1. Growth, deposition, and facies of Pleistocene bathyal coral communities from Rhodes, Greece.
- Author
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Freiwald, André, Roberts, J. Murray, and Titschack, Jürgen
- Subjects
CORALS ,MARINE animals ,BIOTIC communities - Abstract
Modern and widespread deep-water coral ecosystems have become a major target of research during the last decades. So far, only a few fossil counterparts of such carbonate-secreting deep-water communities have been described. This scarcity might be a result of either, a possible miss-identification as a tropical deposit and/or the rare case of tectonic uplift and subsequent access to these deepwater deposits. The early Pleistocene St. Paul’s Bay Limestone on the island of Rhodes (Greece) represents one of the few known examples of the bathyal ‘white coral community’ dominated by Lophelia pertusa which are exposed on land. This occurrence relates to a convergent tectonic setting with large-scale uplifts in the vicinity of the European-African plate boundary that is responsible for the exposure of these early Pleistocene deep-water deposits. The geometry of the St. Paul’s Bay Limestone significantly differs from the mound-forming Lophelia occurrences as known, e.g., from the NE-Atlantic or the Florida Strait. Instead, it appears similar to the modern ‘white coral community’ of the western Mediterranean Sea that is usually associated with submarine cliffs. Much like the latter, the St. Paul’s Bay Limestone demonstrates that the growth and final deposition of the ‘white coral community’ was strongly influenced by the complex relief with steep submarine basement cliffs generated by horst-graben systems. These submarine cliffs not only provided the main habitat for the ‘white coral community’, they also explain recurrent instability and redeposition by debris falls along the submarine cliffs. Such a debris fall mechanism is strongly suggested by: (1) the steep slope angles (>30°), (2) the short transport distance (<20 m), (3) the wedge-like geometry, (4) the lack of grading, (5) the fabric complexity with incorporated fragments of hardgrounds, intraclasts and slightly consolidated sediment, (6) geopetal structures of various directions, thus indicating multiple resedimentation events, and (7) the variety of fragmentation and bioerosion. This resulted in the final deposition of the ‘white coral community’ (1) at the foot of submarine cliffs and (2) in neptunian dykes and, to a minor extent (3) in erosional depressions of the basement rock. In conclusion, the basic characters of the St. Paul’s Bay Limestone in terms of the initial facies, fabric and fauna largely match those described for lithoherms (Florida Strait). The enhanced complexity in terms of the final fabric and the wedge-like geometry appear due to multiple resedimentation events via debris falls along submarine cliffs. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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