Mesozoic Tectonic-Magmatic Events and Gold Mineralization in Eastern

Eastern Shandong Province is situated at the intersection of three tectonic domains as Tetisi, Paleo-Asian Ocean and Pacific Ocean. Interaction process of these three global tectonic domains control and affect the metallogenic environment of eastern Shandong Province. This area has experienced lndosinian orogenic event and Yanshanian oro- genic event during Mesozoic period. Yanshanian orogenic event represents three tectonic episodes. Each episode repre- sents cyclicity of extrusion and extension. This cyclicity is the geological background of mineralization in Ludong gold deposit and other polymetallic deposits. Mineralization geological environment of three world-class gold fields with the reserve over one thousand tons, such as Sanshaodao gold field, Jiaojia gold field and Linglong gold field have the char- acteristics of uniqueness and induplication. Mesozoic tectonic evolution controls tectonic-magmatic event, sedimentary environment and gold mineralization. There is a strong coupling relationship between magma-sedimentary-tectonism -mineralization event and regional tectonic evolution. The formation and location of gold deposits and polymetallic deposits also have close connections with three tectonic episodes of Yanshanian orogenic event. Three mineralization events (160 - 140 Ma, 130 - 110 Ma and 105 - 80 Ma) have coupling relationship with three regional tectonic-magmatic hydrothermal events of Linglong rock mass, Guojialing rock mass and Weideshan rock mass respectively. On the basis of gold mineralization ages gained from 318 samples which have been reported in this area, three age concentration periods have been divided as 81 - 105 Ma, 110 - 130 Ma and 141 - 160 Ma. According to mineralization, deposit types and ore-forming sequences, it is regarded that mineralization in this area is synchronous with three tectonic episodes. That is the first Mo-W-Au tectonic episode, the second Au-Ag tectonic episode and the third Cu-Pb-Zn-Mo-Au tectonic episode mineralization. Typical deposits of Mo-W-Au metallogenic series are Xiangjiashan molybdenum and tungsten deposit, copper deposit and Liucun gold deposit. Au-Ag metallogenic series are major representative type of main min- eralization stages in eastern Shandong Province. It can be further divided into Au-Ag metallogenic sub-series which has close relation with mantle-crust magma interaction in early Cretaceous period; Au-Ag-Cu metallogenic sub-series which has close relation with mantle-crust magma in early Cretaceous period; and Cu-Au-Fe-Ag metallogenic sub-se- ries which has close relation with post-magmatic hydrothermal in early Cretaceous period. Typical deposits are Jiaojia gold deposit, Sanshandao gold deposit and Linglong gold deposit. Cu-Pb-Zn-Mo-Au metallogenic series is the main stage of superimposition mineralization and polymetallic mineralization with a mineralization age at 81 - 105 Ma. This series is closely related to the diorite-granodiorite-granite and quartz diorite porphyry-granodiorite porphyry-monzonite porphyry of the late Weideshan orogenic stage, and acid-intermediate volcanic-sedimentary formation of Shiqianzhuang formation in Qingshan Group.