High Resolution Secular Variation in Oxygen, Carbon, Strontium Isotopic Composition

这项研究将记录的幅度，利率和相对 多种同位素（18O，13C，87Sr/86Sr）之间的变化时间 和元素（Li/A1）示踪剂通过泥盆纪-石炭纪 interval. 地球历史上的这段时期， 海洋碳酸盐记录中18O和13C的剧烈变化， 全球表面温度急剧下降30 - 40 度或海水中18O成分的富集。 配对 化学示踪剂分析将在非生物 泥盆纪-石炭纪生物礁序列的海相碳酸盐岩 Dinant Synclinorium（比利时）-Waulsortian层序 爱尔兰和阿尔伯塔盆地到 测试假设，海洋18O成分的变化是 由于18O通量的增加， 海底扩张脊的热液蚀变。 分析87Sr/86Sr的变化将有助于了解 地幔相对地壳源的贡献 比率将记录的增加与减少的优势 高温、热液蚀变与低温 幔源玄武岩的海底风化作用 的具体目标 研究内容包括：（1）评价相关性， 化学示踪剂之间的变化，以确定 它们是否响应于共同的地质作用;（2） 化学变化经验时间常数的测定 将元素通量的大小限制在 海洋;（3）定量建模，根据经验 关系，以评估海水循环的作用， 大洋中脊玄武岩在确定18O组成的 古海洋

This research will document the magnitude, rates and relative timing of change among numerous isotopic (18O, 13C, 87Sr/86Sr) and elemental (Li/A1) tracers through the Devono-Carboniferous interval. This period in Earth's history, which is marked by a dramatic shift in 18O and 13C of marine carbonates records either a dramatic decrease in global surface temperature of 30-40 degree, or an enrichment in 18O composition of seawater. Paired analysis of chemical tracers will be performed on non-biological marine carbonates from Devono-Carboniferous reefal sequences of the Dinant Synclinorium (Belgium) - Waulsortian Sequence of Ireland and the time equivalent succession of the Alberta Basin to test the hypothesis that a shift in ocean 18O composition was caused by an increase in 18O flux associated with enhanced hydrothermal alteration at submarine spreading ridges. Analysis of 87Sr/86Sr variation will provide insight on relative contributions from mantle versus crustal sources; Li/Al ratios will record the increasing versus decreasing dominance of high temperature, hydrothermal alteration versus low temperature submarine weathering of mantle-derived basalts. Specific goals of the research include: (1) evaluation of correlations, in time and magnitude, of variation among chemical tracers to determine whether they are responding to a common geologic process; (2) determination of empirical time constants of change in chemistry to constrain the magnitude of elemental fluxes into an out of the ocean; and (3) quantitative modelling, based on empirical relationships, to assess the role of seawater cycling through mid- ocean ridge basalt in defining the 18O composition of the paleocean.