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Lower Pleistocene deposits in east part of the Favignana ... 159

the deposition of thin, tabular cross-stratified or hori- beds, a vertical facies succession can be observed:
zontally laminated calcarenites. Exceptionally, storm from the base subhorizontal laminated calcarenites crop
action reworked the sediments developing both mas- out, capped by cross-bedded calcarenites, locally
sive calcarenites, with lags above erosive surfaces, or wedgelike, whose top consists of strongly bioturbated
calcarenites with vertical sequence of tabular cross- calcarenites (Fig. 10)3.
stratified and ripple laminations or erosive channels
filled up by cross-bedded calcarenites. During coloniza- Generally, cross-bedding is inclined towards SE,
tion windows (GOLDRING, 1991), planar trace fossils only locally toward W. The upper part of the Facies Asso-
sets (Cruziana facies) took place. Facies Association C ciation D shows typically the occurrence, particularly in
represents low energy environment connected with a more distal (seaward) part (Fig. 9b), of broad (dozen or
bar trough (CLIFTON, 2006). Sporadic appearance of so meters) erosional channels and washouts (usually up
very coarse sediments could be rather an effect of to 2 m) (Fig. 8): channels are filled-up or by massive
strong storms (ELLIOT, 1986; CLIFTON, 2006) while evo- calcirudites (Fig. 10a) or by calcarenites with trough
lution of beach/nearshore facies could be linked with cross-lamination, partly destroyed by bioturbation. Some
change of sea level (MATEU-VICENS, 2008). Scattered calcarenites show crude concave or chaotic laminations
occurrence of problematic mangrove type roots sug- and can pass into parallel laminated and cross-bedded
gests shoal areas. calcarenites. Exceptional deep channels (up to 5 m)
have been observed in Cala Calamoni, SE from the
3.4 Facies Association D town of Favignana; channels are filled by laminated cal-
carenites and massive calcarenites with scattered bi-
This Facies Association, characterized by the oc- valve shells. Direction of chan- nels are generally N-S,
currence of tabular laminated cross-bedded calcarenites (NW-SE to NE-SW) and locally W-E4.
(Figs 7, 9a), whose lower and upper surface of beds are
erosive, with broad deep channels (Figs 8, 10b) and ab- Facies Association D is also characterized by the
undant trace fossil of Skolithos ichnofacies, is exposed, occurrence of Scolithos ichnofacies (Figs 10c-e, 11a), in
for a thickness that do not exceed 15 meters, along the some localities the Scolithos-type traces cross the earli-
northern island shore (Frascia area), between the town er bioturbated zones (Fig. 10e); less common there are
of Favignana and Cala S. Nicola (Fig. 1c).The main fa- Cruziana (Thalassinoides and Ophiomorpha) ichnofa-
cies, mainly developed in western (landward) part of cies linked with the colonization windows. Concentration
Association D (Fig. 9a), is represented by thick bedded of vertical burrows at the top of the bed is often ob-
(up to 2 m) and coarse-grained calcarenites, with sub- served (Fig. 10d). Mainly between Punta S. Nicola and
horizontal and large-scale cross-bedding. Generally the Madonna traces of Echinoidea have been observed. In
lamination is emphasized by change of grain size and the central part of the Island, near the town of Favigna-
locally by lags of fragments of bivalve shells. Locally na, in very thick cross-bedded and subhorizontal lami-
laminae are pervasive bioturbated. The main feature nated calcarenites, several horizons with Scolithos are
of some cross-bedded strata shows a laminated-to- observed (Fig. 11a). Locally, there are cluster burrows
bioturbated pattern, similar to described from Pleisto- represented by straight radial tubes (few millimeters
cene deposits of Salento area by D’ALESSANDRO & thick) and tens of cm long (Fig. 10g), which resemble
MASSARI, (1977). In few cases, only the lower part of that traces which were made by colony of social insects
each set of inclined laminae is bioturbated; somewhere (CURRAN, 1992). The planar, radial and bifurcated struc-
bioturbation is pervasive. In some thick calcarenite tures (Fig. 10h) can represent root system of plants. The
presence of rooted plants in the Pleistocene sediments

3 Less common are thick-bedded calcarenites, with big scale through cross-bedding, Locally, there are sets of bi-directional cross bedded
bodies, lenses of medium- and fine-grained structurless calcarenites and intercalations of calcirudite represented generally by matrix-
supported conglomerates with rhodoliths (few cm in size), fragment of shells (mainly bivalves, locally Dentalium) and sporadic pebbles of
Mesozoic limestones. Sporadically shells of bivalves (Fig. 10a) and Echinoidea are concentrated on surfaces of cross-bedding.

4 In some places, near the top of the beds, convolute laminations or single small conical forms are visible, the dimension of convolute
raises several tens of cm (Fig. 10b). Locally, there are sets of small, rotated synsedimentary normal faults (Fig. 11b). In few places
small parallel dunes, 30 cm of width, which upper surface can be covered by scattered shells and rhodolithes, are locally developed
on the upper surface of calcarenites.

Associazione di Facies B (zona uppershore), area di Punta Longa, a sud della città di Favignana. a) Conglomerato costituito principal-
mente da rodoliti, a stratificazione incrociata nella sua parte superiore. Il Nord è verso destra. L’unità di misura è di 1 m; b) Particolare,
concentrazione di gusci di molluschi disposti orizzontalmente. Nella parte inferiore è visibile la stratificazione incrociata. La lunghezza del
temperino è 6 cm; c) Calcarenite massiva con stratificazione incrociata mal definita ricoperta da calciruditi a stratificazione incrociata che
passa verso terra a calcareniti grossolane. Le superfici di strato registrano eventi di tempesta. Si noti una faglia sul lato destro della foto
(F). L’unità di misura è 1 m; d) calciruditi suborizzontali, a gradazione inversa con clasti maggiori isolati, troncati da una superficie di ero-
sione sulla quale poggiano calcareniti grossolane e conglomerati, inclinati verso mare, fortemente bioturbati. Si notino le tracce fossili
verticali tipo Scolithos. Alcune di queste attraversano l'unità più bassa. Meno visibili sono i Thalassinoides sviluppati sulle superfici di
strato inclinate – confronta la Fig. 3g. Vedi la penna per la scala; e) Sequenza sedimentaria che inizia con calciruditi contenenti rodoliti e
frammenti di gusci, seguiti da strati orizzontali (f), passanti verso l'alto a calcareniti a stratificazione obliqua, incrociata, bioturbate (cr) e
ricoperte da calcareniti tipo hummocky (b). L’inclinazione delle lamine è verso il mare. La lunghezza della matita è 15 cm; f) Canale loca-
le (Ch) nelle calcareniti suborizzontali grossolane con matrice pelitica. Questo canale, profondo 1,5 metri, è riempito da un gruppo di
corpi sinusoidali a stratificazione incrociata inclinati verso terra. Nota la concentrazione di ciottoli (e.g. vicino il martello). Vedi il martello
per la scala; g) griglia di Thalassinoides al tetto della sequenza mostrata in Fig. 3d. Nota gli strati sottili di peliti che sono molto rari nell'a-
rea di studio; h) dettaglio della griglia di Thalassinoides; i) a luoghi vi è anche la presenza sporadica di Ophiomorpha.