Estimation of atmospheric pCO_2 in the geologic time based on stable carbon isotope ratios of higher plant biomarkers

高等植物光合作用的碳同位素分馏主要受植物生长速率的控制，而植物生长速率与大气CO2分压有一定的关系。陆源沉积岩中高等植物生物标志化合物的复合比稳定碳同位素比值可作为估算大气CO2古空间压力的参数之一。研究了日本和库页岛第三纪非海相富有机质沉积岩（煤和煤质泥岩）中高等植物生物标志物稳定碳同位素比值的变化。因此获得了以下结果。(1)第三系陆相沉积岩中普遍含有二萜烷类和芳香族二萜类化合物，如二芳香族托塔烷和retene。(2)松脂烯与松香烷型二萜芳烃的相对丰度呈正相关，说明它们之间存在成因联系。(3)维生素A和维生素B的缺乏 关于我们 甾烷类化合物与被子植物中的齐墩果烷呈负相关，说明retene主要来源于裸子植物。(4)二苯并呋喃的含量与齐墩果烷的含量呈正相关，表明二苯并呋喃也来源于被子植物。(5)正构烷烃的碳同位素比值随正构烷烃碳数的增加而降低，表明高分子量正构烷烃主要来源于高等陆生植物。(6)始新世煤和煤质泥岩的正构烷烃、β-降异海松烷、二芳全塔烷和retene的碳同位素比值<13>比中新世煤和煤质泥岩的碳同位素比值富集^ C。(7)高压液相色谱法是气相色谱-燃烧-同位素比值质谱联用芳烃分馏的有效方法。(8)高等植物生物标志物碳同位素比随地质时代的变化与大气二氧化碳分压可能的地质变化相一致，高等植物生物标志物复合比稳定碳同位素比可以作为估算地质时期大气pCO 2的有用参数。然而，影响高等植物生长速率的其他环境条件也可能影响高等植物生物标志物的同位素比值。少

Carbon isotope fractionation by photosynthesis of higher land plant is mainly controlled by the growth rate of plants, which is partly related to partial pressure of atmospheric carbon dioxide. Compound specific stable carbon isotope ratio of higher plant biomarkers in the terrigenous sedimentary rocks can be one of parameters for estimation of paleo-patial pressure of atmospheric carbon dioxide. The variation of stable carbon isotope ratio of higher plant biomarkers in the Tertiary non-marine organic-rich sedimentary rocks such as coal and coaly mudstones in Japan and Sakhalin were investigated in the present study. The following results were consequently obtained.(1) Tertiary non-marine terrigenous sedimentary rocks commonly contain diterpanes and aromatic diterpenoids such as diaromatic totarane and retene.(2) Abundance of retene is positively correlated to that of abietane type diterpenoid aromatic hydrocarbons, suggesting their genetic relationship.(3) Abundance of retene and abie … More tane type compounds is negatively correlated to that of oleanane which is derived from angiosperms, suggesting that retene is mainly derived from gymnosperm.(4) Abundance of dibenzofuran is positively correlated to that of oleanane, suggesting that dibenzofuran is also derived from angiosperms.(5) Carbon isotope ratios of n-alkanes tend to decrease with increasing carbon numbers of n-alkane, showing higher molecular weight n-alkanes are mainly derived from higher land plants.(6) Carbon isotope ratios of n-alkanes, β-norisopimarane, diaromatic totarane, and retene in Eocene coal and coaly mudstones are enriched in ^<13>C compared to those of Miocene coal and coaly mudstones.(7) High-pressure liquid chromatography is useful method for aromatic hydrocarbon fractionation for gas chromatography combustion isotope ratio mass spectrometry.(8) Variation of carbon isotope ratio of higher plant biomarker with geologic age is consistent with the possible geologic change of atmospheric carbon dioxide partial pressure.Compound specific stable carbon isotope ratio of higher plant biomarkers can be a useful parameter to estimate the atmospheric pCO_2 in the geologic time. However, other environmental condition, which affect growth rate of higher plant, may be influential to the isotope ratio of higher plant biomarkers. Less