铜官山矿区金口岭铜金矿床围岩蚀变、成矿物理化学条件及成矿机理研究

STUDIES ON WALL-ROCK ALTERATION, PHYSICAL AND CHEMICAL CONDITIONS, AND MECHANISM OF MINE- RALIZATION OF JINGKOULING COPPER-GOLD DEPOSIT IN TONGGUANSHAN ORE FIELD, ANHUI PROVINCE

本文在研究金口岭铜金矿床的围岩蚀变及其与矿化关系的基础上,运用包裹体矿物学、热力学、稳定同位素地球化学等方法,对矿床形成的物理化学条件、成矿物质来源和成矿机理作了深入研究,论证了成岩成矿物质具同源性。本文强调石英闪长岩株下部发生钾蚀变对矿床的形成起重要作用。

This paper has investigated alteration of wall-rock and its relationship with mineralization of Jingkouling copper-gold ore deposit, and pointed out controlling factors on zoning of altered rocks and metal minerals. On the basis of these studies, the authors use inclusion mineralogy, dynamics and stable isotope geochemistry, etc. to research physical and chemical conditions of mineralization, source of material and mechanism of mineralization and has proved that source of mineralizing material is the same as petrogenetic material. The paper emphasizes that K-alteration of lower part of the quartz diorite stock has played a very important role in the formation of the deposit. The main conclusions of the paper are as follows:1. There are apparent zoning of gangue and ore minerals in the deposit. Skarn zoning is controlled by the chemical patential gradients of component, while metal mineral zoning is controlled by the composition, texture and structure of skarn.2. Jingkouling copper-gold ore deposit has the same petrogenetic and metallogenic material sources. The mineralizing fluid differentiating from the deep magma is the direct material source, and the fluid causing the quartz uiorite K-alteration gets more mineralized material as it goes through fracture system in the pluton. Some mineral-forming material drawn by magmatism and magmatic hydrothermalism from wall-rock would have played some part in the minerogenesis.3. High temperature, high saltiness and acid mineralizing fluid introduced into the nearly open skarn zones with rapidly decreasing temperature result in hydrolysis of skarn, rise of pH and increase of aFe2+, aHs- and aH2s- At the same time, the dropping of temperature, decreace of fo2 and heterogeneous mixture of meteoric water, etc., are responsible for decomposition of the chlorine complexed of copper and other mineral-forming elements, the precipitation of sulphide and formation of high-mid temperature copper-gold deposit of magmatic hydrothermal type in the skarn.