Aretz et al_2011.pdf - ORBi - Université de Liège

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Kölner Forum Geol. Paläont., 19 (2011)
M. ARETZ, S. DELCULÉE, J. DENAYER & E. POTY (Eds.)
Abstracts, 11th Symposium on Fossil Cnidaria and Sponges, Liège, August 19-29, 2011
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A similar succession is observed in the Cason di Lanza area at Mt. Zermula, Italy (Figs. 1.3, 1.4). Here
Amphipora Limestone (Figs. 2.5, 2.6) and Devonian carbonate platform sediments, which probably
correspond to the Kellergrat Reef Limestone, are exposed. This Devonian carbonate platform is overlain in
places by Famennian-Tournaisian Clymeniae limestones. The succession is unconformably capped by
siliciclastic deposits of the Hochwipfel Formation. The Carboniferous unit is thrusted on top of a deeper
marine Upper Ordovician-Upper Devonian sequence, which includes deposits of the Hoher Trieb
Formation (Eifelian/Givetian in age) that typically consists of several limestone breccia levels bearing
silicified corals (Figs. 2.7, 2.8). In the Carnic Alps such horizons with silicified corals are generally found in
the distal slope facies. In literature these corals are reported from the “Bank mit verkieselten Korallen”
which is considered to be Givetian? in age (FLÜGEL & HUBMANN 1994; HUBMANN 1995). Following corals are
described. Rugosa: Cystiphyllum? geyeri, Grewingkia? carnica, Barrandeophyllum carnicum, Entelophyllum
articulatum, Entelophyllum? alpinum, Pycnactis mitratum, Sociophyllum torosum, Cyathophyllum? taramelli;
Tabulata: Caliapora heritschi, Caliapora? carnica, Favosites forbesi forbesi, F. thildae.
Our preliminary study revealed that the conodonts obtained from the breccia levels bearing the silicified
corals at Lanza indicate not exclusively Givetian but also Eifelian age (kock. kockelianus to Lower varcus
conodont zones). This shows that the silicified corals were accumulated as re-deposited material derived
from either Eifelian or Givetian reefal limestone of the carbonate platform. Silicified coral taxa discussed by
FLÜGEL & HUBMANN (1994) and HUBMANN (1995) seem to be different from those of Givetian age reported
from the Kellergrat Reef Limestone. Comprehensive study in future should help to clarify the relation of
Middle Devonian coral species obtained from neritic and pelagic strata of the Carnic Alps.
Research is funded by FWF P23775-B17 and project 334000 of the Czech Geological Survey. This is a
contribution to IGCP 596.
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