Collaborative Research: Crustal Overturn in Continental Margin Arcs During Magmatic Surges

俯冲带是一个岩石圈板块在返回地幔之前滑到另一个岩石圈板块之下的地方，导致岩石在深处熔化，这些熔化物上升形成长长的火山链和次火山岩体，它们一起被称为岩浆弧。 由于这些弧和周围的寄主岩石是热的，并且由于板块运动而承受巨大的应力，它们变得广泛变形，形成造山带。大陆边缘造山带及其岩浆弧的演化具有非稳态性。节奏？俯冲、造山、岩浆作用、折返和侵蚀/再沉积。本研究项目考察了这种节奏的细节，特别是在岩浆涌动期间（大量岩浆形成并添加到地壳的时期），以及容易熔化的地壳向俯冲带发生熔化的深度区域的构造运输所起的作用。其目的是测试的假设，在白垩纪中期（105 - 85马）高岩浆潮插曲大部分的弧在南部山脉内华达州和Salinian块侵位在地壳尺度的对流系统。对105-85 Ma岩体悬体的初步研究表明，在岩浆活动上升过程中，变质沉积岩和溢流变质火山岩的寄主岩石发生对流性翻转，并经历了快速的向下位移和高应变流动。这项研究将扩大和综合一些数据集（例如，野外研究、地质年代学、气压测量、垂直位移、应变场、岩浆通量）加上进行广泛的正演数值、热机械模拟，能够结合岩浆上升、粘弹塑性宿主行为、大应变、非线性流变学，和现实的相变来理解这个过程的物理学。火山爆发对人类社会产生了巨大的影响，在我们大气层的形成和in climate气候change变化.此外，造山带的地壳变形会导致地震等短期事件和造山运动等长期事件，这些事件也会影响我们的社会。认识到弧壳，有时，经历翻转，从而将地壳物质纳入上升的岩浆将大大改变岩浆系统的认识，这些系统的地球化学和地质年代学分析，地壳生长的速度。这项研究将提高对这些系统的理解，并将向公众提供基于地理信息系统的地质年代学、热压测量、垂直位移率、应变和应变率以及岩浆通量数据库。来自多个院校的大量本科生将通过南加州大学团队研究计划参与到该研究项目中

Subduction zones, where one lithospheric plate slides beneath another before returning to the mantle, results in melting of rock at depth and the rise of these melts to form long chains of volcanoes and subvolcanic plutons that together are called magmatic arcs. Because these arcs and surrounding host rocks are hot and undergoing tremendous stresses due to the plate motions they become extensively deformed forming orogenic belts. The evolution of continental margin orogenic belts and their associated magmatic arcs has a non-steady state ?tempo? of subduction, orogeny, magmatism, exhumation, and erosion/redeposition. This research project examines the details of this tempo particularly during magmatic surges (periods when large volumes of magma are formed and added to the crust) and what role was played by the tectonic transport of easily melted crust to regions at depth where melt occurs in subduction zones. The goal is to test the hypothesis that during the mid-Cretaceous (105-85 Ma) high magma surge episode much of the arc in the southern Sierra Nevada and Salinian blocks was emplaced within a crustal scale convection system. Preliminary studies of pendants around 105-85 Ma plutons indicate that, during rise of magmatism, metasedimentary and effusive metavolcanic host rocks were convectively overturned and underwent rapid downward displacement and high-strain flow. The research will expand and synthesize a number of data sets (e.g., field studies, geochronology, barometry, vertical displacement, strain fields, magma fluxes) plus perform extensive forward numerical, thermomechanical modeling capable of incorporating magma ascent, viscoelasto- plastic host behavior, large strains, nonlinear rheologies, and realistic phase transitions to understand the physics of the process.Volcanic eruptions dramatically impact human society and play a huge role in both the formation of our atmosphere and in climate change. Additionally crustal deformation in orogenic belts leads to short-term events such as earthquakes and long-term events such as mountain building that also impact our society. The recognition that arc crust, at times, undergoes overturn thus incorporating crustal materials into rising magmas will dramatically change the understanding of magmatic systems, the geochemical and geochronologic analyses of these systems, and rates of crustal growth. This research will improve understanding of these systems and the GIS based databases produced on geochronology, thermobarometry, vertical displacement rates, strain and strain rates, and magma fluxes will be made available to the public. A large number of undergraduates from several institutions will be involved in the research project through the University of Southern California Team Research program