试论阜平杂岩的深熔作用

阜平杂岩中广泛产出浅色脉体,从而显示强烈的混合岩化作用。前人把引起混合岩化作用的机制归因于岩汁交代、重熔或无水深熔作用,似乎与实际的岩相结构不是很一致。矿物自形晶、钠长石净边结构和一些典型的矿物转化反应表明,阜平杂岩的混合岩化作用实际上经历了复杂的过程,主要表现为有水条件下的深熔作用。所形成的熔体有较大的流动性,可迁移一定的距离而进入邻近的岩石,对这些部位而言相当于发生了外来熔体的注入活动,造成熔体注入式混合岩化作用,形成一些交代反应和结构。因此,阜平杂岩混合岩化作用中的变质反应过程既包括长英质矿物的熔融(溶解),还涉及一种含水矿物(如黑云母)转化形成另外一种含水矿物(如角闪石)的化学反应。阜平杂岩的混合岩化作用最重要的机制是水致熔融或含水深熔作用,溶解性重熔或无水深熔作用则较为次要。

On Anatexis of the Fuping Complex in North China Craton

Leucocratic veins are widely distributed in the Fuping Complex, North China Craton, which demonstrates the intensive migmatization. The migmatization was generally ascribed to ichor metasomatism, pressure solution or fluid-absent partial melting, which are not consistent with the actual petrographic textures. Euhedral crystals of some minerals, albite-rim texture and typical transformation between hydrous minerals suggest that the migmatization has in fact experienced a complicated process which is characterized by water fluxed partial melting. The resultant melt was relatively mobile and can easily migrate into adjacent rocks. This is equivalent to injection of foreign melt into the rocks and resulted in melt-injection migmatization, causing some metasomatism reactions and textures. Therefore, metamorphic reaction of the Fuping Complex, resulting from migmatization, may include both melting or dissolution of feldspathic minerals and chemical transformation of one hydrous mineral (e.g., biotite) to another one (e.g., hornblende). The most crucial mechanism of migmatization of the Complex was dominated by water-fluxed melting or fluid-bearing partial melting, with pressure solution or fluid-absent anatexis as secondary factor.