Mantle dynamics beneath Greece from SKS and PKS seismic anisotropy study

Κaviris, George; Fountoulakis, Ioannis; Spingos, Ioannis; Millas, Christos; Papadimitriou, P.; Δρακάτος, Γ.

doi:10.1007/s11600-018-0225-z

Cited by 13 publications

(14 citation statements)

References 98 publications

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“…COB is critical for the regional tectonics, in particular concerning trench-perpendicular strike-slip faulting across CLAB, E-W normal faulting along the Corinth rift to its north turning into N-S normal faulting towards its south . The inferred feature is compatible with the combined results of mantle anisotropy (Endrun et al 2011;Evangelidis, 2017;Kaviris et al 2018) and crustal stress-states . Specifically, the largest angular difference (75°-90°) between the SKS fast polarization directions and the maximum horizontal crustal stress axis, S Hmax , is observed along COB, possibly indicating trench-parallel mantle-flow, correlated with a slab tear that induces strain in a perpendicular direction.…”

Section: The Continental-oceanic Subduction Boundary (Cob)supporting

confidence: 86%

“…S5a in the Supplementary Material) and the respective strain-rate field (ε Η1 , Chousianitis et al 2015) from roughly E-W compression in the north to almost N-S in the south. Moreover, this transition is related to a sharp contrast of the crustal stress-shape and deflection of SKS (Evangelidis, 2017;Kaviris et al 2018) and Rayleigh-wave (Endrun et al 2011) anisotropy orientation.…”

Section: The East Hellenic Subduction Zone (Ehsz)mentioning

confidence: 96%

“…Such a thin lithosphere/laminated mantle lithospheric structure beneath Aegean/W. Anatolia is relevant to asthenospheric convection (e.g., Jolivet et al 2013), as pointed out also by the large amplitude of mantle shear- (Hatzfeld et al 2001;Evangelidis, 2017;Kaviris et al 2018) and Rayleigh-wave anisotropy (Endrun et al 2011).The existence of a shallow LAB/laminated mantle affects volcanism and increased heat-flow which is widely seen throughout the Aegean and W. Anatolia (Pe-Piper & Piper 2002;Serpen et al 2010). More specifically, shallow, low velocity anomalies in NW Greece (cross-sections a 1 -a 2 , b 1 -b 2 , c 1 -c 2 of Fig.…”

Section: The Lithosphere-asthenosphere Boundary (Lab)mentioning

confidence: 99%

“…Hansen et al (2019) argue that a vertical tear occurs beneath CTF, but a trench-parallel one exists from northern Greece to north Peloponnese. Interpretations of this matter based on mantle anisotropy vary (Hatzfeld et al 2001;Endrun et al 2011;Olive et al 2014;Paul et al 2014;Evangelidis, 2017;Kaviris et al 2018). Sachpazi et al (2016) suggest multiple vertical tearing (segmentation) of the slab occurring on along-dip, transverse faults.…”

Section: The West Hellenic Subduction Zone (Whsz)mentioning

confidence: 99%

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Deep structure of the Hellenic lithosphere from teleseismic Rayleigh-wave tomography

Kassaras

Kapetanidis

Karakonstantis

et al. 2020

Geophysical Journal International

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SUMMARY This research provides new constraints on the intermediate depth upper-mantle structure of the Hellenic lithosphere using a three-step Rayleigh-wave tomography. Broadband waveforms of about 1000 teleseismic events, recorded by ∼200 permanent broad-band stations between 2010 and 2018 were acquired and processed. Through a multichannel cross-correlation technique, the fundamental mode Rayleigh-wave phase-velocity dispersion curves in the period range 30–90 s were derived. The phase-velocities were inverted and a 3-D shear velocity model was obtained down to the depth of 140 km. The applied method has provided 3-D constraints on large-scale characteristics of the lithosphere and the upper mantle of the Hellenic region. Highlighted resolved features include the continental and oceanic subducting slabs in the region, the result of convergence between Adria and Africa plates with the Aegean. The boundary between the oceanic and continental subduction is suggested to exist along a trench-perpendicular line that connects NW Peloponnese with N. Euboea, bridging the Hellenic Trench with the North Aegean Trough. No clear evidence for trench-perpendicular vertical slab tearing was resolved along the western part of Hellenic Subduction Zone; however, subcrustal seismicity observed along the inferred continental–oceanic subduction boundary indicates that such an implication should not be excluded. The 3-D shear velocity model supports an N–S vertical slab tear beneath SW Anatolia that justifies deepening, increase of dip and change of dip direction of the Wadati-Benioff Zone. Low velocities found at depths <50 km beneath the island and the backarc, interrelated with recent/remnant volcanism in the Aegean and W. Anatolia, are explained by convection from a shallow asthenosphere.

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Section: The Continental-oceanic Subduction Boundary (Cob)supporting

confidence: 86%

Section: The East Hellenic Subduction Zone (Ehsz)mentioning

confidence: 96%

Section: The Lithosphere-asthenosphere Boundary (Lab)mentioning

confidence: 99%

Section: The West Hellenic Subduction Zone (Whsz)mentioning

confidence: 99%

See 2 more Smart Citations

Deep structure of the Hellenic lithosphere from teleseismic Rayleigh-wave tomography

Kassaras

Kapetanidis

Karakonstantis

et al. 2020

Geophysical Journal International

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“…Tears have been deduced from relatively slow velocities coinciding with SW Anatolia at <200 km depth (e.g., Bakırcı et al., 2012; Berk Biryol et al., 2011; Portner, Delph, et al., 2018), supporting a hypothesis of mantle upwelling through a slab window, which in turn may affect surface magmatic processes (e.g., Roche et al., 2019). Shear‐wave anisotropy studies (e.g., Kaviris et al., 2018; Paul et al., 2014; Wei et al., 2019) detect changes in fast directions from NE‐SW to NW‐SE in the same region, attributed to asthenospheric toroidal flow around slab edges (Confal et al., 2018; Wei et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

Seismic Tomographic Imaging of the Eastern Mediterranean Mantle: Implications for Terminal‐Stage Subduction, the Uplift of Anatolia, and the Development of the North Anatolian Fault

Kounoudis

Bastow

Ogden

et al. 2020

Geochem Geophys Geosyst

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The Eastern Mediterranean captures the east‐west transition from active subduction of Earth's oldest oceanic lithosphere to continental collision, making it an ideal location to study terminal‐stage subduction. Asthenospheric‐ or subduction‐related processes are the main candidates for the region's ∼2 km uplift and Miocene volcanism; however, their relative importance is debated. To address these issues, we present new P and S wave relative arrival‐time tomographic models that reveal fast anomalies associated with an intact Aegean slab in the west, progressing to a fragmented, partially continental, Cyprean slab below central Anatolia. We resolve a gap between the Aegean and Cyprean slabs, and a horizontal tear in the Cyprean slab below the Central Anatolian Volcanic Province. Below eastern Anatolia, the completely detached “Bitlis” slab is characterized by fast wave speeds at ∼500 km depth. Assuming slab sinking rates mirror Arabia‐Anatolia convergence rates, the Bitlis slab's location indicates an Oligocene (∼26 Ma) break‐off. Results further reveal a strong velocity contrast across the North Anatolian Fault likely representing a 40–60 km decrease in lithospheric thickness from the Precambrian lithosphere north of the fault to a thinned Anatolian lithosphere in the south. Slow uppermost‐mantle wave speeds below active volcanoes in eastern Anatolia, and ratios of P to S wave relative traveltimes, indicate a thin lithosphere and melt contributions. Positive central and eastern Anatolian residual topography requires additional support from hot/buoyant asthenosphere to maintain the 1–2 km elevation in addition to an almost absent lithospheric mantle. Small‐scale fast velocity structures in the shallow mantle above the Bitlis slab may therefore be drips of Anatolian lithospheric mantle.

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