SEQUENCE STRATIGRAPHIC MODELS OF THE EARLY MIOCENE IN BAIYUN SAG, PEARL RIVER MOUTH BASIN

The Baiyun Sag, as a deepwater sag, suffered complicated tectonic and depositional environment in Early Miocene. To better understand the evolution of deep-water deposits, sequence stratigraphic models are required. Based on the integrated study of seismic data, well logs and attribute maps, we established the sequence stratigraphic framework of the Miocene in the sag. Three sequence boundaries, i.e. ZJSB1(23.8Ma),ZJSB2(22Ma),ZJSB3(21Ma)were identified. The boundaries of ZJSB1, ZJSB3 are significant unconformities and ZJSB2 an incised channel base. With the above-mentioned boundaries, three sequences, namely ZJSQ1,ZJSQ2,ZJSQ3 were established. Due to the diverse tectonic movement and paleogeomorphology in the Baiyun Sag, there are two deep-water stacking models, the model consisting of channel -deep-water drape shale and the model consisting of mass transport complexes ( MTCs)- sandy clastic flow deep sea fan-channel-deepwater drape shale. In different evolutionary phases, the former is effected by sea level change, while the latter by both tectonic and sea level changes. Paleogeomorphy also plays significant role in sediment distribution. The incised channel usually occurs in high area and deepsea drape shale in low area.