Le litofacies permiane e triassiche della formazione di M. Facito auctt. nell’area di M. Facito (Successione di Lagonegro, Appennino meridionale)

Passerini, Leonsevero and Ciarapica, Gloria (2010) Le litofacies permiane e triassiche della formazione di M. Facito auctt. nell’area di M. Facito (Successione di Lagonegro, Appennino meridionale). Italian journal of geosciences, 129 (1). pp. 29-50. ISSN 2038-1727

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Abstract

Aim of this paper is to obtain a better definition of the stratigraphic succession of the M. Facito fm. that is the oldest part of the Lagonegro Mesozoic basin in Southern Apennines (Italy). Seismic data show that the Lagonegro succession overthrusted the western part of the Apulian Carbonate Platform and so the M. Facito fm. appears as a broken formation composed by a variety of different lithofacies. They were partially described by CIARAPICA & PASSERI (2000) in the two other typical areas. This paper, therefore, contribuetes to obtain a complete panorama of the lithofacies contained in the M. Facito fm. a) Calcirudites with fusulinids (Upper Permian). They are known only as scattered boulders and pebbles in tectonic melange and debris. These boulders are interpreted as tectonic shavings coming from melanges and reworked in the postorogenic debris flow. They are the only witness of the Permian in Southern Apennines. b) Capelluzzo lithofacies (Spathian-Aegean). It consists of black calcilutites, slates and calcarenites with abundant quartz grains. Sedimentary structures allowed us to recognize a coastal environment with offshore facies (thin-bedded black limestones), transition facies (limestones, slates and thin layers of cross-laminated quartz calcarenites) and shore-face facies (amalgamated beds of quartz calcarenites). c) Pietra Maura lithofacies (Anisian p.p.). It is represented by massive limestone with green algae, encrusting organisms, foraminifera and brachiopods. The main outcrops of Pietra Maura and Le Ripe are interpreted as carbonate build-ups. Sometimes they show evidence of exposure on the top. d) Varesano lithofacies (Anisian p.p.). It consists of marls, shales and sandstones. It partially lies by side and partially on the top of the previous lithofacies. The same species of brachiopods are contained in both the Pietra Maura limestone and in the shales and sandstones of Varesano, documenting their same age. Sandstones include quartz-wackes, quartz-psammites and quartz-arenites. In some outcrops they contain beautiful wavy ripples and burrows, but in other places they show turbidites with thick graded beds, flute casts, clay chips and current ripples. Sandstones with wave ripples overlying marls indicate a regressive trend. Turbidites are likely a witness of the successive deepening. e) Bellagamba lithofacies (Ladinian p.p.). This lithofacies marks the birth of the deep-water Lagonegro basin. It contains red nodular limestone (Rosso Ammonitico Auctt.) with very rare ammonites but rich in conodonts (early Fassanian to late Longobardian p.p.), radiolarian chert and true radiolarites. Calcirudites and megabreccias include elements coming from Ladinian build-ups that are not present in the Mt. Facito area but that are well known in other zones as Tempa di Rocca Rossa (Tempa di Rocca Rossa lithofacies, Ladinian p.p.). f) Petina Chiana lithofacies (late Longobardian to early Julian). This lithofacies is characterized by the presence of red shales and thin-bedded calcilutites with radiolarians and thin-shelled pelecypods (filaments). It contains the Ladinian-Carnian boundary and it marks the transition to the overlying Calcari con Selce fm. (Carnian and Norian).Some lithofacies lacking of clear relationships with the previous ones (Lithofacies Incertae Sedis) are also described in this paper. Among them, the Cognone lithofacies, that was settled down in a coastal environment and could be referred to the Anisian. The last subject is devoted to the description of the melange, well developed in the Mt. Facito area. It is possible to distinguish synsedimentary, synorogenic and postorogenic melange. The first one is represented by the Bellagamba lithofacies (radiolarites with calcirudites) that is the expression of the Middle Triassic rifting of the Ionian Ocean. The second one is related to thrust surfaces and it contains shavings of the oldest parts of the Lagonegro succession (Permian limestone and phyllites pebbles) sometimes mixed with Cretaceous elements of the «flysch galestrino fm.». The third one is very common and it consists of weathering products, loose sediments by mass flow and, sometimes, well cemented fluvial conglomerates. The abundance of melanges in the outcrops of Mt. Facito fm. probably lead to misinterpret it as a unique, huge olistostroma. In our opinion the fragmentary character of this formation is mainly due to tectonics

Item Type:	Article
Uncontrolled Keywords:	Stratigraphy, sedimentology, late permian, triassic, southern Apennines, Lagonegro
Subjects:	500 Scienze naturali e Matematica > 550 Scienze della Terra > 551 Geologia, Idrologia, Meteorologia
Depositing User:	Users 66 not found.
Date Deposited:	30 May 2012 11:12
Last Modified:	30 May 2012 11:12
URI:	http://eprints.bice.rm.cnr.it/id/eprint/3539

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