Les shales de Rio Canoni, formation-repere fossilifere dans l'Ordovicien superieur de Sardaigne orientale; consequences stratigraphiques et structurales

Naud, Gérard

doi:10.2113/gssgfbull.s7-xxi.2.155

Cited by 9 publications

(4 citation statements)

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“…Titaniferous minerals (rutile, pseudo-rutile, and anatase) are predominant in coarse-grained facies, whereas zircon and monazite are more abundant in fine-grained layers. This formation is comparable in age and depositional environment with meta-sedimentary strata in the Gerrei and Sarrabus units ( Figure 2), including the Late Ordovician Rio Canoni Shale (Naud, 1979) and Punta Serpeddì Formation (Loi, Barca, Chauvel, Dabard, & Leone, 1992).…”

Section: Monte Santa Vittoria (Msv) Formationmentioning

confidence: 73%

Tectonics, ore bodies, and gamma-ray logging of the Variscan basement, southern Gennargentu massif (central Sardinia, Italy)

et al. 2017

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We present a structural geological map (1:14,000 scale) that covers a 100 km2 area of Variscan basement rocks exposed in central Sardinia. The mapped area is located between 39°56′20′′ N 9°04′59′′ E (northwestern corner) and 39°51′47′′ N 9°13′16′′ E (southeastern corner) on the southern slope of the Gennargentu massif, surrounding the mining village of Gadoni. This village was the hub of a mining district in central Sardinia. The region extends between the external and inner nappe zones of the Variscan orogenic wedge of Sardinia. Despite significant mining, the area lacked an up-to-date structural and stratigraphic synthesis comparable to that achieved in the southern Sardinia. This gap in knowledge was due to: (i) more complex structural deformation; (ii) slightly higher grade regional metamorphism including a late Variscan high-temperature overprint; (iii) difficulty in distinguishing terrigenous stratigraphic units that belong to different tectonic units; and (iv) the absence of key stratigraphic marker for resolve complex structures in the uppermost tectonic unit. Integration of field mapping, structural analysis, portable gamma-ray spectroscopy, and zircon U-Pb ages of intrusive rocks has enabled a new geological map and cross-sections. These contributions synthesize the collisional and postcollisional evolution of the region and its relationship with ore genesis

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Section: Monte Santa Vittoria (Msv) Formationmentioning

confidence: 73%

Tectonics, ore bodies, and gamma-ray logging of the Variscan basement, southern Gennargentu massif (central Sardinia, Italy)

et al. 2017

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“…3), are characterized by Cambrian to Tremadocian-Early Arenigian metasandstone (San Vito Formation); they were deposited on a terrigenous shelf and host a small number of acid metavolcanic bodies dated at 490 Ma (unpublished data). These formations are unconformably (Sarrabese unconformity [9]) capped by a thin continental metaconglomerate (Rio Ceraxa conglomerate ''CRC'') and thick sequence of metamorphosed calc-alkaline [57] volcanic rock (Porfidi Grigi) ranging from basaltic andesite to rhyolite [8,9].…”

Section: The Nappe Zonementioning

confidence: 99%

“…Similarly, the orthogneiss at Lodè, which is considered to be the intrusive counterpart of this volcanism, has yielded an in situ U-Pb zircon age of 456 AE 14 Ma [41]. A Caradocian-Ashgillian transgression throughout the palaeogeographic domain of the Nappe Zone led to the deposition of shoreface to shelf sandstone [49,50,57] (Tuviois and Pta Serpeddì Formations [2]). The different units of the Nappe Zone in Sardinia (Fig.…”

Section: The Nappe Zonementioning

confidence: 99%

A restored section of the “southern Variscan realm” across the Corsica–Sardinia microcontinent

Rossi¹,

Oggiano²,

Cocherie³

2009

Comptes Rendus. Géoscience

150

112

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A complete section of the southern realm of the Variscan orogenic belt can be restored in the Corsica-Sardinia segment. Northern Corsica exposes a nonmetamorphosed Palaeozoic succession lying on Panafrican mica schist related to a microcontinent (most likely Armorica or from a microcontinent from the Hun superterrane) that had drifted away directly from Gondwana. These formations are thrust over the Variscan Internal Zone composed mainly of anatectic high-grade Palaeozoic formations that crop out from central Corsica to northern Sardinia; the metamorphic peak of the eclogite remnants has been dated at c. 420 Ma. The Variscan Internal Zone interpreted here as a collision zone, and also the Eovariscan suture, was intruded in Corsica by Mg-K granite from 345 to 335 Ma. The thrust of this Internal Zone onto the stack of parautochthonous nappes in central Sardinia is cross-cut by the Posada Asinara dextral shear zone. To the south, parautochthonous nappes overthrust the North-Gondwana margin which displays a possible Panafrican basement topped by an Iglesiente-Sulcis nonmetamorphic/anchimetamorphic Palaeozoic succession.

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“…The age is now commonly stated to be about 460 Ma (Middle -Late Ordovician) based on radiometric analyses (Cruciani, Franceschelli, Musumeci, Spano, & Tiepolo, 2013;Dabard, Chauvel, & Loi, 1994;Gaggero, Oggiano, Funedda, & Buzzi, 2012;Loi & Dabard, 1997;Oggiano, Gaggero, Funedda, Buzzi, & Tiepolo, 2010;Pavanetto et al, 2012). -A changing upwards succession from mainly siliciclastic at the bottom to carbonate at the top as follows:(i) quarzites, metagreywackes and metarkoses (Metarcose di Gennamesa, ) that are Late Ordovician in age; (ii) then, fossiliferous metasiltstones and rare metalimestones (Orroeledu Formation in the Meana Sardo Unit, Bosellini & Ogniben, 1968; Punta Serpeddì Formation in the Sarrabus Unit, Loi, Barca, Chauvell, Dabard, & Leone, 1992; Rio Canoni shale in the Gerrei Unit, Naud, 1979) that are Late Ordovician in age; (iii) in turn, these formations are covered by black shales with interbedded metalimestones layers (Scisti neri Formation) that are Silurian to Early Devonian in age (Corradini, Ferretti, & Serpagli, 1998); and iv) at the top, generally massive metalimestones (Calcari di Villasalto, ) that are referable to the Middle Devonian-Early Carboniferous period (Corradini, Barca, & Spalletta, 2003), and marbles (Marmi di Asuni), the age of which is referable to the Devonian based on lithostratigraphic correlation with the Calcari di Villasalto.…”

Section: Stratigraphic Outlinementioning

confidence: 99%

Geology of the Variscan basement of the Laconi-Asuni area (central Sardinia, Italy): the core of a regional antiform refolding a tectonic nappe stack

2014

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The study area extends in central Sardinia between the coordinates 8856′00′′/39855′00′′ (NW\ud corner) and 9803′00′′/39850′00′′ (SE corner). It forms part of the Sardinian Variscides that\ud are characterized here by the western-most aspect of a regional structure known as the\ud Flumendosa Antiform, which runs ENE-trending for more than 50 km along its axis. It\ud represents the envelopment of several, upright km-scale minor folds that refold the different\ud tectonic units of the Variscan Nappe zone characterized by a number of isoclinal folds, with\ud axial plane foliation and thick ductile shear zones. The antiform is in turn deformed by lateorogenic\ud extensional structures, namely asymmetric folds and narrow, low angle ductile\ud shear zones that generally reactivate earlier collisional structures.\ud The 1:12,500 scale map completes the mapping of this important regional structure,\ud meaning that a detailed survey of the entire mega-structure is now available. This enables\ud more detailed structural analyses of poly-deformed areas in low-grade metamorphic\ud conditions to be conducted, given the robust knowledge available of the lithostratigraphic\ud succession and the geometric and kinematic outlines

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Les shales de Rio Canoni, formation-repere fossilifere dans l'Ordovicien superieur de Sardaigne orientale; consequences stratigraphiques et structurales

Cited by 9 publications

References 0 publications

Tectonics, ore bodies, and gamma-ray logging of the Variscan basement, southern Gennargentu massif (central Sardinia, Italy)

Tectonics, ore bodies, and gamma-ray logging of the Variscan basement, southern Gennargentu massif (central Sardinia, Italy)

A restored section of the “southern Variscan realm” across the Corsica–Sardinia microcontinent

Geology of the Variscan basement of the Laconi-Asuni area (central Sardinia, Italy): the core of a regional antiform refolding a tectonic nappe stack

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