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Seismogenic rotational slumps and translational glides in pelagic deep-water carbonates. Upper Tithonian-Berriasian of Southern Tethyan margin (W Sicily, Italy)
No full textSoft-sediment deformation structures (SSDSs), which reflect sediment mobilization processes, are helpful to identify punctual events of paleoenvironmental stresses. In the upper Tithonian-Berriasian calpionellid pelagic limestone of the Lattimusa Fm. outcropping in the Barracù section (W Sicily), paleoenvironmental restoration reveals the occurrence of a deep-water flat basin, characterised by undeformed planar bedding, laterally passing to a gentle slope where the deformed horizons alternate with undeformed beds. Here, two types of gravity slides have been differentiated on the basis of different kinds of SSDSs, brittle deformation, involved lithofacies, geometry and morphology. Type 1 slump sheets, involving marl-limestone couplets, are characterised by chaotic stratification, truncated beds, recumbent folds, tension gashes, clastic dikes and small-scale listric normal faults and thrusts. They moved downslope as a rotational slump, displaying the typical wedge-shaped morphology, becoming thicker toe-wards. Type 2 slump sheets, involving bed packages of lime mudstone, are characterised by arcuate slump scars developing downwards as listric normal faults, associated with rotational beds and bulging. Displaying tabular geometries, they moved coherently along an overall bedding parallel detachment surface as a translational glide characterised by sediment creep. Regional geology indicates that the basin (Sicanian), bordered by a stepped carbonate platform, was affected by synsedimentary tectonics throughout the Mesozoic. The synsedimentary extensional tectonics that affect the Upper Triassic-Jurassic deposits with steeped normal faults, causing tilt-block and instability of the seafloor through fluidization processes, triggered the rotational slumps of the lower portion of the section. Seismic shocks, induced by outside sector tectonics, like those recorded in the adjacent Busambra stepped carbonate platform margin, triggered the rotational slumps that are not related to local-scale faults. To explain the translational glides of the upper portion of the section, the aforementioned outside sector earthquakes produced instability of the sea-floor through thixotropy of marls. In this case, the driving forces (i.e., gravitational) were favoured by the uplifting trend that is well recorded in the Southern Tethyan continental margin. We suggest that the various early deformations represent rotational slump and sediment creep that may be characteristic for slump structures in pelagic carbonates, depending on the involved lithologies (i.e., paleoenvironmental setting) and the intensity/distance of the trigger mechanism (i.e., earthquake epicentre)
STOP 2-Mesozoic and Cenozoic carbonates of the Imerese basin along the Rocca di Sclafani Bagni outcrop
No full textSequence stratigraphy of a mesozoic carbonate platform-to-basin system in Western sicily
No full textSequence stratigraphic studies of the Triassic through Paleogene carbonate successions of platform, slope and basin in western Sicily (Palermo and Termini Imerese Mountains) have identified a sedimentary cyclicity mostly caused by relative oscillations of sea level. The stratigraphic successions of the Imerese and Panormide palaeogeographic domains of the southern Tethyan continental margin were studied with physical-stratigraphy and facies analysis to reconstruct the sedimentary evolution of this platform-to-basin system.The Imerese Basin is characterized by a carbonate and siliceous-calcareous succession, 1200-1400m thick, Late Triassic to Eocene in age. The strata display a typical example of a carbonate platform margin, characterized by resedimented facies with progradational stacking patterns. The Panormide Carbonate Platform is characterized by a carbonate succession, 1000-1200 m thick, Late Triassic to Late Eocene, mostly consisting of shallow-water facies with periodic subaerial exposure.The cyclic arrangement has been obtained by the study of the stratigraphic signatures (unconformities, facies sequences, erosional surfaces and stratal geometries) found in the slope successions. The recognized pattern has been compared with coeval facies of the shelf. This correlation provided evidence of sedimentary evolution, influenced by progradation and backstepping of the shelf deposits.The stratigraphic architecture of the platform-to-basin system is characterized by four major transgressive/regressive cycles during the late Triassic to late Eocene.These cycles, framed in a chronostratigraphic chart, allows the correlation of the investigated shelf-to-basin system with the geological evolution of the African continental margin during the Mesozoic, showing tectono-eustatic cycles. The first cycle, encompassing the late Triassic to early Jurassic, appears to be related to the late syn-rift stage of the continental margin evolution. The following three cycles, spanning from the Jurassic to Eocene, can be related to the post-rift evolution and to thermal subsidence changes
Carbonate Platform/Basin system during the Mesozoic: stratigraphic evolution, erosional surfaces and sequence stratigraphy framework
Full text linkGeological Map of the Rocca Busambra-Corleone region (western Sicily, Italy): explanatory notes
Full text linkThe geology of the Rocca Busambra-Corleone region, in centralwestern
Sicily, is relevant to the understanding of the central sector
of the Maghrebian-Sicilian fold-and-thrust belt.
In the investigated area Mesozoic shallow- and deep-water carbo -
nate deposits pertaining respectively to the Trapanese and the Sica -
nian successions, and a thick Oligo-Miocene numidian flysch body,
crop out. Minor outcrops of Cretaceous-Palaeogene Sicilide complex
and syn-orogenic deposits of the Late Serravallian-Early Messinian
Castellana Sicula and Terravecchia formations are also present.
A structural analysis reveals complex tectonic relationships
between the Trapanese carbonate platform tectonic unit (the Rocca
Busambra carbonate ridge) and the overthrusting Sicanian deepwater
carbonate (Corleone-Barracù) and numidian flysch tectonic
units, outcropping around the carbonate ridge.
In this tectonic frame Rocca Busambra is a 15 km long, E-Wtrending
large antiform, slightly rotated to the NW-SE on its eastern
limb (Pizzo Marabito). The unit forms a southerly verging ramp structure;
it is bound, to the south, by E-W and WNW-ESE striking major
reverse faults and, to the north, by the E-W striking Busambra fault,
that is a back-verging reverse fault characterized by right-handed
strike-slip component of movement. The Busambra carbonate platform
tectonic unit, that appears to have been thrust up to the surface,
is reimbricated above the Sicanian deep-water carbonate and numi -
dian flysch tectonic units; these, in turn, are redeformed. The latter
tectonic event overprinted the original tectonic relationships and took
place during the Late Pliocene, as evidenced in adjacent region
Facies and geometry of an Upper Jurassic-Lower Cretaceous carbonate rimmed-shelf system from Northwestern Sicily
No full textUpper Jurassic-Lower Cretaceous carbonate shallow-water successions, several hundreds of meters thick,
outcropping in the Palermo Mountains (NW Sicily, Italy), are analyzed in their sedimentological features for
environmental reconstructions.
In the Palermo Mts., the northernmost thrust system of the western Sicily fold and thrust belt, tectonic
bodies, consisting of Upper Triassic-to-Eocene shallow-water carbonates (Panormide carbonate platform),
outcrop. Detailed facies and microfacies analyses, stratigraphic measurements and physical stratigraphy studies
of the Tithonian-Neocomian carbonates point out the occurrence of several lithofacies, from tidal flat to reef
environments.
Due to the strong deformation of the Palermo Mts. belt, the study successions outcrop, frequently, in
tectonically separated and isolated bodies, making difficult to recognize their mutual facies relationships.
The grouped facies associations, pertain to:
a) peritidal platform, consisting of regular alternation of grey wackestone with algae and molluscs, packstone
with cavities filled by sparry calcite (birds eyes), stromatolitic laminae, loferitic breccias and oolitic grainstone
(tempestites);
b) shelf margin, consisting of oolitic and bioclastic packstone-grainstone, alternated to bioclastic wackestone
with large mollusc shells, mostly gastropods, algae and benthic foraminifers and bioclastic muddy sands; these
deposits are believed to point out the leeward side of a sand bar, passing to the protected shelf lagoon. In other
sites, the oolitic lithofacies alternated to bioclastic packstone and fine breccias with reef-derived elements are
interpreted as the windward side of the oolite shoal, passing to a high energy zone gradually merging in to reef
complex;
c) reef margin, consisting of boundstone with corals and hydrozoans (Ellipsactinia sp.), intra-reef breccias
and bioclastic grainstone, with rim cements and cavities filled by silt;
d) upper slope-fore reef environment, consisting of bioclastic packstone-to-grainstone and lithoclastic
rudstone with reef-derived elements.
These lithofacies are organized in shallowing-upward cycle sequences. The reconstruction of the lateral
relationships among the several facies associations points out that the studied deposits were formed in a
carbonate rimmed-shelf depositional system, characterized by aggradational and progradational stratigraphic
architecture, along the Sicilian sector of the southern Tethyan margin
Lithostratigraphy of Sicily
No full textThis book offers as comprehensive an overview as possible of the lithostratigraphy of the Italian region of Sicily, taking into account the multiplicity of formational and terminological variability developed over more than a century of studies and publications. It presents stratigraphic terminology, the geological lexicon and the main stratigraphic subdivisions that are not familiar to Sicilian geologists. The new stratigraphic methods and the use of formations as mapping units have prompted the acquisition of new lithostratigraphic data, and a review of the previous units and their comparison with the new collected data, enabling the definition of a number of new lithostratigraphic units. The book summarizes the results in 77 worksheets containing the most important information regarding the lithological, sedimentological and microfacies characteristics, the measured thicknesses, areal extent and the regional aspects, the paleoenvironmental, paleogeographic and paleo-tectonics setting, compiled according to standard procedures and nomenclature rules provided by the International Commission on Stratigraphy (ICS)
Gathering different marine geology data (seismics, acoustics, sedimentological) to investigate active fluid seepage (AFS) in the southern region of the central Mediterranean Sea
No full textActive Fluid Seepage (AFS) at the seafloor is a global phenomenon associated with seafloor morphologies in different geodynamic contexts. Advances geophysical techniques have allowed geoscientists to characterise pockmarks, mounds and flares associated with AFS. We present a range of marine geological data acquired in the central Mediterranean Sea (northern Sicily continental margin, northwestern Sicily Channel and offshore the Maltese Islands), which allow us to identify AFSs. The AFSs are spatially distributed as clusters, aligned or isolated at different depths, ranging from few decametres offshore the Maltese Islands, up to 400 m offshore north Sicily and in the northwestern Sicily channel. Mounds have heights ranging from 2 to 15 m and form hummocky surfaces. Pockmarks with sub-circular planform shapes and U/V-shaped cross-sections are found in sizes ranging from 5 to 530 m. Gas flares occur on both the continental shelf and upper slope
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