An approach to genesis of Cenozoic volcanic fractures in eastern sag of Liaohe basin

Volcanic events were active in eastern sag of Liaohe basin. During Cenozoic, volcano of this area had erupted at different strengths in many periods as affected by Yanshan movement, and the Ⅰ , Ⅱ , Ⅲ episode of Himalayan movement. Fracture types in volcanic reservoirs of this area include primary fracture (including condensed constricted fissure, constricted joint and structural primary joint, and explosive fracture) and secondary fracture (including structural fracture, solution and weathered fracture) . The internal causes of forming of volcanic fracture are rock type, eruption form and position in structure; main external causes are structural movement, solution effect and weathering. The combination of internal and external causes resulted in complex fracture system in this area.