甘南郎木寺中全新世泥炭总有机碳和脂类分子化合物的组合特征  

COMBINED CHARACTERISTIC OF TOTAL ORGANIC CARBON AND LIPID COMPOUNDS FROM MIDDLE HOLOCENE PEAT IN LANGMUSI,SOUTHERN GANSU

作　　者：周静[1] 张平中[1] 贾继红[1] 王宗礼[1] 王永莉[2] 张虹[2] 张德忠[1] 桑文翠[1] 吴秀平[1] 王江林[1] 

机构地区：[1]兰州大学资源环境学院西部环境教育部重点实验室,兰州730000 [2]中国科学院地质与地球物理研究所兰州油气中心,兰州730000

出　　处：《第四纪研究》2008年第4期754-761,共8页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:40471137和40672123);兰州大学交叉学科青年基金项目(批准号:LZU200533)共同资助

摘　　要：根据青藏高原东北部甘肃南部郎木寺泥炭总有机碳含量的时间序列,重建了该区7.3~4.0kaB.P.（中全新世）期间气候演变的历史,其中较为显著的变冷事件分别集中在6.8cal.kaB.P.,5.0cal.kaB.P.和4.3cal.kaB.P.。同时分析了3个不同深度的泥炭脂类分子化合物。结果表明,正构烷烃和直链烷基-2-酮都由长链组分所构成,具有明显的奇碳优势和很高的碳优势指数值（CPI〉5）表明,这些长链组分来自草本高等植物。样品中还检出脂肪酸甲酯系列,也以长链组分为主,可能是沉积早期生物地球化学作用的产物。异构烯烃的存在及菲系列化合物低的甲基菲指数（MPI）和镜质体反射率（Rc）值,说明样品受成岩作用的影响很小而且几乎没有遭受现代的污染,即泥炭保存完好,各个指标可以真实反映泥炭的组成、性质及其形成时的环境条件。根据总有机碳含量的时间序列和不同阶段样品中的脂类分子化石的组合特征,探讨了各阶段气候和植被的演化特征。The research area is located on the edge of the northeast Tibetan Plateau. The peat sampling site is in Langmusi County, with an altitude of 3559m （34°09′ N, 102°34′ E）. The core is 346cm long and sampled at 1 cm intervals. We select the part which is all composed of peat （203 ~ 14cm） ,deposited during 7300 ~ 4000cal. aB. P. This peat sedimentary sequence was selectively investigated by lipid molecular stratigraphy by gas chromatographymass spectrometer（GC-MS）. A variety of molecular fossils are found in this peat profile, including n-alkanes, n- alkan-2-ones, fatty acid methyl esters, polycyclic aromatic hydrocarbons （PAH）and so on. The n-alkanes are ranged from C 16 ~ C33, having a maximum at C31 （ C25 ）. They display a distinct odd/even carbon number predominance, having high C PI values（ 〉 5）. Distribution of fatty acid methyl esters from C16 to C30 was observed,maximizing at C24. The n-alkan-2-ones are ranged from C19 to C33 ,having a maximum at C23. We＇ve also found phenznthrene series in the peat profile. Higher plants are the predominant source of the n-alkane compositions. Combining the distribution of lipids and types of vegetation in and near this area, we can conclude that the source are herbages. n-Alkan-2-ones are from epicuticular waxes of peat-forming plants or microbial cracking of longer-chain n-alkan-2- ones to yield the shorter chain components. Fatty acid methyl esters may be related to biochemical process. Phenznthrene series indicate low maturity of the peat profile. On the side,we also found pristane（Pr）and phytane （Ph） in the profile which show the peat of the Langmusi profile was formed in an anoxic deposit environment. The low methylphenanthrene index（MPI） and Rc values of phenznthrene series indicate the low thermal maturity of the samples. They also show that the samples were preserved well and could reflect the actual composition and features of the deposition, as well as the environment when they were deposited. Based on the establishme

关 键 词：郎木寺 中全新世 泥炭 总有机碳 脂类化合物 

分 类 号：P534.632[天文地球—第四纪地质学] P593[天文地球—古生物学与地层学]