Geological Characteristics And Genesis Discusstion Of The Chundu Porphyry Cu Deposit, Zhongdian, Yunnan Province

Chundu porphyry copper depoist of Yunnan province,lying in Sanjiangmetallogenic belt, belongs to the Zhongdian arc which is part of the Yidun arc. Inrecent years, Pulang copper depoist、Xuejingping copper depoist and other porphyrycopper depoists were found in Zhongdian arc,where has become one of the mostimportant area looking for porphyry copper deposits in China. Chundu porphyrycopper deposit is another new-finding in the west porphyry belt of Zhongdian arc. Thedeposit scale has reached medium-sized. Researches of Chundu copper ore genesis、mineralization controlled conditions and summary metallogenic regularities,are veryimportant to practical significance of the prospecting work for the porphyry copperdeposits within the region.The paper elaborates geological features of the mine on the base of the long-termfield work and practice in prospecting work. Researching on porphyritems petrology,geochemistry, isotope geochemistry, geochronology，the paper discusses the mainfeatures and its evolution of porphyry, and explores the relationship betweenmagmatic evolution and mineralization, and summarizes ore genesis、metallogenicregularities and criteria.The main results obtained can be listed as follows:1、The main porphyry types are diorite porphyry and granodiorite porphyry, whichbelong to the calc-alkaline series of the sub-alkaline rock series, with the I-typegranite characteristics of the crust and mantle sources. Diorite porphyry andgranodiorite porphyry enrich in LILE of Sr、K、Rb、Ba、Th, and relatively deplet inHFSE of Ta、Nb、P、Hf、Ti. There is LREE enrichment and no significant Euanomalies.2、The mineralization age of mineral granodiorite porphyry is217.5±1.9Ma, nomineral diorite porphyry diagenetic age is252.1±2.3Ma.3、Intrusive rocks mainly controlled by fractional crystallization,weakly by partialmeiting. Diorite porphyry and granodiorite porphyry have the same comagmatic room,belonging to homology-phase of the product. Minerlization material is from the mixof mantle and crust. The intrusive rocks form in the tectonic environment of Ganzhi-Litang oceanic crust west to Zhongzan land masses in Indosinian period.4、The hydrothermal alteration of the eare are obvious, the regularity of alterationzoning is relatively poor. There is the phenomenon of partial symmetry. Alterationtypes and their zonation is controled by the instrusvie body spatial distribution.Potassium silicide zone and the phyllic alteration zone with quartz veins of the gridis the most favorable aera to find high-grade ore body.5、Ore body is controled by the spatial distribution of the granodiorite porphyry.The main structural system to NNW and its sub-structural system is the best aera forlooking for deposits.