GEOCHEMISTRY AND PETROGENESIS OF THE LAMPROPHYRES RELATED TO GOLD DEPOSITS IN QIXIA, SHANDONG PROVINCE

The lamprophyres in Qixia area, Shandong Province are always closely associated with gold mineralization. The lamprophyres in the studied area are mainly calc-alkalic spessartite, characterized by high alkali (K) and low Ti, with enrichment of LILEs and LREEs, and depletion of HFSEs and HREEs. Study shows that the lamprophyre should be originated from the partial melting of enriched mantle, which was formed by the metasomatism of fluid in the subduction belt. The magma, formed in island arc calc-alkalic environment, was not significantly mixed with the crustal material during its rising process. The formation of the lamprophyre is the joint effect of multiple dynamic factors.