含熔体差应力状态下中下地壳岩石的变形结构与物质迁移

The Deformation Structure and Component Migration of Middle-Lower Crustal Rocks in Differential Stresses State with Melt

通过对辉长岩、麻粒岩、斜长角闪岩高温高压变形实验样品的研究,确立了含熔体差应力状态下中下地壳岩石共轭扇式变形模型的合理性,划分出垂直于轴向压应力定向和剪切定向两种变形组构。并通过对主要变形矿物、变形组构的识别,详细勾画了辉长岩、麻粒岩、斜长角闪岩3种典型中下地壳岩石的变形结构图式和变形机制。辉长岩为弥散带状变形结构,麻粒岩、斜长角闪岩为共轭扇式模型结构;中下地壳岩石的变形可能主要集中在流变性最强的一种或者几种组分上;变形集中化的过程,也往往是某些组分集中化的过程;变形不仅是造成岩石圈深部层次物化环境不均一性的重要因素,也是成矿的重要条件。

Through particular thin section observation and stress strain analysis on gabbro, granulite and plagioclase amphibolite samples studied by high temperature and high pressure deformation experiment, a conjugate fan structure model, which was proved reasonable, was set up. Two kinds of orientational fabrics, one being compressional stretching orientation, the other shearing orientation, were distinguished out of at the same time. With identification of the major deformation minerals and deformation fabrics, the deformation structure and deformation mechanism of three typical rocks, gabbro, granulite and plagioclase amphibolite from middle-lower crust level were described particularly, such as the dispersing band structure of gabbro sample and conjugate fan structure of granulite and plagioclase amphibolite samples. Conclusions of the paper include： （1）In the middle-lower crust, the deformation of lithosphere is mainly concentrated on one or several components which can flow most easily. （2）With the concentration of deformation, certain component can also concentrates. （3）Deformation is not only the important factor to control the physical or chemical condition of deep inhomogenous lithosphere, but also the important controls to form deposit.