Difference Analysis Of Sedimentary Characteristics In Different Slopes Of Paleogene In Qikou Sag

The rift lake basin slope is the main site for the formation and distribution of large lithologic stratigraphic traps,but is controlled by different tectonic settings and sedimentary backgrounds.There are obvious differences in the internal structure,evolution history and genetic mechanism of different types of slopes,which lead to obvious differences in sequence stratigraphic characteristics,sedimentary characteristics and accumulation characteristics of different types of slopes.This paper takes the Paleogene key slope belt in the Qikou Sag of the Bohaiwan Basin as the research object,and systematically summarizes the genetic type of the slope of the Qikou Sag and the controlling factors of slope formation.On this basis,the author studied the sequence pattern,sedimentary filling characteristics and sand body distribution of different types of slopes,and revealed the differences in sedimentary filling characteristics under different slope backgrounds.The results show that:(1)According to the main controlling factors of the formation of the slope,the Paleogene slope of the Qikou Sag can be divided into differential settlement slope,multi-stage flexing slope,multi-step fracture slope and rotating tilt slope;(2)There are certain differences in sequence stratigraphic patterns in different slopes.The sequence pattern of the differential settlement slope is unitary type.The sequence pattern of the multi-stage flexing slope is multi-stage slope-plateau type.The sequence pattern of the multi-step fracture slope is of step-fault type.The sequence pattern of the rotating tilt slope is the fault-control slope type and the warped gentle slope type.(3)The slope sedimentary system is controlled by the internal tectonic pattern and ancient landform of the slope,and the sedimentary characteristics and sand control mechanisms of each stage of the slope evolution and each part are significantly different.The differential settlement slope braided stream delta is distributed in the high and middle parts of the slope.The low slope is mostly the offshore underwater fan and the deep or deeper lacus sediment.The sand control mechanism is erosion,fault-controlled grooved sand transport,landform sand control;A multi-stage flexing slope develops multiple slope-plateau systems.The high part is braided stream delta deposit,the middle and low part is a transition of braided stream delta sediment and the deep or deeper lacus sediment.The sand control mechanism is erosion and fault-controlled grooved sand transport,flexing slope-plateau system sand control;The high part of the multi-step fracture slope is the braided stream delta plain,the middle part is the braided stream delta plain,the low part is the offshore underwater fan sediment,the sand control mechanism is erosion,regulation groove sand transport,andthe fault-slope-break system sand control;The rotating tilt slope is divided into the early stage of the tilt and the late stage of the tilt.In the early stage of the tilt,there was a braided stream delta plain,a braided stream delta front,and a deep or deeper lacus sediment(offshore underwater fan).In the late stage of the tilt,there is a fan delta plain,a fan delta front,and a lacustrine shale sediment.The sand control mechanism is steep regulation groove sand transport,and provenance-geomorphology sand control.