Comparative Study On The Sedimentary Features And Stratigraphic Correlation Of Xujiahe Formation And Zhenzhuchong Member Strata In Middle Of Sichuan Basin

By applying of the principles and methods of Sedimentology and Sequence Stratigraphy, based on field outcrops, drilling, coring, logging, logging, and seismic data for the study, adopted the ways of combination traditional outdoor, indoor, and modern testing methods, this paper made a deeper study on the sedimentary of Xujiahe formation and Zhenzhuchong member in the middle of Sichuan region. Made analysis and comparison on the interface changes of Xujiahe formation and Zhenzhuchong member in this area, this provides an important basis for identify the boundary line between Xujiahe formation and Zhenzhuchong member.The fossil plants in the study horizon are gymnosperms almost, dominated by cycads and ferns, but the general and species developed differently. The black shale rich in plant fossils in the upper of the sixth member of Xuejiahe formation, and preserved well foe identification; the Zhenzhuchong member doesn't contain complete plant fossils generally, but saw a small amount of carbonized plant debris. The quartz sandstone and quartzose sandstone in the bottom of the Zhenzhuchong member is the lithologic mark of this boundary.Through a large number of outcrop and core observations, found that there are lots of offshore tidal sedimentary structures and bedding, such as bi-clay layer, flow mutation, vein bedding, lenticular bedding, etc. This show that in the later period of Xujiahe in the study area are mainly shallow estuarine facies, including the mouth bar, tidal effects of delta, estuary mud, with the tide on the intertidal zone and other environment. And the Zhenzhuchong member contains plant roots, small siderite particles, strong bioturbation, parallel bedding and other features, reveals that in the period of Zhenzhuchong the middle of Sichuan region is lake delta, and in the northeast area, there are delta front , shunt between the Gulf and the former delta sediments. Ocean tides perhaps make some influences in some areas. The seismic reflection show that the bottom of the J1z cut-off the T3x6, while the bottom of the J1z extrudoclusion this interface, revealed the bottom of the J1z is an unconformity surface, deposited on a land surface which was slightly denudation.The typical logging response characteristics of xujiahe formation is Box-shaped and the upper of T3x6 are funnel-shaped,vase-shaped,overlay funnel-shaped,and so on.But Zhenzhuchong member response characteristics of the main section of the log for the bell-shaped, stacked small funnel, vase-shaped and other forms.in the profile of the connected wells' profile,Compensation for terrain quickly filled by deposition at the age of T3x～J1z. Reveal Sichuan gentle tectonic movement smooth, no specific long-term uplift or subsidence areas, large lakes for the temple has the appearance of regional and create the conditions. Research on 14 Cutting loggings in the northeast of central sichuan,compared the defference of the upper and lower boundary near the Xujiahe formation and zhenzhuchong member. Research on the cutting loggings of the upper and lower of the boundaries of Xujiahe formation and zhenzhuchong member ,the result and combinations are many and varied.According to field section,core,logging,et at al, summarizes the differences in the color, paleontology, sedimentary structures, diagenetic epigenetic minerals, logging curve shaped morphology, etc between the upper and lower boundary near the Xujiahe formation and zhenzhuchong member.