扬子-华夏接合带的韧性剪切与金的迁移富集关系

扬子与华夏地块间发育一条近东西向展布的巨型板块缝合带--华南中部复合混杂岩带,对其次级北东向剪切带(进贤-婺源韧性剪切带)进行的构造地球化学剖面研究发现:①剪切带中构造岩金元素含量总体上高于原岩中金元素含量,从剪切带边部至中心,从原岩带至糜棱岩化带、糜棱岩带,随剪切程度的逐渐增强,金元素含量逐渐增高;②金元素有2个峰值点,1个出现在韧性剪切最强的糜棱岩中,另1个出现在叠加于早期韧性剪切糜棱岩化岩石之上的晚期脆性破裂张性构造角砾岩中;③叠加在原岩(千枚岩、砾岩)上的晚期脆性破裂张性构造角砾岩金元素没有出现富集作用.说明韧性剪切及叠加在韧性剪切之上的脆性破裂均有利于金的富集成矿.

RELATIONSHIP BETWEEN DUCTILE SHEAR ZONE AND GOLD MIGRATION-ENRICHMENT IN THE SUTURE ZONE OF YANGZI AND CATHAYSIA BLOCKS

There exists a huge suture zone between Yangzi and Cathaysia blocks, namely the complex melange belt in the centre of south China, which is distributed near EW direction. By tectono - geochemical section research on its secondary NE - trending shear zone, it is found that the Jinxian -Wuyuan shear zone is closely related to gold migration and enrichment. Generally, the content of gold element in the shear zone is higher than that of un - deformed rocks, and increases gradually with simultaneously strengthening of ductile shear deformation from outside to inner of shear zone. There are two peaks of gold content. The one appears in the strongest part of mylanite in the ductile shear zone, and the other appears in extension structural breccia among brittle fracture which superposing on early mylonitized rocks. No enrichment of gold appears in extension structural breccia among brittle fracture which superposing on un - deformed rocks, like phyllite, conglomerate, etc. All these show that the ductile shear deformation and the extension structural breccia among brittle fracture are beneficial for enrichment and mineralization of gold.