MARGIN: auto 0cm" class=MsoNormal>mes New Roman’,’serif’" lang=EN-US>Accordingly, study of Re-Os isotope system of source rocks, crude oil and bitumen can obtain the absolute dating of hydrocarbon accumulation, which has become a new research discipline in the field of hydrocarbon generation and accumulation geochronology. Re-Os isotope experimental analyses consist of sample dissolution, Re and Os chemical separation and purification, Re and Os isotope mass spectrometry measurements. The Re-Os isotopic analyses for Cambrian bitumen of the Kuangshanliang in the north Longmenshan belt indicate that the timing of petroleum generation and migration occurred at ~164 Ma and the bitumen are derived from two kinds of source rocks. ml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />