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

氧化铁 (III) 岩石和矿物的稳定同位素和微量元素地球化学

• 批准号: 8719070
• 负责人: Crayton Yapp
• 金额: $ 9.02万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1990-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8719070&HistoricalAwards=false
• 关键词: Stable; Isotope; Minor; Element; Geochemistry

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.

该实验室最近的工作表明，普通矿物针铁矿与二氧化硅、碳酸盐或磷酸盐结合是一种重要的新型低温氧同位素地温计。 这些研究的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，它可以作为二氧化碳分压的定量指标。 拟议的研究包括校准赤铁矿-水氧同位素分馏的温度依赖性的实验、证实针铁矿-水氧同位素曲线以及进一步研究针铁矿中的CO2成分作为古代P(CO2)值的可能指标。 其他工作将包括红外工作，以研究针铁矿中二氧化碳的含量和化学形态。 这些知识将应用于显生宙鲕粒赤铁矿和针铁矿铁矿石，这些铁矿石代表了在显生宙两次延长的“脉冲”期间形成的化学沉淀氧化铁的矿石级浓度。 这些脉冲通常与海平面高度稳定、大陆被淹没和海底快速扩张的时期同时发生。 该研究应提供有关当地环境中地表或近地表温度、水-岩石相互作用以及可能的二氧化碳分压的信息。 更一般地说，这些数据可以深入了解南半球大陆冰川作用时期的古气候和海水 0-18/0-16 比率可能的长期变化，从而增加我们对这一时期人们相当感兴趣的时期的情况的了解。显生宙。