The Jemez Tomography Experiment (JTEX)

杰梅兹断层扫描实验 (JTEX)

• 批准号: 9218900
• 负责人: George McMechan
• 金额: $ 3.5万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-06-01 至 1995-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9218900&HistoricalAwards=false
• 关键词: Jemez; Tomography; Experiment; JTEX

The Jemez Tomography Experiment (JTEX) is a cooperative and interdisciplinary research program involving scientist from six major Universities, the Los Alamos National Laboratory with support from the DOE, and the U.S. Geological Survey. The Jemez Mountains volcanic field (JMVF) is a major Late Cenozoic silicic volcanic system. Perhaps its best-known feature is the Valles Caldera and associated 1.1 to 1.6 Ma explosive volcanic products including the Bandelier Tuff. The fundamental questions that relate to the JMVF and other recent silicic volcanic systems and which are addressed in the project are: 1. What is the nature and extent of crustal involvement and accompanying modifications of the crust during the volcanic activity in the JMVF? Are crustal intrusions, pluton, or underplated regions present in the crust beneath the Valles Caldera and Jemez Mountains? 2. How has the JMVF evolved through the last 15 Ma, culminating in eruption of the Bandelier rhyolite ignimbrite and caldera collapse? Petrologic models of silicic magma generation suggest that large volumes of mafic intrusions (on the order of ten times the volume of erupted material) are present in the crust beneath major silicic volcanic centers. Can we image these intrusions geophysically and interpret their relationships to the observed volcanic geology? In order to address these and other questions related specifically to the JMVF and generally to continental magmatism, the principal investigators will conduct intensive geophysical studies of the JMVF, analyze the data collected and interpret the results in concert with petrologic and geochemical information. The new geophysical data will include: seismic refraction/reflection, teleseismic delay time and waveform, gravity, magnetic, and magnetotelluric (MT) data. The program is designed to provide a three-dimensional image of the magmatically modified c rust beneath the JMVF. Tomographic inversion of the explosion seismic and teleseismic data and combined interpretation with the potential field, MT and geologic data will produce the most high resolution 3-D study of crustal scale features that is currently available.

杰梅兹断层扫描实验 (JTEX) 是一个跨学科合作研究项目，由来自六所主要大学、洛斯阿拉莫斯国家实验室的科学家在美国能源部和美国地质调查局的支持下参与。 杰梅兹山脉火山田（JMVF）是一个主要的晚新生代硅质火山系统。 也许其最著名的特征是火山口山谷和相关的 1.1 至 1.6 Ma 火山爆发产物，包括班德利尔凝灰岩。 该项目要解决的与 JMVF 和其他近期硅质火山系统相关的基本问题是： 1. JMVF 火山活动期间地壳参与和伴随的地壳变化的性质和程度是什么？ Valles Caldera 和 Jemez 山脉下方的地壳中是否存在地壳侵入体、岩体或板下区域？ 2. JMVF 在过去 15 Ma 中是如何演变的，最终导致班德利尔流纹岩火凝灰岩喷发和破火山口塌陷？ 硅质岩浆生成的岩石学模型表明，主要硅质火山中心下方的地壳中存在大量镁铁质侵入体（约为喷发物质体积的十倍）。 我们能否对这些侵入进行地球物理成像并解释它们与观察到的火山地质的关系？ 为了解决这些问题以及与 JMVF 和一般大陆岩浆作用相关的其他问题，主要研究人员将对 JMVF 进行深入的地球物理研究，分析收集到的数据，并结合岩石学和地球化学信息解释结果。 新的地球物理数据将包括：地震折射/反射、远震延迟时间和波形、重力、磁力和大地电磁（MT）数据。 该程序旨在提供 JMVF 下方岩浆改造地壳的三维图像。 爆炸地震和远震数据的层析反演以及与势场、MT 和地质数据的结合解释将产生目前可用的地壳尺度特征的最高分辨率的 3-D 研究。