Study On The Zircon Genetic Mineralogy And Geochemistry Of The Intrusive Complex In Sunzhuang Area, Fanshi County, Shanxi Province

Sunzhuang intrusive complex is located in the east of Sunzhuang village in Fanshi county Shanxi province, which is representative intermediate and acidic igneous rocks series in the middle section of Henshan mountains. Yi Xingzhai and Xinzhuang gold deposits are just developed at the north and southeast margin of the Sunzhuang complex, that imply the formation of the two ore deposits are closely related with the complex. Therefore, it's significant to study genetic mineralogy and geochemistry of the complex for dictating the gold deposits geneses.Two questions have been tackled in this paper: zircon genetic mineralogy and geochemistry , and the cognitions are as follows:1. The depth of denudation of the complex is no serious, and its may be divided into five lithology groups: monzonite, monzodiorite, quartz diorite, granodiorite and porphyraceous granite; The rock texture and petrotectonics and mineral zoning maybe suggest that there is magma mixing during the formation processing of the complex and there are later hydrothermal alteration and tectonic stress action after the complex intrusion.2. The major element characteristics show that: the complex has the characteristics of more rich in Si, Al but poorer in Mg, Fe from the intermediate-basic rock to acid rock, and belongs to the high K calc-alkaline series, and the degree of magmatic crystallization differentiation is good. The REE and trace elements study show that: the complex petrogenic process maybe mainly controlled by comagmatic crystallization differentiation, and partially effected by partial melting process of Archaeozoic plagioclase gneiss.3. The study on the zircon morphology, composition and U-Pb geochronology shows that: the crystallization age of the quartz monzodiorite is 133±0.3Ma and its source region is located at the mixing region of the crust and mantle; The magma is composed of mainly crust with partial materials form mantle, and the magma is rich in water and alkaline during the intruding process. During the process of the formation of the Sunzhang quartz monzodiorite, the magma was under oxidation conditions; the rock was affected by later reductive hydrothermal alteration.In conclusion, the Sunzhuang complex intruded in the late Yanshan Period of the Mesozoic which is close to the main mineralization periods(131.4±3.1 Ma),and belongs to crust_mantle mixed type .The intrusion of the Sunzhuang complex had brought partial gold from the mantle; and the formation of rock was conducted under oxidation environment with much water which is good for the transportation of ore materials; post-magmatic hydrothermal alteration was happened under relatively reductive environment which is conductive to the precipitation of gold, that is to say, the formation of the Sunzhang complex is advantageous for the formation of the Yixingzhai gold deposits.