1. College of Earth Sciences��Jilin University��Changchun 130061��China; 2. CNOOC ��esearch Institute ��Beijing 100027��China; 3. ��esearch Institute of Exploration �� Production��Tianjin Branch of CNOOC��Tianjin 300452��China; 4. Sichuan Institute of Geological Engineering Investigation��Chengdu 610000��China

Combining basin margin outcrops with basement drilling and geophysical data��a comprehensive study is conducted on the basement characteristics of basement in Yinggehai Basin for pre- Cenozoic�� Based on the sequence stratigraphic data of 18 outcrop sections��density data of 166 rock samples��and 2 800 sets of magnetic susceptibility data collected from the Song Da zone at the northwestern margin of the basin��a density- magnetic sus- ceptibility crossplot is constructed�� These data additionally provide geological constraints for the interpretations of the seismic profiles and geophysical anomalies within the basin�� A basement geologic map is subsequently drafted with a combination of marine and terrestrial perspectives�� The pre- Cenozoic basement is composed of Presinian�� Cambrian- lower Upper Triassic�� and upper Upper Triassic- Cretaceous�� Spatially�� they distribute along the ��ed ��iv- er fault zone in a NW orientation�� Chronostratigraphically and lithologically��they are characterized by a gradual ag- ing trend from the middle to the two sides�� and by a lithologic pattern of Mesozoic sedimentary rocks at west and Pa- leozoic epi- metamorphic rocks at east��