Monika Wolf

New interpretations of the facies of the rhenish brown coal of West Germany

Abstract New ideas concerning the understanding of the facies of the Rhenish brown coal of West Germany are discussed. These new interpretations are based on a significantly larger number of samples and refined procedures for analysis within the field of paleobotany, palynology, coal petrology and organic geochemistry than were available to P. W. Thomson and M. Teichmuller. The light and dark bands in the coal are mainly the result of different degrees of plant decomposition. The influence of the peat-forming plant communities plays a subordinate role in the petrographical composition of these particular strata of the Rhenish brown coal.

Organic geochemistry and petrography of Tertiary coals and carbonaceous shales from Argentina

A series of eight Tertiary coal and carbonaceous shale samples with vitrinite reflectance values between 0.50 and 0.58% were extracted, fractionated and the saturated and aromatic hydrocarbons analysed for characteristic components by GC and GC-MS. Additionally, a microscopical study was undertaken in order to obtain a more precise picture of the samples under investigation. The saturated hydrocarbon fractions displayed the typical n-alkane distribution for coals of this rank, with CPI values between 2.0 and 3.1. Among the branched/cyclic compounds, pristane and α, β-homohopane were recognised as relevant components pointing to an oxic depositional environment. Detection of benzohopanes (C32–C35) in the aromatic hydrocarbon fractions suggests that bacteriohopanetetrol was a significant constituent of the coal biomass. Taking into consideration the Pr/Ph ratios, ash contents and microscopical characteristics of the samples, aspects of the possible degradation of hopanetetrol to homohopane are discussed. Resin-derived diterpenoids with the phyllocladane and kaurane skeleton were tentatively identified and, although minor compounds, they are interpreted to be a sign of the contribution of Podocarpaceae and Araucareaceae to the coal swamp. Aromatic compounds were dominated by alkylnaphthalene derivatives, presumably formed by C-ring cleavage and aromatisation of higher plant-derived pentacyclic triterpenois, which were main components in the high-boiling range of the fractions investigated. Angiosperms (especially Fagaceae) are postulated as source for these polycyclic compounds and, hence, for some of the polyalkylated aromatic bicyclics detected.

Chemical characteristics of liptinite macerals in humic and sapropelic coals

Abstract According to previous studies alginite does not occur in humic coals. However, in coals from the Saar District, F.R. Germany, alginite was identified by fluorescencemicroscopy. In addition, high amounts of an undeterminable liptinite maceral were found and tentatively explained as an alteration product of alginite. Therefore, organic geochemical methods were used to characterize and identify this unknown liptinite maceral. Organic geochemical parameters such as CPI, pristane/phytane ratio and methylphenanthrene index, show not only a dependence from coal rank but also yield additional information about the type of organic matter input and the depositional environment of the coals. A series of coals of different origins around 0.8% vitrinite reflectance were investigated, to determine how far the geochemical parameters reflect change in facies. The samples included cannel, boghead and resinite-rich coals, as well as isolated durain bands. With increasing amounts of alginite in the coal, the CPI, pristane/phytane- and C 4 -naphthalene/phenanthrene ratios of the extracts decrease. As illustrated by two representatives samples, some resinite- and sporinite-rich coals show a primarily naphthalene derived aromatic composition, whereas some alginite-rich coals of the same rank show phenanthrene and its derivatives to be dominant. With respect to technological properties most coals from the Saar District correspond with a higher rank than indicated by reflectance measurements. Those coals in general show lower values of the aforementioned ratios in comparison with Ruhr coals of similar vitrinite reflectance values.

Facies and rank of the Permian Kupferschiefer from the lower Rhine basin and NW Germany

Abstract The Kupferschiefer of the Lower Rhine Basin and of NW Germany is a typical black shale containing C org values between 0.5 and 9.1%. On average it contains 4% C org . In coal petrographic terms the organic matter of the Kupferschiefer is characterized by well preserved liptinite as sporinite - especially derived from the pollen grains of conifers - in the area of the Lower Rhine Basin and as alginite towards the centre of the Kupferschiefer sea. The high content of bituminite in all of the samples shows that the main source of organic matter is derived from plancton and bacteria. Vitrinite and inertinite are rare. The rank of the organic matter in the sediment varies between the lignite stage (Lower Rhine Basin) and the bituminous coal stage (NW Germany). Geochemical investigations have shown that residual heat from the Krefeld High was active until the lower Zechstein. This has caused a change in the chemical composition of the organic matter but did not express itself in the optical parameters. Inhomogeneities of the organic matter in low-rank and bituminization in higher-rank materials influence the vitrinite reflectance. Fluorescence measurements are more sensitive in sapropelic sediments and oil shales than vitrinite reflectance. It is evident that the red/green ration is more reliable in view of diagenesis studies than the lambda max of the fluorescence spectra. Geochemical parameters are partly much more sensitive towards thermal stress as compared to vitrinite reflectance, e.g. metalloporphyrin concentrations decrease with increasing temperatures. The parameter covers a temperature range from ca. 40°C to 80°C. The weighted average mass of the vanadyl-cycloalkano-porphyrins is suitable to characterize the influence of temperature on the Kupferschiefer between ca. 40°C and 150°C. Summing up, the Kupferschiefer of the Lower Rhine Basin in NW Germany is a sidiment very well suited for parallel petrographic and organic-geochemical research. The results of this might be also of interest in the field of oil prospecting.

Iron porphyrins in the Permian Kupferschiefer of the lower Rhine Basin, N.W. Germany

Immature samples of the Permian Kupferschiefer from the Lower Rhine Basin in N.W. Germany were analysed for tetrapyrrole pigment type and abundance. The sediment, thought to have been deposited in a marine regime with enhanced salinity, was found to contain high concentrations of metalloporphyrins. The porphyrins are complexed to nickel (Ni) and oxovanadium (V=0), but high abundances of iron (Fe) porphyrins were also detected using UV/visible spectroscopy and mass spectrometry. The presence in the latter of series of aetioporphyrins, cycloalkanoporphyrins, di-cycloalkanoporphyrins and benz-cycloalkanoporphyrins was confirmed by accurate mass measurements; HPLC co-injection of deoxophylloerythroetioporphyrin (C32 DPEP) with the demetallated iron porphyrins indicated its presence in the sediment as an iron complex. The study provides the first evidence for the occurrence of Fe porphyrins in geological samples other than coals and lignites, and reports the highest concentrations in sedimentary organic matter to date.

Paleoenvironments of lacustrine coals: the occurrence of algae in humic coals

Abstract According to previous studies, there is a significant difference in the thickness and number of coal seams from the foredeep and the intermontane coal basins (or basins situated on platforms and cratons). Recent petrographic and geochemical investigations on selected coal samples from foredeep and intermontane basins of Europe (Carboniferous and Tertiary) and South America (Permian) show that the coal seams in each of these coal basins have significant differences in their petrographic and geochemical compositions. Many intermontane coals are characterized by more liptinite than foredeep coals. Fluorescence studies show that up to 75% of the liptinite macerals of these humic coals can be attributed to alginite and/or degradation products of algae. This indicates that generally subaquatic conditions occurred more often in the peats that formed within intermontane basins.

Verkieste Amöben in Steinkohlen aus dem Ruhrgebiet — erster Nachweis vonArcella Ehrenberg im Paläozoikum

Within bituminous coals of Westphalian B age pyritized amoebae of the order Testacea (thecamoebians) were detected. They may belong to the genusArcella. The appearance of this genus, known until now only since the Pleistocene, is extended far into the Palaeozoic by this observation.KurzfassungIn Steinkohlen aus dem Westfal B des Ruhrgebietes wurden verkieste Amöben der Ordnung Testacea (Thekamöben) gefunden, die zur GattungArcella zu stellen sein dürften. Damit erweitert sich deren Vorkommen, das bisher nur seit dem Pleistozän bekannt war, bis in das Paläozoikum hinein.

Petrographic and geochemical characterization of pale and dark brown coal from Yunnan province, China

Abstract Fifteen lignite samples from the province of Yunnan were analysed by organic petrography and geochemistry. Twelve of the samples represent the very pale (yellow) Baipao coal, the other three were normal coals of a medium brown colour. The Baipao coal consists mainly of mineral-bituminous groundmass, whereas the normal coal is characterised by well-preserved tissues derived from gymnosperm wood. Up to 190 mg/g C org of extract is extractable from the Baipao coal; only 63 mg/g C org from the normal coal. The n-alkane fraction of the Baipao coal extract consists of high amounts of hopanes and shows the predominance of nor-abietane within the diterpenoids present. The first group of compounds points to intensive bacterial activity, while the second compound indicates not only that gymnosperms are present but also that a relatively oxygen-rich environment existed at the time of deposition. From the petrographic and organic geochemical characteristics it is concluded that the Baipao coal was formed from the same plant source material as the normal coal, but underwent stronger decay.

Chemical characteristics of subbituminous coal lithotypes

Hand-selected lithotypes of a Polish subbituminous coal were examined using organic-geochemical methods and microscopy. The random reflectance of the vitrinite was determined to be 0.52%. Chemical analysis of solvent extracts showed that in this rank region the intra-seam diffusion of bitumen present in the coal is of minor importance. Thus the lithotypes vitrain, durain and fusain each possess significant geochemical characteristics. The extract of the vitrain concentrate is enriched in degradation products of resinous material impregnating the whole vitrain. The fusain concentrate is characterized by a relatively high content of short-chain normal alkanes (C15-C20) and the main feature of the durain is its high pristane content. This indicates a distinct organic matter input or particular diagenetic conditions during coal lithotype formation.

Organisch-chemische Untersuchungen an Kohlen-Maceralen mit der Ionensonde (IMS-3F)

Zusammenfassung Mit der IMS-3F-Ionensonde der Firma Cameca wurden die Massenspektren von drei isolierten Kohlenmaceralen, einem Sporinit, einem Vitrinit und einem Fusinit, aufgenommen. Die Diskussion der Ergebnisse zeigt, daβ alle Spektren Massen enthalten, die eine Zuordnung zu maceralspezifischen Molekulfragmenten erlauben. Am geringsten ist die Zahl charakteristischer Massen beim Fusinit, weil die Registrierung bei der Masse 250 abgebrochen werden muβte. Wahrscheinlich sind die aromatischen Ringe im Fusinit so fest miteinander verbunden, daβ sie sich nicht in kleine Molekulbruchstucke aufbrechen und dann nachweisen lassen. Trotz zahlreicher Unzulanglichkeiten in der Praparation und bei der Aufnahme der Spektren lassen die Ergebnisse die Methode geeignet erscheinen, um Fortschritte in der organischen Geochemie zu erzielen.