An array study of lithospheric structure across the Protogine zone, Värmland, south-central Sweden — signs of a paleocontinental collision

Domains of Archean mantle lithosphere deciphered by seismic anisotropy – inferences from the LAPNET array in northern Fennoscandia

“…3). Stations with similar splitting parameters, evaluated for waves with easterly back-azimuths, form groups almost identical with those delimited by a resemblance of the P-sphere patterns, with null (LP51) or a weak splitting (LP71, LP61) along the domain boundaries (e.g., Plomerová et al, 2001). …”

“…POLENET/LAPNET network of broad-band seismological stations (a) and micro-continental nuclei (mc), island arcs and boundaries of hidden and exposed suspect terranes in the Fennoscandian Shield older than 1.92 Ga (b), (redrawn according to Korja et al, 2006). in the Precambrian region since then, neither on a European scale (Amaru et al, 2008), nor in regional tomography studies based on data of temporary arrays in several regions of Fennoscandia (e.g., Plomerová et al, 2001;Sandoval et al, 2004;Shomali et al, 2002;Eken et al, 2007Eken et al, , 2008. The most significant velocity changes in the upper mantle beneath Precambrian provinces can be related to lateral changes of depth of the lithosphere-asthenosphere boundary (Calcagnile 1991;Cotte et al, 2002;Plomerová et al, 2002Plomerová et al, , 2008Plomerová et al, , 2010Olsson et al, 2007).…”

“…On the other hand, studies of fossil anisotropy in most of Fennoscandia (except of its northern part) allowed us to map individual domains of mantle lithosphere with their own consistent fabrics. The domains differ in orientation of symmetry axes, their dips and sometimes also in symmetry of olivine aggregates approximating the structures (Plomerová et al, 2001Vecsey et al, 2007). The retrieved 3-D self-consistent anisotropic models of the mantle lithosphere are delimited by boundaries/transitions which correlate with surface traces of dominant sutures or distinct tectonic faults, e.g., the TransEuroperan Suture Zone, the Protogene zone in south central Sweden, the Proterozoic-Archean contact zone in southern Finland, and boundaries between Svecofennian domains in Sweden .…”

Proterozoic–Archean boundary in the mantle lithosphere of eastern Fennoscandia as seen by seismic anisotropy

“…Particularly in Northern Europe, anisotropic models of the southern edge of Baltica around the TESZ (Babuška and Plomerová, 2004) or of the mantle lithosphere around the Protogine zone in south-central Sweden (Plomerová et al, 2001) brought a new insight into understanding geodynamic development of Fennoscandia. This paper aims at demonstrating a usefulness of 3D study of seismic anisotropy and its ability to detect contact of two lithosphere domains with similar mean velocities in the mantle, but with different orientation of anisotropic structures.…”

Theory and Observations - Seismic Anisotropy

“…Tilted-axis effects are reported in much of Europe, where they are associated with texture developed during the Variscan orogeny of the late Paleozoic or, in the Fennoscandian Shield, as evidence of Archean continental accretion from a sandwich of old subducted slabs (Plomerova et al, 2001). Tilted-axis splitting effects are also associated with present-day deformation in Tibet (Hirn et al, 1998) and near the Mendocino triple junction of northern California (Hartog and Schwartz, 2000).…”