LITHOSPHERIC STRUCTURE AND DEEP-SEATED MINERALIZATION IN JIAODONG GOLD DEPOSIT CONCENTRATION REGION, SHANDONG, CHINA
Yang Liqiang 1 Wang Guangjie 1 Zhang Zhongjie 1 Deng Jun 2 Zhao Aihua 1 Wang Jianping 2 (1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing100101, China; 2. Faculty of Earth Sciences and Mineral Resources, China Unive
The information of geophysical field was, based on the results of 1∶1 000 00 aeromagnetic anomaly and 1∶2 000 00 Bouguer gravity anomaly in Jiaodong and its neighboring regions, Shandong, China, divided into two parts: deep and shallow focus field. The information of the two different fields was then combined with these of wave velocity anisotropy and deep seated geology. The integrated result was adapted to the analysis of the three dimension structure, the probe into deep seated mineralization and the dynamics of ore forming system. This research indicated that the interaction and conversion of materials and energy in the ore forming system were restricted by the heterogeneity of lithospheric structure, resulting in effects in different aspects, such as texture, tectonics and evolution. The occurrences and processes of deposit concentration region in Jiaodong were basically controlled by the transformation of tectonic regimes. The deposit concentration region is located in the down warping area of the mantle upwelling zone, but gold deposits are located in gradient variation and deformation places of Mohole. The major mineralization intensity is located at the junction between down warping and upward region, while the minor one is located in the upward district of the upward region. The down warping area of the mantle is related to the tectonic regime of compression, but the local deformation following the down warping is connected with the tectonic regime of extension. The gold deposits, controlled by large deep seated faults and shear belts, are mainly distributed near the gradient belts of gravity anomaly and the brink of sub aeromagnetic anomaly regions, the junction between thinning positions of granites and metamorphic rocks. The Tancheng Lujiang fault is a mature lithosphere fault of deep mantle cut, and also a fluid bearing mantle shear zone. Because of long term reduction of lithospheric thickness, the asthenosphere enriched with fluid components and metallogenic elements, occurred under the Tancheng Lujiang fault where occurred the coupling of fluid heat chemistry physics. The shear anatexis of the fault was responsible for the lithogenesis and mineralization, and also for the ore forming reactivation and migration. The mantle ore fluid system was migrated to the upper horizon through this solution divergence and migration along the Tancheng Lujiang fault in the middle late Indo Chinese epoch when the alteration and mineralization took place. The uniqueness of the tectonic position of the Aishan pluton shows that the Aishan pluton might be the center of the convection and intrusion displacement of the crustal mantle magma.