Collaborative Research: Elucidating Physical Processes in Upper Crustal Magma Systems - Evidence from Miocene Intrusive and Extrusive Sequences in Southern Nevada

合作研究：阐明上地壳岩浆系统的物理过程——来自内华达州南部中新世侵入和喷出层序的证据

• 批准号: 0409913
• 负责人: James Faulds
• 金额: $ 8.5万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0409913&HistoricalAwards=false
• 关键词: Collaborative; Research; Elucidating; Physical; Processes

Physical transport processes determine the ways in which magmas traverse the upper crust, how they are modified, where they are deposited, whether and how they erupt, and what their final products will be. This project will investigate the physical mechanisms that transport and distribute magmatic materials using a superb natural laboratory: the Colorado River region south of Las Vegas, where relatively young (~15 million years old) magmatic systems are spectacularly exposed through a combination of steep tilting during rift-related faulting, high relief, and sparse vegetation. Numerous plutons, extensive dike swarms, and thick volcanic sequences document a relatively brief but highly productive episode of magma influx. A key part of the project will be devoted to understanding the plutons (large bodies of intrusive rock, solidified beneath the surface) and what they say about the nature and history of magma chambers (temporary melt-rich zones at depth that solidify to form plutons and may expel magma to erupt at the surface). Plutons, the magma chambers that formed them, dikes that fed the chambers, and dikes that fed volcanic eruptions at the surface all must have dynamic histories, but the physical processes that move crystals, melts, and fragments of solid or near-solid rocks within these systems are not well understood. General distributions of volcanic and intrusive rocks in the study area and details of their internal structure suggest fluid dynamic models that are analogous to fluid and particle transport in surface environments - notably sedimentation and mass wasting processes.The project will address this fundamental, general issue:How do physical transport processes in the upper crust determine the eventual distribution and physical and compositional characteristics of the products of a magma system?To evaluate this broad problem, the focus will be on the following more specific questions:(1) How do depositional processes dictate the construction and ultimate architecture of plutons?(2) How do external factors (recharging, roof collapse, eruption, tectonism) influence internal physical processes within magma chambers?(3) How much, and why, do melt fraction and volume vary over the lifetime of a pluton (~magma chamber)? (4) What determines whether deep-level magmas transit the upper crust unmodified or are modified during residence in magma chambers?; Do magma chambers serve as effective filters, selectively inhibiting further ascent of certain magmas or magmatic materials? (5) What determines whether magma pools to form plutons, remains restricted to dikes, or erupts?Field studies of key areas will characterize critical structures and map patterns that provide evidence for mechanical transport and deposition processes and provide samples for further analysis. These samples will be used for detailed radiometric dating and microanalysis of tracer elements and isotopes in minerals. Complementary lab experiments on liquid + particle analogs of magma will evaluate plausible fluid dynamic processes in the magma systems. Together, the sample geochemistry and geochronology and lab experiments will test field-based magma transport hypotheses.This project will provide ideal research training and constitute the basis for theses for 7 Master's and 12 undergraduate students. The students will present and publish their results and gain experience in combining careful field observation with advanced analytical work, in collaborative research, and in integrating their local efforts into a global framework. This work prepares them not only for further research in petrology, geochemistry, and tectonics, but also for a broad range of Earth science problem solving and teaching. Based on past experience a large proportion of these students will be female and participation by minority students is likely. The study will stimulate exchange of ideas between the PI's and their students and several informal collaborators who will add their own perspectives and expertise and in some cases analytical methodologies. These collaborations, formal and informal field trips, and presentations to specialist and general audiences as well as published work will disseminate developing ideas, foster discussion in a variety of forums, and showcase this spectacular example of magmatic processes. Much of the research will take place in Lake Mead National Recreation area, which will provide an excellent venue for presentation of new ideas to the public. The project will also contribute to a new cooperative program at Vanderbilt involving geology and environmental engineering.Although principally a basic science project, the results of this work will contribute to understanding of eruptive processes and thus will bear upon volcanic hazards.

物理运输过程决定了岩浆穿越上皮，如何修饰，沉积的位置，是否爆发以及最终产品将是什么方式。 该项目将研究使用高级天然实验室运输和分发岩浆材料的物理机制：拉斯维加斯以南的科罗拉多河地区，那里的岩浆系统相对年轻（约1500万年）的岩浆系统通过在与裂谷相关的断层，高度救济，高度救济和稀疏蔬菜的过程中的陡峭倾斜结合而壮大。 许多岩石，大量的堤防和厚的火山序列记录了一个相对简短但高效的岩浆涌入事件。 该项目的关键部分将致力于理解岩石（侵入性岩石的大物体，在表面下方固化）及其对岩浆腔室的性质和历史的看法（在深度的临时融化区域固化以形成plut子，并可能将岩浆驱逐出来，以在地面爆发）。 岩子，形成它们的岩浆室，堤防供室的堤防以及在地面上喂火山喷发的堤防都必须具有动态历史，但是在这些系统内移动晶体，融化和固体或近乎固体岩石的物理过程尚不充分理解。 在研究区域中火山和侵入性岩石的一般分布及其内部结构的细节表明，流体动态模型类似于表面环境中的流体和粒子运输 - 尤其是沉降和质量浪费过程。项目将解决这个基本问题：一般性问题：在上面的范围内，在上面的范围内，在上面的范围内，如何对磁性的特征？问题：（1）沉积过程如何决定岩石的构建和最终结构？（2）外部因素（充电，屋顶倒塌，喷发，构造）如何影响岩浆腔室内的内部物理过程？ （4）是什么决定了深层岩浆是否在岩浆腔室中居住期间未修饰的上皮过境或经过修改？岩浆腔室是否充当有效的过滤器，有选择地抑制某些岩浆或岩浆材料的进一步上升？ （5）是什么决定了岩浆池是否形成岩石，仍然仅限于堤防或爆发？关键领域的现场研究将表征关键结构和地图模式，以提供机械运输和沉积过程的证据，并提供样品以进一步分析。 这些样品将用于矿物质中的示踪剂元素和同位素的详细辐射测定和微分析。 岩浆液体 +颗粒类似物的补充实验室实验将评估岩浆系统中合理的流体动态过程。 样本地球化学和年代学和实验实验一起将测试基于现场的岩浆运输假设。该项目将提供理想的研究培训，并构成7名硕士和12名本科生的论文基础。 学生将展示并发布他们的结果，并获得将仔细的现场观察与高级分析工作，合作研究以及将他们的本地努力整合到全球框架中的经验。 这项工作不仅为岩石学，地球化学和构造学的进一步研究做准备，而且还为广泛的地球科学问题解决和教学做好了准备。 根据过去的经验，这些学生中很大一部分将是女性，少数学生的参与可能是女性的。 这项研究将刺激PI和他们的学生以及几个非正式合作者之间的想法交流，这些合作者将添加自己的观点和专业知识，在某些情况下是分析方法。 这些合作，正式和非正式的实地考察以及向专家和一般受众的演讲以及发表的工作将传播发展的思想，在各种论坛中促进讨论，​​并展示这个奇妙的岩浆过程示例。 大部分研究将在米德湖国家娱乐区进行，该地区将为公众提供新想法的良好场所。 该项目还将为范德比尔特（Vanderbilt）的一项新合作计划做出贡献，涉及地质和环境工程。尽管主要是基础科学项目，但这项工作的结果将有助于理解喷发过程，因此将承受火山危害。