Crustal Evolution and Recycling in a Long-Lived Transcrustal Magma System

在板块碰撞的边界形成的火山是大规模热量和岩浆从地球内部转移到地球表面的重要记录器。这些板块构造过程的长期变化被岩浆成分和性质随时间的演变所记录。在火山下面的岩浆系统被抬升并暴露在地球表面进行研究的地区，可以更好地了解这些过程。本研究将通过比较加州横贯山脉中暴露的岩浆幕的岩石产物，着重于长期岩浆演化关系和与构造过程的联系。这一地区之所以引人注目，是因为随后的构造倾斜和侵蚀使地球表面的岩浆岩暴露出来，这些岩浆岩是在一个非常长寿的岩浆系统中形成的。对各种样品中的岩石和矿物化学进行比较，将使研究人员能够在这个板块边界岩浆系统内的一系列深度范围内创建一个详细的岩浆演化时间轴。作为该项目的重要组成部分，本科地球科学专业的学生将从事实地和实验室数据的定性和定量分析，这将补充他们的课程工作，并提供真实的研究经验。该项目的影响将通过让地球科学学生参与定量研究经验的分层序列来扩大。这项工作的目标是与学生群体是使用一套高影响力的做法，以提高地球科学学生的年复一年的留存率。分层的一套真实的研究经验将有助于建立一个支持性的环境，鼓励坚持，并将有助于扩大代表性不足的群体在STEM。了解长期存在的穿壳岩浆系统的演变和地壳再循环的作用是了解大陆弧的动态演变的一个基本组成部分。在这个项目中，研究人员和学生将记录不同风格的岩浆侵位和岩体组装作为年龄和古深度的函数在倾斜和折返的横向山脉部分的加州大陆弧。这项研究的目的是扩大现有的原型大陆弧结构模型，以反映在更古老的分层大陆地壳内建立的长寿脉冲弧中观察到的地壳演变和再循环过程。整个岩石和锆石颗粒将产生长期弧演化的证据，这将补充现有的大陆弧模型的基础上单脉冲，高通量弧增长。全岩和锆石微量元素数据收集的古深度，年龄和岩体组装率的函数将被用来描述地壳岩浆源的多样性和地壳再循环在这个大陆弧岩浆系统的动力学。特别是岩浆前锆石将补充整个岩石数据，因为Pb/U和微量元素分析的不同人群提供了耦合的年龄和矿物学记录的地壳岩浆起源和演化的生命周期，这个大陆arc.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Volcanoes formed at boundaries between colliding tectonic plates are important recorders of large-scale heat and magma transfer from Earth’s interior to it’s surface. Long-term changes in these tectonic plate processes are recorded by the evolution in composition and behavior of magmas through time. A better understanding of these processes can be achieved in areas where magma systems beneath the volcanoes have been uplifted and exposed to study on the Earth’s surface. This study will focus on long-term magma evolutionary relationships and links to tectonic processes by comparing rock products of magmatic episodes exposed in the Transverse Ranges of California. This area is remarkable because subsequent tectonic tilting and erosion have exposed on Earth’s surface magmatic rocks that formed over a range of depths within a very long-lived magma system. Comparison of rock and mineral chemistry in a variety of samples will allow researchers to create a detailed timeline of magma evolution over a range of depths within this plate boundary magma system. As an important part of the project, undergraduate geoscience students will engage in qualitative and quantitative analysis of field and laboratory data that will supplement their course work and provide authentic research experiences. The impact of this project will be broadened by engaging cohorts of geoscience students in a tiered sequence of quantitative research experiences. The goal of this work with student cohorts is to use a set of high impact practices to improve the year over year retention rate of geoscience students. The tiered set of authentic research experiences will help to build a supportive environment that will encourage persistence and will contribute to broadening of underrepresented groups in STEM.Understanding the evolution of long-lived transcrustal magma systems and the role of crust recycling is a fundamental component of understanding the dynamic evolution of continental arcs. In this project researchers and students will document diverse styles of magma emplacement and pluton assembly as a function of age and paleodepth in the tilted and exhumed Transverse Ranges segment of the California continental arc. The goal of the study is to expand upon the existing model for the architecture of the prototypical continental arc, to reflect observed processes of crustal evolution and recycling in a long-lived and pulsed arc built within much older, stratified continental crust. Whole rocks and zircon grains will yield evidence of long-term arc evolution that will complement the existing continental arc model based on single pulse, high flux arc growth. Whole rock and zircon trace element data collected as a function of paleodepth, age and pluton assembly rate will be used to describe the diversity of crustal magma sources and the dynamics of crust recycling in this continental arc magma system. Premagmatic zircons in particular will supplement whole rock data because Pb/U and trace element analyses of diverse populations provide coupled age and mineralogic records of crustal magma provenance and evolution over the life cycle of this continental arc.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.