The Sequence Stratigraphy Characteristics and Controlling Factors of the Shahejie Formation of the Central Uplift Belt in Paleogene in Huimin Depression, Shandong Province

The sequence stratigraphy studies of the Shahejie Formation in the central uplift belt of Huimin depression of Shandong province indicate that tectonic movement and climate are dominant controlling factors to sequence development. The 2, 3and 4 submembers of Shahejie Formation can be divided into three types of stratigraphic sequence, i.e. the stratigraphic sequence in primary rifting stage, the stratigraphic sequence in violent rifting stage and the stratigraphic sequence in the later rifting stage. The sequence stratigraphy indicates that it is more suitable to divide a sequence into four system tracts in the lacusstrine basin including lowstand system tract (LTS), lake transgressive system tract (TST), highstand system tract (HST) and falling stage tract (FST). According to characteristics of lake level change and its corresponding sediments, the sequence boundary is located between the LST and FST. The red beds stratigraphic sequence is mainly controlled by the climate and has unique characteristics in sequence evolution, which is different from the alluvial fan stratigraphic sequence and also different from the normal lake facies stratigraphic sequence. Influenced by tectonic movement and sediment supply, three kinds of stratigraphic sequence in this region form three kinds of condensed sections, which located in different section of each sequence. The different condensed section will influence the abundance of source rock and resources, and every condensed section controls the distribution and thickness of the source rock.