Study On The Geochronology And Geochemistry Of Quartz Diorite Porphyry And Their Geological Significance, Shihu Gold Deposit In The West Of Hebei Province

Shihu Gold deposit is located in Hebei province, about 66 km to the northwest of Lingshou County. Mesozoic dikes of mining area are well developed. This paper studies quartz diorite porphyry, as one of the Mesozoic dikes exposed in the region which is not yet system research. Quartz diorite porphyry have close relations to the veins, they are nearly parallel distribution in the space. In underground often see quartz diorite porphyry and veins were for "neighbors" relationship, and a few veins were cut into the dikes. It suggests that veins should be formed after the dikes.Rock geochemical studies have shown that quartz diorite porphyry and Mapeng pluton are all the alkaline series metaluminous granites, with I type granite characteristics. Both REE and spider diagram are similar and they should be the product of the same magma evolution. The formation age of Zircon LA-ICP MS chronology of quartz diorite porphyry is 130.6-133.6Ma, and that of Mapeng granite is 127.9-133.9Ma. Therefor they have the similar formation age. Through the evolution sequence of homologous magma components it speculated that quartz diorite porphyry should be slightly earlier than the Mapeng pluton. And according to the analysis of the existing data it speculates that the Metallogenic epoch of Shihu gold deposit is later than that of quartz diorite porphyry and Mapeng pluton and it means that the Metallogenic epoch is slightly after 133Ma.From ore-forming elements of close sulfur studies, the average content of Ag、 Cu、Pb、Zn in quartz diorite porphyry respectively is 7,0.69,1.46 and 1.49 times of that of the world granites, and it reflects that quartz diorite porphyry enrich in some ore-forming elements, which is favorable for mineralization. The average of Au in the quartz diorite porphyry is 20 times of crust abundance. Hydrogen and oxygen isotope analysis reflected that hydrothermal ore-forming fluid comes from magma water, meteoric water mixed with the mineralization process. Sulfur isotope analysis show sulfur source for the mantle sulfur, including the magmatic sulfur release and the leaching out sulfur from igneous rock sulfide. Pb isotope research shows that Pb has a normal Pb isotope characteristic, and Ore Pb is mianly from the deep metamorphism in the lower crust. It speculates that the ore source beds should be plagioclase amphibolite of Archean Chenzhuang Formation in Fuping group. Through the analysis of calculating the mode age of Pb, Mesozoic granite magmas (Mapeng concealed pluton and quartz diorite porphyry) were assimilated and contaminated by the amphibolites of Chenzhuang Fm. in Archean Fuping group.To sum up, quartz diorite porphyry is I type granite and was formed during late yanshanian, consanguinity with Mapeng pluton. It speculates that there existed the concealed pluton of Mapeng granite extended eastward to the bottom of the gold deposit. Shihu gold mining area existing Quartz diorite porphyry accompanying with the veins, rich in Au, probably be one of the source bed. And through associated relations of the veins speculate in the forming process quartz diorite porphyry, its magma activates the concentration of Au in the Fuping group ChenZhuang group amphibolites. For quartz vein capture the surrounding rock formation gold mine gold provide premise...