Co-occurrence of the foraminifer Mohlerina basiliensis with Bacinella–Lithocodium oncoids: palaeoenvironmental and palaeoecological implications (Late Oxfordian, Swiss Jura)
- Védrine, Stéphanie Department of Geosciences, University of Fribourg, Switzerland - School of Earth and Environment, University of Leeds, UK
-
2008
Published in:
- Journal of Micropalaeontology. - 2008, vol. 27, p. 35-44
English
The stratigraphical and spatial distribution of the foraminifer Mohlerina basiliensis and Bacinella–Lithocodium oncoids was studied in the lagoonal deposits of the oncoid-rich Hauptmumienbank Member from the Swiss Jura Mountains (Late Oxfordian, NW Switzerland). Mohlerina basiliensis has a double-layered wall structure (thick outer hyaline-radial calcite layer with a lamellar structure and thin inner microgranular calcite layer) and is preferentially found in low-energy facies and associated with normal-marine bioclasts and Bacinella–Lithocodium oncoids. The distribution of Mohlerina basiliensis is relatively patchy. The ‘distal’ platform facies present a higher abundance and a more extensiv stratigraphic occurrence of this foraminifer. The timing of the ecological evolution is given by the sequence- and cyclostratigraphic framework and illustrates the stepwise flooding of the platform. Bacinella–Lithocodium oncoids have diameters of a few millimetres to several centimetres and are composed of an alternation of Bacinella–Lithocodium meshwork and thin micritic laminae. They are found preferentially in low-energy facies (bioclastic wackestones) of open lagoons. The distribution of Bacinella–Lithocodium oncoids through time and space is also patchy; however, they appear more abundantly in ‘distal’ platform facies. This study reveals the co-occurrence of Mohlerina basiliensis and Bacinella–Lithocodium oncoids and thus suggests similar environmental conditions.
- Faculty
- Faculté des sciences et de médecine
- Department
- Département de Géosciences
- Language
-
- English
- Classification
- Geology
- License
- License undefined
- Identifiers
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- RERO DOC 10542
- DOI 10.1144/jm.27.1.35
- Persistent URL
- https://folia.unifr.ch/unifr/documents/300738
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