Research On Seismic Sedimentology Of Upper Cretaceous In The Middle Section Of Southern Margin Of Junggar Basin Foreland Slope

The southern margin of Junggar basin is located at the northern foot of Tianshan mountain in Xinjiang Prov.It is located on the northern border of Aljin Mountain,western border of Kazakhstan,eastern border to the Beita Mountain.It is the representative of the reborn continental basin.Junggar block experienced the Indosinian movement,Yanshan movement and Himalayan movement from the ancient Cambrian period until the neogene.In late Permian,Junggar basin gradually changed from the lacunae ocean basin to the continental sediments.It has formed giant thick quaternary sediments and produced a variety of rock facies association and sedimentary system in southern region since Carboniferous.The aim layer is Donggou group which formed in Mesozoic cretaceoust.The target is based on dividing sedimentary system of Donggou group under the guidance of seismic sedimentology,earthquake petrology,geomorphology,seismic facies analysis.It is four subjects under the guidance of sequence stratigraphy integrated research relying on the outcrop evidence,single well facies and seismic interpretation data,the seismic facies analysis,palaeogeomorphology analysis technology,They are all powerful evidence of sedimentary system in the late cretaceous period Donggou group.The research suggests that(1)The formation of northern Tianshan is broken and complex in structure due to Indosinian,Yanshan and Himalayan movement.It is difficult to fully display the fine structure model and the sedimentary microfacies boundary from the quantitative angle.The four provenance systems in the middle period of the southern margin of Donggou group are obtained from the macroscopic view with the two dimensional and three-dimensional interpretation results guided by the ancient landscape restoration technology.(2)In the outdoor field,it is observed that the sedimentary structure of the Donggou formation mainly consists of ripple bedding,staggered bedding and horizontal bedding.And it has found that the lithology is mostly gravel fine sandstone,reddish brown gravel and common scour surface from the single well coring.Furthermore,the sedimentary features of river facies are remarkable.(3)In this paper,we get the average absolute amplitude,root-mean-square amplitude attribute from the 2d and 3d seismic work area.The high value area is like a stripe,and also has good correlation with the strike of the river.It can distinguish river sedimentary facies belt boundary of Donggou group.(4)Using qualitative seismic facies to study the regularity of seismic reflection structure and single well sedimentary facies near the well.It can also be used to predict the sedimentary environment of the Donggou formation without well and less well.Based on the ideas of seismic sedimentology,this paper studies the characteristics of the alluvial-river facies in the Donggou period from two aspects of seismic interpretation and geological analysis,which has formed an important reference significance in dividing favorable areas for oil and gas.