Metallogenic Regularity Of Copper Polymetallic Deposits In Zhongza-Derong In The Center Of The "Jinsha-Lancang-Nu Rivers" Metallogenic Belt

"Jinsha-Lancang-Nu rivers" area in southwestern China is located in thejuncture between the Tethys and the Pacific Rim tectonic domain. This area isbeneficial to Cu, Pb, Zn, Ag, Au, Sn and other mineral resources. It is a veryimportant in China and worldwide influenced rare non-ferrous metal metallogenic belt.Zhongza-Derong area is located in the south central region of the southwest"Jinsha-Lancang-Nu rivers" non-ferrous metal metallogenic belt. So far, more than60copper polymetallic mineralized spots have been discovered in this area. There areabout13mineral commodities including Cu, Pb, Zn, Au, Ag, Fe, Sn, Ni, W, Mo, Crand Mn ores. The ore deposits mainly are porphyritic, scarnic, hydrothermal, volcanicand magmatic segregation types.The previous geological prospecting work and scientific researches in the centralregion of the "Jinsha-Lancang-Nu rivers" area have focused mainly on both the JinshaRiver ophiolitic melange belt and the Yidun late Triassic island-arc belt. However, thejuncture between them has been studied with relatively low degree. Thegeochronology researches of igneous rocks (particularly intermediate-acid intrusiverocks) in this area are very weak, and the diagenetic ages of many copper depositsremain controversial. This unfavorable situation extremely limits the division of thetectonic-magmatic thermal events, the determination of the diagenesis age and theunderstanding of regional metallogenic regularity in the "Jinsha-Lancang-Nu rivers"area. In view of this, on the basis of adequate geological field investigations, themetallogeny, the metallogenic epochs and the metallogenic regularity of the copperpolymetallic deposits in Zhongza-Derong area, Sichuan, China are studied in thispaper by means of integrating multi-discipline such as isotope geochronology,petrology, mineral deposits geochemistry and so on. Then the metallogenic series ofcopper polymetallic deposits in this area have initially been set up in this paper. Theconclusions and understanding are obtained in this paper mainly as follow:1. To analyze geochemical features of intermediate-acid intrusive rocks indicates that there exist three distinctive igneous rock belts in Zhongza-Derong area. They areXuejiping, Pulang and Zhuoma-Hongzhuo porphyry belts, which distribute in thedirection of Northwest-Southeast from the West to the East of the area.2.18sets of geochronological data of intermediate-acid intrusive zircon U-Pbwere obtained by means of the LA-MC-ICP-MS method. The diagenetic ages rangefrom332.6±1.3Ma to79.10±0.55Ma. Based on the formation and evolvementhistory of the "Jinsha-Lancang-Nu rivers" area, the dating of intermediate-acidintrusive rocks can be divided four stages: Carboniferous parting intrusive rocks,middle-late Triassic continental uplifting intrusive rocks, late Triassic-early Jurassicsubduction and collision intrusive rocks and late Cretaceous hysteresis collisionintrusive rocks. These4intrusive rocks represent4significant tectonic-magmaticthermal events.3. By integrating analyses of the metallogenic condition and regularity ofmiddle-large scale deposits, it is concluded that the metallogeny and diagenetic age ofChangtai-Xiangcheng igneous rock belt located in the Zhongza-Derong area aresimilar. They both belong to the same metallogenie system. It composes an integratedmetallogenic series, i.e. porphyriticâ†'subvolcanicâ†'thermal in genetic type, copperpolymetallicâ†'polymetallic copper leadâ†'polymetallic silver lead zinc in metallogenicelement combination. The metallogenic temperature of these deposits graduallydecreases from the South to the North.4. There are5metallogenic prospects in Zhongza-Derong area. They areZhongxinrong-riyu copper prospect, Garuo-Shundagong copper gold prospect,Ziwa-Bendu copper gold prospect, Yigongruo-Daoxue-Zhujiding-Zaodui polymetallictungsten stannum copper molybdenum prospect and Kaixiong-Kaigong copperpolymetallic prospect.