Abstract:

The second and third member of the Qingshankou Formation recovered by CCSDSKⅠs borehole (China Cretaceous Continental Scientific DrillingSongkeⅠthe south borehole) is 41561 m long and 100% of cores recovery. The age of the member corresponds approximately to the Coniacian. The sequence and process of lithologylithofacies and cyclic stratigraphy were revealed by a detailed core description. Twelve rock types and two kinds of sedimentary subfacies including deep lake and shallow lake were recognized from the drilling core of the second and third member of the Qingshankou Formation. Ten sedimentary microfacies are present, including dolostone, marl, limestone, oil shale, deep lake turbidite, volcanic ash, seismite, deep lake mudstone, shallow lake mudstone and shallow lake turbidite microfacies. The second and third member of the Qingshankou Formation represents four hundred and twentytwo meterscale cycles (sixthorder cycle), one hundred and thirty fifthorder cycles, twentyone fourthorder cycles and one thirdorder cycles. The special lithologies such as mudstone, seismite, dolostone, volcanic ash and so on are important to researches on source rocks and lacustrine event sediments.

Key words: the second and third member of Qingshankou Formation; sedimentary facies; sedimentary sequence; cyclic stratigraphy; CCSDSKⅠs; Cretaceous Coniacian; Songliao Basin