Modes of Extension, Magmatism and Crustal Scale Fluid Pathways in the Great Basin province, USA, from a Magnetotelluric Transect

美国大盆地省的伸展模式、岩浆作用和地壳流体通道（来自大地电磁断面）

• 批准号: 0838043
• 负责人: Philip Wannamaker
• 金额: $ 38.26万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838043&HistoricalAwards=false
• 关键词: Modes; Extension; Magmatism; Crustal; Scale

Phil Wannamaker from the University of Utah is producing and interpreting a high-quality section view of electrical resistivity structure through the central and western Great Basin, and the southeastern Modoc Plateau. This is being achieved by the addition of 55 wideband magnetotelluric soundings to an existing transect of 179 sites, plus installation of 35 long-period magnetotelluric soundings, to create a transect some 650 km in length span-ning Nevada and northeastern California into westernmost Utah. The magnetotelluric station data will span the range of 0.005 to 10,000 second wave periods, with corresponding imag-ing depths from a few hundred meters to about 300 km, and perhaps greater. The profiling covers fully 100 kilometers of the Modoc Plateau, the actively extending northwestern Great Basin, the Central Nevada Seismic Belt, the relatively quiescent east-central Great Basin of higher elevation, and onlaps the active eastern Great Basin of western Utah. These data are undergoing modern methods of processing, trend analysis, and regularized inversion to pro-duce a well-resolved model with minimal artifacts. The overall goal of the project is to im-prove our understanding of the process of distributed continental rifting. The consequences of rifting can be profound, including the potential for large earthquakes, development of sedimentary basins and, ultimately, breakup of continents to form new ocean basins. Many important hydrocarbon, geothermal and mineral resource occurrences can arise from the structural, magmatic and hydrothermal processes involved in extension. The project specifi-cally is addressing first-order problems regarding vertical strain distribution, magmatic crustal growth, domains of crustal scale fluid flow, and coupling between the lithosphere and asthenosphere remain unsolved. These include the prevalence of crustal scale fault zones which host the largest earthquakes; under what circumstances upper and lower-crustal thin-ning are decoupled; where mantle lithosphere is weak or strong during rifting; whether volumetrically significant magmatic input occurs during the early to middle stages of conti-nental rifting; and how mantle-sourced fluids make their way to the shallow ground water regime. The project also addresses societal benefits including broader understanding of the controls on fault strength, crustal scale hydrology, and the ability to build up damaging stresses. The link between deep geothermal systems and epithermal gold deposits is being illuminated as well. A graduate student is being supported for education into state of the art geophysical instrumentation, parameters of field survey design, practical logistical matters in remote settings, modern methods of inversion, and the relationship between electrical resis-tivity and physico-chemical state in the Earth. Linked companion projects have the potential to provide the first results approaching regional to national scales, and public interest is ex-pected in section views through diverse regions provided by a potential megatransect from near the California Pacific coast to the Colorado Plateau interior at Utah?s eastern border. In addition to the research, the project is supporting the graduate training of a Ph.D. student from an underrepresented group in the earth sciences in magnetotelluric methods. Funding for the research is being provided by the NSF Geophysics and Tectonics programs.

犹他大学的Phil Wannamaker通过中央和西部大盆地以及东南莫多克高原生产和解释电阻率结构的高质量部分。这是通过在现有179个地点的现有样带中添加了55个宽带磁电磁性声音以及安装35个长期磁性磁性磁性声音，以创建占地约650 km的内华达州和东北加州的横断面。磁铁站数据将跨越0.005到10,000次波周期，相应的想象深度从几百米到约300 km，也许更大。该谱分别覆盖了Modoc高原的完全100公里，积极地延伸了西北大盆地，内华达州中部地震带，相对静止的较高海拔的东部大盆地，并占据了犹他州西部的活跃东部大盆地。这些数据正在采用现代的处理，趋势分析和正规化方法，以促进具有最小伪像的精确模型。该项目的总体目的是使我们对分布式大陆裂变过程的理解。裂谷的后果可能是深远的，包括大地震的潜力，沉积盆地的发展以及最终形成新海盆的大陆的破裂。许多重要的碳氢化合物，地热和矿物资源的出现可能来自涉及延伸的结构，岩浆和热液过程。该项目特定于解决有关垂直应变分布，岩浆地壳生长，地壳尺度流体流量的结构域以及岩石圈和运动层之间的耦合的一阶问题。其中包括地震最大地震的地壳尺度断层区的普遍性；在哪些情况下，上下薄膜薄膜被解耦；地幔岩石圈在裂谷过程中是弱或坚固的地方；岩浆输入是否在续裂裂谷的早期至中期发生；以及地幔采购的液体如何进入浅底水状态。该项目还解决了社会福利，包括对故障强度，地壳量表水文学的控制以及建立破坏压力的能力的更广泛理解。深度地热系统与表皮金沉积物之间的联系也被照亮了。一名研究生得到了教育，以教育最先进的地球物理仪器，现场调查设计的参数，远程环境中的实践后勤事务，现代反演方法以及地球上的电恢复性与物理化学状态之间的关系。链接的伴侣项目有可能提供第一个接近国家范围的地区的结果，并且通过潜在的大型坦率从加利福尼亚太平洋海岸到犹他州的科罗拉多高原内政的各种地区提供的各个区域，公共利益是通过各种区域提供的。除研究外，该项目还支持博士学位的研究生培训。来自磁铁学方法中地球科学中代表性不足的群体的学生。 NSF地球物理学和构造计划提供了研究的资金。