On Meso-Neoproterozoic primary petroleum resources

In view of global scale,primary oil and gas reservoirs of the Meso-Neoproterozoic,and even the Lower Cambrian,have been reported in cratons of Siberia,Africa,East Europe,India,Arabia and Australia,especially in the East Siberia and Oman regions,so far the proved oil and gas reserves are up to a scale of 108t to 109t of oil equivalents,which testifies that the Meso-Neoproterozoic petroleum is an energy resource realm worthy of notice.In China,the thermal evolution levels of the Meso-Neoproterozoic,and even the Lower Palaeozoic strata are commonly in overmature phase unfavorable for the preservation of liquid oils,thus,Meso-Neoproterozoic primary oilfields are not yet discovered up to now.However,a large number of oil seepages and/or large scale bituminous veins are found in the Meso-Neoproterozoic,the analysis of the primary petroleum prospectivity would be helpful to guiding the exploration of Meso-Neoproterozoic oil and gas resources.The cumulative thickness of overlying sedimentary covers is not big enough so that the Meso-Neoproterozoic strata have never been deeply buried,or the lithosphere is unusually thickening,resulting in a geological condition of "cool lithosphere and cool basin".Therefore,as the Longmenshan piedmont belt in the Yangtzi Craton and the North Yanshan Depression zone in the North China Craton are taken as examples,the Meso-Neoproterozoic primary hydrocarbons would be always within the category of "liquid oil window",which should still favor the preservation of the Meso-Neoproterozoic primary oil and gas resources.