High-resolution sequence stratigraphy of Lower Jurassic in Ganquan area, Ordos Basin

The classification of high resolution sequence stratigraphy of Lower Jurassic in Ganquan area of Ordos Basin is discussed based on sequence deposition time and identification markers.According to interface types the Lower Jurassic sequences can be divided into 1 super-long-time base-level cycle sequence and 8 long time,32 middle long time,86 short time base-level cycle sequences.By using the technology of isochronous stratigraphic correlation of high resolution sequence stratigraphy the sequence framework is established with the framework of long time base-level cycle sequence and contrasting units of middle time baselevel cycle sequence.The Lower Jurassic in Ordos Basin formed while the basin base fast subsided then slowly uplifted and the coal seams accumulated at the basin margin,which are important evidence to recognize base-level cycle sequences.