【作者】 蔡进功；

【导师】 李从先；

【作者基本信息】 同济大学 ， 海洋地质学， 2003， 博士

【摘要】 本文选取多种泥质沉积物和泥岩，采用不同的处理方法和先进的分析手段，揭示其中有机质的赋存方式及其与蒙皂石、伊利石等粘土矿物的关系，探讨有机质聚集、沉积和保存的规律。由海洋和湖泊泥质沉积物的分离和测试研究，以及泥岩的显微和热分析可知，在泥岩和泥质沉积物中存在多种类型的有机质，它们以不同的方式结合和聚合，包括存在于粘土矿物层间的有机质（有机粘土复合体）、聚合有机质（无定形物）和生物碎屑有机质三种类型。这三种类型与水体中有机质的存在形式相对应，反映了海洋和湖泊水体、泥质沉积物和泥岩中的有机质在形成、聚集和保存上具有的紧密联系。这对从整体上认识有机质聚集方式、不同类型有机质在成烃过程中的差异和贡献，以及探讨全球或区域碳循环均具有重要的意义。经分离和显微分析后，水体、泥质沉积物和泥岩中除了生物碎屑有机质外，还有大量的无生物结构以及在泥岩中局部富集和顺层富集的有机质聚合体，是有机质聚集和保存的另一种重要方式。通过H₂O₂处理和显微分析，发现聚合有机质中常与粘土矿物和黄铁矿共生，表明聚合有机质是有机质之间、有机质与粘土矿物或其它无机物质之间相互聚集而成，对粘土矿物和无机物质在有机质聚集和保存中的作用应引起充分地重视。由激光粒度仪进行的颗粒分级分析及显微分析可以看出，有机质与粘土矿物不论在泥质沉积物，还是在泥岩中都紧密共生，除了生物有机质和聚合有机质外，结合紧密的是大量的可溶有机质，构成了有机粘土复合体。借鉴土壤的分析方法，提出了有机粘土复合度参数，试图对泥质沉积物和泥岩中的有机质和粘土矿物的复合程度进行定量判别研究。初步分析发现，不论在何种泥质沉积物中，特别是在泥岩中有机粘土复合体的复合度均较高，表明有机粘土复合体存在的普遍性，同时也提出了对有机粘土复合度分析方法进一步改进的问题。泥岩中含有大量的有机质是众所周知的事实，但是，不同的温度条件下进行的XRD和热对比分析发现，粘土矿物的层间由于有机质的进入，其层间距和热特征发生改变，成功地证明了在泥质沉积物和泥岩中的可溶有机质大量地保存于粘土矿物的层间，这对有机质的生烃将产生重大影响。对粘土矿物和不同类型的泥岩的对比分析发现，蒙皂石是层间有机质聚集的主要贡献者，即使在埋藏深度大于2000m的泥岩，其中仍然有粘土矿物层间有机质，证明粘土矿物层间有机质是泥岩和泥质沉积物中有机质的一种重要的存在形式。同时，这也预示着粘土矿物的类型和性质，将决定与有机质结合方式和存在形式，因而，在生产实践和理论研究中应重视粘土矿物在有机质保存和转化中的作用。对泥岩进行的差热—色谱分析，发现在250℃以前是蒙皂石层间水（伊利石的吸附水）和泥岩中C15的轻组份吸附烃排出期；在350℃至450℃是泥岩中粘土矿物层间有机质的释放期，并且以C15以上的重组份为主，与原油的组份相近，反映了粘土矿物层间对有机质的容纳量很大，因此，应充分重视粘土矿物的演化与有机质的生烃关系；500℃是粘土矿物层间水的第二次排出期，这是由于粘土矿物层间有机质的释放，解放了被束缚的层间水而滞后排出；450℃-550℃及更高的温度是有机质的裂解烃排出期，以C15以下的轻组份为主。由此可以看出，粘土矿物层间不仅仅吸附一些轻组份的有机质，通过形成有机粘土复合体可以容纳大量的重组份有机质，其键合方式与粘土矿物的层间水有着密切的关系，这对探讨烃源岩的排烃特征具有重要的意义。通过XRD、热分析和差热—色谱分析发现，红色泥岩和浅色泥岩也存在有机粘土复合体，在粘土矿物层间含有C10—C15等较重组份的有机质，这表明在强氧化的条件下粘土矿物也能很好地保护有机质，进一步证明有机粘土复合体对有机质保存的重大意义。有机粘土复合体在自然界中广泛存在，是有机质形成、聚集和保存的重要方式。有机质与粘土矿物在自然界中常相互依存和共生，探讨二者间的关系，回归地质状态下有机质的基本特征，对研究有机质的生烃和保存，分析碳循环，以及认识古气候环境变化等都具有重要的理论和实际意义，因此，对它的研究应引起更充分的重视。更多还原

【Abstract】 The present thesis studied the residing forms of organic matters and itsrelationships with different clay minerals such as smectite and illite in muddysediments and mudstones, by using various sample processes and advanced analyticmethods. On the basins of this, the paper discussed the mechanisms of accumulation,sedimentation and preservation of organic matters in nature.Muddy sediments collected from the seas and lakes were granulometricallyseparated for the measurement of compound degree of organic matter with minerals,and the mudstones with different geologic backgrounds were selected for microscopicobservations and thermal analysis. The results show that there exist three kinds oforganic matters with different combinations and polymerizations in the muddysediments and mudstones, i.e. the one bound in the layers of clay minerals (organo-clay complexes here), the polymerized one (amorphous organic matter), and biogenicorganic fragments. They correspond well with the main forms of organic matter inwaters of the sea and the lake, suggesting the tight relationship in the formation,accumulation and preservation of organic matter between the waters and thesediments. This finding is of great significance for understanding the preservationmechanism of organic matter, the behaviors and contributions of different organicmatters during the hydrocarbon formation, and moreover, for studying the carboncycle globally or regionally.The granulometric separations and microscopic observations revealed that apartfrom biogenic organic fragments in the waters, muddy sediments and mudstones,there have many organic complexes which have not observable biologic structures ordistributing in part and/or in parallel in the sediments accompanying by clay mineralsand pyrite. This indicates that the polymerized organic matter, as an importantpreservation form of organic matter in nature, is formed through the tightcombinations of organic matter with clay minerals and other inorganic materials orthrough self-polymerization.Based on the method in soil analysis, the present study introduced the compounddegree of organo-complex, in order to quantitatively study the compound degree oforganic matter with clay minerals in different geological environments. The results ofgrain size analysis by Laser size analyzer and microscopic observations suggested thatthe organic mattes are tightly combined with clay minerals with the main residingform in the layers of the minerals and producing high compound degrees in differentmuddy sediments and mudstones. The analyses of granulometric separations and GC-MS indicated that most of the organic matters in the organo-clay complexes aresoluble. The soluble organic matters bound in the layers of clay minerals occurredwidely not only in the modern muddy sediments and also in mudstones, which willexert a great control on the formation of hydrocarbon in source rocks.It has been widely known that clays contain abundant organic matter. However, thecombination forms of organic matter with clay minerals still remain unresolved. In the present study pure smectite and illite and mudstones of different types were selectedfor XRD and TG measurements under different temperatures. The results revealedthat the distances between the layers and thermal characters of clay minerals changedwith the increasing temperature because of the combination of organic matter in thelayers of the clay minerals. Even in the mudstones buried below 2000m, the organicmatter can occur in the layers of smectite. This further confirms that organic mattercan largely reside in the layers of the clay minerals and smectite is the main carrier fororganic matter bound in the layers. Therefore, the characters of clay minerals havegreat influences on the combination mechanism of organo-clay complexes, whichsuggesting that we must pay more attentions for studying the preservation andtransformation of organic matters in resource prospecting and theoretic research.The DTA and GC-Ms analyses of the mudstones revealed that below 250℃thelayer-bound water in smectite (or the adsorbed water in illite) and the fraction lighterthan C15 of adsorbed hydrocarbon were discharged, while organic matter bound inthe layers, mostly the heavy fractions (larger than C15) of adsorbed hydrocarbon weredischarged during the temperatures from 350℃to 250℃. the heavy fractions (largerthan C15) of adsorbed hydrocarbon are close to the components of crude oil,reflecting the high capacity of organic matter adsorbed in the layers of the clayminerals. Therefore, the strong relation of the evolution of clay minerals with theformation of hydrocarbon needs to be fully considered. In the temperature of 500℃the water in the layers of the clay minerals again discharged because the releasing ofsoluble organic matter from the layers set free the adsorbed water, while in thetemperatures from 450℃to 550℃and more the disaggregating hydrocarbon releasedwith the fraction lighter than C15 as the main component. In the same way, organicmatter, mainly the fraction of C10-C15, can also reside in the layers of the clayminerals of red mudstone and pale mudstone based on the analyses of XRD, DTA andGC-Ms, which suggesting that even in the strong oxidized environment the clayminerals can well preserve the organic matter from the attack of diagenesis.Furthermore, the above observations revealed that the formation mechanism oforganic matter with the clay minerals might be tightly related with the waters boundin the layers.In conclusion, the organo-clay complex is widely distributed in nature and the maincarrier of organic matter. It exerts great control on the formation, accumulation, andpreservation of organic matters. Organic matter is, therefore, tightly related with theclay mineral. The study on the relationship between them can better reveal thecharacteristics of organic matter in geological bodies, which will be of greatsignificance for studying the formation and preservation of hydrocarbon, the carboncycle and paleoenvironmental changes. Thus, the study on the organo-clay deservesmore attentions in the future.更多还原