Organisch-geochemischer Vergleich ausgewählter Gesteine der Frasnium/Famennium Grenze (Oberdevon) im Bergischen Land und der Eifel
Kloppisch, Marina (Corresponding author)
Publikationen vor 2000; PRE-2000; Retrocat
Jülich Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag 2002
X, 136 p.
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Berichte des Forschungszentrums Jülich 3987
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Please use the identifier: http://hdl.handle.net/2128/24538 in citations.


The present work deals with the organic-geochemical characterization of the socalledPhytoplankton-Blackout" at the Frasnium-Famennium boundary (F-F). Forthis purpose, samples of preferentially low thermal maturity from sequences ofalternating shales and limestones were taken from boreholes brought down in theRheinische Schiefergebirge (Rhenish Slate Mountains).Preliminary investigations were carried out from the well Knoppenbissen, witchproved to be unsuitable for further studies an molecular composition of organicmatter due intense tectonic overprint in this area. For detailed analyses, 31 samplesfrom the well Büdesheimer Bach and 53 samples from the well Paffrather Muldewere available.In general, all samples derived from the two latest mentioned localities can beassigned to as immature. Temperatures measured at times of maximal pyrolyseyield Show little variation (425 ...43°C) and correspond to a vitrinite reflectance ofapproximately 0.5%R$_{\tau}$.Comparison between the sections Büdesheimer Bach and Paffrather Mulde exhibitsslight differences in the molecular composition of organic substances. Basedan the distribution pattern of n-alkanes documented in the chromatograms, thematerial from the well Büdesheimer Bach proved to be less mature as compared tothe well Paffrather Mulde.The total organic carbon content ranges from 0.12% in relatively pure carbonatesto exceptionally high values of up to 7,53% in one of the Kellwasser-horizons.The higher amounts of organic carbon recorded in the Kellwasser-horizons points toa consolidated deposition of organic material in the course of the "Phytoplankton-Blackout"-Event.Analyses an the molecular composition of organic matter were carried out an15 samples from well Büdesheimer Bach and Paffrather Mulde, each. The predominanceof C$_{15}$ to C$_{17}$ in the distribution pattern of n-alkanes gives evidence thatalgae and bacteria contribute to a significant portion of organic matter in the rocks investigated. It was not possible, through, to trace a mass extinction of phytoplankton.Evidences for an extinction was mirrored by high total organic carbon contents.Another hint results from reducing conditions at times of deposition, that could bedetected by means of the pristene/phytene-ratio (Pr/Ph) as well as by the amountof hydrocabons released during pyrolytic degradation of organic matter (Hydrogen-Index, HI).