Characteristics Of Source-to-sink Of The Paleogene In The Shinan Steep Slope Zone Of The Bozhong Sag And Its Control On Glutenite Deposits

Taking the southern steep slope zone of Shijiutuo uplift in Central Bohai Depression as the main research area,using the latest seismic,logging,core and mud logging data,combining with seismic interpretation results and drilling core analysis,the characteristics of the Paleogene "source-to-sink" system in Shinan steep slope zone and its controlling effect on the sedimentation of glutenite are semi-quantitative and qualitative studied.Combining with drilling,logging and seismic data,through stratigraphic division and correlation,four second-order sequence interfaces,three third-order sequence interfaces and two fourth-order tract interfaces in key third-order sequence are identified,and the Paleogene sequence stratigraphic framework in the study area is established.Based on the study of sequence stratigraphy,the characteristics of source-to-sink system in the study area are studied.In terms of provenance characteristics,Mesozoic clastic rocks and volcanic rocks,Carboniferous-Permian clastic rocks,Cambrian-Ordovician limestone and Archaean granite can be seen in the residual basement of the uplift;physical weathering is the main source area in hot and dry climate,while chemical weathering is the main source area in warm and humid climate.In the aspect of detrital material transport channel,combined with seismic data,different types of sand transport channels such as V-type,U-type,W-type and single fault trough are identified on the uplift,Among them,U-type gully and single fault trough have the strongest sediment transport capacity and the widest distribution.In terms of the types and characteristics of basin-controlling faults,the basin-controlling faults in the study area can be seen as echelon,bifurcation and corner faults in plane,plate faults,shovel faults,slope faults and multi-stage faulted terraces in section,and they show episodic activities in the whole Paleogene.In terms of the sedimentary characteristics of glutenite,the Paleogene in the study area developed sandy depositional systems such as nearshore subaqueous fan,fan delta and braided river delta.In the early stage of Shahejie Formation and Dongying Formation,fan deltas and offshore subaqueous fans dominated the sedimentary facies,while in the late stage of Dongying Formation,braided river deltas dominated the sedimentary facies.At the same time,through quantitative and fine characterization of the glutenite,it is found that the glutenite deposits in the Sha-3,Dong-3,Dong-2-lower are thicker,while the glutenite deposits in the Sha-1 and Sha-2 are thinner.Based on the characteristics of source-sink system and distribution of glutenite body,the controlling effect of source-sink factors on glutenite deposit is studied quantitatively and qualitatively.It is found that when the volcanic or granite source is supplied,the physical weathering is stronger in dry and hot climate,the catchment area is larger and the number of inner valleys is larger,the large-scale glutenite body is easy to deposit.When the clastic or limestone source is supplied,the chemical weathering is stronger in wet and warm climate,the catchment area is smaller and the number of inner valleys is smaller,the size of glutenite body is generally smalle;When the fault activity rate is high,the sedimentary glutenite body has small scale,short extension distance and large thinning out angle,while the fault activity rate is small,the glutenite body has large scale,long extension distance and small thinning out angle;Fault wall angle,single fault trough entering lake along source direction,shovel fault with small dip angle and downthrow wall of secondary step fault in multi-stage fault step are often favorable areas for enrichment of glutenite.