| Jinchanshan gold deposit located in eastern of north margin of North China platform, Chifeng-Chaoyang gold mineralization concentration area. In the region, exposed Archean Jianping Group and Proterozoic Minganshan Group metamorphic rocks; Mesozoic middle Jurassic to Cretaceous sandstone, conglomerate, pyroclastic rocks and tuff; and Cenozoic Tertiary and quaternary strata. Magmatism of Hercynian-Yanshan period in study is strong, the mainly are intermediate-acid rocks,and various types of dykes are extensive development. East-West deep fault and NE, NNE rift zone control the distribution of magmatic rocks and deposits in the region area. The are nearly one hundred gold points, and more than ten exploited gold deposits in this area.The main formations outcropped in the mining area are late archean Jianping group,proterozoic Mingan group metamorphic and quaternary sediments. Anjiayingzi granite is the main Magmatic rock in mining area. There are also many dikes such as quartz porphyry, granite prophyry, felsite prophyry, rhyolite prophyry, invaded at late period. The main ore-controlling structure are fault, which strike is NE-NNE. Orebody located in these faults, shape like vein, has a same attitude as the faults. Main Metallic mineral is pyrite, next are chalcopyrite, galena, sphalerite, pyrrhotite and a little of matildite, skutterudite and cobaltite. The main auriferous minerals is electrum, next are native gold and kustelite. The main nonmetallic mineral is quartz, next are chlorite, sericite, potash feldspar, kaolinite and carbonate. The main ore texture have euhedral-half euhedral texture, allotriomorphic granular texture, including texture, metasomatic texture.solid solution separation texture and fragmentation texture. Structure type have massive tectonic type, complex-shaped plaques, disseminated, veinlet disseminated, stringer vein-stockwork, and banded structure, etc.. Wall rock had occurred alteration, mainly of potash feldspathization, sericitization, chloritization, silicification, pyritization, carbonatization and so on. The deposit can be divided into endogenous period and supergene period of both the endogenous period is further divided into quartz-pyrite stage, polymetallic sulfide stage and quartz-pyrite-carbonate ore stage.SiO2 of Anjiayingzi granite closely related with the mineralization is 60.70%-68.01%, MgO ranging from 0.41% to 2.44%; and with high Al2O3≥15%, high Sr (488×10-6 686×10-6), low Y (9.04×10-6-18.60×10-6) and Yb (0.84×10-6-1.76×10-6), and LREE enriched and HREE deficit(La/Yb) N=17.62-56.11),and weak negative Eu anomalies,with geochemical characteristics of typical adakitic rocks. Harker diagrams of the major oxides and Al2O3 (SiO2)/ CaO-Na2O/CaO, Ce/Rb-La/Rb diagrams of major and trace elements have good linear evolution relationship, indicating magma mixed in magma source; oval dark inclusion in granite and granite composition in inclusion, long apatite in biotite phenocrysts, mafic hornblende phenocrysts with biotite, feldspar anti-ring and dark inclusion bodies containing large feldspar phenocrysts of microscopic observation, indicating the same crust-mantle mixed messages. Isr (t) change from 0.7055 to 0.7060 andεNd (t) is-8.19 the whole rock, distribution of isotopic composition along the mantle evolution line; Pb isotopic composition of 206Pb/204Pb=17.194-17.288,207Pb/204Pb=15.340-15.391,208Pb/204Pb=37.243-37.392,structure model diagrams show the Pb isotopic is mainly between the lower crust and upper mantle or between the mantle and the orogenic evolution of lines, have good linear distribution, which indicate crust-mantle mixed feature of Anjiayingzi granite. Petrographic, major and trace element geochemistry and isotope results suggest:rock genesis have different from partial melting of subducted slab, crustal contamination and fractional crystallization processes (AFC) of basaltic magma and partial melting model of eclogite facies lower crust. The sourse maybe mixed between old lower crust and basic melt which come from partial melting of underplate basaltic lower crust.Quantitative model show that fractional crystallization of plagioclase, biotite, zircon and other minerals in evolution of Anjiayingzi granite have a significant affect on changes of the trace element.The study on H-0 isotopic of fluid inclusions in quartzs have shown that metallogenetic fluids in Jinchanshan gold deposit are mainly magmatic water with meteoric water mixed later. Characteristics of S and Pb isotopic in sulfides indicate that metallogenic matter are from deep-derived magma,with crust-mantle mixing characteristics.These isotope results above show that gold mineralization have a close genetic relationship with Anjiayingzi granite. Homogenization temperatures of fluid inclusions in Quartzs are 220-380℃, and salinity is 4.0-40.1ω(NaCl)%, and density is concentrated in 0.66-0.87g/cm3, and pressure and depth estimates are 21.16-34.19Mpa and 0.80-1.29 km, show a shallow metallogenetic environment. Gas and liquid components of fluid inclusions show that metallogenetic fluids in Jinchanshan gold deposit is H2O-CO2-KCl-NaCl-type, that is alkali-rich.In this high-temperature and alkaline fluids, migrate of gold is mainly complexes of sulfide. A variety of mechanisms can result in the precipitation of gold:the deep high-temperature ore fluids are mixed with meteoric water and then fluid cooling, which result in break of balance on Au-S complexes is the main mechanism of gold deposition;With ore fluid migrating along with the broken, water-rock reactions and sedimentation of Fe2+, Zn2+, Pb2+in forming fluids which result in the drop of PH,fO2 and total concentration of sulfur, causing break of balance on Au-S complexes leading to gold deposition.U-Pb zircon age of Anjiayingzi granite rock the direct ore-bearing rock of Jinchansh gold deposit is 132±5Ma. Widely developed of rhyolite porphyry dikes within the ore field in the majority gold veins and alteration zone or parallel distribution with its invasion to the alteration, the emplacement age slightly later than the age of gold mineralization and the same period, the U-Pb zircon age is 124.9-126.5Ma, thus limiting the times of gold mineralization is 132-126Ma, between an late Yanshan. This period is coincide with lithospheric thinning in eastern China, intense magmatic activity and mineralization geological events, which show the Jinchanshan gold deposit and Jiaodong gold deposit, gold deposits in Qinling and other places, all the deep lithosphere destruction into mine response. Anjiayingzi carried deep granite minerals along the NNE (Red Hill-balihan?), magmatic ore-forming hydrothermal fill in the north east, north-trending fault formed the Jinchanshan gold deposit.
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