The Stable Isotope and Minor Element Geochemistry of Iron (III) Oxide Rocks and Minerals

该实验室最近的工作表明， 针铁矿是一种重要的新型低温氧 同位素地质温度计与二氧化硅、碳酸盐或 磷酸盐 这些研究中一个潜在的重要进展是 在天然针铁矿中发现了二氧化碳成分 可以作为二氧化碳排放的定量指标， 压力 拟议中的研究包括实验， 赤铁矿-水氧同位素的温度依赖性 针铁矿-水氧同位素的分馏、证实 曲线，并进一步研究了针铁矿中的CO2组分 作为古P（CO2）值的可能指标。 额外 努力将包括红外工作，以研究这两个数额和 针铁矿中CO2的化学形态 这些知识将 适用于古生代的鲕状赤铁矿和针铁矿 代表矿石品位的铁矿石， 沉淀的，氧化的铁，在两次延长的 “脉冲”在中生代。 这些脉冲通常与 随着海平面上升，大陆被淹没， 海底扩张的速度很快 这项研究应该会产生 地表或近地表温度、水岩 相互作用和可能的CO2分压在当地 环境 更一般地说，这些数据可以提供洞察， 海水中古气候和可能的长期变化0-18/0-16 在大陆冰川作用时期， 南半球，从而增加我们的知识条件 这段时间对中生代有相当大的兴趣。

Recent work in this laboratory has shown that the common mineral goethite is an important new low temperature oxygen isotope geothermometer in combination with silica, carbonate or phosphate. A potentially important development in these studies has been the discovery of a CO2 component in natural goethites that might serve as a quantitative indicator of CO2 partial pressures. The proposed studies include experiments to calibrate the temperature dependence of the hematite-water oxygen isotope fractionation, substantiation of the goethite-water oxygen isotope curve, and further investigation of the CO2 component in goethite as a possible indicator of ancient P(CO2) values. Additional efforts will include infrared work to study both the amounts and chemical speciation of the CO2 in goethite. This knowledge will be applied to Phanerozoic oolitic hematitic and goethitic ironstones representing ore-grade concentrations of chemically precipitated, oxidized iron which formed during two extended "pulses" in the Phanerozoic. These pulses generally coincided with periods of high eustatic sea level, flooded continents, and rapid rates of sea-floor spreading. The study should yield information on surface or near-surface temperatures, water-rock interactions and possibly CO2 partial pressures in the local environment. More generally, such data could provide insight into plaeoclimate and possible secular variations in seawater 0-18/0-16 ratios at a time when there was continental glaciation in the southern hemisphere, thus increasing our knowledge of conditions during an interval of considerable interest in the Phanerozoic.