Rare Gases in Samoan Xenoliths

这是对萨摩亚热点链内三个岛屿残存包体的稀有气体同位素系统学研究。捕虏体赋存于侵蚀后的火山岩中，显然是形成萨摩亚屏蔽火山的玄武岩熔岩提取后残留的地幔。稀有气体(He、Ne、Ar和Xe)将被用来确定萨摩亚地幔来源的演化以及熔体形成和分离期间发生的过程。个别矿物相的稀有气体分析，加上间隙玻璃，将采用各种提取技术，包括真空粉碎、常规阶梯加热熔融和单个矿物颗粒的激光熔融。萨摩亚包体气体含量极高，5 mg的单晶可获得准确的He、Ar同位素分析。这项研究应该有助于更好地理解玄武岩熔体形成过程中从地幔橄榄岩中提取挥发物的过程。

This is a study of the rare gas isotope systematics of residual xenoliths from three islands within the Samoan hotspot chain. The xenoliths occur in post-erosional volcanics and are apparently the residual mantle remaining after extraction of the basaltic lava which formed the Samoan shield volcanoes. Rare gases (He, Ne, Ar and Xe) will be used to determine the evolution of the mantle source for Samoa and the processes occurring during melt formation and segregation. Rare gas analysis of individual mineral phases, plus interstitial glass will employ a variety of extraction techniques, including vacuum crushing, fusion by conventional step-heating, and laser fusion of individual mineral grains. The Samoan xenoliths are extremely gas-rich, and accurate He and Ar isotopic analysis can be obtained on single crystals of 5 mg. The study should lead to a better understanding of the processes involved in the extraction of volatiles from mantle peridotites during the formation of a basaltic melt.