| Zhongdian island arc is part of The Tethys-Himalayan Porphyry Metallogenic Realms, which is one of the three biggest Porphyry Copper Mining Area in the world. It is located in the eastern edge of the metallogenic realms of the south of the Indosinian Yidun arc. Lannitang, Xuejiping, Cilai and Chundu etc. complex porphyry bodies line NNW trending in the west of Zhongdian arc porphyry belt, The obtained mineralization information, ore prospecting exploration, and the result of research, all of them have showed that this area has great mine prospect with excellent mineralization geological conditions.This paper mainly talks about the Indosinian intermediate-acid shallow period-with ultra-shallow spot (porphyry) rock intrusive which is located the west porphyry belt of the Zhongdian island arc and the representative Chundu Porphyry Copper Deposit. With the guidance of theory of plate tectonics, Petrology, Mineral deposits, Regional metallogeny, Deposit Geochemistry, and Porphyry mineralization theory, on the basic of extensive collect and systems analysis the results of previous studies, Through the detailed geological work in field and the analysis of large number of the samples, the deep research of the basis of geological deposits, porphyry rock geochemistry, deposit geochemistry, and diagenetic mineralization model in the deposit, we'd like to investigate The Construction -Coupled magma Ore and rock-controlling mechanism, summarize the metallogenic regularity, and establish metallogenic model, for further, it helps to perfect and enrich the metallogenic theory of Zhongdian arc porphyry belt, and provide a scientific basis for the geological prospecting work and metallogenic prognosis. The main research results are as follows:On the basis of macroscopic geological research and analysis,by means of identification of rock and minerals,major element,trace element,Rare Earth Element and isotope. it reveals that the ChunDu mine and the composite porphyry bodies of Zhongdian island arc west porphyry belt have the basic characteristics of island arc igneous, and the geochemical affinity with adakitic rock. It indicate that the composite porphyry bodies bear the characteristics of the I-type granitoids, It was producing in the structure environment of the Indosinian Ganzi-Litang ocean crust western subduction on Gezan tiny island, It is the product of an active continental margin, Magma is mainly from the lower crust or upper mantle.The composite rock bodies are made up of two phases, diorite porphyrite is the main rock mass which is initial intrusive, and the post-intrusive granodiorite porphyry which is the apophysis or dyke, granodiorite porphyry is host rock of mining rock. The formation of diorite porphyry in the mine was significantly affected by crystal fractionation and by some weak control of partial melting.Granodiorite porphyry was controlled by partial melting as well as fractional crystallization. These two porphyry are comagmatic evolution of crystallization and differentiation. They are homologous magma chamber, and homologous heterogeneous product. Cu,Pb,Zn were mainly from the lower crust or upper mantle. Sulfur was mainly from the deep magma with the characteristics of mantle-derived sulfur,at the same time, there was a certain amount of crustal sediments(Reduced sulfur). Ore-forming fluids mainly were the original magmatic water, and a little surface water.Through deep detailed geological field work and indoor identification of rock and minerals, we identified the types of major alterations are potash feldspathization, silicification, biotitezation, sericitization, propylitization and argillified; and establish alteration zoning model of the research district. With granodiorite-porphry as the center, which is echelon, potassium silicon belt appears outward in proper order (potash feldspar, black mica)→quartz-sericitization belt→(argillization belt)→propylitization belt→hornstone belt. The alteration character is similar to "monzonite alteration", but alteration regularity is relatively worse, there is repetition→slants symmetrical phenomenon. The alteration zone and its space characte-r of zoning are controlled by intrusive rocks. Generally speaking, the copper mineralization has obvious relation with the type of alteration, the strength of mineralization is better in potassium silicon belt, quartz-sericitization belt and its transition belt.Using LA-ICP-MS zircon U-Pb method, we accurated the determine age of rock body. The age of the Chundu's diorite porphyrite is 246.1±3.0Ma-260.8±2.5Ma, and it is the same with the age of both Xuejiping's quartz diorite porphyrite amphibole by 40Ar-39Ar (249.92±4.99Ma) and Cilai's diorite porphyrite zircon by U-Pb (252.3±3.4Ma), with the macroscopical geological relationship and characteristic of the regional magmatic evolution between diorite and wall rocks, suggesting the age of diorite porphyrite should be about 240Ma. The age of Chundu's Ore-bearing granodiorite porphyry is 217.5±1.9-217.3±1.8Ma, and it is consistent with the peak of the ore-forming stage(215Ma) of magmatic activity of Zhongdian arc. From barren diorite porphyrite to granodiorite porphyry the magmation of the complex porphyry bodies had lasting for 25Ma in this area. So long magmatic-hydrothermal system is one of the necessary conditions to form the sizable porphyry copper. According to dating results, combining with the analysis of the Zhongdian arc porphyry belt regional geology, this paper said:There are at least two large acid Shallow magma-ultra-shallow intrusive activity in the west porphyry belt of Zhongdian arc under the diving environment of ocean basin plate. First, Ganzi-Litang ocean occurred the subduction in Middle Triassic-Earlier of Late Triassic to the Zhongza masiff which was in the west, and also occurred the shallow area-ultra-shallow intrusive along the discordogenic fault—Gezahe fault which is NNW,and the main rock types is barren diorite porphyrite which is in the form of rock strains or rock vein. Second, In the Middle-Late period of Late Triassic, dacite magma invaded into the body of the diorite along weak belt of the bottom of the diorite, To form the Chundu granodiorite porphyry; As the western porphyry intrusion with a large number of early diorite barrier or deterrent effects, this phase of magmatism migrated eastward to middle-east porphyry belt, so the west porphyry belt magmatism is relatively weak or emplaced deeper. Rock body in the east porphyry rock is mainly rock strains or rock vein, but in the west porphyry rock the output mainly is rocks sticks or rock dykes and rock body is relatively small. they all have affinity for adakites, current intrusion major rock types are beschtauite, granodiorite porphyry etc., and constitute a host rock of mineralization for porphyry-type copper and molybdenum deposits.After summary the metallogenic model and rules of the porphyry in this mine,system analysis the metallogenic mechanism of Chundu mine and western porphyry of Zhongdian arc porphyry belt,we established Chundu "Echelon porphyry dyke" ore-control mode. Middle Triassic-Earlier of Late Triassic, Ganzi-Litang oceanic crust started to westward subduction, with the deep increasing, it leaded to dehydration and slab partial melting, and then caused partial melting of mantle material and formed intrusion and calcalkaline magma. in the rising process Magma constantly occured differentiation and evolutioned along the Gezanhe deep fault, mainly was in the form of rock strains or rock vein. Untill the mid-late Triassic, the continuous extrusion subduction from east to west, The NNW-trending faults of the Zhongdian arc west porphyry delt generated sinistral strike-slip, which derived some NE-SW fault expanded somwhere, en echelon fault structure system had formed. At the same time,the andesitic magma at the bottom had been changed into dacite magma, When the continually evolving magma invaded into the earlier porphyry rock body or wall-rock along the NNW-trending strike-slip fault structure echelon system, and formed mineral-bearing granodiorite porphyry which was mainly rock strains or rock vein—"En echelon granodiorite porphyry vein". The mineral-bearing hydrotherm which separated from the granodiorite porphyry magma entered into the fissures of the top part of the diorite or granodiorite porphyry. In this process, the atmospheric water dissolving formation minerals in infiltration process mixed with the original magma, and formed the mixed-mineralization fluids. The mixed Ore-forming fluid was rich in mineral, such as Cu,Pb,Zn,Fe etc. and rich in volatile elements, like H2O, CO2, S-2, Cl- and others. With ore-forming fluid flowing into fissures of the diorite or wall-rock, the occurrence of alterationas as silica,potassium-based and phyllic with wall-rocks can be seen,then hydrothermal copper and other metal elements and sulfur formed pyrite, chalcopyrite and other metal sulfides, which precipitated from the ore-bearing hydrothermal, and with decreasing temperature, the metal sulfide ore-forming fluids direct precipitated in the formation of metal sulfide vein. Under the control of NNW-trending strike-slip echelon fault structure system, Chundu copper's ore body is also showing the distribution of en echelon features, it is different from the typical porphyry copper deposit-"echelon porphyry" ore-controlling mode, this control mode ore has an important representation in Zhongdian arc west porphyry belt.This paper analysises systematic the geological conditions of Chundu copper deposit and porphyry delts in western of Zhongdian arc and summaries the prospecting criteria. According to the ore-controlling model of the "En echelon porphyry vein". We chose six exploration targets, and also point out in the prospecting work, we should deeply hold on the control rules of the "Echelon-porphyry vein" ore-bearing model on porphyry and ore mining, and we should focus on the parallel NNW echelon faults slip systems and make a good work plane. The deep exploration work should be given more attention.
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