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72 S. Todaro et al. / Sedimentary Geology 333 (2016) 70–83
pelagic carbonates and Oligo-Miocene sandstones and clays (Abate spectacular views of the sedimentary facies that form the succession.
et al., 1991, 1993). We focus our attention on the Upper Triassic limestones as they record,
The Triassic–Jurassic neritic carbonates occur in the structural units among others, the spongy-like dissolution morphologies.
of this area, and in general in the Maghrebian thrust and fold belt, and
represent remnants of the extensive shelf that evolved along the
north-African Margin, close to the westward termination of the Ionian 3. Methods
Tethys (Zarcone et al., 2010; Zarcone and Di Stefano, 2010; Fig. 2).
During Norian–Rhaetian time, huge sponge reefs rimmed this large Field observations, on inactive quarries, were focused on determin-
flat-topped carbonate platform, which were replaced by sandy ing the presence of peculiar diagenetic features of the Upper Triassic
(oolitical–skeletal) margins during the earliest Jurassic (Di Stefano, succession. In particular, we analyzed and measured the cycle stacking,
2002). The internal zones of the platform were transitional to more re- the facies distribution and those horizons which were affected by the
stricted and partly evaporitic areas today known in the subsurface of the stratabound dissolution. Detailed observations were carried out in par-
Sicily Channel and the Egadi Islands. ticular on the horizons in which the spongy pattern is well preserved.
The studied succession crops out along the northern slope of Monte About twenty samples were collected through either a geological ham-
Sparagio, a large structural unit in the southern sector of the San Vito mer or an electric drill equipped with a 3.5 cm diameter corer. A thin
Peninsula that gives rise to an approximately 10 km long, W–Etrending, section was made of all samples and analyzed by transmitted-light
elongated mountain ridge (Fig. 1C). This succession consists of a microscopy.
400 meter-thick, Norian–Rhaetian succession of parallel bedded, Cathodoluminescence observations, carried out through an Olympus,
whitish gray peritidal limestones and dolomitized limestones that are CITL 8200 mk3, were used to examine the paragenesis and the degree of
grouped in the Sciacca Formation. They are overlain by about 150 m of recrystallization of cements. Major element (Mg, Ca) and trace-element
Hettangian–Sinemurian limestones (Inici Fm.) with the same cyclic fa- (Fe, Mn and Sr) compositions were determined by Cameca SX 100 Elec-
cies development (Fig. 1D). Based on the dominance of peritidal facies tron Microprobe at the School of Earth, Atmospheric and Environmental
with thick paleosols, a paleogeographic location of this succession in in- Science of University of Manchester using an accelerating voltage of
terior zones of the platform has been inferred (Fig. 2). The tectonic frag- 15 kV, beam current of 20 nA and a beam width of 1 μm used. The values
mentation created by the Maghrebian orogeny does not allow a reliable of (Ca, Mg) CO 3 and SiO 2 summed to 100% (±1%) in all cases, except
distance from the original platform margin to be determined, but it is where analyses were adjacent to hematitic silt. In this case, the sum of
estimated to be several tens of kilometers. The peritidal carbonates are the oxides exceeded 100% by 3–12%. These analysis points were exclud-
covered by thin and discontinuous beds of pelagic Rosso Ammonitico ed from all further data analysis.
and by Upper Jurassic slope limestones with Ellipsactinia. Powders for stable isotopic analyses were sampled using a micro-
The Monte Sparagio mountain ridge is part of a large area that has driller with a diamond tip. Stable isotope analyses were performed at
been intensely exploited for ornamental stones and is known as “Bacino Liverpool University under the supervision of Dr. J. Marshall and at the
Marmifero di Custonaci”. Quarries are mainly located in the Cretaceous Institute for Geology, Mineralogy and Geophysics of Rhur-University
slope limestones but also in Triassic and Lower Jurassic peritidal carbon- of Bochum under the supervision of Prof. A. Immenhauser and Dr. A.
ates, and those faces that have been cut by diamond wire offer Niedermayr.

Fig. 2. Paleogeographic reconstruction of the central Mediterranean area which shows the main sedimentary domains of Sicily during Late Triassic times. The black triangle indicates the
inferred location of the studied succession (mod. from Zarcone and Di Stefano, 2008).