Geological Characteristics, Metallogenic Conditions And Prospecting Direction Of ShiHu Gold Deposit In Lingshou Country, Heibei Province

Shihu gold deposit is located in the SE of Mapeng intrusions, it situated on the north of Taihangshan tectonic-magmas belt which is one of the most important deposits within this area. In order to discuss the Ore-forming geological conditions, metallogenic material source and diagenetic-metallogenic epoch of Shihu gold deposit, we research of the granite and quartz-diorite porphyrite for U-Pb chronology; Besides, System to determine the geochemistry of the granite diorite, quartz-diorite porphyrite, mineralized alteration rock and wall rock, respectively. At the same time, combining with the analysis of characteristics of ore deposit geology, diagenesis-metallogenic mechanis. Based on the above research, the author try to explore the genesis and metallogenic model of Shihu gold deposits, and summarizes the ore prospecting criteria and pointes out the prospecting direction.The Shihu gold orebodies mainly occurs in metamorphic rocks of the Tuanbokou group, within the mining area has been found more than 50 mineralized alteration zone. The orebodies strictly control by the direction of SN, NW faults. The common shape of ore bodies are vein or lenticular, and show the characteritics of branch-compound, pinchout-reappearance. The alterations of wall rock are potassium, silicification and beresitization, sericitization, chloritization and carbonatization. Gold mineralization is mainly relevant with beresitization and smoke-grey quartz vein. Ore types are quartz vein, fracture altered rock and quartz vein-fracture altered rock. Besides, the ore body generally located in the upper or lower of quartz-diorite porphyrite dike and near the outer contact zone.Geochemical shows that the Mapeng granodiorite and mineralization-alteration rock has a relatively uniform distribution pattern of rare earth and trace elements, and in harmony with wall rock is not good, it proves that the source of ore-forming fluid is close to Mapeng granodiorite. Mapeng granodiorite has the characteristics of high potassium and calcalkaline, high Sr/Y ratio show it belong to adakite granite, besides, basic magma element is higher than acid magma elements; Mapeng granodiorite rich in LREE, deplete in HREE, strongly fractionation between light and heavy REE and weakly negative Eu anomaly; high content of Sr-Ba and ratio value of Sr/Y, La/Yb. These suggest that that Mapeng intrusion is formed by mantle-derived magma mixed with granite magma. Combined with the analysis of the ore-forming elements, shows that the mantle-derived magma invasion and mixed with granite magma play an important role to the source of ore-forming fluid and ore-forming materials. During rise on, the granitic magma is as a carrier for ore-forming fluid and materials to protect them. The acidic magma that originated in lower curest also provide a part of ore-forming fluid and materials. So this paper thanks that the metamorphic rocks of Tuanbokou group may provide some of the ore-forming materials, but not the main source bed of Shihu gold dposit.The quartz-diorite porphyrite and granodiorite has obvious different geochemical characteristics, suggesting that the different origins of them. The characteristics of rare earth elements and trace elements of quartz-diorite porphyrite also show different with mineralized alteration rock. Combined with the feature of deposit geology, first put forward in this paper, quartz-diorite porphyrite dikes are close to orebody in time and space, these should be the quartz dioritic porphyrite dikes as impermeable layers and form a certain sealing effect for ore-forming fluid, it makes the enrichment of mineralization and alteration near these dikes.This paper reports the data of U-Pb zircon age of Mapeng granite is 124.8±1.4 Ma(MSWD=0.74) and the age of dioritic porphyrite dike is 127.3 ± 1.1Ma(MSWD=1.15). The genesis of Shihu gold deposit is close to Mapeng granodiorite. 124.8±1.4Ma should be the lower limit of metallogenic epoch, and slightly later than this age. Shihu gold deposit formed in lithospheric thinning and craton destruction tectonic setting during Mesozoic, this feature is different from the typical orogenic gold deposit; the geodynamics setting is different from typical orogenic gold deposits. Shihu gold deposit should be a kind of anorogenic gold deposits or craton destruction type gold deposit.Based on the research of Shihu gold deposit, the author system summarizes the ore-prospecting criteria of Shihu gold deposit. Based on the knowledge obtained in this paper, we points out that the south and southeast of Mapeng rock mass is good prospective area of gold deposits for Mesozoic metallogenic; Using the genetic relationships that between dike and orebody location, can indicate favorable metallogenic prospect areas; It can also be used to speculate distribution characteristics of shallow and deep orebody and ore-forming characteristics of deep orebody. According to this guidance and combination with other research of orebody 101, suggesting in the deep that to the south side of 101 orebody is likely to have a good gold mineralization.