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Die Kerogen-Fazies der Tonstein-Blattertonstein- Rhythmite des Ober-Barreme/Unter-Apt im Niedersachsischen Becken (Norddeutschland) am Beispiel der Bohrung Hoheneggelsen KB 50.
| Below, R. and Kirsch, K-H. | |
| 1997 | |
| Paleontographica, abt. B, band 242, 1997: pp. 1-90.Paleontographica, abt. B, band 242, 1997: pp. 1-90. | |
| Die Kerogen-Fazies der Tonstein-Blattertonstein- Rhythmite des Ober-Barreme/Unter-Apt im Niedersachsischen Becken (Norddeutschland) am Beispiel der Bohrung Hoheneggelsen KB 50. |
Below, R. and Kirsch, K-H., 1997. Die Kerogen-Fazies der Tonstein-Blattertonstein- Rhythmite des Ober-Barreme/Unter-Apt im Niedersachsischen Becken (Norddeutschland) am Beispiel der Bohrung Hoheneggelsen KB 50. Abstract The kerogen-facies of Upper Barremian and Lower Aptian sediments from borehole Hoheneggelsen KB 50 (Niedersachsen/ Germany) is analysed. Similar distribution patterns of the terrestrial palynomorphs as well as the Prasinophyta typically opposite to species diversity of Dinoflagellate-cysts, reflect the changing influence of the continental system onto the marine environment during the Upper Barremian and Lower Aptian. During the deposition of the Blattertonstein/Tonstein-alternance and the Fischschieferhorizon terrestrial influence could be very high with significant freshwater runoff forming a widespread wedge with reduced salinity stratified over normal saline marine bottom watermasses resultin~ in a characteristic Pollen/Prasinophyta/Dinoflagellate-cyst association of the laminated, COrg-rich, dark Blattertonsteine, deposited under anoxic conditions of seafloor-water. The minimum input of terrestrial palynomorphs within those sediments that immediately follow the Fischschieferhorizon indicates a sudden and remarkable change to a normal marine environment that is no longer continentally influenced. Trends within the distribution patterns of terrestrial palynomorphs, Prasinophyta and Dinoflagellate cyst-associations as well as significant changes of their abundance are discussed. The socalled marine: continental-index generally used in kerogen analysis to estimate the continental influence to the marine environment, is criticized as being unsuitable for palaeoecological reconstructions in comparison to the simple calculations of procentual frequency of taxa within associations.