THE CENOZOIC BLIND VOLCANICS OF THE NORTHERN SHANDONG PROVINCE AND ITS PETROLIUM GEOLOGICAL SIGNIFICANCE
鲁北新生代隐伏火山岩及其石油地质意义

The outcrop areas of the volcanics are in two basins: Chanwei and Dezhou basins, and three fault-rifted zones: Binxian, Wudi, Yinan, and near the Wu-3 well of Chengzhikou. The volcanic eruption here are divided into three stages and six substages, i.e. the Tertiary stage includig 3 substages of the early-mid, mid-later and late Eocene, the Neogene stage and the Quaternary stage. Lithologically, the volcanics have basalt, andesite, quartz tholeiite, olivine tholeiite, olivine basalt, alkaliolivine basalt, picrite-porphyrite and sublake pyroclastics(i, e. basaltic tuff and basaltandesitic volcanic breccia). The first stage is talc-alkaline, with quartz tholeiite. The 2nd one is alkaline, with olivine tholeiite etc., partly containing nepheline. The 3rd stage is super-alkaline basanite, with nepheline and lencite. Geotectonically, our working area belongs to rift basins near continental margin. This condition are favourable for the deposition of source rocks rich in organism, the formation of different types of reservoirs, oil-bearing traps and the long-period stablity of heat flow, which are great help in the maturated transformation of organism. The volcanics and its related diabase may bring about nice secondary pores themselves, a fracture reservoir, which is an important oil-deposit. Moreover, volcanics sometimes can play a role as cap or seal of rocks and base of trapping structures. Therefore, the study on volcanics not only has a theoretical significance about tectonic movement and magmatic activity, but also possesses an actually important value in the petroleum geological exploration.