Minerals Standard Characteristics? Metallogenic Fluid Characteristics And Genesis Of Yu'erya Gold Deposit In Eastern Hebei Province

Yu'erya gold deposit,which is located in North China Craton is one of the most typical gold deposits in eastern Hebei.The ore-forming geological body of the deposit is the Yu'erya granitic complex and it contains about 95%gold ore bodies.However,the classification of the granite types and their relationship with gold mineralization have not been thoroughly investigated.Thus,petrological and mineralogical studies are conducted on the intrusion of different types of rocks in the deposit based on the detailed field investigation and rock ore microscopic observation.The ore mineral typomorphic characteristics and metallogenic fluid characteristics were analyzed by electronic probe inclusions microscopic temperature measuring hydrogen and oxygen isotopes of carbon and oxygen isotope geological pressure gauge and other methods,and the valley ear cliff gold mineralization is discussed.The main conclusions can be drawn as below:1.Alaskite,alaskite contains abundant spessartine,medium-fine-grained miarolitic granite and granite pegmatite are found in the middle of blind shaft deep mining in the north ore belt of Yu'erya mine for the first time.They are the products of magma-hydrothermal transition process,which demonstrate one-way consolidation?UST?structure,and quartz fine network veins,pegmatite and biotite schlieren were developed inside,which proves that the magma dissolves a lot ore-forming hydrothermal fluid.2.Pyrite is the main gold bearing mineral in Yu'erya ore body,which is lack of sulfur element.And the content of Co,Ni in the pyrite shows that pyrite leads to the magmatic hydrothermal and is closely related to hydrothermal tungsten-tin-molybdenum mineralization.And the contents of As,Se and Te indicate Yu'erya deposit belongs to alkaline rock hydrothermal type deposit,and ore-forming elements Au and S elements which is related to the magmatic activity may come from deep sources.It can be drawn that Yu'erya gold deposit belongs to medium temperature deposit by the study of trace elements in the sphalerite in the ore body combined with the calculation results of Ti geothermometer.3.The gold mineralization in Yu'erya orebody can be divided into four stages according to the different mineral combination and field intersect.Among them,the 1st stage in the mineralization and the 2nd and 3rd stages in main metallogenic stage belongs to medium temperature and low salinity H₂O-NaCl-CO₂ system,and the late stage belongs to a low temperature and low salinity H₂O-NaCl systems.The ore-forming pressure calculated by isovolumetric line method is in the range of 48.6¹79.2MPa.It is consistent with the calculation result of sphalerite geological pressure which ranges from 55.85 to 156.10 MPa,suggesting that mineralization depth of Yu'erya gold deposit in the range of 1.83⁶.76 km.It can be discovered from the H-O isotope of quartz in gold-bearing quartz veins that early ore-forming fluid is mainly composed of magma water,while late ore-forming fluid contains atmospheric precipitation.The C-O isotope of calcite results show that the ore-forming fluid is mainly derived from the mantle-magmatic.The results indicate that there are strong genetic relationships between Yu'erya gold deposit and the granitic intrusion,and the deposit is a typical intrusion related gold deposit.