Studty On The Mineralization And Prognosis In Qiyugou Gold Deposit, Henan Provice

The metamorphic core complex of Mt. Xiong'er, formed in the background of regional extension of Mesozoic Era, plays a controlling role in the formation of gold deposits in the mining area. The ore-controlling structures in the metamorphic core complex mainly include gently inclined structural fracture zone in the detachment fault, gently inclined fault, steep inclined fault and explosive breccia pipe near the detachment fault. Qiyugou ore-field is mainly controlled by steep inclined fault and explosive breccia pipe near the detachment fault. The gold deposits of explosive breccia pipe type are of great importance to the ore-field.Through the key analysis to J4 deposit and the contrastive study between this deposit and others, the following achievements and conclusions are made.(1) The metallogenic geological conditions of the research area have been deeply analyzed from geological, geophysical, and geochemical aspects. The research also enriches the theory that the explosive breccia pipe typed gold deposits and the structural altered rock typed gold deposits in the mining area are controlled by metamorphic core complex. In Mesozoic era, the regional structural process shifted from compression to extension, followed by the formation of Mt. Xiong'er metamorphic core complex, the uprush of deep-seated materials, the large-scaled emplacement of magma and the large-scaled mineralization of gold.(2) Through the key analysis to J4 deposit, new understanding to the metallogenic characteristics of explosive breccia typed deposits has been obtained, which offers a new mind for studying explosive breccia typed gold deposits. The height of 490m above sea level in J4 deposit is regarded as a borderline; above that it is characterized by vein-typed mineralization, while below that it is characterized by irregular mineralization. Furhthermore, the hydrothermal fluid alteration in the J4 explosive breccia rock body is characterized by concentric ring zones. From the core to outer zone of explosive breccia rock body are the following rock zones: quartz-potash feldspathization zone, quartz-biotite zone and propylitization zone. The irregular mineralization is mainly located at the contacting zone between quartz-potash feldspathization zone and quartz-biotite zone.(3) Through contrastive study, J4 deposit is confirmed to be the explosive center (mineralization center) of the ore-field. It is concluded that there are two metallogenic systems in this ore-field, namely, the granite-porphyry gold metallogenic system and the monzonitic-porphyry molybdenum metallogenic system. The first system is formed earlier than the second one. Multi-type deposists are the outcome of same source and phase, but are formed in different metallogenic stages and structural space. The metallogenic materials mainly come from magma fluid, with partially coming from stratum. In addition, the metallogenic fluid is neither magmatic thermal water nor thermal brine, but between the two types. Compared to the deposits with same type in domestic and abroad, the explosive breccia typed deposits in the ore-field has its unique characteristics, which includes complicated breccia components, diverse mineralization, various types of minerals, clear zoning of hydrothermal alteration and few associated components.(4) The metallogenic models of deposit and ore-field have been initially established. It is firstly put forward that there are four phases of ore-formation in the ore-field. The irregular ore-bodies are firstly formed, followed by structural altered rock typed gold deposits (Gongyu deposit), polymetallic sulphide typed gold deposits and molybdenum mineralizaion.(5) In terms of the heterogeneity of irregular mineralization, the concept of"mineralization area"is put forward, which is to be a good guide to the delineation and exploration of gold ore bodies. According to the comprehensive surveying predictors, the ore prospecting prospective of the explosive breccia rock bodies in the ore-field has bee assessed, which is of great importance to the ore prospecting.