Melt Generation and Transport Beneath the Slow Spreading Kolbeinsey Ridge

摘要 (0422278) - Sims 目前来自慢速扩张扩张脊的 U 系列数据非常少，这些数据对于更好地了解洋中脊玄武岩中 238U- 230Th 不平衡和其他同位素系统的全球系统学至关重要。 这项研究的目标是测量（并编译）来自浅层、缓慢扩张的 Kolbeinsey 山脊和冰岛北部 Tjorne 断裂带的一组样品中的 Nd、Sr、Pb 和 Hf 同位素组成以及 U-Th-Ra 和 U-Pa 不平衡。 待分析的样品已经收集完毕，并且之前已经由其他人对其主要元素和微量元素成分进行了表征。 预计合并的U系列、主量元素、微量元素和同位素数据将使我们能够更好地了解科尔宾塞海脊和其他缓慢扩张的洋中脊下方的熔体生成和传输过程，并评估U系列不平衡（和其他微量元素分馏）受熔融过程和/或源异质性控制的程度。 来自缓慢扩张的海脊的数据将与来自快速扩张的东太平洋隆起和其他洋中脊系统的数据进行比较，以评估：（1）U-Th不平衡是否与轴向深度相关，正如在深部和中深度海脊中观察到的那样； （2）如果来自各个洋脊段的数据显示了轴向扩张速率与其在Th等时线图上的斜率之间的关系，那么这种关系是否需要富集和贫化地幔源的混合； (3) 冰岛羽流是否影响科尔宾塞海岭 拟议研究的更广泛影响包括一名女博士生的支持、与三个海外实验室的国际合作、建模者和分析地球化学家之间的合作、以及改进的测量技术和更好校准的Th同位素标准，这对于使用238U-230Th不平衡数据的许多固体地球和海洋学应用至关重要。

Abstract (0422278) - SimsCurrently there are very few U-series data from slow-spread spreading ridges and such data are critical to better understanding the global systematics of 238U- 230Th disequilibria and other isotopic systems in mid-ocean ridge basalts. The goal of this research is to measure (and compile) Nd, Sr, Pb and Hf isotopic compositions and U-Th-Ra and U-Pa disequilibria in a suite of samples from the shallow, slow-spreading Kolbeinsey ridge and from the Tjorne Fracture Zone, north of Iceland. Samples to be analyzed have already been collected and have been previously characterized for major- and trace element compositions by others. It is anticipated that the combined U-series, major and trace-element and isotopic data will allow us to better understand melt generation and transport processes beneath the Kolbeinsey Ridge and other slow-spreading mid-ocean ridges, and to assess the extent to which U-series disequilibria (and other trace-element fractionations) are controlled by melting processes and/or source heterogeneities. Data from slow spreading ridges will be compared with those from the fast spreading East Pacific Rise and others mid-ocean ridge systems to evaluate: (1) whether U-Th disequilibria is correlated with axial depth as has been observed for deep and intermediate depth ridges; (2) if data from individual ridge segments show a relationship between axial spreading rate and their slope on Th isochron plots and, it so, does the relationship require mixing of enriched and depleted mantle sources; and (3) whether the Iceland Plume influence the Kolbeinsey Ridge Broader impacts of the proposed study are the support of a female PhD student, international collaboration with three overseas laboratories, collaboration between modelers and analytical geochemists, and improved measurement techniques and better-calibrated Th isotopic standards which are critical for many solid Earth and oceanographic applications that use 238U-230Th disequilibria data.