Mineralization Enrichment Regularity And The Genesis Discussed Of Jiaojia Gold Deposit, Shandong Province Laizhou

Jiaodong is one of the most important gold producing area in China, ts reservesaccount for1/3of rock gold in our country has proven, its importance is self-evident.Jiaojia gold deposit located in the northwest of Jiaodong gold concentrate,28km north ofLaizhou City, and the east of the Yishu fault zone, in Jiaojia-Metro fault structure.Mesozoic period, as the Izawa Naiqi plate dive into Eurasia by the SE-NW, Jiaodong enterinto a major orogenic-ore-forming stage.Jiaojia gold deposit was significantly affected by the fractured zone control which hasa strong wall rock alteration，and is typical of the type of gold mineralization. ArcheanJiaodong Group metamorphic rocks within the mining area is mainly the form of aresidual body, the rocks are biotite granulite, amphibolite rocks dominated, magmaticrocks exposed are Linglong granite and Guojialing granodiorite，in the northern of themining areas saw both the contact zone. The zircon U-Pb age about linglong granite andGuojialing granodiorite is of158.53±0.79Ma and135.56±0.53Ma that this studyacquired,. Jiaojia gold deposit has a extremely significant feature，that is a large number oflamprophyre closely linked with the gold mineralization in time and space spread into zhegold deposit.Jiaojia-Metro fracture is main ore-controlling and ore structure in a mining area the,the ore body is located in the footwall of the fault zone. The wall rock alterations includepotassium, silicification, phyllic, pyrite phyllic and carbonate-based, among them, goldmineralization have a close relationship with silicification and pyrite phyllic alteration.Tetradymite is a new identified mineral of the mining area in this work.A iconic mineralassemblage of the gold mineralization enrichment is the combination of chalcopyrite,pyrite, and tetradymite. To determine Jiaojia gold deposits are mainly experiencing twomineralization periods,meaning ore-forming hydrothermal mineralization and supergeneoxidation, the period in which hydrothermal mineralization can be divided into fourmineralization stages: namely, pyrite-quartz stage, gold-pyrite-quartz stage, gold-quartz-polymetallic sulfide stage and carbonate phases. Through studying the geological characteristics of the ore deposits, combined with alarge number fluid inclusions test analysis of ore samples showed that: Jiaojia gold depositore-forming fluids are CO₂-H₂O-of NaCl system; ore-forming fluids have characteristicsof low salinity （1.43⁴.79wt%NaCl）, low density （0.624⁰.870g/cm³）, ore-formingtemperature is between223.8³48.7°C, belongs to a medium temperature range. In thispaper, author applies the fluid inclusions CO₂-H₂O isochore intersection method toestimate the ore-forming pressure, the results showed that the the metallogenic pressurerange from63MPa to126MPa. And tries to use the New Zealand tectonic geologist Sibson（1988） to establish the nonlinear relationship between fluid pressure and depth of the faultzone, according to SunFengyue （2000） quoted Sibson’s research findings into the formulaof hydrothermal vein gold-deposit mineralization depth, to estimate the mineralizationdepth of6.40⁷.34km. Isotope results about hydrogen, oxygen, helium, argon showedthat the ore-forming fluids is mainly the mantle-derived fluid-based and accompanied by asmall amount of magmatic fluids and atmospheric precipitation joined.Isotope studies oflead and sulfur showed that the forming material comes mainly from the upper mantle;mineralization age of the Jiaojia gold deposit is of124±1Ma for late Yanshanianmetallogenic.In summary, determine the genetic type of Jiaojia gold deposit belong to mesothermalvein-type gold deposit which is controlled by faults and mantle-derived fluids involved inmineralization.The cognition angle from the mineralogy and petrology is supported by thetetradymite discovery within the mining area and its close relationship with the goldmineralization, and the common phenomenon of Extensively developing Lamprophyre,which SunFengyue （1995） proposed the Jiaodong gold deposits of mantle-derived fluidmineralization. Also pointed out that the lamprophyre high content of gold is importantevidence of mantle-derived fluid from the upper mantle bring gold. Most of the telluriumgold deposit and tellurium containing gold deposit located in the mantle plume activityarea, showing the deep fluid plays an important role in the transport.We think,amongtellurium minerals related to gold mineralization in Jiaodong, Te,Au, Cu may togetherwith the mantle fluids from the mantle, and then participate in the mineralization.Author believes that, in the conversion period of the the Yanshan late collision tostretch, lithospheric delamination-thinning, large-scale volcanic eruption, resulted in adeep mantle material and energy strongly upwelling, leaded to the ore-forming elements inthe upper mantle bring out （Te, Au, Cu, etc）, the ore-bearing thermal fluids centrallyuninstall to mineralization in the brittle fracture.Jiaojia gold deposit ore bodies strictly controlled by faults, ore-controlling fracture displays the characteristic of the inverse dextral fault activities in metallogenic period,industrial orebodies strike easterly tendency and on the angle slows the local tensile parts,industrial minerals body side of the V to the SW direction, side angle30°³5°. Controllingfaults have the undulating features either the strike or the tendency, so the favorablestructural positions of the output of the ore bodies in space reproduce according to certainrules, so as to control a segment of the gold mineralization rich sets. The vertical-controledore bodies are the first enrichment segment, the main elevation ranges from30m to1200m,The ore bodies no pinchout. Strike between56-136lines.In the basis that the spatial variation law of the comprehensive analysis of theore-controlling structure surface, the dynamic characteristics of the ore-controlling faults,spatial orientation mechanism of mineralization of the ore bodies, author analyzedthat:there is another mineralization enrichment segment in the deep mining area, meaningthe slowing down of the occurrence is a mineralization favorable section, namely thesecond mineralization enrichment segment. Provide a theoretical basis for furtherexploration.