Abstract: It is much more difficult to identify fractures in marine-continental transitional facies tight clastic rocks from well logging,so a study was proposed to carry out quantitative identification on single-well fracture development sections in marine-continental transitional facies clastic formations by using array sonic logging data, combined with the Gassmann equation, adaptive matrix mineral and skeleton modulus extraction method, and DEM theoretical model. It is shown that the extracted Ko(matrix mineral bulk modulus of clastics)ranges from 13 to 58 GPa, which is slightly higher than Ks (bulk modulus)and Kd (dry rock skeleton bulk modulus), and μo(matrix mineral shear modulus) ranges from 5 to 18 GPa, which is slightly higher than μs (shear modulus). Shear wave time difference can be predicted effectively with relative error 3.5% from adaptive method. Fractures can be predicted by introducing modulus parameters extracted by the adaptive method into the DEM theoretical model, and its coincidence rate is apparently superior to that of the conventional logging method, the fracture parameter method,the multi-parameters probability discriminance method and the R/S method. In conclusion, the newly proposed fracture identification method is reliable, with its calculation results highly coincident with practical value.