Sedimentary facies and cyclostratigraphy of the Cretaceous first member of Nenjiang Formation in the Southeast uplift zone,Songliao Basin and its correlation with the CCSD-SK-I

Described(centimeter scale) the field section of Cretaceous Nenjiang Formation(K_2n) in southeast uplift zone of Songliao Basin.There are three sedimentary subfacies including deep lake,shallow lake and coastal lake subfacies.The water level fluctuated frequently with large fluctuation amplitude.The first member of Nenjiang Formation was composed of 34 meter-scale cycles, 11 fifth-order cycles and 2 fourth-order cycles in the field section.Ostracoda limestone layer,dolomite concretion and volcanic ash layer which developed in the field section were also found in the core section of CCSD-SK-I.Comparing the Fischer plots between the field section and the core section,from the fifteenth cycle to twenty-fifth cycle,the depocenter of Songliao Basin moved from southeast to northwest corresponding to the uplift of eastern basin.