ALVIN Diving in the Intra-Transform Spreading Centers of the Siqueiros Transform

该项目将重点研究Siqueiros变换断层的转换内扩张中心的岩石学和地球化学特征，通过Alvin野外填图确定转换域的构造历史，从每个断层陡坎的围岩中恢复的变形岩石的构造研究，以及对过去4 Ma来影响Siqueiros变形发展的构造作用的认识。在变形过程中将有18次阿尔文潜水，以及一个夜间岩石取心和疏浚计划，该计划将提供沿扩张轴和沿着走滑断层的不同地点的额外样本。SeaBeam将在夜间使用，为每个扩展轴绘制详细的10米等高线地图。需要解决的问题包括：哪些进程负责启动变换内传播？当一个新的扩散中心开始时，熔岩类型的演化序列是什么？地幔中与改造有关的主要成分不连续的性质是什么？地幔中化学不均质性的规模有多大？独特的岩浆类型是否沿着转换断层产生？

This program will focus on a petrological and geochemical characterization of the intra-transform spreading centers in the Siqueiros transform fault, on determining the structural histroy along the transform domain through ALVIN field mapping, structural studies of deformed rocks recovered from the walls of each fault scarp, and on understanding the tectonci processess that have influenced the development of the Siqueiros tranform for the past 4 Ma. There will be eighteen ALVIN dives in the transfrom and a night-time program of rock coring and dredging that will provide additional samples from along the spreading axis and at various sites along the strike- slip faults. SeaBeam will be used at night to produce detailed 10 m contour maps of each spreading axis. Questions to be addressed include: What processes are responsible for initiating intra-transform spreading? What is the evolutionary sequence of lava types erupted when a new spreading center start? What is the nature of major transform-affiliated compositional discontinuities in the mantle? What is the scale of chemical heterogeneity in the mantle? Are unique magma types generated along transform faults?