Various data including common thin sections

cast thin section

cathode luminescent thin sections and poroperm characteristics were used to analyze the influence of petrologic characteristics on diagenesis and pores development of the Yanchang Formation in Longdong area

Ordos Basin.The results show that the types and contents of debris

the contents of minor minerals(such as mica)and the size of the clastic particle are the main factors affecting diagenesis.The existence of large amount of plastic debris from rocks such as mudstone and phyllite reduces the strength of rock.These plastic debris are vulnerable toe compressional deformation during burial and can form pore-filling pseudo matrix.The existence of soluble debris from rocks such as carbonates and intermediate and acidic volcanic debris can enhance solubility of rocks

being favorable for the formation of dissolution pores.With the pore water participation

the hydration of minor minerals can release potassium ion which causes alkaline environment.This can reduce quartz stability

and promote the pressure solution of quartz and the formation of the sutures.On the other hand

the silicon-aluminum-iron composition being released from mica alteration could form chlorite membrane cement around quartz and feldspar particles

and kaolinite and iron bearing mineral cement in intergranular pores.These cements can reduce porosity and permeability.Grain size mainly controls the compaction resistance and bond strength of sandstone.