Search results for "Tectonics"

Strain analysis and vorticity of flow in the Northern Sardinian Variscan Belt: Recognition of a partitioned oblique deformation event

2008

Abstract A field example of strain partitioning has been analysed along the Nurra–Asinara transect of the NW Sardinian Variscan chain (Italy). The section in the Nurra–Asinara area is in a continuous sequence of tectono-metamorphic complexes made of low- to high-grade metamorphic rocks affected by a polyphase tectonic history. The principal fabric of the area is controlled by a D2 progressive deformation phase in which the strain is partitioned into folds and shear zone domains. The D2 stretching lineation and shear sense show a clear change from south to north. The principal meso- and micro-structures, vorticity gauges and a quantitative kinematic analysis of local strain suggest that the …

Relationship Between Neotectonics And Fluid Escaping In The Northern Sicilian Continental Margin

2011

New exploration in the marine environments has revealed that the fluid escape structures are often associated with neotectonic elements and are aligned along the same direction. Sometimes is observed the migration of fluid along fault planes to the sea floor as gas venting (Forrest et al., 2005). This paper aims to recognize and to classify the different types of structures associated with fluid seepage, particularly those that develop along alignments coinciding with or parallel to the neotectonic lineaments, in order to assess the interactions between tectonics and fluid circulation. The study area extends, from west to east, from the Gulf of Castellammare to the Gulf of Termini (offshore…

Integrated neotectonic and morphometric analysis of northern Sicily

2006

Sicily is characterised by active deformations, as suggested by the presence of very recent faulted deposits and by widespread seismicity. The northern portion of the Sicilian belt has undergone strike-slip tectonics since the Pliocene, as the effect of the south Tyrrhenian border dynamics. Integrated methodologies of analysis have been utilised to evaluate the neotectonic setting of the northern sector of the island. To this aim, we have elaborated mesostructural, morphotectonic and morphometric data obtained from field survey, photogeological analysis and from the elaboration of digital elevation model (DEM) data relative to 31 drainage basins. The data sets have been compared with the up…

The Sinemurian and Pliensbachian ammonites of the «Calcaires de Laffrey » (Isère, France). Description of a new taxon Pseudojamesonites nov. gen. mou…

2009

Some ammonites, formerly collected by René Mouterde within the Sinemurian and Pliensbachian beds of the “Calcaires de Laffrey” (Isère, France), are first described and illustrated in this work. The Sinemurian (Semicostatum chronozone) assemblage, chiefly constituted by Arnioceras gr. robustum (Quenstedt, 1884), is rather usual for the NW European faunas. Conversely, the Pliensbachian (Jamesoni chronozone, Brevispina subchronozone) assemblage is very peculiar. It is chiefly constituted by a very rare species Pseudojamesonites nov. gen. mouterdei nov. sp. (Eoderoceratoidea) which is here described for the first time. The presence, in significant proportion, of this new taxa in the Early Plien…

Key-ring structure gradients and sheath folds in the Goantagab Domain of NW Namibia

2011

Abstract The concept of deformation phases is one of the corner stones of structural geology but, despite its simplicity, there are situations where the concept breaks down. In the Goantagab Domain of NW Namibia, structures in an area of complex deformation can be subdivided into at least four sets, attributed to four deformation phases on the basis of overprinting relations. Three of these sets of structures, however, formed during the same tectonic event under similar metamorphic circumstances but slightly different flow conditions. These sets of structures show gradational transitions in space that can be understood by a concept of “key-ring structure gradients”, where older D A structur…

Understanding Paleomagnetic Rotations in Sicily: Thrust Versus Strike-Slip Tectonics

2018

The paleomagnetic investigation of the western Sicily Maghrebian belt has revealed since the 1970s that large clockwise rotations up to 140° with respect to the Hyblean-African foreland occurred synchronous with Tertiary shortening of the chain. The observation that rotations decrease stepwise from internal to external tectono-stratigraphic units led in the 1990s to a widely accepted model postulating that rotational thrust-sheet emplaced during forward orogenic propagation. More recently, other authors suggested that clockwise rotations from Sicily are conversely the result of late orogenic dextral strike-slip tectonics. Here we report on a paleomagnetic investigation of 30 Jurassic-Eocene…

Tectono-sedimentary constraints to the Oligocene-to-Miocene evolution of the Peloritani thrust belt (NE Sicily)

1999

Abstract The Peloritani thrust belt belongs to the southern sector of the Calabrian Arc and is formed by a set of south-verging tectonic units, including crystalline basement and sedimentary cover (from the top: Aspromonte U.; Mela U.; Mandanici U.; Fondachelli U.; Longi-Taormina U.), piled up starting from Late Oligocene. At least two main terrigenous clastic formations lie with complicated relationships on top of the previous units: the Frazzano Fm (Oligocene) and the Stilo-Capo d'Orlando Fm (Late Oligocene?–Early Miocene), as syn-to-post-tectonic deposits. These clastic deposits have different characteristics, in space and time, representing or flysch-like sequences involved in several t…

Proterozoic mobile belts compatible with the plate tectonic concept

1983

Les ostracodes paleogenes du Togo: Taxonomie, biostratigraphie, apports dans l'organisation et l'évolution du bassin

1989

Paleogene ostracodes (P5 to P9/P10) from Togo include 59taxonomic units in several wells and one outcrop (Tabligbo). One new genus: Afranticythereis and eight new species are erected: Actinocythereis lomensis, Buntonia klologoensis, Buntonia parasemitecta, Hermanites regulosa, Leguminocythereis isobopaensis, Paraplatycosia dinglei, Poularia neokoldaensis, Soudanella seddohi.. The vertical succession of ecological zones ECO1 to ECO5 is related to a rythmic sequence: open facies followed by a restricted one. The first two (Upper Paleocene/Lower Eocene boundary) are equivalent to the ecological zone Z1 recognized from Mauritania to Guinea. The next two (ECO3/ECO4: Lower/Middle Eocene) should b…

Tectono-climatic evolution of a Neogene intramontane basin (Late Miocene Carboneras subbasin, southeast Spain): revelations from basin mapping and bi…

2002

Exceptional 3-D exposures of fault blocks forming a 5km x 10 km clastic sediment-starved, marine basin (Carboneras subbasin, southeast Spain) allow a test of the response of carbonate sequence stratigraphic architectures to climatic and tectonic forcing. Temperate and tropical climatic periods recorded in biofacies serve as a chronostratigraphic framework to reconstruct the status of the basin within three time-slices (late Tortonian---early Messinian, late Messinian, Pliocene). Structural maps and isopach maps trace out the distribution of fault blocks, faults, and over time, their relative motions, propagational patterns and life times, which demonstrate a changing layout of the basin bec…