1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. Management Center of Oil and Gas Exploration, Shengli Oilfield, Dongying 257000, Shandong, China;
3. Oil & Gas Survey, China Geological Survey, Beijing 100029, China

In order to determine the magnetic susceptibility characteristics and to summarize the influencing factors, the authors collected samples of various volcanic rocks and measured them for magnetic susceptibility from the Carboniferous Batamayineishan Formation in the eastern Junggar Basin. The average susceptibilities are 11.705×10^-3 SI, 6.325×10^-3 SI, and 0.345×10^-3 SI for basic, intermediate, and acid volcanic rocks, respectively. The magnetic susceptibility can effectively differentiate the three types of volcanic rocks with different magnetic mineral assemblages. The volcanic rocks in the study area are strongly influenced by diagenesis, and the magnetic susceptibilities are affected by mineral compositions, diagenesis mode, texture and structure,and rock alteration. Further study shows that calcareous, siliceous and other diamagnetic minerals metasomatically replaced the strong magnetic minerals such as pyroxene and hornblende phenocrysts in the rocks at different extent and filled in the apertures as the main interstitial materials, which is the major reason that results in the obviously low susceptibilities of the basic-intermediate volcanic rocks in the study area.