Ancient Atmospheric P(CO2), Paleoclimates and the Stable Isotope Geochemistry of Low Temperature Iron Oxides

古代大气 P(CO2)、古气候和低温氧化铁的稳定同位素地球化学

• 批准号: 9204313
• 负责人: Crayton Yapp
• 金额: $ 22.48万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-07-01 至 1996-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9204313&HistoricalAwards=false
• 关键词: Ancient; Atmospheric; CO2; Paleoclimates; Stable

The actual role of CO2 as a "greenhouse" gas in the Earth's past can only be learned from proxy data on ancient atmospheric Pco2 and corresponding climatic temperatures. Research conducted in this laboratory has found that the oxygen isotope systematics of the common mineral goethite (a-FEOOH) make it a suitable indicator of paleotempeatures and ancient sources of water. Furthermore, we have discovered that goethite contains an apparent Fe(CO3)OH component in solid solution whose abundance is related to ancient ambient Pco2. These characteristics of natural goethites have been used to deduce tropical temperatures and atmospheric CO2 pressures 440 million years ago. A broader application of these properties of goethite is planned. Part of the work well involve experimental study of the isotopic effects of substitution of Al for Fe in goethite. Such information is of importance to isotopic paleoclimatic research involving goethites in tropical soils, where degrees of Al substitution can be high. another portion of the proposed research will undertake the study of the oxygen isotope systematics of goethite + phosphate as a promising mineral pair oxygen isotope paleothermometer. The two-component CO2 mixing model for soils (as manifested in the Fe(CO3)OH component of surficial goethite) will be tested further as a third aspect of the research with data obtained from goethite in active Cenozoic laterites. Goethite-bearing Mesozoic oolitic ironstones and laterite will also be isotopically, etc., analyzed to evaluate ancient temperatures, water sources and possibly atmospheric CO2 pressures.

只有从古老的大气PCO2和相应气候温度的代理数据中学到的二氧化碳作为“温室”气体的实际作用才能学到。 在该实验室进行的研究发现，普通矿物谷石（A-feOOH）的氧同位素系统学使其成为古植物和古代水源的合适指标。 此外，我们发现，谷石岩在固体溶液中包含一个明显的Fe（CO3）OH分量，其丰度与古代环境PCO2有关。 天然圆锥体的这些特征已被用来推断热带温度和4.4亿年前的大气二氧化碳压力。 计划对这些谷石的这些特性进行更广泛的应用。 这项工作的一部分很好地涉及实验研究，以实验替代Al代替对Gothite的同位素作用。 此类信息对于在热带土壤中涉及的同位素古气候研究至关重要，在这里，Al替代程度可能很高。 拟议的研究的另一部分将研究对谷藻 +磷酸盐的氧同位素系统学作为有前途的矿物对氧同位素层含量计。 土壤的两组分二氧化碳混合模型（如Fe（二氧化碳）OH的表面谷杆菌成分所示）将作为研究的第三个方面进一步测试，并在活跃的新生代后代中获得的数据获得了研究的第三个方面。 经过含有高铁石的中生代的橄榄岩铁石和后石也将是同位素等，以评估古老的温度，水源和可能的大气二氧化碳压力。