The Hydrothermal Alternation And The Mineralization Conditions Of Temperature And Pressure Of The Songjizhuang Gold Deposit In Rushan Jiaodong Region

Songjiazhuang gold deposit located in the west of North China Plate, Jiaonan orogenic belt,Weihai Heave, the west side is Muping-Jimo fracture, the stratum is uncomplicated, structure of the deposit is developmental, the geological condition of mineralization is great.The Songjiazhuang desposit which is the kind of pyrite-quartz vein gold deposit in the south of Qinghushan-Tangjiagou fracture. There are four lentoid orebodies be found in this desposit until now, which is in the No. I mineralization-alteration belt. The wall rock's thickness of orebodies is different between the top and bottom, changes besides 3 meters to 8 meters.The ore of Songjiazhuang is devided into oxidized ore and primary ore. The oxidized ore distribute under the earth's surface 5 meter or 8 meter, they all be collected up. The primary ore include pyrite-quartz vein contain gold ore and metalsulfide-quartz vein contain gold ore. The main gangue mineral are plagioclase,orthoclase,quartz,biotite, sericite. The mineralization stages contain beresitization, pyrite-quartz, quartz-pyrite, polymetallic sulfides, and quartz-carbonate stages.The alteration of Songjiazhuang desposit is complex, it contains many kinds of alterations, such as sericitization, chloritization, sericite-quartz alteration, pyrite-sericite-quartz alteration, potash feldspathization, siliconization, pyritization and carbonatization. The element migration is complex during the alteration, gold and other mining-element sediment along the alteration. Characteristic of REE and sericite with Cr prove that ore-forming fluid come from deep focus.The inclusions of Songjiazhuang desposit are small as 2?8um, they are basically the kind of aqueous vapor+aqueous liquid with anomalistic shape, unevenly distributed in the mineral. Thermometry of fluid inclusions shows that the homogeneous temperature of main mining time change between 213??330?, and it always appearance between 260??290?.The equilibrium temperature of albite and potassium feldspar is 380±50? by Barth geothermometer, and the equilibrium temperature is 409±30? by J.C.Stormer geothermometer. The crystallization temperature of hornblende and plagioclase is between 570?-640? by the isothermal chart of their Ca's distribute. The crystallization temperature of hornblende and Biotite is between 620?-690? by the temperature-pressure chart of them, and the chart also shows that the pressure is between 5kba-6kba.Carbon and oxygen isotopes analysis of Songjiazhuang desposit on ?18OV-SMOW and ?13C V-PDB graph shows that the cultellations nearby the earth mantle polyphase system, trend to Low T Alteration and sedimentary strata union area. It illustrates that the mining fluid come from the earth crust, and the material of earth mental play an important role in the metallogenesis, atmospheric water join in evolution of mining fluid.