Sr-Nd-Pb-Th Isotopic Composition of Lavas and Xenoliths Fromthe Canary Islands: Changes in Lithospheric Composition as a Function of Distance From the African Continent

本研究拟开展Sr-Nd-Pb-Th同位素地球化学研究 （1）加那利群岛五个岛屿的火山岩和深成岩 （2）兰萨罗特岛橄榄岩捕虏体， 拉帕尔马岛，第二西端的岛屿。 最西端岛屿Sr-Nd-Pb-Th同位素初步数据 从东部岛屿公布的数据显示， 同位素组成的变化作为距离的函数， 西非. 这些变化可能反映了 地幔柱与岩石圈地幔熔融， 东部为大陆-大洋过渡型（富 地幔成分），以海洋为主的西部（与 亏损地幔成分）。 这项研究对选址有重要意义 （岩石圈、软流圈、地幔柱） 组成部分，以及大陆岩石圈的再循环 地幔在裂谷。

This proposal is to study the Sr-Nd-Pb-Th isotopic geochemistry of: (1) volcanics and plutonics from five of the Canary Islands and (2) peridotite xenoliths from Lanzarote, the easternmost island, and La Palma, the second westernmost island. Preliminary Sr-Nd-Pb-Th isotope data from the westernmost islands and published data from the eastern islands suggest systematic variation in isotopic compositions as a function of distance from West Africa. It may be that these variations reflect interaction of plume melts with the lithospheric mantle, which changes from transitional continental-oceanic in the east (with an enriched mantle composition) to predominantly oceanic in the west (with a depleted mantle composition). The study has important implications for the location (lithosphere, asthenosphere, plume) of the various mantle components, and for the recycling of continental lithosphereic mantle during rifting.