SEDIMENTARY CHARACTERISTICS OF ELITU FORMATION IN ZHENGXIANGBAI QI OF INNER MONGOLIA IDENTIFIED BY MARKOV CHAIN ANALYSIS

The lithologic characteristics of each layer of Elitu Formation are identified by field survey of geological section. The sedimentary cycles of the strata are studied by Markov chain analysis, and the sedimentary environment is further analyzed with the basic geological data. Two lithologic cycles characterized separately by sandstone-silty mudstone-siltstone-mudstone and sandstone-limestone-mudstone are identified, which represent the facies sequence of shallow sea continental shelf-deepwater turbidite and continental shelf shallow sea reef beach sediments respectively. Combined with the section, three facies including continental shelf, slope and basin(trough) can be further identified as several subfacies such as tidal flat beach, beach front slope, turbidite beach bar, beach, slope basin, gentle slope, deepwater trough and reef beach. Two transgression semi-cycles and one complete transgression-regression cycle can be recognized in the section. It is concluded that the final closure time of Paleo-Asian Ocean should be after the period of Elitu Formation.