Observational Constraints on Melt-Rock Reactions during Melting of the Upper Mantle

最近的研究表明，蛇绿岩中的纯橄榄岩体，可能也是层状洋壳中的纯橄榄岩体，是玄武岩熔体迁移和化学相互作用的熔体输送管道。在这个提议中，Lundstrom提出要检验这个一般假设的两个方面。首先，他提出测试的假设，熔体移动通过纯橄榄岩实际上是非常丰富的，并在地幔中的镁铁质异质熔融产生。他建议通过测量来自蛇绿岩样品和地幔捕虏体的地幔尖晶石中氧和锂的同位素组成来做到这一点。第二个测试，使用从Trinity蛇绿岩的样品，是为了确定是否存在梯度的锂和其他不相容的元素同位素作为距离纯橄榄岩体的函数。

Recent work has indicated that dunite bodies in ophiolites, and presumably also in layered ocean crust, represent melt transport conduits through which basaltic melt has migrated and interacted chemically. In this proposal, Lundstrom proposes to test two aspects of this general hypothesis. First, he proposes to test the hypothesis that the melts that moved through the dunites are in fact very enriched and produced by melting of mafic heterogenieties in the mantle. He proposes to do this by measuring the isotopic compositions of oxygen and lithium in mantle spinels from ophiolite samples and mantle xenoliths. A second test, using samples from the Trinity ophiolite, is to determine whether there exist gradients in lithium and other incompatible element isotopes as a function of distance from dunite bodies.