Research On The Sequence Stratigraphy And Lithofacies Paleogeography Of The Majiagou Formation In Fuxian And Adjacent Areas

The thesis based on "National Major Projects" of professor, selected the "Research on the Sequence Stratigraphy and Lithofacies paleogeography of the Majiagou Formation in Fuxian and Adjacent Areas" as a doctoral thesis topic. The thesis taken the stratigraphy, petrology, sedimentology, sequence stratigraphy and lithofacies palaeogeography as the theoretical guidance, based on the outcrop observation and measured data, combined with the identification results of rock slices, made full use of the database thchnology based on the log analysis, under the guidance of the regional structure, studied on sequence stratigraphy and lithofacies palaeogeography of the study area, revealed the ancient geography variation in the system tracts frame.Combined with outcrop observation and analysis of drill core, Geophysical phase, the Majiagou formation in study area can be defined as carbonate platform depositonal system, according to the ancient geographical and hydrodynamic conditions, that can be classified as open platform, restricted platform and evaporation platform.By the Mie theory as a guide to wavelet analysis, combined to lithologic characteristics, the sequence boundaries can be identified, the three sequences can be divied in study area, and sequence stratigraphy division and contrast program was developed. The program was compared with other exploration wells within the Basin. Therefore, the consistency of partition sheme was determined. The Majiagou formation in study area can be divided into4three sequences. The boundaries of three sequence located respectively at the bottom of Ma1section, the bottom of Ma3section, the bottom of Ma5section and the bottom of Ma54sub-section. SQ1is type I sequence, equivalent to Ma1section-Ma2section. SQ2is type Ⅱ sequence, equivalent to Ma3section-Ma4section. SQ3is type Ⅱ sequence, equivalent to Ma510sub-section～Ma55sub-section. SQ4is type Ⅱ sequence, equivalent to Ma54sub-section-Fengfeng formation. Because of the exploratiory wells dirilled Ma5section focused in the Fuxian area, the exploratiory wells the data was more complete in Fuxian area were futher divided into foursequence. SQ3and ISLST of SQ4that equivalent to Ma5section can be further divided into11four sequences, that were SQ3-1～SQ3-7, SQ4-1-SQ4-4.SQ1comprised LST(Ma1section), TST(the lower part of Ma2section) and HST(the upper part of Ma2section); SQ3comprised ISLST(Ma3section), TST(the lower part of Ma4section) and HST(the upper part of Ma4section); SQ4comprised ISLST(Ma54sub-section-Ma51sub-section), TST-HST(Fengfeng formation). Ma5section located SQ3-the lower part of SQ4, SQ3was divided to7four sequence, the lower part of SQ4was divided to4four sequence. SQ4-1～SQ4-4, SQ3-1～SQ3-3were equivalent respectively to Ma510sub-section-Ma57sub-section, SQ3-4and SQ3-5were equivalent to Ma56sub-section,SQ3-6and Q3-7were equivalent to Ma55sub-section,SQ4-1-SQ4-4were equivalent respectively to Ma54sub-section～Ma51sub-section.The thesis explored the evolution of land-sea distribution in Majiagou deposition period in the study area,11systems tracts thickness maps and systems tracts lithofacies palaeogeography maps were drawn. The thesis analysised the evolution of palaeogeography in Ma5depositon period,11systems tracts lithofacies palaeography maps were drawn.