An integrated geochemical and geodynamical approach to the origin of off-axis melt production at a range of mid-ocean ridge settings

了解海洋地壳是如何形成的，以及不同化学成分的熔体是如何形成的，是地幔和地壳之间全球地球化学循环的一个重要方面，但目前还没有得到充分的约束。本文研究了不同洋中脊扩张中心背景下的顺轴和离轴火山作用的地球化学关系，试图建立一种综合的动态地球化学和地球物理模拟方法，以更好地理解地幔非均质性与洋中脊系统的相互作用。这项工作的一个关键组成部分将是检查四个研究得很好的洋中脊（东太平洋隆起、冰岛、加拉帕戈斯群岛和胡安·德·富卡脊）的地球化学，以预测产生离轴融化所需的融化程度和深度，并将这些预测与地幔的物理现实起源联系起来。为了建立一个更完整的离轴地球化学变化的地球化学记录，我们将对东太平洋隆起附近20个海山的样品进行Sr、Nd和Pb的放射性同位素分析，这些同位素是岩浆和岩浆分异过程的标志。一个主要的研究目标是开发强大的一维和二维模型，以确定是否存在全球一致的离轴过程，支撑大洋中脊之下的地幔融化。这项工作的更广泛的影响包括从一个在科学领域代表性不足的群体中发展博士后的职业生涯，并通过佛罗里达当地博物馆向公众宣传。更广泛的影响还包括与一位英国科学家的国际合作，博士后将在合作者的实验室度过一段时间，并在最先进的地球化学分析技术和地球动力学建模方面接受交叉培训。

Understanding how ocean crust is created and its how melts of different chemistry are created is an essential but presently poorly constrained aspect of global geochemical cycling between the mantle and crust. This research investigates the geochemical relationship between on- and off-axis volcanism at a variety of mid-ocean ridge spreading center settings to try and develop an integrated dynamic geochemical and geophysical modeling approach to better understand the interaction of mantle heterogeneities with the mid-ocean ridge system. A key component of this work will be to examine the geochemistry of four well-studied mid-ocean ridges (East Pacific Rise, Iceland, Galapagos, and the Juan de Fuca Ridge) to predict the degree and depth of melting required to produce off-axis melts and relate these predictions to physically realistic origins in the mantle. To create a more complete geochemical record of off-axis geochemical variation, samples from 20 seamounts near the East Pacific Rise will be analyzed for the radiogenis isotoes of Sr, Nd, and Pb, which are indicators of magmatic and magma differentiation processes. A major reserach goal is to develop robust one and two dimensional models to determine whether or not there are globally consistent off-axis processes that underpin mantle melting beneath mid-ocean ridges. The broader impacts of the work include developing the career of a postdoc from a group under-represented in the sciences and public outreach through a local Florida museum. Broader impacts also include international collaboration with a UK scientist, with the postdoc spending time in the collaborator's laboratory and being cross-trained in state-of the art geochemical analytical techniques and geodynamical modeling.