The Galapagos Plume Geodynamics, a Geochemical Approach

本研究的目的是提供额外的限制，以提高我们的知识的加拉帕戈斯羽及其相互作用的加拉帕戈斯蔓延中心。本研究将探讨与加拉帕戈斯地质演化有关的两个科学问题。 首先，为了了解哪些过程是负责的地球化学变化的加拉帕戈斯熔岩和目前的模型是最适合解释它们，我们提出了一项研究，结合氧和放射性同位素分析的主要和微量元素组成相同的样品集。 其次，我们建议开发一个地球动力学图片的上涌速度和熔融的地幔下加拉帕戈斯群岛。传统上，地幔上涌和熔融的地球动力学图像是通过详细的地球物理研究获得的。在过去的15到20年里，对铀系（238 U-230 Th，230 Th-226 Ra，235 U-231 Pa）的研究使科学家能够利用地球化学工具对地幔上涌和熔融进行成像。与其他放射性同位素系统相比，U系列的半衰期较短，这将使我们能够初步了解现今的地幔成分，一套熔岩所代表的熔融程度，并估计群岛不同点的地幔上涌。将铀系列、氧和其他放射性同位素与在同一样品中测得的主要和微量元素含量结合起来，再加上正在进行的地球物理研究，将为我们提供最好的机会，以获得加拉帕戈斯羽流和周围软流层的可靠地球动力学图像。

SaalEAR-0207136 The goals of this study are to provide additional constraints to improve our knowledge of the Galapagos plume and its interaction with the Galapagos Spreading Center. Two scientific issues pertaining to the geological evolution of the Galapagos will be addressed as part of this study. Firstly, in order to understand which processes are responsible for the geochemical variations of the Galapagos lavas and which current model is most suited to explain them, we propose a study that combines oxygen and radiogenic isotope analyses with major and trace elements compositions on the same sample set. Secondly, we propose to develop a geodynamic picture of the upwelling velocities and melting of the mantle beneath the Galapagos archipelago. Traditionally, geodynamic pictures of mantle upwelling and melting have been obtained through detailed geophysical studies. In the last 15 to 20 years, the study of U-series (238U-230Th, 230Th-226Ra, 235U-231Pa) has allowed scientists to image the mantle upwelling and melting using a geochemical tool. In contrast to other radiogenic isotope systems, the short half lives of the U-series will allow us to get a first look at the present-day mantle composition, the extent of melting represented by a suit of lavas and estimate the mantle upwelling at different points in the archipelago. The combination of U-series, oxygen and other radiogenic isotopes with major and trace elements contents measured in the same samples combined with ongoing geophysical studies, will provide our best opportunity to obtain a reliable geodynamic image of the Galapagos plume and the surrounding asthenosphere.