The Moho Depth and Crustal Structure beneath Bulgaria Obtained from Receiver Function Analysis

Georgieva, Gergana; Николова, С.

doi:10.7546/cr-2013-66-5-13101331-15

Cited by 2 publications

(1 citation statement)

References 6 publications

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“…This work estimates that the 410-km density boundary beneath the Sredna Gora zone is 50 km higher than the normal depth (410 km) in adjacent areas. The structure of the crust and the transition zone of the mantle were considered in the articles (Georgieva, 2015;Georgieva and Nikolova, 2013).…”

Section: Introductionmentioning

confidence: 99%

Deep Structure and Dynamics of the Central Balkan Peninsula from Seismic Data

Vinnik

Georgieva

Oreshin

et al. 2021

Izv., Phys. Solid Earth

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Abstract—Analysis of P- and S-receiver functions for 19 seismic stations on the Balkan Peninsula has been performed. Half of the stations are in Bulgaria. The crustal thickness varies from 28–30 to 50 km. The ratio of longitudinal and shear wave velocities in the upper crust reaches 2.0 in some places. In the southwest of the study area, the 410-km seismic boundary is uplifted by 10 km relative to nominal depth. The elevation may be caused by hydration and/or cooling of the mantle transition zone under the influence of the Hellenic subduction zone. A low S-wave velocity layer related to the 410-km boundary may be located atop this boundary. In the northwestern part of the study area this layer is present in spite of the absence of the 410-km boundary. A similar paradox has been previously noted in central Anatolia. Indications of a low-velocity layer are present at a depth exceeding 410 km. The simultaneous inversion of the receiver functions of the two types (P and S) and the Rayleigh wave phase velocities reveals a large (7–9%) decrease in the S-wave velocity in the upper mantle of southern Bulgaria and northern Greece. The thickness of the low-velocity layer (asthenosphere) is about 50 km. The lithosphere-asthenosphere boundary (LAB) is at depths of 40 to 60 km. In terms of tectonics, this zone is characterized as the South Balkan extension system. To the north of 43° N, the S-wave velocity in the upper mantle is usually at least 4.4 km/s and the LAB is not detected or is detected at a depth of over 80 km. The SKS analysis of azimuthal anisotropy reveals lateral zoning in the upper mantle that is correlated to velocity zoning. Probably, the mechanically weak low-velocity mantle of the South Balkan system is easily deformed, and the azimuth of the fast direction of anisotropy (20°) indicates the direction of extension. At the northern stations, the fast direction (about –30°) may be a reflection of an older process.

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Section: Introductionmentioning

confidence: 99%

Deep Structure and Dynamics of the Central Balkan Peninsula from Seismic Data

Vinnik

Georgieva

Oreshin

et al. 2021

Izv., Phys. Solid Earth

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The crustal thickness in the Rhodope Metamorphic Complex area from the perspective of the present-day geological knowledge

Georgiev

2023

Rev. Bulg. Geol. Soc.

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The crustal thickness in the area of the Rhodope Metamorphic Complex decreases from west to east from ~50 km to ~30 km. This regional-scale feature is mostly due to the different rates of extension that the basement rocks experienced in different parts of the complex. In our model, we postulate that the crustal thickness in the area is an effect of the late Eocene zipper-like or hinge-like extensional tectonics that caused a larger amount exhumation of high-grade metamorphic rocks in the eastern parts of the area and lesser one in the west. This zipper-like orogen parallel extension caused a vast tectonic erosion and progressive thinning of the crust from west to east.

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The Moho Depth and Crustal Structure beneath Bulgaria Obtained from Receiver Function Analysis

Cited by 2 publications

References 6 publications

Deep Structure and Dynamics of the Central Balkan Peninsula from Seismic Data

Deep Structure and Dynamics of the Central Balkan Peninsula from Seismic Data

The crustal thickness in the Rhodope Metamorphic Complex area from the perspective of the present-day geological knowledge

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