RELATIONSHIP BETWEEN THE INJECTED BASALT IN QINGSHANKOU FORMATION AND OIL/GAS IN ZHONGYANG DEPRESSION, SONGLIAO BASIN

The Cretaceous Qingshankou Formation of Songhuajiang Group comprises the main source rocks of Songliao Basin. It is proved that basalts have been injected into this formation in Qianan and Taikang areas of the central depression zone. The authors of this paper approach to the relationship between the distributive characters of the basalt and oil/gas. It is considered that axial injection and eruption of the basalt occurred along the heigh-tened Moho discontinuity of the basin during the late sedimentation stage of Qingshankou Formation. The seismic waves have rather high velocity in the basalt area and constitute dune reflective configurations. The logging curves in the basalt area are characterized by "one high and three lows". Generally speaking, drag structures related to the basalt eruption would develop beneath the basalt body while primary structures related to the dune configuration and differential compaction would develop above the basalt body. Therefore, such an area would be favourable for the traps of oil/gas. In addition, gentle baking of the source rocks by the basalt eruption and injection would improve the prospect for oil/gas exploration.