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: 0818783
• 负责人: Michael Foote
• 金额: $ 13.48万
• 依托单位: University of Chicago
• 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=0818783&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：将为胡安德富卡海岭的主奋进油田（MEF）开发相分离和热液循环的二维和三维数值模型。这些模型将集成可用的喷口流体温度、盐度和热流数据，以及所有其他相关约束，例如岩浆透镜体几何形状和深度、喷出层厚度和喷口场面积。一个特定的目标是了解 MEF 温度和盐度从西南到东北梯度的原因。除了开发代表 1988 年至 1995 年间 MEF 行为的准稳态环流模型外，现有数据还将用于模拟系统对 1999 年岩浆事件的响应，以及自那时以来热液输出的下降。初步模拟表明，喷口温度、盐度和热量输出主要受地壳渗透率分布和底部边界条件控制，从而控制了深部两相区的温度和面积范围。该研究计划涉及三个相互关联的任务：（1）开发二维单通道模型，以匹配整个 MEF 的西南到东北温度和盐度梯度； (2) 开发涉及堤坝安置的二维模型，以了解对 1999 年事件的响应以及随后的系统衰退； (3) 开发 3-D 单通道单相和两相热液循环模型，其中包括 2A 层诱导循环的影响，并受到所有可用热流数据的约束。这些将是洋中脊热液系统的第一个相分离的 2 维和 3 维数值模型，也是受喷口温度、热液热输出和喷口盐度的时间序列数据约束的特定喷口场的第一个数值模型。这些也将是堤坝附近 NaCl-H2O 流体的相分离和热液循环的第一个完全数值模型。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，该模型的结果将为海底热液系统中的相分离过程提供重要的见解，并为脊轴的渗透性结构提供约束。这些结果将有助于确定热液热量输出的衰减是由岩浆结晶和深度冷却控制还是由地壳渗透性演化控制。更广泛的影响：虽然这些模型特定于 MEF，但结果将增进对大洋中脊相分离和热液循环的理解，这是一个广泛的跨学科研究领域。 3D 两相代码 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可供一般使用时放在 PI 的个人网站上。这项研究将在跨学科研究的重要领域培训一名新研究生女学生，并训练学生使用数字代码。该研究还将促进年轻女性研究人员的科学发展。这项研究的结果将被纳入大学流体过程课程中。