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1

Tectonic evolution of the Sicilian Thrust System (central Mediterranean)

Napoli G., Nigro F., Renda P., Ślqczka A., Favara R.

Geological Quarterly

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2012

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Vol. 56, No. 4

579--600

EN

The Sicilian Thrust System (STS) is a south-verging (Africa-verging) fold-and-thrust belt including a Mesozoic-Paleogene sedimentary sequence. This thrust stack owes its origin to the deformation of pre-orogenic strata deposited in different palaeogeographic domains belonging to passive margins of the African plate. The STS was deformed during the Neogene, following the closure of the Tethys Ocean and the continental collision between the Sardo-Corso Block and the north Africa margins. The thrust pile was detached from the underlying basement during the Miocene-Pleistocene. The regional-scale structural setting recognized allows us to reconstruct the tectonic evolution of the STS as follows: I - piggy-back thrusting from the Late Oligocene to the Langhian, inducing the building of the Inner Sicilian Chain (ISC); II - piggy-back thrusting from the Langhian to the Tortonian, inducing the formation of the Middle Sicilian Chain (MSC); III - generalized extensional deformation in the chain-foredeep-foreland system from the Tortonian to the Early Pliocene; IV-a new onset of piggy-back thrusting after the Early Pliocene allowed the building of the Outer Sicilian Chain and out-of-sequence thrusting in the previously developed ISC and MSC.

2

Extensional tectonics during Maghrebides Chain building since late Miocene : examples from Northern Sicily

Giunta G., Nigro F., Renda P.

Annales Societatis Geologorum Poloniae

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2000

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Vol. 70, No. 1

81-98

EN

The Northern Sicilian-Maghrebian Chain courses W-E from the Trapani Mts to the Peloritani Mts and is composed by a set of tectonic units deriving from the Miocene-Pleistocene deformation of the Northern African Continental Margin. Inside it three main geotectonic elements ("external", Sicilide and "Austroalpine") are present and outcrop juxtaposed with a W-E trend. The external element composes the more western Trapani, Palermo and Western Madonie Mts, the Sicilide composes the Eastern Madonie and Nebrodi Mts, while the "Austroalpine" composes the more eastern Peloritani Mts. The orogen shows a culmination in the Trapani Mts and a depression in the Peloritani Mts. The main plicative stages are relatable to late Oligocene-early Miocene from the more internal sectors, while the deformation of the more external sectors starts from early-middle Miocene. The Sicilian chain body is re-involved in tectonism since late Tortonian, which persists until the recent time. During this interval, the deformation of the Sicilian Chain continued by activation of fault systems with different displacements. In the present paper, an important extensional tectonic stage is recognised, starting from the Tortonian; it is supported by structural data and shows through several geological sections across the northern sectors of the Sicilian orogen. This deformation is of exceeded wedge critical taper values, controls the early stages of the Tyrrhenian Basin opening, and is represented by low-angle fault system, producing tectonic omissions in the stratigraphic sequence. The detachment fault system is subsequently displaced by a complicated grid of Plio-Pleistocene net- and strike-slip fault system that controls the genesis of tectonic depressions in the northern off-shore areas of the Sicilian Chain. This neotectonic system may be reconnect to a W-E trending simple shear system, which controls the more recent Tyrrhenian Basin development.

3

The North-Central Sicily Belt : structural setting and geological evolution

Nigro F., Renda P.

Annales Societatis Geologorum Poloniae

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1999

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Vol. 69, No. 1-2

49-61

EN

North-Central Sicily represents an Apenninic-Maghrebian Chain sector, deriving from the Miocene- Pliocene deformation of different palaeogeographic domains-derived successions (carbonate platforms and pelagic basins), piled-up in ramp-flat and duplex style, and belonging during the Mesozoic-Tertiary to the Northern African Continental Margin. These domains are represented by outcropping basinal sedimentary successions (Imerese-Sicanian Basin), geometrically interposed between carbonate platform rock bodies: the Panormide (innermost) and the Hyblean-Pelagian Domains (more external). In this paper, using stratigraphic and structural data, we propose a new palaeogeographic model, in which the main differences from previous interpretations consist in the position of the Imerese Basin, here identified as the juncture between the Panormide Domain and the Sicanian Basin Auct., and the position of the Trapanese pelagic carbonate platform, considered as the juncture between the Hyblean-Pelagian Domain and the Sicanian Basin Auct. Tectono-sedimentary steps characterising the evolution of the Sicilian Miocene-Pliocene Foredeep illustrate the deformational history of the area. Two geological cross-sections depict the structural architecture of the tectonic edifice, characterised by different thrust sheets piled-up during the Miocene-Pleistocene time. The more external tectonic units are formed by elements deriving from the Plio-Pleistocene deformation of the northern margin of the Hyblean-Pelagian Domain. The "intermediate" tectonic units derive from the Miocene-Pliocene deformation of the Imerese- Sicanian Domain and the inner tectonic units are constituted by Panormide and Sicilide Domains-derived successions, deformed during the Miocene. A mostly neotectonics-related transcurrent faults reoriented the previous thrust sheets through NW-SE and W-E trending faults, producing large-scale positive flower structures which involved the geometrically deepest Hyblean-Pelagian substrate.

4

Plio-Pleistocene wrench tectonics in the Western Sicily Chain

Nigro F., Renda P.

Annales Societatis Geologorum Poloniae

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1999

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Vol. 69, No. 3-4

99-112

EN

Western Sicily represents a fragment of the Apenninic-Maghrebian Chain, largely built during the Miocene and formed by a set of tectonic units with southern vergence of folds and ramp-flat style of thrust surfaces. The thrust tectonics-related structures are displaced by a high-angle fault system, which bounds the main Mesozoic "carbonatic massifs" and generally interpreted as a neotectonic dip-slip extensional tectonics-related faults. The present paper, with the support of mesostructural analysis, presents an important Plio-Pleistocene strike-slip tectonics, represented by high-angle net- and strike-slip fault system. Different scale flower structures and associated fold systems, which cut the Miocene tectonic units, characterise the areas along the main transcurrent fault zones. Strike-slip neotectonics is mostly represented by right-lateral NW-SE/W-E and left-lateral N-S/NE-SW transcurrent faults, which may represent a W-E trending deep-seated Riedel system connected to the Tyrrhenian spreading. The NW-SE first order synthetic structures appear to control the opening of several rhomboidal tectonic depressions located in north-western Sicily and its offshore, and are counteracted by W-E trending transpressional structures located in the central Sicily mainland. An attempt at semi-quantitative restoration shows the neotectonic evolution of north-western Sicily during the Pliocene and Pleistocene, characterised by the progressive activation towards the east of en-échelon strike-slip fault strand, in an overall horsetail splay geometry, which produced releasing bends in off-shore and restraining bends in the mainland.

5

Neotectonic events and kinematics of rhegmatic-like basins in Sicily and adjacent areas. Implications for a structural model of the tyrrhenian openning

Nigro F.

Annales Societatis Geologorum Poloniae

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1998

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Vol. 68, No. 1

1-22

EN

The last few Ma kinematic history of the Southern peri-Tyrrhenian orogenic belt has been reconstructed with the purpose of delineating a possible model of its recent geodynamic evolution. Unpublished field survey data, geophysical soundings, aerial photographic support and a review of literature have been utilised in order to propose a deep structural model of mainland Sicily and adjacent off-shore areas. A review of the published geophysical data and the interpretation of some published seismic profiles, coming from the offshore areas, facilitate the neotectonic structural setting of the Central Mediterranean. The observed field geometries of the Sicily mainland, and a comparison with the marine data, are used to formulate a dynamic model, characterised by the development of several mega-shear systems, related to the northward Africa motion and active since the late Miocene?early Pliocene, superimposed onto a previous very complicated mobile belt geometries, that controlled the opening of several rhegmatic-like basins.

PL

W celu skonstruowania współczesnego modelu ewolucji południowego peri-tyrreńskiego pasa orogenicznego dokonano rekonstrukcji jego kinematycznej historii w ostatnich kilku milionach lat. Dostępne w literaturze dane geofizyczne i interpretacje profili sejsmicznych usytuowanych na Morzu Tyrreńskim umożliwiły poznanie neotektonicznej struktury centralnej części Morza Śródziemnego. Obserwowane na Sycylii struktury tektoniczne i ich porównanie z wynikami badań na obszarach morskich zostały użyte do skonstruowania dynamicznego modelu rozwoju licznych systemów wielkoskalowych ścięć (mega-shear) związanych z ruchem Afryki ku północy. Systemy te były aktywne od późnego miocenu do wczesnego pliocenu, oraz zostały nałożone na wcześniejszy bardzo skomplikowany mobilny pas strukturalny, który kontrolował otwieranie się basenów typu regmatycznego.