Integrated Geochemical Analysis and Numerical Modeling of Hydrothermal Processes in the Alta Contact Aureole

[903274bowman]该项目将使用综合的地质、岩石学、地球化学和数值模拟方法，研究与犹他州阿尔塔的阿尔塔斯托克热光圈接触变质作用相关的流体流动、热量/质量传递、矿物反应和流体-岩石相互作用的基本过程。本研究的目的是：1)利用成熟的地球化学（氧、碳、锶同位素、硼浓度）和岩石学示踪剂，绘制上光环区大理岩流体通量和变质温度的空间格局；2)建立改进的能量/质量输运和流体-岩石反应的数值模型，该模型考虑了流体生产（侵入岩和围岩）、矿物反应、围岩渗透性的瞬态变化和可变的火成岩接触几何形状的影响。这些数值模型将模拟变质温度和地球化学蚀变的映射模式，以提供定量约束：1)光晕中流体流动的几何形状、通量和时间尺度；2)产生观测到的流体通量模式的渗透率和渗透率分布；反应动力学和交换动力学对流体-岩石相互作用过程的影响。特别是，我们将研究流体生产、渗透率瞬态变化和火成岩接触几何对该接触变质热液系统流动模式和流体通量的影响。计算机代码的开发和本研究中产生的新见解也将适用于其他类型的地壳热液系统中的流体流动和流体-岩石相互作用过程。

9903274BowmanThis project will investigate, using an integrated geological,petrological, geochemical, and numerical modeling approach, fundamentalprocesses of fluid flow, heat/mass transport, mineral reaction, andfluid-rock interaction associated with contact metamorphism in the AltaStock thermal aureole, Alta, Utah. The objectives of the study are to: 1)map the spatial patterns of fluid flux and metamorphic temperatures in themarbles of the Alta Aureole using well-established geochemical (oxygen,carbon, strontium isotopes, boron concentrations) and petrologic tracers;and 2) develop improved numerical models of energy/mass transport andfluid-rock reaction which incorporate the effects of fluid production (inboth intrusion and wallrocks), mineral reaction, transient changes inpermeability of the wallrocks, and variable igneous contact geometry. Themapped patterns of metamorphic temperatures and geochemical alteration willbe simulated with these numerical models to place quantitative constraintson: 1) the geometry, flux, and timescale of fluid flow in the aureole; 2)the permeabilities and permeability distributions that produce the observedpatterns of fluid flux; and 3) the impacts of reaction and exchangekinetics on processes of fluid-rock interaction. In particular, we willinvestigate the impacts from fluid production, transient changes inpermeability, and from igneous contact geometry on flow patterns and fluidfluxes in this contact metamorphic hydrothermal system. The computer codesdeveloped, and the new insights generated in this study of the Alta aureolewill also be applicable to fluid flow and processes of fluid-rockinteraction in other types of crustal hydrothermal systems.