| 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.
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