Search results for " tectonics."
showing 10 items of 134 documents
New insights from recently migrated CROP multichannel seismic data at the outermost Calabrian arc accretionary wedge (Ionian sea)
2011
This study addresses selected aspects of the stratigraphic-structural setting of the outermost Calabrian Arc accretionary wedge and underlines relationships between structural development and Messinian evaporite stratigraphy through the analysis of re-processed CROP multichannel seismic reflection profiles. A detailed seismostratigraphic analysis, calibrated with P-velocities compiled by previous works, images a general bipartition of the Messinian evaporite deposits: the transparent «lower subunit» appears to have undergone ductile-flow deformation», with the development of salt-cored thrusting structures, and the layered «upper subunit» appears to be characterized by brittle deformation. …
Numerical investigation of deformation mechanics in fold-and-thrust belts: Influence of rheology of single and multiple décollements
2012
[1] Thin-skinned fold-and-thrust belts related to convergence tectonics develop by scraping off a rock sequence along a weaker basal decollement often formed by water-saturated shale layers or low-viscosity salt horizons. A two-dimensional finite element model with a viscoelastoplastic rheology is used to investigate the structural evolution of fold-and-thrust belts overlying different types of decollements. In addition, the influence of multiple weak layers in the stratigraphic column is studied. Model shale decollements are frictional, with lower friction angles as the cover sequence. Model salt layers behave linear viscous, due to a lower viscosity as the cover sequence, or with a power …
Fluid geochemistry and CO2 output in the southern Apennine (Italy): Preliminary results from the study of cold and thermal waters
2019
Waveforms clustering and single-station location of microearthquake multiplets recorded in the northern Sicilian offshore region
2013
In 2009 December, the OBSLab-INGV (Istituto Nazionale di Geofisica e Vulcanologia) deployed an Ocean Bottom Seismometer with Hydrophone (OBS/H) near the epicentral area of the main shock of the Palermo seismic sequence of 2002. The monitoring activity had a total duration of about 8 months. During this experiment, the OBS/H recorded 247 very local microearthquakes, whose local magnitude is between -0.5 and 2.5 and TS - TP delay time between 0.2 and 5 s, almost all ofwhichwere undetected by the Italian National Seismic Network. This local microseismicity has been analysed using an innovative clustering technique that exploits the similarity between the waveforms generated by different events…
Foreland Basin System Evolution along the Sicilian Fold and Thrust Belt
2016
Foreland Basin System tettono-sedimentary evolution along the Sicilian Fold and Thrust Belt
Constraining lithospheric flow.
2016
The motion of Earth's tectonic plates—the lithosphere—is driven by the subduction of relatively cold and dense oceanic plates into the mantle. The resulting forces drive the motions of continental plates, but the manner in which this happens depends on the effective viscosities of the lithosphere and mantle. On page 1515 of this issue, Liu and Hasterok ( 1 ) discuss a novel method of constraining viscosities of the lithosphere from geophysical data.
Active tectonics in the Calabrian Arc: Insights from the Late Miocene to Recent structural evolution of the Squillace Basin (offshore eastern Calabri…
2023
The Calabrian Arc represents one of the most active sectors of the upper plate of the Tyrrhenian-Ionian subduction system. This research aims to reconstruct the evolution of the Squillace Basin (Ionian offshore of the Calabrian Arc) from the Late Miocene to Recent times and recognise active shallow and deep structures using a multiscale approach. The latter is based on interpreting high-penetration and high-resolution seismic reflection profiles, calibrated with well-log data coupled with bathymetric data and the distribution of instrumental earthquakes. Data highlight three steps in the evolution of the Squillace Basin. A Late Miocene extensional event led to the formation of WNW-ESE orien…
Metastable staurolite-cordierite asemblage of the Bossòst dome: Late variscan decompression and polyphase metamorphism in the Axial Zone of the centr…
2004
Abstract A kilometre-scale shear zone is recognized in the Cambro–Ordovician schist of the Bossost dome, a Variscan metamorphic and structural dome in the Axial Zone of the central Pyrenees. Non-coaxial deformation is recorded by rotated garnet and staurolite porphyroblasts following regional metamorphism M 1 , while coaxial conditions prevailed during later contact metamorphic M 2 growth of andalusite and cordierite. Mineral compositions and bulk rock analyses show that garnet–staurolite–andalusite–cordierite assemblages are significantly enriched in Mg and Mn over the garnet–staurolite assemblage, which lacks sufficient Mg for cordierite to form. The garnet–staurolite assemblage preserves…