Noble Gas Distribution and Migration in the Oceanic Crust

本建议旨在测量735B和1256D孔的ODP岩心辉长岩、闪长岩和辉绿岩中的惰性气体。将通过真空和加热方法提取气体。将测量He、Ne和Ar，并将其比率用于分离气体的大气、放射性和非放射性成分。3He特别令人感兴趣，因为这种同位素的唯一可能来源是地球的地幔。初步测量表明，He在大洋侵入岩，特别是变形岩石中的含量高得惊人。变形使地壳中增加了惰性气体的假设将通过对1256D孔的花岗变晶岩脉的深入研究来检验。初步结果还揭示了样品中稀有气体浓度的惊人的小尺度变化，可能与角闪石浓度和含水熔融有关。这一假设将通过一个角闪石双辉岩的详细断面进行检验，特别注意矿物学和流体包裹体。这将是第一次对大洋辉长岩中稀有气体浓度进行全面研究，也是有史以来第一次对角闪石进行全面研究。研究结果将引起广大地球科学家的兴趣。这项工作将对海洋地壳中挥发物的起源和丰度产生影响，并最终对与俯冲有关的火山产生影响。该项目有一个国际组成部分，将为博士学位提供资金。学生，并将通过WHOI奖学金和与当地州立大学的合作，涉及本科生。

This proposal seeks to measure noble gases in odp drill core gabbros, diorites and diabases from holes 735B and 1256D. The gases will be extracted by in vacuo and heating methods. He, Ne, and Ar will be measured and ratios used to separate atmospheric, radiogenic and non-radiogenic components of the gas. 3He, in particular, is of interest because the only possible source for this isotope is the Earth's mantle. Preliminary measurements reveal that He is surprisingly high in oceanic intrusive rocks, especially deformed rocks. The hypothesis that deformation adds noble gas to the crust will be tested by a depth study of granoblastic dikes from hole1256D. Preliminary results also reveal surprising small scale variability in noble gas concentration within samples, possibly related to amphibole concentration and hydrous melting. This hypothesis will be tested by a detailed transect in an amphibole diorite with special attention paid to mineralogy and fluid inclusions.This will be the first comprehensive study of noble gas concentration in oceanic gabbroic rocks and the first ever in amphibole. The results will be of interest to a broad range of earth scientists. The work will have implications for the origins and abundance of volatiles in ocean crust and, ultimately, subduction-related volcanos. The project has an international component, will provide funds for a Ph.D. student and will involve undergraduates through WHOI fellowships and collaboration with a local state college.