Abstract:

The volcanic cones of Early Tertiary are widely distributed in Huimin sag,Shandong.According to core descriptions, thin-section identifications, petrochemical analysis and comprehensive researchs of logging data and features of sesmic profiles, the development characteristics and formation mechanism of the volcanic cones have been studied profoundly. It is revealed that in the studied area, the lithology of the main volcanic cone is basaltic pyroclastic rock, and the volcanic activities have the characteristics of long term and multistage. The magma was mainly origined from the magma chamber in the middle and shallow crust, and the near east-west fault systems were the major passages through which magma was erupted to the earth surface and formed volcanic cone.The activity intensity and combinational models of the faults controlled the developments and distributions of volcanic cones. On the basis of the above, the eruptive models of volcanic rocks are summerized,which are  fracture, transitional and central eruptive models. There are different volcanic activities, petrofacies distribution and hydrocarbon-bearing in different kinds of eruptive models.

Key words: Huimin sag, volcanic cone, fault systems, magma chamber, eruptive model