Melt Generation and Transport Beneath the Slow Spreading Kolbeinsey Ridge

摘要(0422278)-SIME目前来自缓慢扩张海脊的U系列数据很少，这些数据对于更好地了解大洋中脊玄武岩中238U-230Th不平衡和其他同位素系统的全球系统学至关重要。这项研究的目的是测量(和汇编)来自冰岛北部Kolbeinsey海脊和Tjorne断裂带的一组样品中的Nd锶、PbHf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，并且之前已经由其他人描述了主元素和微量元素的组成。预计，U系列、主要元素和痕量元素及同位素数据的结合将使我们能够更好地了解科尔宾西海脊和其他缓慢扩展的大洋中脊之下的熔体生成和迁移过程，并评估U系列不平衡(和其他微量元素分馏)在多大程度上受到熔融过程和/或来源不均质性的控制。来自缓慢扩张脊线的数据将与快速扩张的东太平洋隆起和其他大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，就像在深脊和中脊观察到的那样：(2)如果来自单个脊段的数据在Th等时线图上显示了轴向扩展速率与其斜率的关系，那么这种关系是否需要富集源和贫化地幔源的混合；以及(3)冰岛羽状物是否会影响科尔拜恩西岭，以及(3)拟议研究的更广泛影响是：一名女博士生的支持、与三个海外实验室的国际合作、模型师和分析地球化学家之间的合作、改进的测量技术和校准更好的Th同位素标准，这些标准对于许多使用238U-230不平衡数据的固体地球和海洋应用是至关重要的。

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.