The Analysis of Sedimentary Evolution Mode of Denglouku-Formation in Gulong Area of Songliao Basin

Abstract

By making use of the datum of seismic, drilling, logging and cores, this thesis conducted a study on the sequence stratigraphic framework and sedimentary characteristics of Denglouku-Formation in Gulong area, and analysed the sedimentary evolution mode of Denglouku Formation in Gulong area. The results show that Denglouku Formation in Gulong area can be divided into one supersequence Ⅰ, four third-order sequences (Sq1-Sq4). The depositional systems developed in Denglouku Formation in Gulong area mainly include alluvial fan, fan delta, sublacustrine fan, fluvial facies, braided river delta, shallow water delta, and lake sediment and so on. The distribution features and sedimentary evolution pattern of depositional systems of each third-order sequence are significant difference. The formations of Sq2 and lower Sq1 are controlled by rift faulting and their characteristics of sedimentary filling conform to the continental faulted basin sedimentary evolution mode. Sq3 and Sq4 formation and upper formation of Sq2 have characteristics of depression sequence stratigraphic. The upper formation of Sq2 and Sq3 formation belong to the "river - shallow delta" sedimentary model of depression basin. And Sq4 formation conforms to the “flood-overlake” model in depression basin in droughty climate.