浙江省花岗岩交代变质过程中一些矿物的作用(英文)

THE ROLE OF SOME MINERALS DURING GRANITE METASOMATISM IN ZHEJIANG PROVINCE,SOUTHEAST OF CHINA

对浙江省内花岗质岩石样品薄片在偏光显微镜下鉴定,试图建立矿物学与微构造之间的联系,确定裂隙分布矿物学控制因素,并调查微裂隙与交代变质蚀变之间的关系.薄片显示花岗质岩石主要由斜长石、钾长石、石英和云母组成.其中长石和云母解理发育,在结构上更易于变形,而石英则表现为均质特征,其中的裂隙比其他矿物(长石、云母)中更发育.这些解理和裂隙接纳流体进入并造成交代变质.在此过程中,黑云母被白云母交代而形成石英并释放出钾,这些钾进而交代斜长石而形成钾长石.值得关注的是,一些矿物颗粒边界显现出很少的变形,如钾长石-斜长石边界和石英-石英边界呈现较低程度的颗粒间碎裂,并变得可能比以前更坚硬,这是因为重结晶作用和交代作用胶结了以前的碎裂结构.最后,变形作用影响到整个岩石,为流体通过岩石打开通道,进一步的微裂隙对大规模钾交代变质作用的发生至关重要.研究区内花岗岩的矿物学及裂隙特征表明,交代作用可以作为可靠的构造标志,用以恢复浙江花岗岩现代和古裂隙的几何特征.

To study the effects of some minerals in coarse grained granite specimen during metasomatic process, firstly, we have observed fracture localization and propagation by using polarized light microscope that allows us to observe the association between microfracture types and mineralogical composition. The samples in this study were collected from granitic rocks in Zhejiang province, Southeast of China. Thin sections are made and examined with the aid of polarized light microscope. This research tries to make link between mineralogical composition and microstructures to determine the controls, if any, of minerals on fracture distribution; and to investigate the relationships between the microfractures and the metasomatic alteration. The results of thin section observations showed that feldspars, quartz and biotite are the main constituents of granites and we demonstrated that the mechanisms governing the metasomatic alteration of rock also lead to the development of alkali characteristic of the granite in the study area.