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

智力优势：将为胡安德·富卡山脊上的主奋进领域(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，以及所有其他相关约束，如岩浆透镜的几何形状和深度、挤出层厚度和喷口区域面积。一个特别的目标是了解MEF从西南到东北温度和盐度梯度的原因。除了开发一个准稳态环流模型来描述1988年至1995年间MEF的行为外，现有的数据将被用来模拟该系统对1999年岩浆事件的响应，以及自那以来似乎热液输出的下降。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边界条件的控制，而底边界条件控制着深部两相带的温度和面积范围。该研究计划涉及三项相互关联的任务：(1)发展2-D单程模式，以便匹配MEF西南向东北方向的温度和盐度梯度；(2)发展包括堤坝就位的2-D模式，以了解对1999年事件和随后的系统衰退的响应；(3)发展3-D单程热液循环的单相和两相模式，其中包括在所有可用热流数据的约束下，在2A层中诱导环流的影响。这将是第一个大洋中脊热液系统相分离的2-D和3-D数值模型，以及第一个受喷口温度、水热输出和喷口盐度时间序列数据约束的特定喷口领域的数值模型。这也将是第一个关于堤坝附近氯化钠-水流体相分离和水热循环的全数值模型。最后，这些结果将为主要热液系统如何及时衰变提供重要的见解。因此，这一模拟的结果将对海底热液系统的相分离过程提供重要的见解，并对脊轴的渗透性结构提供约束。这些结果将有助于确定热液输出的衰减是由深部的岩浆结晶和冷却控制的，还是由地壳渗透性的演化控制的。广泛的影响：尽管这些模型将针对MEF，但结果将有助于加深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。三维两相程序FISH的开发将成为热液模拟的重要工具。FISH的2-D和3-D版本以及用户手册将在PIS的个人网站上发布，当它们可供普遍使用时。这项研究将在跨学科研究的重要领域培养一名新的女研究生，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员的科学发展。这项研究的结果将被纳入大学一级教授的流体过程课程。

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.