Acritarchsof Fengtai Formation In Madian Area And Their Relationship With Source Rocks

After identification,it is found that the Acritarchs is mainly paleontology of the Fengtai Formation in the Madian area.And the Leiosphaeridia is the most type in Acritarchs.The AHC(Asteridium-Heliosphaeridium-Comasphaeridium)assemblage is not found at the base of the Cambrian.However,there are Cambrian endemic paleontological species such as Asteridium and Skiagia are found at the top of Fengtai Formation.After comparative analysis biostratigraphy of Acritarchs and its vertical evolution.The similar assemblage is found at the bottom of Fengtai Formation like late Neoproterozoic strata,and the upper part of the Fengtai Formation is similar to the Cambrian strata.The division of Fengtai Formation was discussed Combined with the evidence of the Acritarchs evolution and the extinction events of late Neoproterozoic.The Fengtai Formation is divided into two segments,one is the buttom is Neoproterozoic strata,and the top is Cambrian strata.Therefore,the Fengtai Formation is considered as a transitional stratum from Neoproterozoic to Cambrian.To analysis the assemblage and form of Acritarchs at the Fengtai Formation is found that the shell was smaller at the Neoproterozoic to the Cambrian,and the type was decreased.This is similar to the same layer in other regions,it is related to Glacier events and water depth changes.The color of the Acritarchs mainly are brown black and black in the Fengtai Formation,the maturity of the source rocks is very high.And the difference of the Acritarchs in the vertical direction leads to the difference of the abundance,distribution and the preservation in the source rocks.It has a profound effect on the diagenesis process of source rocks.The gas production potential of Fengtai Formation is analyzed because the Fengtai Formation is considered to have good potential of gas production.The source rock is still in the range of gas production,but because of the high maturity,biogas is difficult to generate.The experiments were designed to make a more comprehensive understanding of the gas production in the Fengtai Formation.And it is found that source rock can be decomposed before the early stage of the diagenesis.This also provides evidence for evaluation of the Fengtai Formation source rocks.