Collaborative Research: Testing the Timescale and Geometry of Incremental Pluton Assembly Through 3-D Modeling and Thermochronology

合作研究：通过 3D 建模和热年代学测试渐进式冥王星组装的时间尺度和几何形状

• 批准号: 0538129
• 负责人: Drew Coleman
• 金额: $ 28.6万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538129&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; Timescale; Geometry

This research is designed to test the hypothesis that plutons record geochronologic, thermochronologic and field evidence for incremental assembly. Although suggested by theoretical considerations, geochronologic and field data in support of incremental growth (particularly over millions to tens of millions of years) are hotly debated. Hornblende, biotite and potassium-feldspar argon thermochronology of rocks in the Sierra Nevada batholith are being used to address several broad questions. First, slow incremental pluton assembly has largely been inferred from uranium-lead zircon ages, and argon-argon dates from the same samples are providing a robust test of the reliability of the uranium-lead results. Second, if large "homogeneous" plutons were assembled incrementally, then contacts between increments have been overlooked in the field, and new mapping using bulk rock magnetic susceptibility is being used to identify cryptic contacts. Finally, modeling pluton and wall rock temperature histories indicates that cooling paths are sensitive to both the rate and the geometry of incremental pluton assembly. Therefore, cooling histories based on the zircon and titanite uranium-lead systems, and hornblende, biotite and potassium-feldspar argon systems, are being compared to modeled cooling histories in order to resolve spatial arrangements of intrusive increments and the rates at which they are added. This research is addressing the physical and chemical evolution of magma chambers, including mechanisms of intrusion, development of pluton fabrics, and permissible magmatic differentiation processes. The complex thermal histories of plutons and their wall rocks suggested by our modeling bear on interpretation of hornblende argon-argon dates from plutons; the maximum temperatures and durations of contact metamorphism; the thermal, structural and petrologic evolution of early intrusions as they become the wall rocks for later intrusions; the interpretation of paleomagnetic data collected from plutons; and the extent to which formation of large-volume eruptible magma bodies is recorded by plutons. This research focuses on the rates of assembly of magma chambers that feed volcanoes at the surface of the Earth. It employs a variety of dating techniques that act as checks and balances on each other in an effort to understand how, and how fast, the magma bodies are constructed, and their potential for catastrophic eruption. The incremental assembly hypothesis predicts that growth of "super volcano" magma chambers will be profoundly different than the construction and thermal histories of magma chambers that feed other volcanoes. We should be able to use this understanding to assess the potential for catastrophic eruption of huge volcanic complexes such as Yellowstone. The research is supporting the Ph.D. research of a student from the University of North Carolina, as well as the educational activities of other M.Sc. and undergraduate students at the University of North Carolina and the University of Utah. The project includes the development of new collaborative ties between Los Alamos National Laboratory, New Mexico Tech, University of North Carolina, and the University of Utah. The research is also an ongoing part of our support of the National Parks. It is contributing to our efforts to update the geology exhibits in Yosemite National Park, and play a role in Ranger training for the Park.

这项研究旨在检验以下假设：岩石记录了增量组装的地质学，热量规学和现场证据。尽管由理论考虑提出，但对支持增量增长的测量和现场数据（尤其是数百万到数百万年）还是有争议的。内华达山脉岩石中的岩石岩石岩石热量体的Hornblende，Biotite和Potassium-Feldspar氩气体学用于解决几个广泛的问题。首先，从铀铅锆石年龄推断出缓慢的增量岩体组装，而同一样品的氩气则为铀铅铅的可靠性提供了强大的测试。其次，如果将大型的“同质”岩体增量组装在一起，则在现场忽略了增量之间的接触，并且使用散装岩石磁化率的新映射被用于识别隐性触点。最后，对岩石和壁岩温度历史进行建模表明，冷却路径对增量pluton组件的速率和几何形状都敏感。因此，将基于锆石和钛铁矿铀铅系统以及角闪烁，生物岩和钾 - 菲尔德斯帕尔氩系统的冷却历史与建模的冷却历史进行了比较，以解决侵入性增量的空间排列及其添加的速度。这项研究是针对岩浆室的物理和化学演化，包括侵入机制，plut子织物的发展以及允许的岩浆分化过程。我们的建模熊在解释角蓝色阿尔贡（Argar）的解释中提出的岩石及其壁岩石的复杂热历史记录。接触变质的最高温度和持续时间；早期入侵的热，结构和岩石学演变成为后期入侵的壁岩石。从岩体收集的古磁数据的解释；岩体记录了大批量爆发的岩浆体的形成程度。这项研究的重点是岩浆室的组装速率，这些岩浆室在地面表面供电。它采用了各种约会技术，它们彼此相互检查和平衡，以了解如何建造岩浆物体以及它们的灾难性喷发潜力。增量组装假设预测，“超级火山”岩浆室的生长将与供应其他火山的岩浆腔室的结构和热历史有很大不同。我们应该能够利用这种理解来评估巨大的火山复合物（例如黄石）的灾难性喷发的潜力。该研究支持博士学位。来自北卡罗来纳大学的学生以及其他硕士学位的教育活动的研究以及北卡罗来纳大学和犹他大学的本科生。该项目包括在洛斯阿拉莫斯国家实验室，新墨西哥理工学院，北卡罗来纳大学和犹他大学之间建立新的合作关系。这项研究也是我们对国家公园的支持的持续部分。这有助于我们为更新优胜美地国家公园的地质展览的努力，并在公园的游侠训练中发挥作用。