Abstract:

Volcanic eruption is layered and rhythmic，so，the stages of volcano activities are the basic units dividing and correlating volcanic rock formations.The determination of stages can be helpful to solve the problems of division and correlation of carboniferous volcanic rock formations in the northwest rim of Junggar Basin，Xingjiang.In this paper，the results of statistics of lithologic and electronic characteristics are probed to describe the law of stage change of volcanic rocks，and the characteristics of volcanic rock change in different stages are revealed.The method of lithologic texture division is used to study carboniferous volcanic lithology in Ke well 92 region，by researching the types of volcanic rocks，transporting means of volcanic materials，the products of volcanic action and the disposing relationship，the dividing ways and the distributing model of volcanic lithologic facies are set up，it is presented that volcanic lithologic facies are composed of crater subfacies，near crater subfaices，lava platform subfacies，volcanic sedimentary subfacies and secondary level mocrofacies，and the lithology and special distribution of different stages and different volcanic eruptive materials are described based on lithologic division.

Key words: Junggar Basin, igneous rocks, stage division, lithologic facies study, lithologic texture and composition classification