Parasequence analysis of the field outcrop sections based on the sedimentary microfacies analysis: An example from the Ordovician Majiagou Formation in Linfen, eastern Ordos Basin

On the basis of the precise measurement of the Ordovician Majiagou Formation strata and sedimentary microfacies analysis of the Jinwangfen section in Linfen, eastern Ordos Basin, 32 parasequences have been discriminated for the Majiagou Formation, and may be classified into the following two categories. The parasequence I spanning a number of micro-environments displays the shallowing-upward facies transition whereas the parasequence II deposited in a single micro-environment displays a thickening-upward trend of the sequences. The former is wide-spread while the latter is seldom in the study area. The formation of the above-mentioned types of parasequences tends to depend on the relationship and interaction of sediment supply, short-term sea-level fluctuations and stratigraphic subsidence.