Sökning: "mantle lithosphere"
Visar resultat 1 - 5 av 9 avhandlingar innehållade orden mantle lithosphere.
1. Isotropic and Anisotropic P and S Velocities of the Baltic Shield Mantle : Results from Analyses of Teleseismic Body Waves
Sammanfattning : The upper mantle structure of Swedish part of Baltic Shield with its isotropic and anisotropic seismic velocity characteristics is investigated using telesesismic body waves (i.e. P waves and shear waves) recorded by the Swedish National Seismological Network (SNSN). LÄS MER
2. Strain quantifications in different tectonic scales using numerical modelling
Sammanfattning : This thesis focuses on calculation of finite and progressive deformation in different tectonic scales using 2D numerical models with application to natural cases. Essentially, two major tectonic areas have been covered: a) salt tectonics and b) upper mantle deformation due to interaction between the lithosphere and asthenosphere. LÄS MER
3. Seismic structure of the central Svecofennian lithosphere
Sammanfattning : Lithospheric structures in the Fennoscandian Shield in Sweden have been studied by a number of large-scale wide-angle seismic reflection/refraction (WARR) and normal-incidence reflection profiles since the 1960s. Among these were the over 2000 km long Fennoscandian Long Range (FENNOLORA) project in 1979 and the Baltic and Bothnian Echoes from the Lithosphere (BABEL) in 1989, which provided valuable images of the subsurface down to over 60 km depth including the Moho. LÄS MER
4. Analyses of Seismic Wave Conversion in the Crust and Upper Mantle beneath the Baltic Shield
Sammanfattning : Teleseismic data recorded by broad-band seismic stations in the Swedish National Seismic Network (SNSN) have been used in a suite of studies of seismic wave conversion in order to assess the structure of the crust and upper mantle beneath the Baltic Shield. Signals of seismic waves converted between P and S at seismic discontinuities within the Earth carry information on the velocity contrast at the converting interface, on the depth of conversion and on P and S velocities above this depth. LÄS MER
5. U-Pb baddeleyite geochronology of Precambrian mafic dyke swarms and complexes in southern Africa - regional scale extensional events and the origin of the Bushveld Complex
Sammanfattning : Dolerite dykes are formed when iron- and magnesium-rich (mafic) mantle-derived magmas ascend through the lithosphere (upper part of the mantle) and crystallize as ‘hydro-fractures’ within the crust. Dykes may exist in great numbers to form dyke swarms (linear or radiating), which can be linked to time periods of continental break-up, or attempted break-up events, associated with voluminous volcanism. LÄS MER