libri’,’sans-serif’; FONT-SIZE: 10.5pt; mso-bidi-font-size: 11.0pt; mso-fareast-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: ’Times New Roman’; mso-ascii-theme-font: minor-latin; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; mso-bidi-theme-font: minor-bidi" lang=EN-US>Solid bitumen was found in the outcrops of laminated algal dolomite of the Middle Protozoic Jixian System in the southwest margin of the Ordos Basin. Bitumen was distributed in the Jixian System and migrated upward into the overlying purple sandstone of the Lower Cretaceous Luohandong Formation. Bitumen was distributed on rock bed surface or in rock pores and fractures as laminas and small veins. Distribution characteristics of chloroform bitumen A normal alkanes and the analysis of terpene and steroid biomarkers show that the bitumen is sourced from lower aquatic and algal organisms, and the laminated algal dolomite of the Jixian System is the most possible source rocks of the bitumen. The study area has the material basis and accumulation conditions for the formation of oil and gas.