Geochemistry of superhigh-wax crude oils and soluble organic matters in source rocks of Nanyang and Damintun downwarps are studied.The content of wax and saturated hydrocarbon in oii is about 50%

80% respectively.From this

we could see that terrestrial lipoid has a great contribution to the wax-bearing petroleum

and the origin of the later might be related to the parent matters rich in phyto-wax.The similarity in distribution of normalalkanes from pyrolytic kerogen

from extraction of source rocks as well as from crude oil has proved that the super high-wax crude oil of Nanyang depressionare resulted from the sapropelic source rocks near the threshold depth of mature stage.Both Nanyang and Damintun downwarps were fault-confined lakes in Tertiary developed nearby with coniferous trees.This kind of forest had certainly con-tributed a great deal of materials rich in phytogenic-wax which give rise to the foundation for formation of superhigh-wax crude oil in these basins.The meta-akaline hydrological environment was favourable to the accumulation of terrestrial lipoid and phytogenic-wax in such a downwarp like Nanyang.