Magmatic to Solid-State Fabric Transition in a Post-Tectonic Tonalite Pluton

约翰森0087661岩浆房是大洋和大陆岩石圈结构的重要组成部分，对地壳和地幔的热行为和力学行为产生了深远的影响。岩浆室的力学性质在冷却和结晶过程中发生变化，因为对变形的适应从岩浆流动转变为固态过程。因此，要了解岩浆房的热-机械演化，关键是要了解岩浆和固态流动的相对重要性，以及它们之间过渡的性质。该项目正在研究保存在墨西哥下加利福尼亚州圣何塞岩体中的这种过渡。该岩体晚于区域变形，因此从岩浆向固态流动的转变反映了内部岩浆室的动力学。这种转变在后构造深成岩中很少观察到，我们的结果将使其他正在研究更复杂的同构造实例的人受益。沿着岩体的四个断面，正在进行空间定向样本的详细测绘和收集。利用X射线成分填图、显微结构分析和电子背散射衍射研究，追踪变形结晶岩体的化学演化，评价岩浆面理的变形机制和成因。该项目正在支持一名博士生，缅因州大学的几名大四本科生将参与其中，作为他们Capstone体验的一部分。

Johnson0087661Magma chambers are an essential component in the construction of oceanic and continental lithosphere, and profoundly influence the thermal and mechanical behavior of the crust and mantle. The mechanical properties of a magma chamber change during cooling and crystallization, as accommodation of deformation changes from magmatic flow to solid-state processes. Thus, to understand the thermo-mechanical evolution of magma chambers, it is crucial to understand the relative importance of magmatic and solid-state flow, and the nature of the transition between them. This project is investigating such a transition preserved in the San Jose pluton, Baja California, Mexico. The pluton postdates the regional deformation, and so the transition from magmatic to solid-state flow reflects internal magma-chamber dynamics. Such transitions are rarely observed in post-tectonic plutons, and our results will benefit others who are working in more complex syntectonic examples. Detailed mapping and collection of spatially oriented samples is taking place along four transects in the pluton. X-ray compositional mapping, microstructural analysis and electron backscatter diffraction studies are being employed to track the chemical evolution of the deforming and crystallizing pluton, and to evaluate deformation mechanisms and the origins of the magmatic foliations. The project is supporting a PhD student, and several senior undergraduates at the University of Maine will participate as part of their Capstone Experience.