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

本文旨在研究加那利群岛五个岛国的火山岩和深成岩类以及最东端的兰萨罗特岛和第二西端的拉帕尔马岛的橄榄岩包体的锶-钕-铅-钍同位素地球化学。最西端岛屿的初步锶-钕-铅-钍同位素数据和东部岛屿公布的数据表明，随着距离西非的距离，同位素组成发生了系统的变化。这些变化可能反映了热柱熔体与岩石圈地幔的相互作用，岩石圈地幔在东部从大陆-海洋过渡(地幔成分丰富)转变为西部以海洋为主(地幔成分贫化)。该研究对岩石圈、软流圈、地幔各组分的定位以及大陆岩石圈地幔在裂谷作用中的再循环具有重要意义。

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.