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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Correlation of Mid-Devonian coral deposits of the Carnic Alps across the
Austro-Italian border
Erika KIDO 1 , Thomas J. SUTTNER 1 , Monica PONDRELLI 2 , Carlo CORRADINI 3 , Maria
G. CORRIGA 3 , Luca SIMONETTO 4 & Stanislava BERKYOVÁ 5
1 Austrian Academy of Sciences (CPSA) c/o University of Graz, Institute for Earth Sciences (Geology &
Paleontology), Heinrichstrasse 26, A-8010 Graz, Austria; erikakido07@yahoo.co.jp, thomas.suttner@unigraz
2 Università D'Annunzio, International Research School of Planetary Sciences, viale Pindaro 42, I-65127
Pescara, Italy, monica@irsps.unich.it
3 Università di Cagliari, Dipartimento di Scienze della Terra, via Trentino 51, I-09127 Cagliari, Italy;
corradin@unica.it, maria.corriga@unica.it
4 Museo Friulano di Storia Naturale, via Marangoni 39-41, I-33100 Udine, Italy;
luca.simonetto@comune.udine.it
5 Czech Geological Survey, P.O.B. 85, 118 21 Praha 1, Czech Republic; berkyova.s@seznam.cz
Mid-Devonian strata of the Carnic Alps are distinguished into ten different units representing a neritic
to pelagic succession within an area of approx. 240 km 2 . Here we mainly concern Middle Devonian coralrich
deposits of the neritic succession assigned to the Spinotti and Kellergrat Reef limestones and distal
slope sediments of the Hoher Trieb Formation (Fig. 1).
The Spinotti Limestone is well exposed at the Mount Seewarte and represents the Eifelian to Givetian
shallow water platform facies. According to SCHÖNLAUB et al. (2004), this formation is divided into four
units, bioclastic crinoid limestone (unit A), stromatoporoid debris limestone (unit B), and birdseye
limestone (units C and D) in ascending order. Units A and B of the Spinotti Limestone are regarded as
Eifelian in age (KREUTZER 1992a,b; HUBMANN et al. 2003). Although Unit A, at the base of the formation,
yields abundant and well preserved tabulate and rugose corals, they have not been studied in detail yet.
The birdseye limestone of units C and D yields distinctive intervals of branched stromatoporoids
(Amphipora) which are succeded by dolomitic beds rich in brachiopods, that, following SCHÖNLAUB et al.
(2004), might already indicate Givetian age. Near Costone Stella, Amphipora-rich horizons (generally called
Amphipora Limestone) are interfingering with birdseye limestone. Apart from stromatoporoids, these
horizons include solitary rugose corals (SCHÖNLAUB et al. 2004). That unit is continuously exposed towards
the south side of Mount Hohe Warte (track #143a) where it is succeded by the Kellergrat Reef Limestone.
At Forcella Monumenz near the Marinelli Refuge (Fig. 1.1), the massive limestone is unconformably
overlain by Carboniferous sediments of the Hochwipfel Formation. Approx. 185 meters below the top,
single broken specimens of Thamnopora (Fig. 2.1) are found together with other tabulate corals, high
trochospiral gastropods and brachiopods. Near the top of the Devonian limestone Amphipora is observed
(Fig. 2.2) just before the first lithoclastic breccias appear. Conodonts from those breccias indicate already an
early Carboniferous age. Unfortunately, the complex tectonic overprint in this area conceal the original
depositional relations, in particular at the top of the massive limestone with the Hochwipfel Formation and
in correspondence of a large limestone block at Cra. Val di Collina (Fig. 1.2: abandoned quarry at trail
#149). Within the limestones of the abandoned quarry abundant reef organisms are found that belong to
the Kellergrat Reef Limestone (Figs. 2.3, 2.4). Ten rugosan species belonging to nine genera are described
from this limestone (OEKENTORP-KÜSTER & OEKENTORP 1992; FLÜGEL & HUBMANN 1994). They are Favistella
(Dendrostella) trigemme, Battersbyia sp., Acanthophyllum concavum, Acanthophyllum sp., Grypophyllum sp.,
Stringophyllum sp., Cyathophyllum? bathycalyx, Columnaria sp., Alaiophyllum jarushevskyi, and Temnophyllum
sp. cf. T. latum. Tabulate corals consisting of 13 species in 8 genera are reported e.g. by VINASSA DE REGNY
(1918), HERITSCH (1943) and FLÜGEL (1956): Favosites fidelis fidelis, F. forojuliensis, F. forojuliensis pinnatus,
Pacypora coralloides, Striatopora major, Alveolites collinensis, A. crinalis, Caliapora? julica, Squameoalveolites sp.,
Coenites carnicus, C. mariae, C. polonica and Plasmopora carnica. The Kellergrat Reef Limestone also yields
Amphipora rudis, which is considered to indicate a Givetian to Frasnian age (compare HUBMANN et al. 2004).
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