Tethyan and Alpine Controls on the Crustal Architecture of the Tunisian and Algerian Atlas and Tell: Needs for Coupled Deep Seismic Soundings and Tomography

2018 ◽  
pp. 11-14 ◽  
Author(s):  
François Roure ◽  
Sami Khomsi ◽  
Dominique Frizon de Lamotte ◽  
Rémi Lepretre
Keyword(s):  
Deep Seismic Soundings

Results of deep seismic soundings along international profile VII in Czechoslovakia and poland

1973 ◽  
Vol 17 (3) ◽  
pp. 205-217 ◽  
Author(s):  
Břetislav Beránek ◽  
Milica Mayerová ◽  
Milada Zounková ◽  
Alexander Guterch ◽  
Rufin Materzok ◽  
...  
Keyword(s):  
Deep Seismic Soundings ◽  
International Profile

scholarly journals GEOPHYSICAL STUDIES AND TECTONISM OF THE HELLENIDES

2017 ◽  
Vol 43 (1) ◽  
pp. 32 ◽  
Author(s):  
J. Makris
Keyword(s):  
Upper Mantle ◽  
Aegean Sea ◽  
Velocity Model ◽  
Normal Faults ◽  
Tectonic Deformation ◽  
Flow Density ◽  
Crust And Upper Mantle ◽  
The North ◽  
Deep Seismic Soundings ◽  
Western Greece

By constraining gravity modelling by Deep Seismic Soundings (DSS) and the Bouguer gravity field of Greece a 3-D density-velocity model of the crust and upper mantle was developed. It was shown that in the north Aegean Trough and the Thermaikos Basins the sediments exceed 7 km in thickness. The basins along the western Hellenides and the coastal regions of western Greece are filled with sediments of up to 10 km thickness, including the Prepulia and Alpine metamorphic limestones. The thickest sedimentary series however, were mapped offshore southwest and southeast of Crete and are of the order of 12 to 14 km. The crust along western Greece and the Peloponnese ranges between 42 and 32 km thickness while the Aegean region is floored by a stretched continental crust varying between 24 to 26 km in the north and eastern parts and thins to only 16 km at the central Cretan Sea. The upper mantle below the Aegean Sea is occupied by a lithothermal system of low density (3.25 gr/cm³) and Vp velocity (7.7 km/s), which is associated with the subducted Ionian lithosphere below the Aegean Sea. Isostasy is generally maintained at crustal and subcrustal levels except for the compressional domain of western Greece and the transition between the Mediterranean Ridge and the continental backstop. The isotherms computed from the Heat Flow density data and the density model showed a significant uplift of the temperature field below the Aegean domain. The 400°C isotherm is encountered at less than 10 Km depth. Tectonic deformation is controlled by dextral wrench faulting in the Aegean domain, while western Greece is dominated by compression and crustal shortening. Strike-slip and normal faults accommodate the western Hellenic thrusts and the westwards sliding of the Alpine napes, using the Triassic evaporates as lubricants.

Three adaptive filters for the detection of body waves, with application to deep seismic soundings

1975 ◽  
Vol 65 (4) ◽  
pp. 995-1012
Author(s):  
Marc Souriau ◽  
J. L. Veinante
Keyword(s):  
Adaptive Filtering ◽  
Prediction Error ◽  
Adaptive Filters ◽  
Initial Step ◽  
Body Waves ◽  
Digital Data ◽  
Polarization Filter ◽  
Systematic Analysis ◽  
Point Analysis ◽  
Deep Seismic Soundings

Abstract This paper deals with the sequential adaptive filtering of body waves based on a systematic analysis of correlations (covariances) between available digital data of deep seismic soundings. The initial step is to develop a fast algorithm for computing the covariance. We show how a simple recursive filter is well-fitted. First, a deconvolution filter based on the prediction error is developed; for ease in computation, it is derived from a one-point analysis. Second, we use a polarization filter defined by Flinn (1965). Through a theoretical analysis of the seismic field, we show how the filter is biased when it is applied to rectilinear signals in a nonisotropic noise, and we justify an empirical adjustment. Third, an original filter is based on the permanent analysis of space correlations between seismic stations, inside an arbitrary discrete fan of apparent velocities. Applied to three contiguous tracks with arbitrary spacings, the filter is able to enhance any phenomenon with a variable velocity so long as that velocity is included inside the fan. By spectral analysis, space aliasing and velocity resolution are specified, and capabilities of other procedures are revised. The three filters are applied to the same experimental data in order to estimate their relative efficiency.

Tectonic setting and origin of the Proterozoic rapakivi granites of southeastern Fennoscandia

1992 ◽  
Vol 83 (1-2) ◽  
pp. 165-171 ◽  
Author(s):  
Ilmari Haapala ◽  
O. Tapani Rämö
Keyword(s):  
Tectonic Setting ◽  
Parental Magma ◽  
Transitional Zone ◽  
Isotopic Evolution ◽  
Domal Structure ◽  
Deep Seismic Soundings ◽  
Mafic Magmas ◽  
Thin Crust ◽  
High Level ◽  
Dyke Swarms

ABSTRACTThe 1·65–1·54 Ga rapakivi granites of southeastern Fennoscandia represent the silicic members of a bimodal magmatic association in which the mafic members are tholeiitic diabase dykes and minor gabbroic-anorthositic bodies. They are metaluminous to slightly peraluminous A-type granites and occur as high-level batholiths and stocks in an E-W-trending belt extending from Soviet Karelia to southwestern Finland. The Soviet Karelian granites were emplaced into the contact zone between Archaean craton and Svecofennian juvenile 1·9Ga-old crust, while the Finnish granites were intruded into the Svecofennian crust. Deep seismic soundings show that the rapakivi granites and the contemporaneous, mainly WNW or NW-trending diabase dyke swarms are situated in a zone of relatively thin crust. Below the Wiborg Batholith there exists a domal structure in the lithosphere in which a transitional zone (mafic underplate) occurs between the crust and the mantle.The Nd isotopic evolution of the rapakivi granites (εNd(T) −3·1—−0·2) corresponds to the evolution of the 1·9Ga-old Svecofennian crust, as do their Pb isotopic compositions. This implies that the Finnish granites represent anatectic melts of the Svecofennian crust. In contrast, the Soviet Karelian granites show isotopic composition indicative of substantial incorporation of Archaean lower crust material. Petrochemical modelling of one of the Finnish batholiths shows that its parental magma could have been generated by c. 20% melting of a granodioritic source and that fractional crystallisation was important during the subsequent evolution of this magma.The rapakivi granites are redefined as A-type granites that show the rapakivi texture at least in larger batholiths. The field, geochemical, and seismic data indicate that the classical Finnish rapakivi granites were generated in an anorogenic extensional regime by partial melting of the lower/middle crust. The melting, and possibly also the extensional tectonics, were related to upwellings of hot mantle material which led to intrusion of mafic magmas at the base and into the crust.

Sign in / Sign up

Export Citation Format

Share Document