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Lower Pleistocene deposits in east part of the Favignana ... 167

sodes (BRIDGE & DEMICCO, 2008; CLIFTON,

2006; ELLIOT, 1986; JOHNSON & BALDWIN,

1986). Long lasted, wind-induced currents

deposited thick, seaward-dipping cross-

bedded calcarenites, spreading out on dis-

tance of hundreds meters. A submarine bar

system, probably developed along an up-

lifted block of the pre-Pleistocene platform

and run generally from north towards south.

Stacks of bedforms with subhorizontal la-

mination and through cross-bedding dip-

ping seaward and landward, with decrease

of bioturbation and occurrence of erosional

channels, can be regarded as crest part of

bar facies, similar to suggestion of DAVID-

SON-ARNOTT & GREENWOOD (1971). Sea-

ward slops of bars are probably represent-

ed by a sequence, where number of biotur-

bated bedforms and sets of small scale

trough increase in number and where gen-

erally the planar bedding dips seawards.

This successions are exposed in

Bue Marino area, in the easternmost part Fig. 17 - A model of currents distribution and Facies Associations, east from paleo-

of the Favignana Island. Occurrence of Favignana Island. Prevailed southward longshore currents. Scale bar dimension is

layers, with offshore and onshore dipping approximate. Vertical scale is roughly estimated.

sets of cross-bedding, shows on periodical Modello della distribuzione di correnti e delle associazioni di facies ricostruite per il

migration of dunes sea- and shoreward by settore orientale della paleo-isola di Favignana, caratterizzata dalla prevalenza di
wave induced currents, but seaward correnti dirette verso sud parallele alla riva. Le scale, orizzontale e verticale, sono
movements predominated. The magnitude approssimative.

and direction of all of these currents was varying during ELLIOT (1986): temporary tectonic uplift could be create

weather and long-term sea-level changes, and was also an effect of sea-level changes of a part of the shelf, thus

connected with vertical tectonic movements. It can be increasing the erosion by wave actions: it removed clas-

suggested that the observed bedforms were generated tic material from higher part of the uplifted bar toward

by giant long periods waves and by related surges, such deeper sea.

as those generated by propagation of hurricanes and/or

tsunamis into shallow water areas (D’ALESSANDRO & 4. CONCLUSIONS
MASSARI, 1997; TINTI, 1993). Periods of high wave

energy were interrupted by fair weather periods, during

these latter wave cross-ripple beds develop and the sea The distribution of bedforms, sedimentary struc-

bottom was colonized by burrow animals of Cruziana tures and ichnofacies allow to distinguish eastwards

ichnofacies while the upper part of deposited bedforms from shoreline of paleo-Favignana Island several cha-

was intensively bioturbated. The occurrence of bioturba- racteristic Facies Associations connected with fore-
tion suggests favorable conditions only in lower part of shore/shoreface (F A A), upper shoreface (F A B), up-
foreset laminae thus suggesting the persistence of a per/middle shoreface (F A D) and lower shoreface (F A
sea depth useful for a better concentration of food. On E) depositional zones with a system of inner bars (F A D
the contrary the uppermost part of sequence, totally de- p.p.) and outer bars (F A E p.p.) parallel or oblique to

void of trace fossils, can represents facies of short dura- the shoreline separated by trough (F A C) (Fig. 17-18).

tion aeolian dune. Considerable thickness of Facies Widely distribution washouts, rip channels and sedi-

Association (over … m), the lacking of distinct changes ments of tractional currents in all Facies Associations

of facies in vertical profile and of distinct progradation suggest deposition above wave-base level. Temporary

suggest a fault-induced lowering of this part of offshore developed partly emerged dunes have been recognized.

area. Flat erosional surfaces near Cavallo area show Only negligible part of clastic material was derived from

similarities to shoreface erosion planes described by erosion of uplifted part of paleo-Favignana Island that

probably had greater northward extension,

however bulk of the bioclastic material ac-

cumulated on Favignana inner shelf origi-

nated from shoreline material and is com-

posed of debris from molluscs, calcareous

red algae, bryozoan, foraminifera, etc. The

main role in distribution of clastics was

played by storms that induced strong and

Fig. 18 - Schematic profile of facies distribution in shoreface zone east from Favigna- very strong longshore currents along the
na Island with two bar systems. shoreline: These currents were shunted
offshore and cut and filled channels across
Profilo schematico della distribuzione delle facies di spiaggia nel settore orientale the bars. Landward movement of clastic
dell’Isola di Favignana, con evidenziati i due sistemi di barra.