Geology-geochemistry, metamorphism and deformatiom of albitites and their bearings on copper mineralization: an example from the Lala copper deposit in Huili, Sichuan

The detailed studies have been conducted on the geology-geochemistry,metamorphism and deformation of albitites and their bearings on the mineralization of the Lala copper deposit in Huili,Sichuan.The NWW-trending (nearly E-W-trending) shear deformation caused by the Precambrian tectonic movements in the Lala district is believed to be responsible for the generation of cataclasis and mylonitization of the albitites in this area,and for the formation of such textures and structures as cataclastic texture,mortar structure,micro-augen structure,pressure shadow and fish-shaped mica,which brought about the increase in porosity.The ore-bearing fluids from the diabase and gabbro masses emplaced along the nearly E-W-trending major fault and metamorphic hydrothermal solutions originated from regional metamorphism infilled and replaced the fissures and pore spaces within the cataclastic-mylonitic structures.The subsequent alterations resulted in the precipitation and mineralization of copper,molybdenum and cobalt sulfides,and in the formation of the albitite-type impregnated or vein-netvein copper ores.In the places where the phlogopitazation occurred,the schist-type copper ores were formed by metamorphism.It follows that the Lala copper depoist is of dynamic metamorphic-hydrothermal origin.