摘要
白银地区的细碧—石英角斑岩系,形成于岛弧或弧后盆地的板块构造环境。该构造环境具有形成拉斑玄武质岩浆的条件和存在钠质源区。细碧—石英角斑岩系的钠交代,发生在岩浆房上部,岩浆上升过程和海底环境。因而,该区细碧—石英角斑岩系既具有类似原生岩浆的结构特点,亦有很明显的碱质交代作用特征。其成因应归属次生交代成因。
The spilite-quartz keratophyre series in Baiyin district was formed on island arc or in back-arc basin related to convergence plate tectonics that gave birth to the tholeiitic magma and provided the source of sodium for promoting Na-metaso-mation.The latter process holding in spilite-quartz keratophyre started while it was in the magma chamber and continued in its ascension and spreading over the sea floor. Thus, both textures of primary magmatic rocks and alkali metasomatism might be discovered in the spilite-quartz keratophyre rocks though its origin should be attributed to metasomatism.
关键词
白银地区
岩石
成因
石英斑岩
alkali metasomatism, spilite-quartz keratophyre series, Baiyin district
