Search results for "Tectonic"
showing 10 items of 470 documents
Surface expression of eastern Mediterranean slab dynamics: Neogene topographic and structural evolution of the southwest margin of the Central Anatol…
2012
The southwest margin of the Central Anatolian Plateau has experienced multiple phases of topographic growth, including the formation of localized highs prior to the Late Miocene that were later affected by wholesale uplift of the plateau margin. Our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1.5 km elevation to <7.17 Ma, and regional lithostratigraphic correlations imply that the age is <6.7 Ma. Single-grain CA-TIMS U-Pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10.6 Ma, indicating a maximum age that is consistent with the biostratigraphy. Our structural measurements within the uplifte…
The barren Messinian Tripoli in Sicily and its palaeoenvironmental evolution: suggestions on the exploration potential
2016
New observations on the Sicily Messinian Tripoli have yielded a variably thick diatomitic, calcareous and shaly rock interval marked by an upwards disappearance of calcareous and siliceous plankton (barren lithosome), coexisting with a variability in vegetal remains and significant amounts of amorphous organic matter (AOM). Facies analysis associated with biostratigraphy and palaeoecology of the several field and borehole sections has been framed in a well-accepted chronological scheme that points to this barren interval coinciding with the stratigraphic upper and younger part of some Tripoli sections (bituminous Tripoli) located in the northern part of the study area. Biostratigraphically,…
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…
Record of latest Barremian-Cenomanian environmental change in tectonically controlled depressions from the Jura-Burgundy threshold (Jura Mountains, e…
2019
The area of the western Jura Mountains constitutes the former Jura-Burgundy threshold between the Tethys Ocean and the epicontinental Paris Basin Sea. During the Barremian, the area was covered by a shallow-water Urgonian carbonate platform. Tectonic processes influenced the architecture of the Urgonian platform and were notably responsible for the formation of fault-related depressions on top of the Urgonian series, which were subsequently transformed into incised valleys and then to marine depocenters. Their sedimentary infills are mostly represented by the Perte-du-Rhône Formation and record stepwise environmental change on the innermost platform, which was strongly influenced by the nea…
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…