Discussion on metallogenic environment, mineralization and genesis of Dahongshan Iron-Copper Deposit, Yunnan

摘要

Dahongshan Iron-Copper Deposit (Hereafter to be shorted as DICD) is located to the northeast of the Honghe fault at the western margin of the Yangtze Paraplatform, and at the southern end of the Kangdian Axis. DICD is composed of a large-scale high-grade iron deposit and a large-scale high-grade copper deposit, hosted in the Pre-Sinian palaeomarine volcanic rocks. DICD is a combination of various deposits, which are interactive in genesis, approximately centered around a volcanic intrusion activity center. These deposits constitute a typical plaeosubmarine volcanic eruption-sedimentation metallogenic series. The study on the Early Proterozoic Dahongshan Group meta-volcanic rocks indicates that the volcanic rocks have typical nature of ocean-ridge tholeiite and that the magma sources have the features of little enriched transitional mantle (T-type MORB). Combined with the palaeotectonic study, we consider that the volcanic rocks are the product of marginal basins during the process of extension. Rifting caused the relatively enclosed reducing marine basins, in which the well-known "Dahongshan" iron-copper deposit was formed under the volcanic eruption-sedimentation-superimposition.