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

Northwest Jiaodong peninsula, which reserves account for1/4of rock gold in our country and hasmore than20large-scale gold deposits and numerous samll-middle gold deposits, is an impotant goldindustrial base of China. Sanshandao gold deposit located in the north of Northwest Jiaodong goldconcentrate,28km north of Laizhou City, in Sanshandao-Cangshang fault structure. Jurassic period, asthe Izawa Naiqi plate dive into Eurasia by the SE-NW, Northwest Jiaodong began to enter into animportant orogenic-ore-forming stage.The strata exposed in Sanshandao mine area is Archean Jiaodong Group, its ithology is mainlycomposed of plagioclase gneiss, interbedded with some biotite leptynite and biotite schist. TheMagmatic rocks are widely distributed in Sanshandao mine area, mainly are late Jurassic linglongadamellite and early Cretaceous guojialing granodiorite, dikes such as lamprophyre and dioriticporphyrite are well developed. Structures are well developed in the Sanshandao mine area,andSanshandao-Cangshang fault is the largest scale。Sanshandao-Cangshang fault in mine area is1700mlong and45°trend, dip to SE, dip angle between35°~50°.and has a continuous and stable principalsection,this fault is the important ore-controlling and ore structure. Sanshandao gold orebodys are alllocated in the footwall of the principal section.No.1orebody is the main deposit body of Sanshandao gold deposit, it is located in the footwall ofthe principal section and is NE45°trend, dip to SE, dip angle between30°~50°.Ore types are mainlyberesite and beresitizational granitic cataclasite,Ore type is gold-bearing beresite. The main metallicminerals in the ore are pyrite, electrum and native gold, secondly for arsenopyrite, galena andchalcopyrite, the main nonmetallic mineral are quartz, sericite and residual feldsparh. The main oretextures are crushing structure and grain structure. Ore structures are mainly disseminated structure.Wall rock alterations are well developed, include potassium, phyllic, pyrite phyllic and carbonate-based, among them, pyrite phyllic has the most intimate relationship with gold mineralization. Sanshandaogold deposit is mainly experience two mineralization periods: hydrothermal mineralization periods andsupergene oxidation periods, and the hydrothermal mineralization periods can be divided into fourmineralization stages:Ⅰquartz-pyritestage, Ⅱ quartz-pyrite-gold stage, Ⅲ quartz-gold-polymetallic sulfide stage and Ⅳ quartz-carbonate phases, Stage Ⅱ and stage Ⅲ are main stage ofgold-rich mineralization,Test analysis on fluid inclusions of ore samples show the ore-forming fluids are low salinity(3.85%~11.60%NaCleqv) and low density(0.70~0.96g/cm3)and rich in CO2, mineralization temperatureis concentrated in260~320°C, mineralization pressure ranges from70~110MPa, while mineralizationdepth ranges from6.78~8.69km.Hydrogen and oxygen isotopes diagram shows ore-forming fluidsderive mainly from deep mantle fluids, and accompanied by a small amount of magmatic fluids.Sulfur and lead stable isotope diagram shows that ore-forming materials derive mainly from mantle andAu derives mainly from upper mantle sources.Based on above cognition, and compared with the Jiaojia gold deposit in the same region, I holdthat Sanshandao gold deposit belongs to mesothermal vein-type gold deposit which is controlled byfaults and mantle-derived fluids involved in mineralization.Sanshandao gold deposit orebodys strictly controlled by fault, the intercepting effects of faultgouge made gold orebodys all located in the footwall of the principal section. Industrial orebodieshave the laws of segmentation enrichment in either the strike or the tendency. Industrial orebodiesstrike easterly tendency and on the angle slows the local tensile parts, it shows in metallogenic periodthe ore-controlling fracture was a right-latera normal fault. Industrial minerals body side to the NEdirection, side angle about42°. It was considered by integrated analysis that there is anothermineralization enrichment segment in the deep of gold deposit.provide a theoretical foundation for thefurther prospecting work.