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Kleine Geologie des Kellerwaldes (Exkursion F am 5. April 1991)
No full textEs gibt keinen geologischen Führer für den Kellerwald, nicht einmal eine zusammenfassende Darstellung der Geologie. Ich folge daher der Anregung von WOLFGANG FRANKE, für die Teilnehmer der 111. Tagung des Oberrheinischen Geologischen Vereins in Bad Wildungen eine kurze Geologie des Kellerwaldes zu schreiben. Es ist nicht möglich, ein Gebirge von der kleinräumigen Vielfalt des Kellerwaldes auf einer eintägigen Exkursion auch nur annähernd vollständig darzustellen. Die Auswahl der Aufschlüsse beabsichtigt daher, einen Eindruck von der extremen Fazies-Differenzierung der Sedimente und dem komplizierten Gebirgsbau zu vermitteln. Der Text geht über die Bedürfnisse einer eintägigen Exkursion hinaus, bleibt aber noch immer bei sehr pauschalen Beschreibungen und Deutungen stehen. Er soll nicht eine Monographie ersetzen, sondern ein Schlüssel zu den verstreuten neueren Arbeiten zur Geologie des Kellerwaldes sein. Mit deren Hilfe sollte es möglich sein, sich ein Bild vom Bau des Gebirges zu machen
Ein Diskussions-Beitrag
No full textWhen discussing the relationship between lithology and faunal distribution patterns in a part of the Ooser Plattenkalk-sequence (Upper Devonian, Adorf-Stufe, Eifel Mountains, Germany), Böger (1966) quoted that neither the theory of Krebs 1962 (interchange of shallow and deeper marine environments) nor the interpretation of Meischner 1964 (intercalation of calcareous turbidites, “allodapic limestones”) is satisfactory.
It is pointed out here that Böger's observations can be explained by a rather simple mechanism: Calcareous ooze of turbidity currents is transported to the farthest parts of near-reef basins where it gives rise to the precipitation of carbonate, if the hydrographical conditions are favourable. By the same turbidity current the bottom water is replaced by oxygen-rich water and the migration of low pH, low Eh water from the sediment up into the bottom water is prevented by the newly formed sediment layer. This gives for a short time an opportunity for the development of a more advanced benthonic fauna
Perniciöse Epökie von Placunopsis auf Ceratites
No full textAn adult Ceratites semipartitus encrusted by epifaunal Placunopsis ostracina is described. The epizoans are orientated in relation to the slope of the substratum and according to their time of attachment to the ammonoid shell. Geometrical analysis of the orientation leads to the following conclusions: (1) During and after the growth of the last whorl, several, probably 4, swarms of larvae of Placunopsis settled upon the Ceratites specimen. (2) The dead body was for some time kept upright, the living chamber showing upwards. During this time, larvae of Placunopsis became attached again. (3) The ammonoid shell was then laid down, its left flank in contact with the sediment. In this position it was for the last time settled upon by Placunopsis which died whilst juvenile.
Provided that the phases of attachment corresponded to annual spawning periods of Placunopsis, the last whorl of the Ceratites was formed with decreasing velocity of growth within about 4 years.
Placunopsis became attached with its right valve, the posterior end of the body showing upwards, and the direction of growth being declined from the vertical by 65°. Placunopsis either preferred to settle within a distinct zone of the living chamber of the ammonoid close to the lowermost part of the shell or was able to grow up here only. Ceratites semipartitus was therefore probably nectonic.
Both the host and the epizoan were influenced to their disadvantage by their fatal partnership. A relationship of this kind therefore should not be called a symbiosis
Rhenaer Kalk und Posidonienkalk im Kulm des nordöstlichen Rheinischen Schiefergebirges und der Kohlenkalk von Schreufa (Eder)
No full textFormation processes and dispersal patterns of the sediments along the Istrian coast of the Adriatic
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