摘要
Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors researched biomarker characteristics of the Linxi Formation source rocks in the area of Taohaiyingzi, and analyzed the information and petroleum geological significance that were indicated by source of organic matter, sedimentary environment, maturity and so on. Gas chromatography peak of saturated hydrocarbons from Linxi Formation source rocks showed ‘‘the former peak'' of the single peak distribution and the C23-dominant main peak. This indicates that the main source of organic matter was mixed organic matter; Pr/Ph ratios ranged from 0.3 to 0.6, indicating a strongly reducing sedimentary environment.Molecular fossil assemblages in Linxi Formation source rocks were abundant in tricyclic terpane with long side chains, had high level of gammacerane, and showed dominant distribution of C27 steranes. Gammacerane ratios range from 0.15 to 0.29, with an average of 0.19, implying that Linxi Formation hydrocarbon source rocks were formed in the environment of micro-saltwater water to half-saltwater water. The hopanes/steranes ratios are mainly between 0.6 and 1.0, with an average of 0.84, implying that bacteria and algae had almost the samecontribution to organic matter. C27 steranes abundance is high and the ratio of C27steranes/C29 steranes is 1.13,showing that algae is the main source of hydrocarbon precursors.
Based on gas chromatography and gas chro- matography mass spectrometry techniques, the authors researched biomarker characteristics of the Linxi Formation source rocks in the area of Taohaiyingzi, and analyzed the information and petroleum geological significance that were indicated by source of organic matter, sedimentary environment, maturity and so on. Gas chromatography peak of saturated hydrocarbons from Linxi Formation source rocks showed ＂the former peak＂ of the single peak distribution and the C23-dominant main peak. This indi- cates that the main source of organic matter was mixed organic matter; Pr/Ph ratios ranged from 0.3 to 0.6, indicating a strongly reducing sedimentary environment. Molecular fossil assemblages in Linxi Formation source rocks were abundant in tricyclic terpane with long side chains, had high level of gammacerane, and showed dominant distribution of C27 steranes. Gammacerane ratios range from 0.15 to 0.29, with an average of 0.19, implying that Linxi Formation hydrocarbon source rocks were formed in the environment of micro-saltwater water to half-saltwater water. The mainly between 0.6 and 1.0, hopanes/steranes ratios are with an average of 0.84, implying that bacteria and algae had almost the same contribution to organic matter. C27 steranes abundance is high and the ratio of C27 steranes/C29 steranes is 1.13, showing that algae is the main source of hydrocarbon precursors.
