No abstract

ABSTRACT:Gola, M.R., Karger, M., Gazda, L. and Grafka, O. 2013. Organic geochemistry of Upper Carboniferous bituminous coals and clastic sediments from the Lublin Coal Basin (Poland). Acta Geologica Polonica, 63 (3), 425−442. Warszawa.Bituminous coals and clastic rocks from the Lublin Formation (Pennsylvanian, Westphalian B) were subjected to detailed biomarker and Rock-Eval analyses. The investigation of aliphatic and aromatic fractions and Rock-Eval T max suggests that the Carboniferous deposits attained relatively low levels of thermal maturity, at the end of the microbial processes/initial phase of the oil window. Somewhat higher values of maturity in the clastic sediments were caused by postdiagenetic biodegradation of organic matter.The dominance of the odd carbon-numbered n-alkanes in the range n-C 25 to n-C 31 , high concentrations of moretanes and a predominance of C 28 and C 29 steranes are indicative of a terrigenous origin of the organic matter in the study material. This is supported by the presence of eudesmane, bisabolane, dihydro-ar-curcumene and cadalene, found mainly in the coal samples. In addition, tri-and tetracyclic diterpanes, e. g. 16β(H)-kaurane, 16β(H)-phyllocladane, 16α(H)-kaurane and norisopimarane, were identified, suggesting an admixture of conifer ancestors among the deposited higher plants. Parameters Pr/n-C 17 and R dit in the coal samples show deposition of organic matter from peat swamp environments, with the water levels varying from high (water-logged swamp) to very low (ephemeral swamp). Clastic deposits were accumulated in a flood plain environment with local small ponds/lakes. In pond/lake sediments, apart from the dominant terrigenous organic matter, research also revealed a certain quantity of algal matter, indicated, i.a., by the presence of tricyclic triterpanes C 28 and C 29 and elevated concentrations of steranes.The Paq parameter can prove to be a useful tool in the identification of organic matter, but the processes of organic matter biodegradation observed in clastic rocks most likely influence the value of the parameter, at the same time lowering the interpretation potential of these compounds.The value of Pr/Ph varies from 0.93 to 5.24 and from 3.49 to 22.57 in the clastic sediments and coals respectively. The microbial degradation of organic matter in both type of rocks and during early stages of diagenesis is confirmed by a high concentration of hopanes, the presence of drimane homologues, bicyclic alkanes and benzohopanes. Moreover, bacteria could also have been connected with the primary input of organic matter, which is shown by the presence of e.g. C 30 neohop-13(18)-ene.

Coal and hydrocarbons have been exploited from the Carboniferous rocks of the Midland Valley for over 200 years. This work characterises organic matter from the Mississippian black shales of the Midland Valley from Wardie, Scotland. Biomarker analysis allowed the estimation of the degree of microbial transformation of organic matter, type of kerogen and thermal maturity during hydrocarbon generation. Parameters based on the biomarker indicators confirm a generally mixed type II/III kerogen. However, some samples contain mostly terrestrial organic matter, whilst others contain predominantly marine organic matter, which shows that the sedimentary environment varied greatly throughout the basin. The presence of gammacerane suggests water column stratification and anoxic conditions. Organic matter was much better protected from postdepositional alteration within the concretions, where higher TOC (total organic carbon) and TS (total sulphur) contents occur, than in the surrounding sediments. This can be induced by very early diagenetic formation of these concretions which protected organic matter from late diagenetic degradation.Estimated values of vitrinite reflectance (Rc, Rcs) show that the sedimentary rocks reached the catagenesis stage. Most samples exhibit maximum organic matter maturation temperatures of around c60-90 C. However, stable isomers of phenyldibenzo [b,d ]thiophene detected in some samples indicate that in some cases post-depositional hydrothermal activity affected maturation of organic matter increasing temperatures to as high as c174 C.

No abstract

Analysis of molecular composition of organic matter in lithics can determine correlations between organic matter and rock source. The paper presents the possibilities and limitations of using this method in Earth Sciences and Archaeology. Kivonat Szerves alkotóelemek vizsgálata: régészeti és földtudományi alkalmazásokA kőzetekben található szerves anyagok molekuláris összetétele árulkodó lehet a kőzet eredetének helyét illetően. E cikkben bemutatjuk ezen elemző módszer felhasználásának lehetőségeit és korlátait a földtudományokban és a régészetben.