Tectonic-Magma-Mineralization Of The W-Sn Polymetallic Ore Concentration Area In Southern Hunan Province

As an important part of the Nanling Mesozoic magmatic-metallogenci belt, the W-Sn polymetallic ore concentration area in Southern Hunan Province is located at the east section of Nanling Hercynian depression zone, which superior mineral resources, such as tungsten, tin and bismuth etc., occupy a decisive position in the country, even all over the word. By thorough analysis and systemic comparison of the typical deposits and magamtic plutons, especially geochemistry of different metallogenetic granites, the source formation mechanism of granitic magma, as well as including composition and character of ore-forming fluids, the author re-recognized Yanshanian magmatic activity, ore-forming fluid action and mineralization process in Southern Hunan Province, and established the conceptual model of the magmatic intrusive contact structural system. The following are the major progresses.1. Based on the study of petrology and geochemical characteristics of the typical granites, the tectonic environment and genesis of metallogenetic granites are discussed , and it is proposed that a large part of materials for mineralization might be derived from the Early Yanshanian granites.2. Differentiation characteristics of chemical compositions of the granites are studied, especially the influence on the granitic differentiation and mineralization of the volatile components.3. By analyzing the geochemical characteristics of different metallogenetic granites, the metallogenetic specialization of different granites is preliminarily discussed.4. Fluid inclusion measurement leads to preliminary ascertaining characteristics of the ore-forming fluids of different deposit and reflecting the different influence on the mineralization of the different fluids.5. The ore-forming material source is found out through analyzing lead isotopic, rare earth elements and trace elements of altered rocks.6. The mineralization age of Yaogangxian tungsten deposit is measured by using Re-Os dating of molybdenite, and the duration of mineralization is studied.7. A conceptual model of the magmatic intrusive contact structural system is set up on the basis of the researches on ore-forming geological conditions, metallogenic regularity, ore-forming geochemical characters, and the spatiotemporal coupling relationship with magma intrusive process.