海南二甲多因复成金矿床时序分析与成矿模式研究

ANALYSES BY TIME SERIES AND METALLOGENIC MODEL OF THE POLYGENETIC COMPOUND GOLD DEPOSITS OF THE ERJIA DISTRICT,HAINAN ISLAND

The Erjia gold ore field in western Hainan island,southern China is composed of three types of the gold deposis: the altered mylonite type, the altered cataclasite type and polymetal quartz vein type. They were hosted by the migmatized metamorphic rocks of the Mid-Proterozoic Baoban Group, and controlled by northeast-trending Gezhen ductile shear zone and lateral ductile-brittle and brittle faults.Mineralization of the ore field had experienced long term and complex geological evolutionary processes. These processes consist of the formation of the source bed, the preliminary enrichment of the metamorphic-migmatized hydrothermal solution, the reworking and re-enrichment of the ductile shearing, and the superimposing of the magmatic hydrothermal solution with a small amount of meteroic waters. The time series of these ore-formig events closely related to geological structural evolution in the region.Based on available geological and isotopic dating data. the time series of these ore-forming events can roughly be defined to have occurred in the wuling epoch (1800-1400 Ma), Jinning epoch (1400-1000 Ma), Caledonian-Hercynian epoch (500-250 Ma), and Indo-China and Yenshan epoches (after 250Ma), respectively.In view of the above, we have established a synthetical metallogenic model for the polygenetic compound gold deposits of the Erjia gold ore field.