Volcanic rocks, basin evolution and related CO2- Au mineralization in Shengli Oilfield, China

According to geological and geochemical characteristics, the volcanic rocks from the Shengli Oilfield can be divided into three major types. The quartz tholeiite basalt erupted in the initial stage of the basin openning, which underwent an obvious contamination by materials derived from continental crust. The olivine tholeiite occured in the inner part of the basin, accompanied with the main extension of the basin. The alkali-olivine basalt occured, along the boundary faults, in the later stage of the basin evolution, namely, the down-depressing stage, which was controlled by deep fractures. From the guartz tholeiite through the olivine tholeiite to the alkali-olivine basalt, the magma chamber must have migrated from the shallower to the deeper. The alkali-olivine basalt is highly enriched in CO2, Au, alkali, LREE, LILE and relatively depleted in Cr and Ni, which may be derived from the enriched and replaced mantle, so as to have closely space-temporal genetic relations with the CO2 gas-fields and Au mineralization.