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

在碰撞的构造板块之间的边界处形成的火山是大规模热量和岩浆从地球内部转移到地表的重要记录者。这些构造板块过程的长期变化是通过岩浆的成分和行为随时间的演变记录的。在火山下方的岩浆系统已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。这项研究将通过比较加州横向山脉中暴露的岩浆事件的岩石产物，重点关注长期岩浆演化关系以及与构造过程的联系。这个区域之所以引人注目，是因为随后的构造倾斜和侵蚀暴露了地球表面的岩浆岩，这些岩浆岩是在一个非常长寿的岩浆系统内的不同深度范围内形成的。通过比较各种样本中的岩石和矿物化学，研究人员将能够创建该板块边界岩浆系统内一定深度范围内岩浆演化的详细时间表。作为该项目的重要组成部分，地球科学本科生将对现场和实验室数据进行定性和定量分析，这将补充他们的课程作业并提供真实的研究经验。通过让地球科学专业的学生参与一系列分层的定量研究经验，该项目的影响将得到扩大。这项与学生群体合作的目标是利用一系列高影响力的实践来提高地球科学学生的逐年保留率。分层的真实研究经验将有助于建立一个支持性环境，鼓励坚持不懈，并有助于扩大 STEM 中代表性不足的群体。了解长寿命穿地壳岩浆系统的演化和地壳循环的作用是了解大陆弧动态演化的基本组成部分。在该项目中，研究人员和学生将记录加州大陆弧倾斜和挖掘的横向山脉部分中不同类型的岩浆侵位和岩体聚集，作为年龄和古深度的函数。这项研究的目标是扩展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和脉冲弧中观察到的地壳演化和再循环过程。整个岩石和锆石颗粒将产生长期弧演化的证据，这将补充基于单脉冲、高通量弧生长的现有大陆弧模型。收集的作为古深度、年龄和岩体聚集率函数的全岩石和锆石微量元素数据将用于描述该大陆弧岩浆系统中地壳岩浆来源的多样性和地壳再循环的动态。特别是前岩浆锆石将补充整个岩石数据，因为不同群体的 Pb/U 和微量元素分析提供了地壳岩浆来源和该大陆弧生命周期演化的年龄和矿物学记录。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.