Collaborative Research: Miocene Volcanism in the Sierra Nevada, California: Stratigraphy, Volcanology, Geochronology and Structural Geology

合作研究：加利福尼亚州内华达山脉的中新世火山活动：地层学、火山学、地质年代学和构造地质学

• 批准号: 0125779
• 负责人: Cathy Busby
• 金额: $ 30万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125779&HistoricalAwards=false
• 关键词: Collaborative; Research; Miocene; Volcanism; Sierra

AbstractEAR-0125779Busby and GansUniversity of California, Santa BarbaraThis Collaborative Research proposal between the UC Santa Barbara and the University of Southern Mississippi will establish a regional stratigraphic structural and geochronological framework for Miocene volcanic rocks of the northern to central Sierra Nevada, and at the same time reconstruct structural settings and volcanological processes. The main motivation is to evaluate the tectonic significance and relationship of these mid-Miocene volcanic rocks to modern and ancient subduction, Basin and Range extension, and hotspot settings. Detailed volcanic and sedimentary lithofacies maps will be produced and used to determine the nature and timing of synvolcanic faulting. Petrography, image analysis and Scanning Electron Microscope (SEM) imaging of the Sierran breccias will be employed to study and quantify clast and matrix types, morphologies, dimensions and fragmentation styles (brittle, ductile, transitional), and results will be compared with published examples of volcanic breccias of all plausible origins. Preliminary XRF geochemical analysis of representative suites (including all samples to be dated) will be completed and compared with compositions of clasts with matrices in the breccias. To test for geological consistency in our age data, sampling for 40Ar/39Ar geochronology will concentrate on stratigraphic successions containing at least three or four different datable units. Ar geochronology of single mineral grains (total fusions) as well as incremental step heating experiments will be completed.

美国加州大学圣巴巴拉分校和南密西西比大学的合作研究计划将建立内华达山脉北部至中部中新世火山岩的区域地层结构和地质年代学框架，同时重建构造环境和火山学过程。主要目的是评价中中新世火山岩的构造意义及其与今古俯冲、盆地和山脉伸展、热点环境的关系。将绘制详细的火山和沉积岩相图，并用于确定同火山断裂的性质和时间。将使用Sierran角砾岩的岩石学、图像分析和扫描电子显微镜（SEM）成像来研究和量化碎屑和基质类型、形态、尺寸和破碎风格（脆性、延展性、过渡性），并将结果与所有可能起源的火山角砾岩的已发表实例进行比较。初步的XRF地球化学分析将完成代表性套件（包括所有待定年的样品），并与角砾岩中碎屑与基质的组成进行比较。为了测试我们年龄数据的地质一致性，40Ar/39Ar地质年代学的采样将集中在至少包含三到四个不同数据单元的地层序列上。完成单矿物颗粒（总熔合物）氩年代学和增量阶跃加热实验。