Noble Gases and Isotope Systematics in Continental and Hot Spot Volcanism

氦数据现在可以从大约 地球上的40个热点，显示出明显的双峰 同位素比值大于和小于MORB值的分布。 该建议的一部分是用于测量3 He/4 He比率 在卡罗琳和马克萨斯岛链的熔岩上， 已知其具有大于MORB（甘氨酸）的比率， 等于或小于MORB（马克萨斯，仅基于少数样品）。 第二，也是主要的拟议努力，是继续 三大大陆裂谷同位素系统学研究 山谷地形：埃塞俄比亚裂谷（加上Rungwe玄武岩， 东非大裂谷的南端），蛇河 平原上也有哥伦比亚河泛滥玄武岩的研究， 来自玛丽伯德地和维多利亚地的南极玄武岩。 的 第三项工作是继续研究稀有气体系统学 OIB熔岩斑晶（橄榄石，cpx）和玻璃中的（He-Ne-Ar） 当应用到Ne和Ar同位素比的问题， “未耗尽的地幔”源相比，大气的比例。

Helium data now available on small numbers of samples from about 40 of the earth's hotspots, show a well- marked bimodal distribution of isotope ratios greater and less than MORB values. One part of this proposal is for the measurement of 3He/4He ratios on suites of lavas from the Caroline and Marquesas island chains, which are known to have ratios greater that MORB (Carolines) and equal or less than MORB (Marquesas, based on a few samples only). The second, and major proposed effort, is the continuation of studies of the isotopic systematics of three major continental rift valley terrains: the Ethiopian Rift (plus the Rungwe basalts at the southern terminus of the East African Rift), the Snake River Plain with studies also of the Columbia River flood basalts, and the Antarctic basalts from Marie Byrd Land and Victoria Land. The third effort is the continuing study of rare-gas systematics (He-Ne-Ar) in phenocrysts (olivine, cpx) and glass from OIB lavas as applied to the question of the Ne and Ar isotope ratios of the "undepleted mantle" source as compared to atmospheric ratios.