Division of Volcanic Cycles and Stages of the Haerjiawu Formation in Malang Depression,Santanghu Basin

In order to study the reservoir distribution feature of volcanic rock,it is necessary to divide the cycle and eruptible stage.The paper divides the cycle and eruptible stage through varieties of methods such as thin section authentication,eruption rhythm recognition,electrical characteristics analysis and seismic reflection feature analysis.Lithology of volcanic rock is lava and pyroclastic rock by the thin section analysis.There are four types of volcanic eruption rhyme.Those are overflow,transition from overflow to explosive,explosive and the mixed type of lava and pyroclastic rock.The overflow type is the main type of volcanic eruption rhyme.Volcanic rock of Haerjiawu Formation is divided four stages by assembling the different rhyme.The four stages can be divided into two sub-cycles.There is an intermittent process of eruption and dormant.