The Liguride and Subliguride units of the Candia Hills (Apuan Alps): lithostratigraphy and tectonic setting. A detailed field mapping (scale 1:5000) of the area located at the west side of the Apuan Alps (Candia Hills, Massa-Carrara province) has been carried on. The lithostratigraphic features and new findings of calcareous Nannofossils from the units outcropping in this area are reported. The Candia Hills area represents an interesting sector belonging to the Northern Apennine where ligurian (Ottone Unit; Bertotti et al., 1986; Elter et al., 1991, Zanzucchi et al., 1993; Elter et al., in stampa), subligurian (Canetolo and Sanguineto-Marra units; Plesi, 1974; Labaume, 1992, Elter et al., in stampa; Pagani e Zanzucchi, 1970) and non-metamorphic tuscan unit (Tuscan Nappe), overriding the Apuan Metamorphic Complex, are exposed. A good knowledge of this sector could help to understand the complex miocenic tectonic events that led to Apuan Alps exumation (Carmignani et al., 1980; Coli, 1989; Carmignani e Kligfield, 1990). A tectonic stack of units belonging to the liguride and subliguride domains overlies the Macigno Formation of the Tuscan Nappe. The sequence of the Ottone Unit consists of thick calcareous turbidites with minor intercalations of ophiolite-bearing polimict pebbly-sandstones and -mudstones. The Canetolo Unit consists of the Argille and calcari Formation (Early-Middle Eocene) characterized by two lithostratigraphic units ("shaly-calcareous" and "calcareous") whose relationships are connected to an early folding phase. Between Canetolo Unit and Tuscan Nappe a non-continuous level of silty-marlstones has been recognized; the calcareous Nannofossils assemblage seems indicate a late Oligocene age. This unit has been here called "Mt.Olivero formation" and it can be probably referred to the subliguride domain (Sanguineto and Marra units of the Northern Apennines; Plesi, 1974; Labaume, 1992, Elter et al., in stampa; Pagani e Zanzucchi, 1970; Cerrina Feroni et al., 1990). Near Case Lazzoni the contact between the Canetolo Unit and the overlying Ottone Unit is characterized by the presence of two tectonic slides; the first tectonic slide is made up of ophiolite-bearing pebbly-mudstones belonging to the Ottone Unit sequence. The second one is represented by medium- to thick-bedded siliciclastic arenites; the meaning of these arenites, still doubtful, would be clarified in other sectors of the Apuan Alps where this lithostratigraphic unit probably crops out. Along the Candia Hills traverse the tectonic setting is characterized by the hinge zone of a N140 trending wide antiform overturned to SW ("Tyrrenian vergence"); this "post-nappe" structure can be considered the SE longitudinal extension of the Castelpoggio-Ortonovo antiform that has been described northward the study area (Cerrina Feroni et al., 1995). Key words: Liguride units, Subliguride units, Apuan Alps, lithostratigraphy.
Le unità Liguri e Subliguri delle Colline del Candia (Alpi Apuane): litostratigrafia ed assetto tettonico
PANDOLFI, LUCA;
1996-01-01
Abstract
The Liguride and Subliguride units of the Candia Hills (Apuan Alps): lithostratigraphy and tectonic setting. A detailed field mapping (scale 1:5000) of the area located at the west side of the Apuan Alps (Candia Hills, Massa-Carrara province) has been carried on. The lithostratigraphic features and new findings of calcareous Nannofossils from the units outcropping in this area are reported. The Candia Hills area represents an interesting sector belonging to the Northern Apennine where ligurian (Ottone Unit; Bertotti et al., 1986; Elter et al., 1991, Zanzucchi et al., 1993; Elter et al., in stampa), subligurian (Canetolo and Sanguineto-Marra units; Plesi, 1974; Labaume, 1992, Elter et al., in stampa; Pagani e Zanzucchi, 1970) and non-metamorphic tuscan unit (Tuscan Nappe), overriding the Apuan Metamorphic Complex, are exposed. A good knowledge of this sector could help to understand the complex miocenic tectonic events that led to Apuan Alps exumation (Carmignani et al., 1980; Coli, 1989; Carmignani e Kligfield, 1990). A tectonic stack of units belonging to the liguride and subliguride domains overlies the Macigno Formation of the Tuscan Nappe. The sequence of the Ottone Unit consists of thick calcareous turbidites with minor intercalations of ophiolite-bearing polimict pebbly-sandstones and -mudstones. The Canetolo Unit consists of the Argille and calcari Formation (Early-Middle Eocene) characterized by two lithostratigraphic units ("shaly-calcareous" and "calcareous") whose relationships are connected to an early folding phase. Between Canetolo Unit and Tuscan Nappe a non-continuous level of silty-marlstones has been recognized; the calcareous Nannofossils assemblage seems indicate a late Oligocene age. This unit has been here called "Mt.Olivero formation" and it can be probably referred to the subliguride domain (Sanguineto and Marra units of the Northern Apennines; Plesi, 1974; Labaume, 1992, Elter et al., in stampa; Pagani e Zanzucchi, 1970; Cerrina Feroni et al., 1990). Near Case Lazzoni the contact between the Canetolo Unit and the overlying Ottone Unit is characterized by the presence of two tectonic slides; the first tectonic slide is made up of ophiolite-bearing pebbly-mudstones belonging to the Ottone Unit sequence. The second one is represented by medium- to thick-bedded siliciclastic arenites; the meaning of these arenites, still doubtful, would be clarified in other sectors of the Apuan Alps where this lithostratigraphic unit probably crops out. Along the Candia Hills traverse the tectonic setting is characterized by the hinge zone of a N140 trending wide antiform overturned to SW ("Tyrrenian vergence"); this "post-nappe" structure can be considered the SE longitudinal extension of the Castelpoggio-Ortonovo antiform that has been described northward the study area (Cerrina Feroni et al., 1995). Key words: Liguride units, Subliguride units, Apuan Alps, lithostratigraphy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
