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E. Tondi et al. / Journal of Structural Geology 37 (2012) 53e64 55

Fig. 2. (a) Stratigraphic section of the carbonate grainstones cropping out at Cala San Nicola with scale in meters and circle sizes proportional to grain sizes. (b) Four field photos of
the main lithofacies and one photomicrograph referenced by Roman numerals to lithofacies in the stratigraphic section.

a connected network in 2D. Both shape and size of these pores compactive shear bands and well-developed faults with slip
change according to the grain size and sorting in the rock (Fig. 2b). surfaces and fault rocks. In the following text, the latter elements,
Intergranular pores can reach a few mm in diameter in the very for the sake of simplicity, will be referred to as faults. Field data
coarse-grained lithofacies. The overall host rock porosity measured were then used to compute the scaling relationships among the
by both image analysis (2D) and laboratory measurements of different parameters for single bands, zones of bands and faults.
representative cylindrical cores (3D, Patrick Baud’s personal The field work was conducted at Cala San Nicola (Fig.1b), where the
communication) ranges between 30% (lithofacies III, Fig. 2) and 50% thickest and most homogenous Pleistocene carbonate lithofacies
(lithofacies IV, Fig. 2). Microsparry cement is always present, in crop out extensively (III, Fig. 2). There, several scan lines and
small amounts, at the grain contacts and/or within intragranular detailed structural maps at a 1:1 scale were constructed during
porosity. In addition, syntaxial overgrowth cement is present several field campaigns.
around echinoid plates and spines.
3. Field data 3.1. Geometry and kinematics

The compactive shear bands and strike-slip faults in Favignana, At Cala San Nicola (Fig. 1b), we identified three different sets of
the subject of this study, are similar to those reported by Tondi deformation bands. One of these sets occurs parallel to bedding
(2007) within the marine deposits, of Lower Pleistocene age, (Fig. 3), and is mainly in the coarser grained and more porous
cropping out in the coastal plain of Castelluzzo (San Vito Lo Capo carbonate beds (lithofacies IV, Fig. 2). The bed-parallel bands do not
Peninsula, NW Sicily). At both localities, the compactive shear show any amount of visible shearing, and are reminiscent of the
bands occur in coeval marine deposits overlying the Mesozoic- compaction bands documented in the Majella Mountain area,
Cenozoic basement, and show similar geometries and kinematics. central Italy (Tondi et al., 2006a; Antonellini et al., 2008; Agosta
For this reason, we rely on the observation and discussion provided et al., 2009). Given the lack of evidence for deformation related to
by Tondi (2007) about the microstructural and textural character- shear, these structures were not examined as part of the present
istics of the bands, as well as on the micromechanical processes study. The two sets of high-angle to bedding deformation bands
involving pore collapse and pressure solution responsible for their consist of compactive shear bands, which are either single bands or
formation. At Favignana, thanks to the magnificent and widespread zones of bands (Fig. 4a and b). Faults including compactive shear
exposures, the field work focused on: (i) geometry, (ii) kinematics, bands with continuous slip surfaces, and the associated cataclastic
(iii) dimensional parameters (i.e. length, thickness and amount of fault rock, mark an advanced stage of deformation within this
displacement) of the two sets of compactive shear bands, zones of carbonate grainstone (Fig. 4c).