Collaborative Research: Elucidating the Geologic Record of Late Paleozoic Subduction Initiation Along the Southwestern Margin of Laurentia, Southern California and Sonora, Mexico

该项目的主要目的是记录晚古生代西南劳伦边缘对俯冲开始的时间和反应。虽然俯冲带岩石圈的再循环是板块构造理论的一个基本组成部分，但俯冲带的形成方式是一个缺乏约束的过程，这主要是因为现代的例子很少，而古代的例子大多不被认识或保存得很好。为了更好地了解俯冲开始是如何在地层序列中被记录下来的，以及大陆边缘的古地理是如何随着板块收敛的开始而演化的，研究人员将对加利福尼亚南部（埃尔帕索山脉地区）和墨西哥北部（Carborca地块）暴露的独特的沉积岩和火山岩序列进行研究。我们认为，记录俯冲起始的大陆边缘序列具有可预测的深变浅趋势，并且随着时间的推移，砂体组成和碎屑锆石物源的变化明显，反映了源区古地理的变化。对火山序列和同期侵入岩的地球化学和地质年代学研究将用于限制岩浆产物的时间和岩石成因，我们认为这将记录寒冷的新生大陆弧环境的独特条件。该项目的研究结果对建立俯冲带的诞生和发展的全球模型具有重要意义。这个项目是加州州立大学北岭分校和北亚利桑那大学的研究人员之间多学科合作的成果，这两所大学都是为少数民族服务的机构。除了该项目的科学目标外，本研究还将为硕士和本科生提供培训和指导，并促进代表性不足的群体参与STEM研究。样本收集和研究结果将用于开发教学资源、社区外展和进一步研究。

The principle aim of this project is to document the timing and response of the southwestern Laurentian margin to the initiation of subduction during late Paleozoic time. Although the recycling of lithosphere at subduction zones is a fundamental part of plate tectonic theory, the manner by which subduction zones initiate is a poorly constrained process, largely because there are few modern examples and ancient examples are largely not recognized or well preserved. Unique sequences of sedimentary and volcanic rocks exposed in southern California (El Paso Mountains region) and northern Mexico (Carborca Block) will be investigated in order to better understand how subduction inception is recorded in stratigraphic successions and how the paleogeography of continental margins evolves in response to the onset of plate convergence. We propose that continental margin successions recording subduction initiation will have predictable deepening and shallowing trends and distinct changes in sand composition and detrital zircon provenance through time reflecting the changing paleogeography of source regions. An additional geochemical and geochronologic investigation of volcanic sequences and coeval intrusions will be used to constrain the timing and petrogenesis of magmatic products, which we suggest will record conditions unique to cold, nascent continental arc settings. Results of this project may contribute significantly to global models of the birth and development of subduction zones. This project is a multi-disciplinary and collaborative effort between researchers at California State University - Northridge and Northern Arizona University, which are both minority-serving institutions. In addition to the science goals of the project, this research will provide training and mentorship for masters level and undergraduate students and promote the involvement of underrepresented groups in STEM research. Sample collections and study results will be used for the development of resources for teaching, community outreach, and further research.