Deep-crustal Reactive Fluid Flow in the Mesozoic White-Inyo Magmatic Arc, California

水，除了在地球上明显存在之外？S表面，也是深层大陆地壳的一个组成部分。在地壳中，水在结构上被束缚在矿物中，存在于岩石的孔隙空间中，甚至在地球表面以下许多公里处。在板块俯冲和大陆碰撞等构造事件中，水在变质反应中从矿物中释放出来，与孔隙水一起可以作为热传递的介质，并可以促进正在变形的岩石的弱化。在这个项目中，首席研究员和学生们将研究发生在加利福尼亚东部白英约山脉中生代的流体流动。在这一时期，白英约山脉深埋在北美地壳的西部边缘，经历了变质作用、岩浆作用和火山作用，因为海洋法拉龙构造板块俯冲到大陆之下。地质证据表明，深部流体通过增强花岗岩岩体的寄主岩石的变形，促进了花岗岩岩体的侵位，并对范围内地壳的热液蚀变负责。PI和学生将通过分析收集岩石中保存的变质矿物之间的热力学平衡关系，通过分析碳酸盐矿物中碳氧比的流体诱导变化以及计算机模拟来研究中生代热液系统。预计影响流体流动几何形状和潜在对流热输运的关键因素是白英约范围内岩石渗透率的变化。该项目的预期结果将是更好地了解地壳深部流体对大陆边缘地质发展的影响。白因约山脉是大陆岩浆弧的一个极好的例子。弧内岩浆活动发生在180 ~ 165 Ma和102 ~ 83 Ma两个时期，与内华达山脉岩浆活动在时间上重叠。先前的构造和变质学研究已经确定，这些岩体侵入了一个包含绿片岩相页岩、灰岩、钙质泥质岩和砂岩的区域背斜。岩体的侵入形成了非均质水动力系统，流体的非均质流动源于岩石的不同渗透率和片理性。在该项目中，将使用矿物平衡、变质反应和碳酸盐矿物中的C和O同位素比率来确定哪些岩石经历了同变质流体流动。该项目的岩石学和地球化学部分将成为岩浆弧内接触光圈和区域尺度上反应性流体流动的计算机模拟的基础。计算机模拟将流体流动与热传递和变质反应相结合，并将包括熔体结晶潜热、变质反应热以及由反应和钚产生的流体的规定。该项目将对了解岩浆弧内的传导和对流热传递以及流体在促进大陆地壳深部岩石变形和再结晶方面的作用产生影响。

Water, besides being obviously present on the Earth?s surface, is also an integral part of the deep continental crust. In the crust, water is bound-up structurally in minerals and occurs in pore spaces of rocks, even many kilometers below the Earth's surface. During tectonic events, such as plate subductions and continental collisions, water is released from minerals during metamorphic reactions, and together with pore water can serve as a medium for heat transport and can promote weakening of rocks that are undergoing deformation. In this project, the Principal Investigator and students will study fluid flow that has occurred during the Mesozoic era in the White-Inyo Range of eastern California. During this era, the White-Inyo Range was buried deep within the western margin of North American crust that was experiencing metamorphism, magmatism, and volcanism as the oceanic Farallon tectonic plate was subducting beneath the continent. Geologic evidence in the range suggests that deep-crustal fluids promoted the emplacement of granitic plutons, by enhancing deformation of their host rocks, and were responsible for hydrothermal alteration of the crust within the range. The PI and students will study the Mesozoic hydrothermal system by analyzing the thermodynamic equilibrium relationships among preserved metamorphic minerals in collected rocks, by analyzing fluid-induced shifts in the ratios of carbon and oxygen in carbonate minerals, and by computer simulations. It is expected that the key factor that influenced the geometry of fluid flow and potential advective heat transport was variable permeability of rocks within the White-Inyo range. The expected outcome of the project will be a better understanding of the influence that deep-crustal fluids have on the geologic development of continental margins.The White-Inyo Range is an excellent example of an exhumed continental magmatic arc. Magmatism in the arc occurred during two time periods, 180-165 Ma and 102-83 Ma ago, and it overlapped in time with magmatism in the Sierra Nevada Range. Previous structural and metamorphic studies have established that the plutons intruded a regional anticline that contains greenschist-facies shales, limestones, calcareous argillites, and sandstones. Intrusion of the plutons generated heterogeneous hydrodynamic systems, with heterogeneous fluid flow stemming from variable permeabilities and foliations of the rocks. In the project, mineral equilibria, metamorphic reactions, and C and O isotope ratios in carbonate minerals will be used to determine which rocks experienced syn-metamorphic fluid flow. These petrologic and geochemical portions of the project will be the foundation for computer simulations of reactive fluid flow, on both contact-aureole and regional scales, within the magmatic arc. The computer simulations will couple fluid flow with heat transport and metamorphic reactions, and they will include provisions for latent heat of crystallization of melts, heats of metamorphic reactions, and for fluids generated by the reactions and plutons. The project will have an impact on understanding conductive and advective heat transport within magmatic arcs and on the role that fluids have on promoting deformation and recrystallization of rocks in the deep continental crust.