Collaborative Research: Origin and Significance of High Potassium Volcanism: Insights from the Ancestral Cascades, California

关于美国西部地质历史的主要科学问题之一是确定内华达州山脉的断层和隆起是何时开始的。这个时间是至关重要的，因为它会影响我们对特定断层应变率的理解，从而对地震危险产生影响。这个问题也很重要，因为这种隆起与板块边界的诞生相吻合-大盆地和塞拉微板块之间的边界。火山活动长期以来一直被认为与板块边界活动的变化有关。在这个项目中，合作小组将研究内华达州山脉高钾火山活动的性质，作为这一新板块边界诞生的潜在信号。高钾火山活动长期以来一直被视为构造活动的指标，但其起源仍不清楚。初步的现场和地球化学数据显示，存在一个祖先的喀斯喀特弧在中部山脉内华达州和东部加州，和一个潜在的联系之间的开始的板块边界和岩浆活动，导致了一系列的高K喷发。因此，中部Sierra地区为研究高钾岩浆岩的地球化学以及这种不寻常的岩浆活动是否反映了内华达州山脉的拆沉和隆升提供了一个理想的场所。该研究将为喀斯喀特岛弧高钾岩石的岩石学研究提供一个重要的和急需的地质和年代学框架，并使研究人员能够评估高钾火山作用起源的三种岩石学-构造模型。该项目建立了加州大学圣巴巴拉分校（UCSB）和加州州立大学弗雷斯诺分校（Fresno）之间的研究联系（CSU弗雷斯诺），这将使来自CSU弗雷斯诺的学生有与教师和研究生在一个研究型机构密切合作的宝贵经验。科罗拉多州立大学弗雷斯诺分校是一所被指定为西班牙裔服务的RUI机构;目前，科罗拉多州立大学弗雷斯诺分校地质系的学生中有60%是女性，2006年入学的学生中有一半是女性和西班牙裔。这代表了地质学专业人口的重大转变，这些学生能够参与RUI项目至关重要。凯茜·巴斯比博士为CSU弗雷斯诺和UCSB的女学生提供了宝贵的导师，也是这两个机构年轻女性的榜样。在这项建议中寻求的学生支持也是至关重要的CSU弗雷斯诺作为招聘工具，使学生进入地质学。

One of the major scientific questions regarding the geologic history of the western U.S. is to identify exactly when faulting and uplift began in the Sierra Nevada. This timing is crucial because it impacts our understanding of strain rates on particular faults, and hence has an impact on seismic hazards. The issue is also important since such uplift coincides with the birth of a plate boundary-the boundary between the Great Basin and the Sierra microplate. Volcanic activity has long been known to be associated with changes to the plate boundary activity. In this project, the collaborative team will examine the nature of high potassium volcanism in the Sierra Nevada as a potential signal of the birth of this new plate boundary.High potassium volcanism has long been looked to as an indicator of tectonic activity, but its origin remains unclear. Preliminary field and geochemical data show the existence of an ancestral Cascades arc in the central Sierra Nevada and eastern California, and a potential link between the inception of a plate boundary and the magmatism that led to a series of high K eruptions. For that reason, the central Sierra region provides an ideal place to study the geochemistry of high potassium magmatic rocks and the possibility that this unusual magmatism is a reflection of the delamination and uplift of the Sierra Nevada. The research proposed will provide an important and much-needed geologic and geochronologic framework for petrologic study of high-K rocks of the ancestral Cascades arc and enable to researchers to evaluate three petrologic-tectonic models for the origin of high potassium volcanism.This project establishes a research linkage between the University of California-Santa Barbara (UCSB) and California State University-Fresno (CSU Fresno) that will allow students from CSU Fresno to have the invaluable experience of working closely with faculty and graduate students at a research-oriented institution. CSU Fresno is an RUI institution that has been designated Hispanic serving; women currently comprise 60% of the students in the CSU Fresno Geology Department, and half of the incoming students in 2006 are female and Hispanic. This represents a significant shift in the demographics of the population of Geology majors, and it is crucial that these students are able to become involved in RUI projects. Dr. Cathy Busby provides an invaluable mentor to female students at both CSU Fresno and UCSB, and a role model for young women at both institutions. The student support sought in this proposal also is crucial to CSU Fresno as a recruitment tool to bring students into Geology.