RUI/Collaborative Research: Evaluating the Influence of Crustal Deformation on Episodic Magmatism: Southern Coast Mountains Batholith, British Columbia

该项目将评估导致科迪勒型岩浆弧中大陆地壳非稳定生长的过程。这些岩基是汇聚边缘大洋岩石圈俯冲的结果，但控制岩浆产生速度的过程尚不清楚；即使在俯冲持续的弧形区域，岩浆活动也是强烈的幕式(例如内华达山脉岩基、半岛山脉岩基、中央安第斯山脉)。短期(1000万-1500万年)强烈的岩浆活动或“爆发”可能产生多达90%的石器时代总体积，在其间的间歇期间几乎没有岩浆作用发生。地球化学和同位素特征表明，与在间歇期形成的岩浆相比，在爆发期间产生的岩浆含有更多的上板块物质。这种模式提出了一个问题，即岩浆增加导致的大陆增长主要是受俯冲大洋板块的行为控制，还是受板块边缘大陆岩石圈的构造控制。我们正在通过对不列颠哥伦比亚省南部海岸山脉岩基的综合地质、年代学和地球化学研究来研究这个问题。这个项目直接解决了地球科学中的一个基本问题：大陆是如何生长的？除了该项目的研究目标外，这一努力还加强了四个学术机构的学生的科学教育和培训，这些机构因其学生群体的多样性而得到认可。让学生参与实地考察、实验室分析、数据解释和结果展示，为他们提供了对科学过程和职业选择的所有方面的见解，并增加了对STEM领域的保留。由于这个项目而产生的样本和数据集正被用于设计问题集和为调查人员教授的课程设计解释性练习。在这个项目的过程中产生的数据将被添加到国家科学基金会资助的数据库中，如NAVDAT，供更大的社区访问。

This project will evaluate processes responsible for the non-steady-state growth of continental crust in Cordilleran-type magmatic arcs. These batholiths develop as a result of subduction of oceanic lithosphere at convergent margins, but the processes that control the tempo of magma production are unclear; even in arcs where subduction is continuous, magmatism is strongly episodic (e.g. Sierra Nevada batholith, Peninsular Ranges batholith, Central Andes). Short periods (10-15 million years) of intense magmatism or 'flare-ups' may generate as much as 90% of total batholithic volumes, with little magmatism occurring during intervening lulls. Geochemical and isotopic signatures indicate that magmas produced during flare-ups incorporate more upper plate material than magmas formed during lulls. This pattern raises the question of whether continental growth by magmatic addition is controlled primarily by the behavior of the subducting oceanic plate or by the tectonics of the continental lithosphere at the plate margin. We are investigating this question through an integrated geologic, geochronological and geochemical study of the southern Coast Mountains Batholith in British Columbia. This project directly addresses a basic question in earth science: how do continents grow? In addition to the research goals of this project, this endeavor is enhancing the scientific education and training of students at four academic institutions recognized for the diversity of their student populations. Engagement of students in fieldwork, laboratory analysis, data interpretation and presentation of results are providing them with insights into all aspects of the science process and career options, and increase retention in STEM fields. Samples and datasets generated as a result of this project are being used to design problem sets and interpretive exercises for classes taught by the investigators. Data generated during this the course of this project is being added to NSF-funded databases, such as NAVDAT, for access by the larger community.