and liquid water found in the surface and many near-surface environments of Earth. Research performed in this laboratory has shown that the stable isotope ratios of oxygen, hydrogen and carbon in certain iron(III) oxides contain information on ancient temperatures, sources of water and organic contributions to aqueous carbonate systems associated with iron(III) oxide precipitation. In addition trapped CO2 abundance data from geothites may be related to ambient CO2 partial pressures at the time of mineral formation. The oxygen isotope systematics of ubiquitous phosphate-iron(III) oxide pairs will be studied to determine if they contain information on paleotemperatures. Knowledge obtained from this and our previous studies of iron(III) oxides will be applied to isotopic, chemical and attendant petrographic investigations of Phanerozoic oolitic ironstones, recent bacterially mediated iron(III) oxide precipitate and Late Precambrian banded iron formation(BIF). Fe(III) carbonate abundance and carbon-13 variations in a Late Ordovician weathering surface could provide knowledge of ambient CO2 partial pressures and the role of organic matter in this ancient environment. Oxygen, hydrogen and carbon abundance and isotopic data from tropical oolitic ironstones that date from global "greenhouse" and "icehouse" intervals in the Phanerozoic will be obtained. The ancient tropical temperatures and sources of water will be compared for the deposits that represent these putative global climatic extremes. Oxygen isotopic measurements of a Late Precambrian quartz-hematite BIF should provide insight into the depositional environment of this deposit. Paleoclimatic data of the type to be obtained in this research are essential to an ultimate understanding of the possible link between global tectonics and the types of climatic regimes that could produce apparent tropical continental ice sheets in the Late Precambrian or polar ice sheets in the Late Ordovician.