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16 B. Abau, G. Lo Cicero & L. Montmrari
Fig. l · Sttuctur.al :scheme of Sicily;
Us = Ustica lsb.nd. Eol =
Eolr.n hl•nds, El;. :. Egadi
W»~.c!s, E• = Em•.
Maugeri-Patané (1924, 1932}; Schmidt-Friedberg et al. Bctween the neritic limestones and the others, allo-
(1960}; Ognibcn (1960}; Wendt (1963, 1971}. dapic sediments may be found. Further paleoenvironmen-
tal informatico carne from neptunian dykes (Weodt 1965)
From the Sixt ies of the last century micropaleonto-
logical contributions - initially by oil industry and Gov- and from coeva[ hardgrounds Uenkins 1970;Jenkins et al.
ernmental lnstirutions • and facies analyses (R;go & Bar-
bieri 1959; Barbieri 1964; Montanari 1965, 1966} have 2002). Ali these lithofacies cbaractcrizc scveral sedimen-
been taken into consideration.
tary "facies-domains" (Fig. 3). The first lithofacics per-
Jurasslc framework
rains 10 carbonale plarforms o r ramps, whjch started to
Our stratigraphic analysis on jurassic sediments grow since the Late Triassic; tbeir age extends from Early
allows to individuate fou r deposits assemblages, corre- w Middle Liassic and sometimes up to Late Jurassic.
sponding to sedimentary environments (Fig. 2): neri tic
limesrones; Cephalopoda-bearing red condensed pelag- T hc depositional sites changed their characteris-
ites; nodular white to reddish Ammonite-bcaring lime- tics in time. TiU the M iddle Liassic the plarforms were
stones ("Rosso Ammonitico" or R.A. auct.); argillites clevated compared to the adjacent hemipelagic basins.
and radiolarites.
Since rhe Late Pliensbachian (spinatum Zone) in the Pe-
loritani domain and since the Early Toarcian (falciferum
Zone) in the Maghrebian domain, almost ali of them
drowned, becoming sites for pelagic red Ammonite-
bearing condensed limestones. Tbc basins, whicb were
adjacent 10 the p latforms, are characterized by either
Fig. 2 - Four mainjurassic lithofacies
usoci.ation.s. Not~ pbr(orms
and st;amount4ype nruclures
with condensed Middle U~s
sic "Rosso Ammonilico-" s.I.
(R.A.) crossed by neptuni:an
dykes. Bl:tck Jinc:s for inJerrcd
bouom currents; s.c.d. • ~t·
ur:uion comptnution depth.
