Signatures of Changing Eruptive Style, and Bias in the Sedimentary Record of Volcanism, Challis Volcanic Field, Idaho

这个项目是一个为期三年的研究改造火山岩 在爱达荷州中部始新世查利斯火山区的沉积。 该项目侧重于两个主要目标。 一是 确定沉积类型和模式的变化， 是由不同类型的火山爆发引起的。 第二个目标 是对火山作用沉积记录的偏差分析。 查利斯火山区的沉积物代表了一个很长的时期 火山活动（5100万至4000万年前）的特点是， 初期主要是非爆炸性中间体 火山作用之后是形成破火山口的火山作用。 沉积 与这种火山作用有关的系统包括高-和低- 弯曲的溪流、湖泊（粘土岩-凝灰岩和浊积岩 组成部分），以及火山泥流沉积的泥石流裙。 的 研究将确定不同喷发类型的信号， 多种沉积环境组合。 这项研究将 还可以确定哪些环境对扰动最敏感 因此，包含了最好的火山记录， 活动 研究以野外为导向，结合岩石地层学， 火山灰指纹和岩相地层学， 实现项目所需的详细关联框架 目标. 这些方法需要测量详细的地层 剖面、砂岩、杂岩和砾岩岩石学，以及 剖面中沉降凝灰岩的化学分析。

This project is a three-year study of reworked volcaniclastic deposits in the Eocene Challis volcanic field in central Idaho. The project focuses on two major goals. The first is identification of changes in sedimentation style and pattern that result from different types of volcanic eruptions. The second goal is analysis of bias in the sedimentary record of volcanism. Deposits of the Challis volcanic field represent a long period of volcanic activity (51 to 40 million years ago) characterized by an initial period of predominantly non-explosive intermediate volcanism followed by caldera-forming volcanism. The sedimentary system associated with this volcanism comprises high - and low - sinuosity streams, lakes (claystone - tuff and turbidite components), and debris - flow aprons deposited by lahars. The study will identify the signal of different eruption types in a diverse assemblage of depositional environments. The study will also identify which environments are most sensitive to perturbation by eruption and therefore, contain the best record of volcanic activity. The study is field - oriented, combining lithostratigraphy, tephra fingerprinting, and petrofacies stratigraphy to produce the detailed correlation framework needed to achieve the projects goals. These methods require measurement of detailed stratigraphic sections, sandstone, diamictite, and conglomerate petrology, and chemical analyses of fallout tuffs in the sections.