TY - JOUR A1 - Matos, Catarina A1 - Silveira, Graca A1 - Matias, Luis A1 - Caldeira, Rita A1 - Ribeiro, M. Luisa A1 - Dias, Nuno A. A1 - Krüger, Frank A1 - Bento dos Santos, Telmo T1 - Upper crustal structure of Madeira Island revealed from ambient noise tomography JF - Journal of volcanology and geothermal research N2 - We present the first image of the Madeira upper crustal structure, using ambient seismic noise tomography. 16 months of ambient noise, recorded in a dense network of 26 seismometers deployed across Madeira, allowed reconstructing Rayleigh wave Green's functions between receivers. Dispersion analysis was performed in the short period band from 1.0 to 4.0 s. Group velocity measurements were regionalized to obtain 20 tomographic images, with a lateral resolution of 2.0 km in central Madeira. Afterwards, the dispersion curves, extracted from each cell of the 2D group velocity maps, were inverted as a function of depth to obtain a 3D shear wave velocity model of the upper crust, from the surface to a depth of 2.0 km. The obtained 3D velocity model reveals features throughout the island that correlates well with surface geology and island evolution. (C) 2015 Elsevier B.V. All rights reserved. KW - Madeira island KW - Volcanic rift zone KW - Crustal structure KW - Ambient noise tomography Y1 - 2015 U6 - https://doi.org/10.1016/j.jvolgeores.2015.03.017 SN - 0377-0273 SN - 1872-6097 VL - 298 SP - 136 EP - 145 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Knapmeyer-Endrun, Brigitte A1 - Krüger, Frank T1 - Moho depth across the Trans-European Suture Zone from P- and S-receiver functions JF - Geophysical journal international N2 - The Mohorovicic discontinuity, Moho for short, which marks the boundary between crust and mantle, is the main first-order structure within the lithosphere. Geodynamics and tectonic evolution determine its depth level and properties. Here, we present a map of the Moho in central Europe across the Teisseyre-Tornquist Zone, a region for which a number of previous studies are available. Our results are based on homogeneous and consistent processing of P-and S-receiver functions for the largest passive seismological data set in this region yet, consisting of more than 40 000 receiver functions from almost 500 station. Besides, we also provide new results for the crustal vP/vS ratio for the whole area. Our results are in good agreement with previous, more localized receiver function studies, as well as with the interpretation of seismic profiles, while at the same time resolving a higher level of detail than previous maps covering the area, for example regarding the Eifel Plume region, Rhine Graben and northern Alps. The close correspondence with the seismic data regarding crustal structure also increases confidence in use of the data in crustal corrections and the imaging of deeper structure, for which no independent seismic information is available. In addition to the pronounced, stepwise transition from crustal thicknesses of 30 km in Phanerozoic Europe to more than 45 beneath the East European Craton, we can distinguish other terrane boundaries based on Moho depth as well as average crustal v(P)/v(S) ratio and Moho phase amplitudes. The terranes with distinct crustal properties span a wide range of ages, from Palaeoproterozoic in Lithuania to Cenozoic in the Alps, reflecting the complex tectonic history of Europe. Crustal thickness and properties in the study area are also markedly influenced by tectonic overprinting, for example the formation of the Central European Basin System, and the European Cenozoic Rift System. In the areas affected by Cenozoic rifting and volcanism, thinning of the crust corresponds to lithospheric updoming reported in recent surface wave and S-receiver function studies, as expected for thermally induced deformation. The same correlation applies for crustal thickening, not only across the Trans-European Suture Zone, but also within the southern part of the Bohemian Massif. KW - Body waves KW - Cratons KW - Crustal structure KW - Europe Y1 - 2014 U6 - https://doi.org/10.1093/gji/ggu035 SN - 0956-540X SN - 1365-246X VL - 197 IS - 2 SP - 1048 EP - 1075 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Czuba, Wojciech A1 - Grad, Marek A1 - Mjelde, Rolf A1 - Guterch, Aleksander A1 - Libak, Audun A1 - Krüger, Frank A1 - Murai, Yoshio A1 - Schweitzer, Johannes T1 - Continent-ocean-transition across a trans-tensional margin segment: off Bear Island, Barents Sea JF - Geophysical journal international N2 - P>A 410 km long Ocean Bottom Seismometer profile spanning from the Bear Island, Barents Sea to oceanic crust formed along the Mohns Ridge has been modelled by use of ray-tracing with regard to observed P-waves. The northeastern part of the model represents typical continental crust, thinned from ca. 30 km thickness beneath the Bear Island to ca. 13 km within the Continent-Ocean-Transition. Between the Hornsund FZ and the Kn circle divide legga Fault, a 3-4 km thick sedimentary basin, dominantly of Permian/Carboniferous age, is modelled beneath the ca. 1.5 km thick layer of volcanics (Vestbakken Volcanic Province). The P-wave velocity in the 3-4 km thick lowermost continental crust is significantly higher than normal (ca. 7.5 km s-1). We interpret this layer as a mixture of mafic intrusions and continental crystalline blocks, dominantly related to the Paleocene-Early Eocene rifting event. The crystalline portion of the crust within the south-western part of the COT consists of a ca. 30 km wide and ca. 6 km thick high-velocity (7.3 km s-1) body. We interpret the body as a ridge of serpentinized peridotites. The magmatic portion of the ocean crust accreted along the Knipovich Ridge from continental break-up at ca. 35 Ma until ca. 20 Ma is 3-5 km thicker than normal. We interpret the increased magmatism as a passive response to the bending of this southernmost part of the Knipovich Ridge. The thickness of the magmatic portion of the crust formed along the Mohns Ridge at ca. 20 Ma decreases to ca. 3 km, which is normal for ultra slow spreading ridges. KW - Controlled source seismology KW - Dynamics of lithosphere and mantle KW - Crustal structure KW - Atlantic Ocean Y1 - 2011 U6 - https://doi.org/10.1111/j.1365-246X.2010.04873.x SN - 0956-540X VL - 184 IS - 2 SP - 541 EP - 554 PB - Oxford Univ. Press CY - Oxford ER -