Petrology of tremolite rocks in the high-pressure metamorphic terranes

加利福尼亚的Franciscan杂岩和日本的Kamuikotan变质带与较深的高级变质岩蛇纹岩混杂岩伴生，而日本三百川变质带的蛇纹岩含量较少，不伴生任何蛇纹岩混杂岩。前者可能是在张应力体制下形成的，后者可能是在挤压应力体制下形成的。蛇纹岩仅产于三巴加瓦带高品位泥质片岩中，表明蛇纹岩在开始吸积时已从楔形地幔供给俯冲板块顶部的远洋沉积物。桑巴加瓦带和马里亚纳弧前查莫罗海山蛇纹岩附近的透闪石岩和多硅白云母绿泥石片可能表明沿楔形地幔蛇纹岩和远洋沉积物之间的边界发生了广泛的交代作用。进一步研究这些交代岩石的力学和物理化学行为，对于了解洋陆板块俯冲边界上的现象具有重要意义。

The Franciscan Complex, California, and the Kamuikotan metamorphic belt, Japan, are accompanied by serpentinite melange with deeper high-grade metamorphic rocks, whereas the Sanbagawa metamorphic belt, Japan, contains less amounts of serpentinite and is not accompanied by any serpentinite melange. The former were probably formed under a tensional stress regime, and the latter under a compressional one. The restricted occurrence of serpentinite to the high-grade pelitic schist in the Sanbagawa belt suggests that the serpentinites had been supplied from wedge mantle into pelagic sediments on the top of subducting plate at the initiation of accretion. Tremolite rocks and phengite-chlorite schists near serpentinite in the Sanbagawa belt and from Chamorro Seamount, Mariana forearc, may suggest the widespread metasomatism along the boundary between wedge mantle serpentinite and pelagic sediments. Further research on the mechanical and physico-chemical behaviors of these metasomatic rocks are important to understand the phenomena along the subduction boundary between oceanic and land-ward plates.