Melt Generation and Transport Beneath the Slow Spreading Kolbeinsey Ridge

文摘(0422278)- SimsCurrently很少有u系列slow-spread传播山脊的数据,这些数据对于更好地理解全球分类学至关重要的238 u - 230在大洋中脊玄武岩和其他同位素系统失衡。本研究的目的是测量（并汇编）来自冰岛北部科尔拜西山脊和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。待分析的样品已被收集，并已由其他人事先对其主要和微量元素组成进行了表征。预计综合u系列、主元素、微量元素和同位素数据将使我们更好地了解科尔拜西脊和其他缓慢扩张的洋中脊下的熔体产生和输送过程，并评估u系列不平衡（和其他微量元素分异）在何种程度上受熔体过程和/或源非均质性的控制。将缓慢扩张脊的数据与快速扩张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不平衡是否与深脊和中脊观测到的轴向深度相关；(2)在等时线图上，各个脊段的数据是否显示轴向扩张速率与其坡度之间存在关系，如果存在，是否需要将富、贫地幔源混合在一起；(3)冰岛羽流对Kolbeinsey Ridge的影响更广泛的影响是：一名女博士生的支持，与三个海外实验室的国际合作，建模师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.