The Application Of Seismic Stratigraphy On The Analysis Of Prototype Basin

The basin type in Kongdian Stage of Eocece, the southern Kongnan of HuanghuaDepression is initially faulted basin. These days residual basin has been evolved fromprototype basin through different stages, dissimilar influencing factors and unequallevels of superposition, transformation and deformation, and there are also differencesin the basin structure, basin type and deposition characteristics in four sequences andtectonic regions, so the petroleumgeological characteristics of four layers are unequalin the period of Kongdian basin, not conductive to the oil and gas exploration anddevelopment. Therefore, a clear understanding of the factors that transformation anddeformation in Kongdian basin, how the prototype basin conducted this process, thepattern of the single layer after superposition, transformation and deformation, thesedimentary response, the superimposed relationship between the lower and upperlayers appears to be very necessary.The previous study on the prototype basin mostly has been conducted on thecompressional basin, whereas less experience on the extensional basin. In this thesis,one systematic research theory and methods on the prototype basin recovery of theextensional basin has been summarized by the main application of SeismicStratigraphy, combining with the disciplines of Structural Geology, Geophysics,Sedimentology. Firstly, establishing four layers of Structural-Sedimentary Frameworkin seismic profiles associated tectonic activities, sedimentary response and tectonicactive stages to analyze the tectonic factors affecting the deposition of the Kongdianstage prototype basin. Distinguishing pre-depositional tectonics, syn-depositionaltectonics and post-depositional tectonics was to define how tectonic events hadaffected the deposition and transform the basin pattern of prototype basin. Combining with results of previous studies, the patterns, the structure, and tectonic sedimentaryfeatures, evolution stages of prototype basin have been commonly restored. The resultsreveal five tectonic activities controlled the deposition, transformation and deformationon prototype basin: Tectonic stretching, Cangdong Fault, Xuxi Fault, Kongdian Archand Kongdian Sub-arch, yet tectonic active stages, degree of development anddeposited response of these factors are obviously and relatively different in dissimilarsequences and tectonic regions. However, the study based on the division of HuanghuaDepression into Nanpi Tectonic Unit and Cangdong-cangzhuang Tectonic Unitdisplays that tectonic active stages, degree of development and deposited response ofthese factors exist in unity and inheritance. In Nanpi Tectonic Unit, the impacts fromtectonic stretching, Cangdong Fault and Xuxi Fault on the deposition of prototypebasin, transformation and deformation in post-depositional prototype basin, thetectonic stages in four sequences of prototype basin are continuous: Depression Period(SQ1)â†'Depression Period (SQ2)â†'Initially Faulting Period-Faulting Period (SQ3)â†'Faulting and Filling Period (SQ4), and in Cangdong-cangzhuang Tectonic Unit, theinfluences from tectonic stretching, Cangdong Fault, Xuxi Fault and Kongdian Archand Kongdian Sub-arch on the counterparts are also continuous: Initially FaultingPeriod (SQ1)â†'Depression Period (SQ2)â†'Faulting Period-Faulting and FillingPeriod (SQ3)â†'Faulting and Filling Period (SQ4).Based on the analysis of outliers on the Vertical Second Derivative of Gravityanomaly, the ways of stratigraphic Correlation, Geologicalthe Extrapolation andAnti-section was used to recover the distances from prototype basin boundaries to theresidual basin boundaries aiming at four dissimilar Basin Margin Types: Truncation,Thinning cut, Thiching cut and Equi-thichness cut. Using the Balanced ProfileTechnology calculated the amount of tectonic stretching in different deposition stagesand tectonic regions. The results show that the recovering distances coincidewith or are close to the maximum range of prototype basin ensured by Vertical SecondDerivative of Gravity anomaly in SQ2of Wang Guantun area, SQ3and SQ4ofCangdong Fault zone, proving to be of the reliability and feasibility in the recoveringresults. The SQ1prototype basin deposition range is far smaller than its counterpart inresidual basin, then the SQ2prototype basin deposition range is close to its counterpartexcept that exceeding the residual basin boundaries and closing to the the maximumboundaries in Wang Guantun area, the SQ3and SQ4prototype basin deposition rangesare slightly larger than their counterparts in residual basins, revealing a great amount ofsediment filling after tectonic stretching, Cangdong Fault and Xuxi Fault avtivities. Finally, integrating with the types of prototype basin, the structures of prototypebasin, and deposition ranges of prototype basin respectively made an inversion in theprocess of deposition and superposition, transformation and deformation on prototypebasin in Nanpi Tectonic Unit and Cangdong-cangzhuang Tectonic Unit in KongdianStage of Eocece, the southern Kongnan of Huanghua Depression.