CHARACTERISTICS AND SIGNIFICANCE OF BIOMARKER COMPOUNDS IN SOURCE ROCKS OF HONGSHUIZHUANG FORMATION IN LINGYUAN AREA, WESTERN LIAONING DEPRESSION

Gas chromatography(GC) and gas chromatography-mass spectrometry(GC-MS) are used to analyze the organic matter sources, sedimentary environment and thermal evolution degree of source rocks. The results show that the distribution of n-alkanes(m/z85) of source rocks from Hongshuizhuang Formation is dominated by front peak type unimodel. The main peak carbon is mostly nC₁₈, indicating the organic source is mainly lower organism. The tricyclic terpenes show a normal distribution with C₂₀ or C₂₃ as the main peak, and the ratio of C₂₄-tetracyclic diterpenes/C₂₆ tricyclic terpenes is 0.35-1.38, averagely 0.65, indicating that there is input of lower organism in Hongshuizhuang Formation. The steranes show the dominant C₂₇ sterane L-shape distribution, suggesting that the source of hydrocarbon generation material be lower aquatic organism. The Pr/Ph ratio is 0.16-0.85, with obvious phytane predominance, indicating a strong reducing environment and partially reducing environment. The gammacerane index(Ga/C₃₀H) is 0.06-0.66, averagely 0.21, reflecting the source rocks were formed in brackish water environment. The Sterane C₂₉-αββ/(αββ+ααα) is 0.26-0.46, averagely 0.42, showing the source rocks are mostly in the mature stage.