Clastic Dikes as Conduits for Episodic Fluid Flow in the Upper Crust

碎屑岩脉作为上地壳中间歇性流体流动的管道

• 批准号: 9304581
• 负责人: James Boles
• 金额: $ 15.78万
• 依托单位: University of California-Santa Barbara
• 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: 1993-09-15 至 1996-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9304581&HistoricalAwards=false
• 关键词: Clastic; Dikes; Conduits; Episodic; Fluid

9304581 Boles The proposed study seeks to identify and quantify processes by which clastic dikes serve as conduits for episodic and rapid fluid flow in the upper crust. This study will investigate transport mechanisms for breccia components in clastic dikes in silicious shales of the Miocene Monterey Formation, coastal California, and in Paleozoic limestones both in Titus Canyon, Death Valley, and in the Shell Creek Range, NE Nevada. Minimum velocities of fluid flow will be calculated using relations among flow velocity, clast size, viscosity, and fluid and clast densities in fluidized beds. These parameters will be estimated based on field and thin section investigators, fluid inclusion studies, and published density values of similar rock types. Episodic fluid flow through the dike can be inferred if the calculated flow velocity through the dike is much faster than seepage by darcian flow. In addition, mechanism leading to fragmentation of wall rock and breccia components in clastic dikes will be investigated. Identification of the latter process would allow estimated on the magnitude and rate of drops in pore pressure. Rapid drops are considered as characteristic for clastic dikes serving as conduits for large scale, episodic fluid flow. Stable isotope and trace element measurements across crack seal veins associated with clastic dikes will determine if the dikes were chemically closed or open systems. Strontium isotope analyses of wall rock and vein filling minerals will indicate if vein cementation occurred in a closed or open system. The proposed investigations will increase the present understanding of fluid flow mechanisms within the upper crust. Findings of this study may influence research in applied fields such as transport of contaminants and heat in fractured rocks of earthquake hazard analysis. ***

小行星9304581 拟议的研究旨在确定和量化的过程中，碎屑岩脉作为管道的幕式和快速的流体流动在上地壳。 本研究将探讨角砾岩成分的输送机制，在硅质页岩中的中新世蒙特利组，沿海加州，并在古生代石灰岩都在提图斯峡谷，死亡谷，并在壳牌溪山脉，东北内华达州的碎屑岩脉。 流体流动的最小速度将使用流化床中的流速、碎屑尺寸、粘度以及流体和碎屑密度之间的关系来计算。 这些参数将根据现场和薄片调查、流体包裹体研究和类似岩石类型的已公布密度值进行估算。 如果计算出的流经堤坝的流速比达西流的渗流快得多，则可以推断出流经堤坝的间歇性流体流动。 此外，还将研究碎屑岩脉中导致围岩和角砾岩组分破碎的机制。 后一个过程的识别将允许估计孔隙压力下降的幅度和速率。 快速下降被认为是碎屑岩脉作为大规模、幕式流体流动的管道的特征。 通过对与碎屑岩脉有关的裂缝封闭脉的稳定同位素和微量元素测量，将确定岩脉是化学封闭的还是开放的系统。 围岩和脉状充填矿物的锶同位素分析将指示脉状胶结作用发生在封闭或开放系统中。 拟议的调查将增加目前对上地壳内流体流动机制的了解。 这项研究的结果可能会影响在应用领域的研究，如污染物和热在地震危险性分析的裂缝岩石中的传输。 ***