Anatomy and Evolution of the Intracontinental Reno-MarysvaleMagmatic Zone in the Great Basin of Nevada and Utah

这是1986年8月开始的一项由nsf资助的为期两年的项目的延续，该项目旨在获得里诺-马里斯维尔岩浆带的综合时空成分-体积数据。里诺-马里斯维尔岩浆带横跨内华达州和犹他州的大盆地，由大量渐新世到中新世早期的火山灰流凝灰岩和少量安山岩到流纹岩熔岩组成。研究包括：(a)杨百翰大学的PI对火山序列和岩石学进行实地研究和取样，对整个岩石进行x射线辐射，并对斑晶和玻璃进行显微探针分析。(b)伯克利地质年代学中心的A.L. Deino和加州Menlo Park美国地质勘探局的C.S. Gromme分别测定了区域广泛的灰流片的高精度、单晶40Ar/39Ar年龄和自然剩余磁化方向。(c)杨百翰大学的PI对区域火山灰流凝灰岩片的对比和凝灰岩和熔岩的空间-时间-体积-成分数据的汇编。(d)分别由亚利桑那大学的J. Ruiz和J. l . Wooden和美国地质勘探局（Menlo Park， CA）测定Sr、Nd和Pb同位素数据。这些数据将提供一个大陆内主要火山省在时间和空间上演化的详细图像，并将允许解释模型的概念处理：(1)挤压岩浆成分的时空依赖变化和喷发类型-火山碎屑与熔岩。(2)幔源成分和地壳成分对岩浆系统质量和热能收支的相对贡献。(3)大洋岩石圈的俯冲作用和地壳热、力学、密度状态的变化对地壳发育的促进作用

This is the continuation of a two -year, NSF-funded project begun August, 1986 to obtain integrated space-time-composition-volume data on the Reno-Marysvale magmatic zone, a region that spans across the Great Basin of Nevada and Utah consisting of voluminous, Oligocene through early Miocene ash-flow tuffs and minor andesite to rhyolite lavas. The research involves: (a) Field study and sampling of volcanic sequences and petrographic, whole-rock XRF, and microprobe analyses of phenocrysts and glass by PI's at BYU. (b) Determination of high-precision, single- crystal 40Ar/39Ar ages and natural remanent magnetization directions of regionally-extensive ash-flow sheets by A.L. Deino at the Berkeley Geochronology Center and C.S. Gromme at the USGS, Menlo Park, CA, respectively. (c) Correlation of regional ash- flow tuff sheets and compilation of space-time-volume-composition data on tuffs and lavas by PI's at BYU. (d) Determination of Sr, Nd, and Pb isotopic data by J. Ruiz and J.L. Wooden at the Univ. of Arizona and USGS, Menlo Park, CA respectively. These data will provide a detailed picture of the evolution in time and space of a major intracontinental volcanic province and will allow conception of interpretive models dealing with: (1) Time- and space-dependent changes i composition of extruded magma and in type of eruption--pyroclastic versus lava. (2) Relative contributions of mantle-derived versus crustal components to the mass and thermal energy budget of the magma systems. (3) Contributing roles played by subducting oceanic lithosphere and changing thermal, mechanical, and density state of the crust.***//