Advances in organic geochemistry / Достижения в области органической геохимии

It is known that methane (and, in smaller amounts, higher hydrocarbons) is liberated during the coalification process. The amounts of methane developed vary in the different stages of coalification. Calculations on the basis of ultimate analyses of coals of different rank done by Mott (1943), Patteisky(1952, 1964) and Jüntgen and Karweil (1966) lead to the conclusion that greater amounts of methane start to be developed when the stage of bituminous coals with about 30% of volatile matter (dry and ash-free) is reached, whereas the gas developed from lignite and less metamorphosed bituminous coals is mainly carbon dioxide.

Figure 1, from a paper by Patteisky and Teichmüller (1960), shows the trend of the H/C ratio against the O/C ratio during coalification. The hydrogen content decreases sharply when the carbon content reaches 87% (corresponding to about 29% volatile matter). The formation of methane, which is supposed to proceed parallel to the decreasing amount of hydrogen, becomes very important in the stage of coking coals, and continues up to the stage of anthracites, where more than one-third of the total amount of methane is formed (Fig. 2). The total amount of methane liberated during the coalification process of bituminous coals and anthracites is estimated to be of the order of 200 litres per kilogram of coal. Jüntgen and Karweil (1966) have calculated that only a small fraction of the total methane formed during the coalification process can be retained by the coal. <...>

Carbon isotope study on methane from german coal deposits
The significance of carbon isotope variations in marine sediments
Carbon isotope effects in methane production by thermal cracking
Hydrogen isotopic fractionation of water passing through trees
Geochemical aspects of the occurrence of porphyrins in west venezuelan mineral oils and rocks
Researches concerning porphyrins and metal complexes of porphyrins from the posidonomya shales of swabia (brd)
Pent acyclic triterpanes* from petroleum and their significance
Correlation problems among crude oils
Étude sur les transformations physiques et chimiques des pétroles en liaison avec les conditions géologiques
Influence of temperature, pressure, and a clay mineral on the evolution of the chemical structure of an aromatic fraction of a crude oil
Influence du mode d'échantillonnage sur la composition chimique des fractions légères d'une huile brute
Geochemical prospecting for petroleum
Application of data processing methods to geochemical prospecting for petroleum
Pore fluid in shales and its geochemical significance
Diffusion of light paraffin hydrocarbons in water from 2°cto80°c
Origin of trace metal enrichment in bituminous shales
Nitrogenous constituents of deep-sea sediments
Étude des premiers stades d'évolution de la matière organique dans des mares en milieu récif al (polynésie française)
Structural characteristics of humic substances in recent lake sediments
Botanical, chemical and micro-biological studies of peat accumulation processes in the everglades of florida
Fatty acids in sediments including the green river shale (eocene) and scottish torbanite (carboniferous)
Evidence for transformations of normal fatty acids in sediments
The mechanism of the generation of petroleum hydrocarbons from a fatty acid
Thermal alteration of the organic matter in sediments
Influence de l'origine des matières organiques et de leur degré d'évolution sur les produits de pyrolyse du kérogène
Characterization of the insoluble organic matter of sediments by pyrolysis
A laser-micropyrolysis system for the study of organic sediments and inclusions
Experimental diagenesis of the nautilus shell
Indications of high-temperature processes in organic geochemistry
Possible taxonomic interpretation of some palaeozoic and precambrian carbohydrate residues
Aliphatic hydrocarbons from the pre-cambrian of north america and south africa
Hydrocarbons in meteorites
Primitive photosynthetic organisms
On the synthesis of peptides under primitive earth conditions