Study On The Geochemical Characteristics Of Metamorphic Volcanic Rocks In The Dahongshan Group, Dahongshan Area, Central Yunnan, China

The study area is located in the western margin of the Yangtze block, Xinping County, which is famous for Dahongshan type iron copper deposit. As the ore bearing formation which is defined as a set of marine volcanic eruption sedimentary metamorphic rocks is the most complete one in this area. With the development of mining production, geological workers put forward some new ideas about the formation of metamorphic volcanic rocks in the formation of rocks, mineralization, tectonic evolution and so on. On the basis of previous studies, through field geological work identified metamorphic volcanic rocks of the macroscopic geological features, rock and mineral microscope to identify the metamorphic volcanic rocks petrography, geochemistry method to identify the geochemical characteristics of metamorphic volcanic rocks.Based on the above research to identify metamorphic volcanic rocks of the forming environment and the magma source region characteristics, and to explore its relationship with mineralization, enrich the metallogenic theory of Dahongshan area.The main thesis of this study made the following understanding:(1) The mineral assemblage characteristics of sodic volcanic rocks is albite and magnetite; the mineral assemblage characteristics of green schist is Albite、hornblende、sericite、 actinolite、biotite、quartz、Muscovite、chlorite、a small amount of magnetite; the mineral assemblage characteristics of amphibolites is Amphibole、feldspar、quartz、garnet、little magnetite.(2) We believe that the volcano metamorphic protolith nature belongs to tholeiite series through the analysis of the elemental geochemical data of rock testing. The REE patterns show metamorphic rocks of the volcano less enrichment of light rare earth right type, flat curve, the Eu、Ce anomaly of most of the green schist and amphibolite is not obvious and the sodic volcanic rocks and mineral have the same Eu positive anomaly and this shows that the rocks have high temperature hydrothermal leaching, inherited the ore-forming fluid positive Eu anomaly. The high field strength elements of Ta, Nb, Zr, Hf and Ti of green schist and amphibolite have no significant losses, similar to E-MORB. The Ta, Nb, Zr and Hf of some of the sodic volcanic rocks show a positive anomalies, reflect the characteristics of basalt in the plate and which indicate that the magma is derived from the mantle, and it has been mixed with the crustal material in the process of evolution.(3)We believe that metamorphic volcanic rocks formed in continental rift environment which has deeply tensile tensile and the magma source region may be an inhomogeneous lithospheric mantle material which shows the partial enrichment, partial loss of uneven characteristics according to the field geological feature of rock, rock geochemistry characteristics* previous studies on the isotopic characteristics and the stability of high field strength elements diagram of tectonic environments for comprehensive judgment.(4) We believe that the formation of continental rifting basin provides a good place for mineralization and the source of the ore-forming material is formed by the magma of the magma and the sea water of the metamorphic volcanic rock and the formation and transformation of the ore deposit has experienced three important stages:the stage of the mineralization stage of the volcanic action-the enrichment stage of the regional metamorphism-the magmatic intrusion and the transformation of the hydrothermal fluid according to the geochemical characteristics of metamorphic volcanic rocks and the combination of the previous sulfur, hydrogen and oxygen stable isotope data.