Melt Generation and Transport Beneath the Slow Spreading Kolbeinsey Ridge

摘要（0422278）- SimsCurrently有很少的U系列数据从缓慢蔓延的扩张脊和这样的数据是至关重要的，以更好地了解全球系统的238 U-230 Th不平衡和其他同位素系统在大洋中脊玄武岩。 本研究的目的是测量（和编译）Nd，Sr，Pb和Hf同位素组成和U-Th-Ra和U-Pa不平衡的样品从浅，缓慢扩展Kolbeinsey脊和Tjorne断裂带，冰岛北部的一套。 已经收集了待分析的样品，并已由其他人事先确定了主要和微量元素的组成。 预计铀系、主要元素和微量元素以及同位素数据的综合将使我们能够更好地了解科尔拜因塞海脊和其他缓慢扩张的洋中脊下的熔体生成和输送过程，并评估铀系不平衡（和其他微量元素分馏）在多大程度上受熔融过程和（或）来源不均匀性的控制。 本文将慢扩张海脊的资料与快扩张的东太平洋海隆和其它洋中脊系统的资料进行比较，以评价：（1）U-Th不平衡是否象深、中深度海脊那样与轴向深度相关;（2）如果个别脊段的数据在Th等时线图上显示轴向扩展速率与其斜率之间的关系，那么，这种关系是否需要富集地幔源和贫化地幔源的混合;（3）冰岛地幔柱是否影响科尔拜因西海岭 拟议的研究的更广泛的影响是一个女博士生的支持，与三个海外实验室的国际合作，建模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的校准Th同位素标准，这是许多固体地球和海洋学应用中使用238 U-230 Th不平衡数据的关键。

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.