Molecular evidence for life in the 3.5 billion year old Warrawoona chert   总被引：1，自引：1，他引：0  

Sylvie Derenne  Franois Robert  Audrey Skrzypczak-Bonduelle  Didier Gourier  Laurent Binet  Jean-Noël Rouzaud 《Earth and Planetary Science Letters》2008,272(1-2):476-480

The biological origin of organic matter in the oldest siliceous sediments (cherts) is still debated. To address this issue, the insoluble organic matter (kerogen) was isolated from a chert of the Warrawoona group. The chemical structure of the kerogen was investigated through a combination of analytical techniques including solid-state ¹³C nuclear magnetic resonance and pyrolysis. Although dominated by aromatic hydrocarbons, the pyrolysate comprises a homologous series of long chain aliphatic hydrocarbons characterized by odd-over-even carbon number predominance. This distribution is only consistent with a biological origin. As kerogen must be contemporaneous of the solidification of the chert, this observation should be regarded as an evidence for the presence of life on Earth, 3.5 By ago.  相似文献   

Primary alteration—oxidation of marine algal organic matter from oil source rocks of the North Sea and Norwegian Arctic: new findings     

Ganjavar Khavari Khorasani  Johan K. Michelsen 《Organic Geochemistry》1992,19(4-6)

The presence of partially oxidized algal organic matter in oil-prone marine source rocks, is the rule rather than the exception. Partially oxidized, algal kerogen can still act as a significant source of liquid hydrocarbons. However, the corresponding peak of C₁₂ + hydrocarbon generation is shifted to a considerably lower maturity level compared with that of the classical Type II kerogen. The extent of primary alteration-oxidation of marine algal kerogen is monitored by means of solid state microfluorescence spectroscopy. A new parameter, the Primary Alteration Factor (PAF) is established, and the relationships between PAF and H/C, O/C, HI, TOC and between PAF and %₀δ¹³C are determined. The present data show large variations in the bulk chemistry of immature marine algal kerogens, and reveal evidence for gradational dehydrogenation/oxidation of the source organic matter. This contrasts with the recently proposed mechanism for kerogen formation. SEM analysis reveals a relationship between the physical breakdown of algal organic matter and the formation of liptodetrinite. FTIR analysis shows that the incorporation of primary oxygen in the kerogen macromolecules is not in the form of carbonyl or carboxyl functionalities. The presence of highly unreactive, stable oxygen, associated with aromatic structures in partially oxidized algal kerogen, is suggested by resistance of the kerogen to graphitization. The FTIR data also suggest the presence of aryl ether oxygen. The present findings raise fundamental questions regarding the mechanisms of kerogen cracking and kerogen formation, and have important implications for petroleum exploration.  相似文献   

Structural investigations of sulphur-rich macromolecular oil fractions and a kerogen by sequential chemical degradation     

H.H. Richnow  A. Jenisch  W. Michaelis 《Organic Geochemistry》1992,19(4-6)

Structural studies of a sulphur-rich kerogen and macromolecular oil fractions from the Monterey Formation were performed by selective sequential chemical degradation. The method provides low-molecular weight compounds as former building blocks of the network which allow detailed analyses on a molecular level. The degradation sequence is based on three subsequently performed reactions—a selective cleavage of sulphur bonds in the first step carried out with Ni(0)cene/LiAlD₄, an ether and ester bond cleavage (BCl₃), and an oxidation of aromatic entities by ruthenium tetroxide as a final step. Each step of this sequence afforded a considerable amount of low-molecular weight material which was separated chromatographically and studied by GC and GC/MS, while the high-molecular weight or insoluble fractions were subjected to the next reaction step.The chemical degradation products—hydrocarbons and carboxylic acids—are discussed in terms of incorporation into the macromolecular structure, distribution of heteroatomic bridges and the genetic relationships between the different macromolecular crude oil fractions and kerogen.Labelling experiments with deuterium provided evidence for a simultaneous linkage by oxygen and sulphur functionalities or by aromatic units and sulphur bonds of cross-linking macromolecular network constituents.The determination of sulphur positions in the macromolecule suggests early diagenetic sulphur incorporation into the biological precursor compounds and subsequent formation of a cross-linked network.  相似文献   

Tertiary deltaic and lacustrine organic facies: comparison of biomarker and kerogen distributions     

Joseph A. Curiale  Rui Lin 《Organic Geochemistry》1991,17(6)

Biological marker and kerogen compositional data in Tertiary deltaic and lacustrine settings were compared and contrasted. The two settings are represented by (a) coals and organic-carbon-rich shales in a ick deltaic sequence from the Far East, constituting three distinct organic facies, and (b) humic coals and spropelic oil shales in a restricted intermontane (freshwater) lacustrine sequence from western Montana (U.S.A.), constituting two distinct organic facies. Wedistinguish the organic facies in each depositional setting by systematic differences in gross compound class distributions, kerogen and infrared spectral characteristics, molecular character of pyrolyzates, sterane carbon number distribution and sterane/hopane ratios. The kerogens of the three deltaic organic facies are characterized by varying quantities of vitrinite, resinite, sporinite, cutinite and fluorescent amorphinite. Triterpane distributions reveal numerous terrigenous compounds, including oleanane, oleanenes and unidentified C₃₀ (presumably) resin-derived components. The two organic facies of the freshwater lacustrine setting are distinguishedased upon either a vitrinite or an alganite/fluorescent amorphinite predominance in the kerogen. Numerous characteristics facies-related markers are also present, including dehydroabietane (land plant resins) and 4-methylsteranes (perhaps from freshwater dinoflagellate input). The available molecular and petrographic data are evaluated, and characteristics are proposed for distinguishing five organic facies of these two depositional settings. The successful simultaneous use of molecular geochemistry and organic petrography in this study provides a format for refining the organic facies concept.  相似文献   

冲绳海槽沉积物干酪根特征     

唐运千 《海洋学研究》1992,10(1):50-58

本文采用元素分析、镜下观察、红外光谱、扫描电镜和热解分析等技术,分析了冲绳海槽柱状样中腐植酸、富里酸和干酪根的化学、物理特征,并探讨了它们之间的成因关系和干酪根类型。沉积物的产烃能力甚差,每吨沉积物仅能生成0.49～1.18kg烃类物质。  相似文献   

衰减全反射-傅里叶红外光谱法快速测试干酪根样品     

冉敬  杜谷  潘忠习 《岩矿测试》2010,29(2):113-117

生油母质干酪根是石油地质工作研究的重要对象。文章利用衰减全反射(ATR)技术对干酪根样品进行傅里叶变换红外光谱分析,通过与传统压片法谱图进行峰形峰位特征、结构参数比较,表明:①ATR谱具有与压片法吸收谱类似的谱图特征;②与压片法吸收谱相比,ATR谱的吸收强度较弱;③ATR技术和压片法所获得的红外结构参数具有可比性。由于ATR技术具有无需制样、可以减少水分干扰等优点,因此可以作为干酪根样品快速测试的方法应用于干酪根样品的类型鉴别、热演化程度研究和来源对比。  相似文献   

内蒙古西部额济纳旗及邻区石炭系-二叠系烃源岩干酪根C同位素的特征和影响因素     

卢进才  魏仙样  魏建设  李玉宏  陈高潮 《地质通报》2010,29(2)

许多研究者认为,烃源岩干酪根C同位素组成主要受干酪根类型的影响,可以作为评价烃源岩类型、沉积环境和进行油气源对比的重要指标,并得到广泛应用.对额济纳旗及邻区典型剖面石炭系-二叠系烃源岩有机碳(TOC)的丰度、地球化学特征、热演化特征和干酪根C同位素分布的研究表明.研究区石炭系-二叠系烃源岩为浅海陆棚相沉积环境形成的泥质岩,TOC含量中等,以Ⅱ类干酪根为主,烃源岩演化进入成熟-过成熟阶段,干酪根C同位素县有显著偏重的特点.并且干酪根C同位素组成明显与热演化程度和有机碳丰度有关,随着烃源岩演化程度的不断提高,重碳同位素不断富集,在成熟-过成熟阶段,对C同位素的影响可达4‰～6‰随着TOC含量的增加,干酪根C同位素显著偏轻,影响值可达4‰以上.由于研究区烃源岩已进入成熟-过成熟阶段,干酪根C同位素的分布在演化过程中已经发生较大变化,干酪根类型的影响相对降低或已不显著,不能再作为评价烃源岩干酪根类型的指标.  相似文献   

南极布兰斯菲尔德海峡表层沉积物干酪根          下载免费PDF全文

唐运千  卢冰  眭良仁 《极地研究》1995,7(3):76-86

本文采用元素分析、红外光谱、扫描电镜和热解分析等手段研究南极布兰斯菲尔德海峡表层沉积物中干酪根的化学和物理性质。南极样干酪根的芳香度与Ｃ／Ｈ原子比呈线性关系。红外光谱特征表明，干酪根中含有大量苯和其同系物如甲苯、乙苯、１，２－二甲苯和１，４－二甲苯等化合物。南极样的热解烃最高仅１．８２×１０－３，总烃平均量０．８９×１０－３，反映了有机质的贫乏。  相似文献   

Sorption properties of 1, 3, 5-trichlorobenznene on kerogen     

Chen YANG Guoying SHENG Zhi DANG 《中国地球化学学报》2006,25(B08):261-262

Kerogen is an important organic matter fraction widely spread in soils and sediments. It plays a major role in the sorption and sequestration of hydrophobic organic contaminants （HOCs） such as trichlorobenzene （TCB）. It is known that kerogen is geochemically heterogeneous due to the differences in source materials and diagenesis history. We hypothesized that kerogen derived from different source materials and diagenetic history exhibits different sorption properties for TCB. We employed two different kerogen materials （coals） as the original materials and two series of kerogen for a given series with an identical source material but different alteration history were yielded through thermal treatment at temperature ranging from 200 to 500℃. The original and treated materials were characterized for their physicochemical properties. Sorption experiments were conducted with batch reactor systems using 1, 3, 5-TCB as the HOCs sorbates and the original and treated materials as the sorbents.  相似文献   

Release of sulfur- and oxygen-bound components from a sulfur-rich kerogen during simulated maturation by hydrous pyrolysis     

Anke Putschew  Christine Schaeffer-Reiss  Philippe Schaeffer  Martin P Koopmans  Jan W de Leeuw  Michael D Lewan  Jaap S Sinninghe Damsté  James R Maxwell 《Organic Geochemistry》1998,29(8):1875-1890

An immature sulfur-rich marl from the Gessosso-solfifera Formation of the Vena del Gesso Basin (Messinian, Italy) has been subjected to hydrous pyrolysis (160 to 330°C) to simulate maturation under natural conditions. The kerogen of the unheated and heated samples was isolated and the hydrocarbons released by selective chemical degradation (Li/EtNH₂ and HI/LiAlH₄) were analysed to allow a study of the fate of sulfur- and oxygen-bound species with increasing temperature. The residues from the chemical treatments were also subjected to pyrolysis–GC to follow structural changes in the kerogens. In general, with increasing hydrous pyrolysis temperature, the amounts of sulfide- and ether-bound components in the kerogen decreased significantly. At the temperature at which the generation of expelled oil began (260°C), almost all of the bound components initially present in the unheated sample were released from the kerogen. Comparison with an earlier study of the extractable organic matter using a similar approach and the same samples provides molecular evidence that, with increasing maturation, solvent-soluble macromolecular material was initially released from the kerogen, notably as a result of thermal cleavage of weak carbon–heteroatom bonds (sulfide, ester, ether) even at temperatures as low as 220°C. This solvent-soluble macromolecular material then underwent thermal cleavage to generate hydrocarbons at higher temperatures. This early generation of bitumen may explain the presence of unusually high amounts of extractable organic matter of macromolecular nature in very immature S-rich sediments.  相似文献