Mantle Signals in Arcs: Transport Models From Geochemistry and Seismicity

这项提议的研究将探索汇聚边缘火山中下地壳的岩浆运输速率，从而解决地球动力学中最基本的问题之一：岩浆如何从地幔楔的源区移动到地表？此外，本研究的结果将提供弧岩浆成因的一级控制，将地幔源和熔融过程与地壳管道系统联系起来，并为弧火山下地幔衍生熔体的聚集提供见解。该项目旨在采用综合方法，结合地球化学、地震学和流体动力学的限制。该项目将使我们更好地了解活火山下的岩浆运输，并改进我们对此类火山监测数据集的解释。目前的岩浆运移模型表明，地幔源熔体在地壳中的储存和演化时间较长。这个项目将测试是否存在一种快速的岩浆运输模式，即使是大型的、长期存在的弧岩浆系统，以及什么条件可能促进这种从地幔到地表的快速上升。地球化学数据的时间整合性常常使其无法与记录瞬变过程的地球物理信号进行直接比较。然而，利用元素在岩浆晶体中快速扩散的地球化学速度计可以弥补这一观测空白，并推动地球化学工具在短时间尺度岩浆过程中的应用，否则只能通过地球物理进行研究。这种技术已成功地应用于近地表岩浆过程；本项目旨在将这种方法扩展到整个地壳岩浆上升路径。

The proposed study will explore magma transport rates in the middle to lower crust of convergent margin volcanoes and therefore address one of the most fundamental questions in geodynamics: How do magmas move from their source region in the mantle wedge to the surface? Furthermore, results from this study will provide first-order controls on arc magma petrogenesis, connecting the mantle source and melting process with the crustal plumbing system as well as provide insights on the aggregation of mantle-derived melts beneath arc volcanoes. The project is designed to use an integrative approach combining constraints from geochemistry, seismology, and fluid dynamics. The project will lead to a better understanding of magma transport beneath active volcanoes and improve our interpretation of monitoring dataset from such volcanoes.Current models for magma transport in convergent margins suggest the prolonged storage and evolution of mantle-derived melts in the crust. This project will test whether a fast mode of magma transport even for large, long-lived arc magma systems exists and what conditions may facilitate such rapid ascent from the mantle to the surface. The time-integrative nature of geochemical data often precludes a direct comparison to geophysical signals that record transient processes. However, geochemical speedometers employing fast elemental diffusion in zoned magmatic crystals may bridge this observational gap and advance the application of geochemical tools to short time scale magmatic processes otherwise only investigated through geophysics. Such techniques have been successfully employed for near-surface magmatic processes; this projects aims at extending such approaches to the entire crustal magma ascent path.