Mafic Dicks Features And The Rlationship With Gold Mineralization In Shandong Province

Shandong Province is located in the southeastern margin of the North China Craton, is a very important gold focus area. Most of the gold deposits in the area, there are a lot of mafic rocks, including lamprophyre, diorite, gabbro, diabase. For a long time, on the relationship between the causes of the mafic rocks and gold mineralization is inconclusive. This article is based on petrographic, geochemical and mineralogy methods, attempts to summarize the mafic dikes of temporal and spatial distribution, discuss its causes, source material relationship with gold mineralization, provide the basis for research in this area gold mineralization patterns and explore gold mineralization rule.Studies have shown that, Mafic dikes in Shandong Province mainly potassium calc-alkaline and shoshonite series, showed large LILE enrichment(LILE), light rare earth elements(LREE), depleted in high field strength elements(HFSE), heavy rare earth elements(HREE). Most of them formed mainly volcanic arc environment, causes, and the Pacific plate subduction to the north there is a certain relationship. Its cause is due to the enrichment of incompatible elements lithospheric mantle partial melting, fractional crystallization and a certain degree of crustal melt rises occurred in mafic mineral contamination.Further studies also showed there are differences in the characteristics of the mafic dikes of different regions. Among them, Jiaodong is most of lamprophyre and diorite, Luxi mostly diabase, gabbro, diorite. In addition, rock index characteristics and REE characteristics show: the mafic dikes magmatic differentiation degree and alkalinity of Qixia and Yishui is weaker and lower than the other areas, other regions are similar. Sr-Nd isotopic characteristics also revealed: Jinan and Laiwu Zouping gabbro and diorite is EMⅠ mantle, It should be the product of ancient lithospheric mantle melting. Jiaodong most mafic dikes are EMⅠ+EMⅡmantle, as well as the Shangyu and Yishui diorite, This mantle may be affected by the impact of the Yangtze subduction.By calculating mafic dikes pyroxene and amphibole of temperature and pressure conditions showed that: 1. From Luxi(1139.50~1201.08 ℃, 0.08~5.77kbar) to Qixia(1178.85~1272.69℃,3.71~12.36 kbar), for diabase, a pyroxene of temperature and pressure conditions on the rise, so the formation depth increases; 2. For lamprophyre, Zhaolai(1197.02~1284.38 ℃, 5.38~13.44kbar) pyroxene temperatures and pressures were significantly higher than the Muru(1100.81~1278.53℃,0.27~12.90 kbar), so the formation of deeper depth; 3. Crystallization temperature and pressure inside several dikes amphibole calculation results show: Luxi Tongshi mine maximum(6.02~9.41 kbar); Jiaodong northwest Linglong mine(2.73~5.91kbar), Qixia Hushan Mine(3.45~6.13kbar), Muru Guocheng mining(4.24~7.47kbar) and Wanggezhuang region followed(0.35~5.95kbar); Temperature and pressure conditions of Tongjing Luxi mining(1.15~6.91kbar) and Qixia some areas(0.07~0.56kbar) are relatively low.In summary, mafic dikes in time and space relationships consistent with the gold veins and mafic dikes tend to have a higher gold content. Therefore considers(8 mafic dikes) plays an important role in the process of gold mineralization, indicative significance for gold mineralization.