利用马尔可夫链分析识别内蒙古正镶白旗额里图组沉积特征

通过野外地质剖面实测识别了额里图牧场额里图组各层岩性特征，利用马尔可夫链分析方法分析该剖面下岩段地层的沉积旋回，综合地质基础资料，进一步分析了沉积环境.结果识别出一个以砂岩-粉砂质泥岩-粉砂岩-泥岩为特征和一个以砂岩-灰岩-泥岩为特征的两个岩性旋回，分别代表浅海陆棚-深水浊积岩相序和陆棚浅海礁滩相沉积.结合剖面分别划分出陆棚、斜坡和盆地（海槽）3个相，进一步识别出潮坪滩相、滩前斜坡相、浊积滩坝相、滩相、斜坡盆地相、缓坡相、深水海槽相和礁滩相等亚相.整个剖面由两次海侵半旋回和一次完整的海侵海退旋回组成.研究认为古亚洲洋的最终闭合时限应该在额里图组时期之后.

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.