Messanae Universitas Studiorum

Assetto geologico degli affioramenti mesozoici peloritani

Montanari, L. (1989) Assetto geologico degli affioramenti mesozoici peloritani. Accademia Peloritana dei Pericolanti Classe FF.MM.NN., 67. pp. 9-26.

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Peloritans are Sicilian-Maghrebid Chain’s uppermost sector; they are made up of cristalline hercynic basement with its Liassic-Cenozoic sedimentary cover.
The Mesozoic-Paleogene succession is differentiated according to three South Alpine-equivalent (Fig. 1):
i) Taormina-type sequence, where after the ubiquitarian siliciclastic Hettangian base («Verrucano» Auci.) Liassic neritic calcdolomites and furthermore ammonitic and globigerinid-bearing ooze developed. The sharp change from neritic to pelagic situation occurred owing to a DomerianToarcian almost generalized crustal drop in that area.
ii) S. Marco-type succession, where Liassic is represented by neritic biogenic cristalline calcarenites, which are crossed by neptunian dykes with filling of reddish Middle Jurassic condensed limestones. This succession indicates neritic and pelagic carbonate plateaux, which intercale and end the basins (Fig. 2).
iii) Longi-type sequence, where cherty sometime euxinic hemipelagites occurred since Low Lias to Middle Cretaceous.
Both first and latter successions contain in their Upper Cretaceous-Eocene ooze «scaglia» certain megabreccia-resediments with clast of the second one; so, it is here suggested that many positive «flower» structures (owing to transpressive stress) had been formed during the same sinistral transcurrent phase in the area of the ancient plateaux at the time. A first occurrence of megabreccias is found in the Jurassic basinal Longi-type sequence, where megaclasts of Liassic S. Marco-type form thick amalgamated resediments («calcare massiccio» Auctj. This evenience is reputed to the des1r.ction of ari extemal sector of the S. Marco high $(SM_2)$, which resisted to the dìp at the Lias’s end and which emerged during the Aalenian eustatic lowstand.
Last megabreccia has been encountered in the outcrops which previous Authors believed carbonate-platform tectonic unit («Novara Unit») and occurred in OligoMiocene paralic-towards-flysch stratigraphic Unit at the expense of an
Australpine-equivalent sedimentary domain when the first folding began (Fig. 5). The globigerinid-bearing scaglia is sometime in geometric conform contact with older Jurassic pelagic limestùees without the intermediate Low & Middle Cretaceous and sometime without the Malm or Dogger beds. It is therefore suggested a tectoriic contact according to: a stock of Low Angie Normal Faults (LANFs) along ductile layers, with beginning at the scaglia’s base, which put at the seme piane etherochronous beds (Fig. 3).
(This mechanism is present also in the more external sectors of the Sicilian chain and may be extended to adjacent paleodomains).
For these reasons, the contact of the scaglia with older rocks without interrnediates is reputed to be both stratigraphic (when scaglia wraps up the megabreccia boulders) and tectonic, so that it is necessary to correct the figures which interprete as «normal» these contacts (Fig. 4).

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Item Type: Article
Subjects: M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Fisiche, Matematiche e Naturali > 1989 > Supplemento 1 parte 2
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Medico-Biologiche > 1989 > Supplemento 1 parte 2
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Giuridiche, Economiche e Politiche > 1989 > Supplemento 1 parte 2
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Lettere Filosofia e belle Arti > 1989 > Supplemento 1 parte 2
Depositing User: Dr M P
Date Deposited: 08 Oct 2012 10:21
Last Modified: 08 Oct 2012 10:21

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