Collaborative Research: Numerical Modeling of the Main Endeavour Vent Field, Juan de Fuca Ridge

合作研究：胡安德富卡山脊主奋进喷口场的数值模拟

• 批准号: 0819084
• 负责人: Robert Lowell
• 金额: $ 16.55万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-11-01 至 2012-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0819084&HistoricalAwards=false
• 关键词: Collaborative; Research; Numerical; Modeling; Main

Intellectual Merit: Two- and three-dimensional numerical models of phase separation and hydrothermal circulation will be developed for the Main Endeavour Field (MEF) on the Juan de Fuca Ridge. The models will integrate available vent fluid temperature, salinity, and heat flow data, along with all other relevant constraints, such as magma lens geometry and depth, extrusive layer thickness, and vent field area. A particular goal is to understand the reason for the southwest to northeast gradients in temperature and salinity across the MEF. In addition to developing a quasi-steady state circulation model that represents the behavior of the MEF between 1988 and 1995, the available data will be used to model the response of the system to the magmatic event of 1999, and what appears to be the decline in hydrothermal heat output since that time. Preliminary modeling shows that vent temperature, salinity and heat output are controlled primarily by crustal permeability distribution and the bottom boundary conditions, which control the temperature and areal extent of the two-phase zone at depth. The research program involves three inter-related tasks: (1) the development of 2-D single-pass models in order to match southwest to northeast temperature and salinity gradients across the MEF; (2) the development of 2-D models involving dike emplacement to understand the response to the 1999 event and the subsequent system decline; (3) the development of 3-D single pass single phase and two-phase models of hydrothermal circulation that includes the effect of induced circulation in layer 2A, constrained by all available heat flow data. These will be the first 2- and 3-D numerical models of phase separation for a mid-ocean ridge hydrothermal system and the first numerical models for a particular vent field that are constrained by time series data of vent temperature, hydrothermal heat output, and vent salinity. These will also be the first fully numerical models of phase separation and hydrothermal circulation of a NaCl-H2O fluid near a dike. Finally, the results will provide important insights into how a major hydrothermal system decays in time. The results of this modeling will thus provide important insights into the process of phase separation in seafloor hydrothermal systems and provide constraints on the permeability structure of the ridge axis. The results will help determine whether the decay of hydrothermal heat output is controlled by magmatic crystallization and cooling at depth or by the evolution of crustal permeability.Broader Impacts: Although these models will be specific to the MEF, the results will lead to increased understanding of phase separation and hydrothermal circulation at mid-ocean ridges, which is a broad field of interdisciplinary study. The development of the 3D two-phase code FISHES will become an important community tool for hydrothermal modeling. The 2-D and 3-D versions of FISHES, and a user's manual, will be placed on the PIs' personal websites when they are available for general use. This research will train a new graduate female student in an important area of interdisciplinary research and train the student in the use of numerical codes. The research will also advance the scientific development of a young female researcher. The results of this research will be incorporated into courses on fluid processes taught at the university level.

智力优势：将为Juan de Fuca海岭的Main Endeavour Field（MEF）开发相分离和热液循环的二维和三维数值模型。这些模型将整合现有的喷口流体温度、盐度和热流数据，沿着所有其他相关的约束条件，如岩浆透镜几何形状和深度、喷出层厚度和喷口区域。一个特别的目标是了解整个MEF的温度和盐度从西南到东北梯度的原因。除了开发一个准稳态环流模型，代表的MEF的行为在1988年和1995年之间，可用的数据将被用来模拟系统的反应，1999年的岩浆事件，以及什么似乎是热液热输出的下降，因为那个时候。初步模拟表明，喷口温度，盐度和热量输出主要由地壳渗透率分布和底部边界条件，控制温度和面积范围的两个阶段区的深度控制。该研究计划包括三个相互关联的任务：（1）开发二维单程模型，以匹配西南到东北的温度和盐度梯度跨越MEF;（2）开发二维模型，包括堤防定位，以了解对1999年事件的响应和随后的系统衰退;（3）在现有热流资料的约束下，建立了考虑2A层诱导环流影响的三维单相和两相热液环流模型。这将是第一个洋中脊热液系统相分离的二维和三维数值模型，也是第一个受喷口温度、热液热量输出和喷口盐度时间序列数据约束的特定喷口场数值模型。这也将是第一个完全数值模型的相分离和热液循环的NaCl-H2O流体附近的堤坝。最后，研究结果将为了解主要热液系统如何随时间衰减提供重要见解。因此，这一建模的结果将提供重要的见解，在海底热液系统的相分离过程中，并提供脊轴的渗透性结构的限制。结果将有助于确定热液热输出的衰减是否是由岩浆结晶和冷却的深度或地壳permeability.Broader的影响的演变控制：虽然这些模型将是特定的MEF，结果将导致增加相分离和热液循环的理解在大洋中脊，这是一个广泛的跨学科研究领域。三维两阶段代码FISHES的开发将成为热液建模的重要社区工具。FISHES的2-D和3-D版本以及用户手册将在PI的个人网站上发布，供一般使用。这项研究将在跨学科研究的一个重要领域培训一名新的女研究生，并培训学生使用数字代码。这项研究还将促进一名年轻女性研究人员的科学发展。这项研究的结果将纳入大学一级讲授的流体过程课程。