Search results for " tectonics."

Tectonic evolution in the Archaean and Proterozoic

1991

Kre high heat flow probably favoured global hotspot activity with crustal growth of Iceland type through vertical magmatic accretion. The tectonic environment for the generation of about 3.9-2.5 Ga granite-gneiss-greenstone terrains with volurnlnous production of tonalite-trondhjemite-granodlorite magmas is still uncertain, and both piate ma@ and intrapiate scenarios arc possible. Deformanon atylea in greenstones and adjacent high-grade orthognersses with intercalated shallow-water supracrustal assemblages suggest extensive horizontal shortening and crustal interstacking. This probably resulted from collisional and/or rotational motion and produced significant intracrustal melting as early …

Precambrian plate tectonics: Criteria and evidence

2006

Tomography Application to Complex Seismic Data of the Tjornes Fracture Zone (Iceland)

2014

The Tjornes Fracture Zone (TFZ) is an active seismic zone in Northeast Iceland. It plays a key role to understand the geodynamic movement and location of tectonic plates. However the seismic experiment can not be performed close to earthquake sources, because sources are mainly located in the Greenland Sea. The unusual geological structure of TFZ and the limited conditions of an experiment lead to significant deviations between real observations and the values that are calculated in accordance with theoretical models. Consequently, there is a loss of adequacy and stability of tomography systems. Outcomes of the method, which takes into account this problem, are analyzed in the present chapt…

Lower pleistocene deposits in east part of the Favignana island, Sicily, Italy

2011

Diffuse degassing of carbon dioxide at Somma-Vesuvius volcanic complex (Southern Italy) and its relation with regional tectonics

2004

Abstract A systematic survey of soil CO 2 concentrations was carried out on the flanks of Somma–Vesuvius volcano in order to constrain possible pathways responsible of carbon dioxide diffuse degassing taking place during the present state of quiescence. Measurements were performed at 1162 sites in late winter–spring 2000, highlighting that soil CO 2 concentrations range from 50 to 10500 ppmV. A statistical analysis was developed in order to define the threshold value of anomaly and separate the biogenic CO 2 component, produced by soil respiration, from the inorganic component of deep provenance. A computer routine was also elaborated to interpret the grid of CO 2 anomalous concentration va…

DETECTION OF PLIO-QUATERNARY FAULTS IN MADONIE MOUNTAINS (SICILY) BY USING QUANTITATIVE GEOMORPHIC AND STRUCTURAL GEOLOGY ANALYSES

2011

The Northern Madonie Mountains (Northern-Central Sicily), sector of the Sicilian Maghrebian chain, consist of a tectonic thrust system developed through two subsequent main contractional events: 1) a shallow-seated compressional event developed during the Middle-Upper Miocene; 2) a deep-seated transpressional event occuring since the Late Miocene. Lower Pliocene (Trubi) to Quaternary clastic deposits unconformably lie on the tectonic units and are partially involved by deformation. In the selected area, syntectonic sedimentary basins characters are able to define the timing of deformation only until the Lower Pliocene; to resolve this gap of information application of quantitative geomorphi…

Quaternary tectonics from landscape evolution in southern Italy: new clues from a multidisciplinary morphometric approach

2022

Deep-rooted “thick skinned” model for the High Atlas Mountains (Morocco). Implications for the structural inheritance of the southern Tethys passive …

2006

A re-interpretation of the deep structure of the High Atlas is presented through integration of geophysical and geological data, highlighting the architectural significance of the southern Tethys palaeomargin. Previous crustal models suggest the occurrence of a flat intra-crustal detachment at a depth of � 20 km, a zone where surface thrusts merge and below which the lower High Atlas crust appears continuous. However, within this study seismic refraction data, electrical resistivity surveys and gravity modelling all appear to detect a jump in crustal thickness between the High Atlas and the northern plains. We interpret these data as penetration by thrusts within the ‘‘South-Atlasic fault’’…

Asymmetric continental deformation during South Atlantic rifting along southern Brazil and Namibia

2017

Abstract Plate restoration of South America and Africa to their pre-breakup position faces the problem of gaps and overlaps between the continents, an issue commonly solved with implementing intra-plate deformation zones within South America. One of these zones is often positioned at the latitude of SE/S Brazil. However, geological evidence for the existence of a distinct zone in this region is lacking, which is why it remains controversial and is not included in all modeling studies. In order to solve this problem we present a study of multiple geological aspects of both parts of the margin, SE/S Brazil and its conjugate part NW Namibia at the time of continental breakup. Our study highlig…

Seismogenic rotational slumps and translational glides in pelagic deep-water carbonates. Upper Tithonian-Berriasian of Southern Tethyan margin (W Sic…

2017

Abstract Soft-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 Barracu 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. T…