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JOURNAL OF MAPS 7
Downloaded by [Universita di Palermo] at 02:49 07 January 2016 (a) and 5(b)). We also found interbedded at different Scattered patches of Holocene sediments unconform-
levels decimetric thick red palaeosols (Figure 5(i) and ably overlie the Meso-Cenozoic rocks. They consist
5(l)), made up of siltites and sandy clays with rare cen- of mostly calcareous, very coarse to medium-sized
timetric carbonatic clasts. A palaeosols layer separates sands with gravelly lithoclasts and bioclasts made
the lower cemented carbonatic breccias and megabrec- up of algal nodules and skeletal grains (mostly
cias (DETb) from the overlying red, not cemented bivalves, gastropods and bryozoans).
levels (DETa; Figure 5(d)), as shown along the trail
from Punta Troia to Marettimo village, in the Punta In the innermost sector of the continental shelf (0–
Troia fan (Figure 5(a)), near the cemetery, and close 20 m of water depth), a ring of the Mesozoic carbonate
to the village. rocks outcrop on the very rough sea-bed, characterized
by a number of several meter-high cliffs, at the base of
4.2.2 Marine coastal deposits which boulders, up to 20 m in size, have accumulated
Between 0 and 10 m a. s.l., we found very thin levels of (Lo Iacono, 2003). Along the southern sector of the
marine coastal deposits, composed of polygenic, grain- island, thin beds of the Marettimo Formation can be
supported, fossil-bearing (mainly bivalves and gastro- detected along the submerged coastal belt. Off the east-
pods) conglomerates (Figure 5(e)). They pass upwards ern coast, isolated carbonate relief of the Marettimo
to micro-conglomerates and sands with reddish matrix Formation outcrop at Scoglio del Cimitero and il Cam-
and faunas (Patella ferruginea, Conus testudinarius mello. Wave cut platforms are very narrow, a few
(SIT); Figure 5(f) and 5(g)) of the MIS 5.5 meters wide or totally absent.
(Tyrrhenian).
On the whole, the coast shows bluff or cliff mor-
At Punta Troia, at Case Martorana, along the coast phologies with only several very small pocket beaches.
between the village and the cemetery, and at Punta More vertical and higher (up to some tens of meters)
Galera (Main Map), a marine coastal wedge with Tyr- cliffs coincide with the Monte Falcone Formation out-
rhenian fauna is interbedded between the cemented crops (e.g. Punta Bombarda, Punta Pegna).
alluvial fan deposits and the overlying more recent
not cemented continental deposits (Figure 5(c) and 5 6. Structural analysis
(h)). On the shore near Molo Nuovo a yellow fossil-
bearing calcarenitic layer underlies the older alluvial Currently, the Marettimo structural edifice can be
fan cemented deposit (MRS; Figure 5(d)). described as a portion of a tectonic wedge, which con-
sists of two tectonic units (Bassano unit and Falcone
5. Marettimo offshore unit) characterized by a southeastward direction of
transport.
The continental shelf off Marettimo Island is
bounded by a sharp shelf-break located between 80 Folding and faulting patterns were analysed at many
and 140 m of depth (Main Map); it displays an sectors of the island (Main Map). The structural analy-
approximate rhombohedric shape in plan view that sis, concerning bedding, axial plane stylolite cleavage,
suggests structural control by NW-SE- and WNW- extensional veins, slickenlines and crystal fiber linea-
ESE-trending faults. The shelf is up to 13 km wide tion, allowed recognition three different tectonic events
southwards but only 2–3 km wide off the western, and associated structures: the extensional, compres-
northern and eastern coasts. This area is a very sional and transpressional events.
young, undernourished platform with a number of
bathymetric breaks-of-slope and well-preserved mor- 6.1 Extensional event
phological features such as palaeo-cliffs, rills and iso-
lated relief (Lo Iacono, 2003). ENE-WSW normal faults, southwards-dipping and
displaying local syntectonic geometries, affect the car-
The continental shelf is characterized by a wide- bonate rocks of MAR, around the cemetery (Figure 6
spread surface of marine erosion, scoured on the (a) and 6(b)). On the Punta Troia promontory (Main
Meso-Cenozoic. This erosional surface, separating the Map), the Jurassic carbonates and dolomites of the Fal-
Holocene from older rocks, has a polygenetic origin cone Unit are displaced by high-angle ENE-WSW nor-
related to the last glacio-eustatic fluctuation that mal faults. The fault planes affecting the Liassic
occurred in the last 100 ky. conglomerates and breccias (MFA1–2) are covered by
the marls and radiolaria-bearing marly limestone
Data from seismo-acoustic profiles and scuba-div- (APT) along buttress unconformity surfaces (Figure 6
ing observation (www.videpi.com; Agate et al., 2005; (c) and 6(d)). Another effect of the extensional stress
Catalano et al., 1993; Hermand et al., 2000) allow the field is the ENE–WSW alignment of basaltic rocks
recognition of submerged outcrops of carbonate inside the Triassic marls of the Marettimo Formation
Mesozoic rocks (MAR, MFA) and terrigenous (MARb) in the Bassano succession (Main Map).
Oligo-Miocene rocks (FOR) unconformably covered
by Plio-Pleistocene deposits (NO, ISD, OSD).