Relationship Between Carboniferous Sedimentary Facies and Source Rock in Qaidam Basin

This paper researched sedimentary styles and characteristics and discussed about Carboniferous sedimentary evolution of different stages as well as relationship between Carboniferous sedimentary facies and source rock. It is epicontinental sea in Carboniferous of Qaidam. Sedimentary environment can be divided into three sedimentary facies:shore facies,carbonate plateau facies,neritic marine basin facies and six subfacies:shallows subfacies,tidal flat subfacies,swamp subfacies,open platform facies,restricted platform subfacies and inner shelf subfacies. There are two marine ingression in Early Carboniferous and everlasting transgression in Late Carboniferous. Sedimentary environment evolves from offshore to epeiric sea and mainly develops paralic sedimentary environment. The overlapping phenomenon arose in the north foreland because of wide area transgression. The distribution of source rock is controlled by sedimentary facies:mudstone,carbargilite and carbonate are favourable source rocks,which develop in swamp subfacies or inner shelf subfacies of carboniferous in the northeast of Qaidam basin; restricted platform subfacies is also a favourable source rock distributed area because of deeper water,smaller kinetic energy,abundant organic material,which develop in relatively restricted area of Lower Carboniferous in the southwestern margin of Qaidam basin.