Search results for "LITHOSPHERE"
showing 6 items of 96 documents
Rifted margin formation in the South Tyrrhenian Sea: A high resolution profile across the North Sicily passive continental margin.
2000
A new, 150 km long seismic line across the continental margin of north Sicily has been acquired and interpreted. The overall structure of the margin is controlled by extension, which caused crustal thinning and widespread normal faulting. Two main thinned zones are observed in the south in correspondence with the Cafalù basin and farther to the north at the continent-ocean transition. Zones of thinned crust coincide with zones of intense normal faulting. Extension began in late Tortonian times and caused the opening of the Cefalù basin controlled by a northward dipping listric fault. Messinian stretching affected most of the future margin and provoked a widening of the Cefalù basin and norm…
Lithospheric P- and S-wave velocity models of the Sicilian area using WAM tomography: Procedure and assessments
2013
We present 3-D models of the P- and S-wave velocity distributions in the crust and uppermost mantle beneath Sicily, Calabria (Southern Italy), and surrounding submerged areas, obtained by tomographic inversion of traveltimes of regional body waves phases. Our method combines double-difference tomographic inversion with a post-processing procedure [Weighted Average Model method (WAM)]. This procedure was applied to a set of models consistent with the experimental data. We tested the ability of the WAM procedure to mitigate the uncertainty associated with the arbitrary nature of the many input parameters required for each inversion. The local reliability and resolution of the obtained models …
An integrated approach to investigate the seismotectonics of northern Sicily and southern Tyrrhenian
2009
Abstract This paper deals with a comparison among recent structure and seismicity in the hinge zone between northern Sicily and southern Tyrrhenian, corresponding to both emerged and submerged northern portion of the Maghrebian chain. This hinge zone is part of a wider W–E trending right-lateral shear zone, mainly characterized by both a synthetic NW-SE/W–E oriented, and antithetic left-lateral N–S/NE-SW fault systems, which has been affecting the tectonic edifice, since the Pliocene. The inland structures have been mapped using aerial-photo interpretation, geological mapping and mesostructural analysis to reconstruct the stress regime in the study area. On the contrary, the offshore struct…
Inversion of gravity anomalies over spreading oceanic ridges
2005
Abstract Models of spreading ocean ridges are derived by Bayesian gravity inversion with geophysical and geodynamic a priori information. The aim is to investigate the influence of spreading rate, plate dynamics and tectonic framework on crust and upper mantle structure by comparing the Mid Atlantic Ridge (MAR), the Indian Ocean Ridge (IND) and the East Pacific Rise (PAC). They differ in mean spreading rate, dynamic settings, as attached slabs, and plume interaction. Topography or bathymetry, gravity, isostasy, seismology and geology, etc. are averaged along the ridges and guide the construction of initial 2D models, including features as mean plumes, i.e. averaged along the ridge. This is …
Numerical modelling of PT-paths related to rapid exhumation of high-pressure rocks from the crustal root in the Variscan Erzgebirge Dome (Saxony/Germ…
2002
Abstract The Bohemian Massif in the Central European Variscides contains many crustal slices with (ultra-)high-pressure rocks related to continent-continent collision. After closure of pre-existing oceans during the Devonian, excess crustal thickness was maintained for about 50 Ma until at around 340 Ma large volumes of high-pressure rocks from the crustal root were exhumed within a few million years. We relate this event to delamination and complete detachment of the lithospheric mantle, causing a crustal-scale isostatic instability. In the Erzgebirge dome, a model region in the northern part of the massif, an array of interrelated PTtd-paths with “decompression/cooling” and “decompression…
Andean Cenozoic volcanic centers reflect basement isotopic domains
1992
Isotopic data for Quaternary volcanic centers from lat 17.5° to 22°S in northern Chile provide evidence for crustal contributions to arc magma genesis in the central Andes and delineate basement domains. Crustal thickness, distance from trench, height of volcanic edifices above the seismically active subduction zone, and sediment supply to the trench are all constant along this segment of the arc. The only significant variable is crustal age (Paleozoic in the south, Proterozoic in the north). Pb isotopic compositions of Quaternary lavas in the northern sector are lower ( 206 Pb/ 204 Pb = 17.89-18.28) and Sr and O isotope ratios are less variable ( 87 Sr/ 86 Sr = 0.7058-0.7077, δ 18 O = +6.5…