Shear-velocity structure of the Tyrrhenian Sea: Tectonics, volcanism and mantle (de)hydration of a back-arc basin

Greve, Sonja M.; Paulssen, Hanneke; Goes, Saskia; Bergen, Manfred van

doi:10.1016/j.epsl.2014.05.028

Cited by 19 publications

(39 citation statements)

References 47 publications

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“…Major compositional variations in magmatism are observed along strike [e.g., Peccerillo and Frezzotti, 2015], possibly controlled by slab tearing unraveled by major gaps in high-velocity anomalies [Rosenbaum et al, 2008]. Our tomography model confirms the existence of major gaps in the Adriatic slab at the boundary between the Northern and the Southern Apennines (Figures 2a and 7) as highlighted by Lucente et al [1999], Piromallo and Morelli [2003], Giacomuzzi et al [2011], and Greve et al [2014]. These gaps match with major faults affecting the Apenninic wedge at the surface.…”

Section: Downdip Slab Continuity and Implications For Cenozoic Magmatismsupporting

confidence: 68%

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Continuity of the Alpine slab unraveled by high‐resolution P wave tomography

et al. 2016

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The question of lateral and/or vertical continuity of subducted slabs in active orogens is a hot topic partly due to poorly resolved tomographic data. The complex slab structure beneath the Alpine region is only partly resolved by available geophysical data, leaving many geological and geodynamical issues widely open. Based upon a finite‐frequency kernel method, we present a new high‐resolution tomography model using P wave data from 527 broadband seismic stations, both from permanent networks and temporary experiments. This model provides an improved image of the slab structure in the Alpine region and fundamental pinpoints for the analysis of Cenozoic magmatism, (U)HP metamorphism, and Alpine topography. Our results document the lateral continuity of the European slab from the Western Alps to the central Alps, and the downdip slab continuity beneath the central Alps, ruling out the hypothesis of slab break off to explain Cenozoic Alpine magmatism. A low‐velocity anomaly is observed in the upper mantle beneath the core of the Western Alps, pointing to dynamic topography effects. A NE dipping Adriatic slab, consistent with Dinaric subduction, is possibly observed beneath the Eastern Alps, whereas the laterally continuous Adriatic slab of the Northern Apennines shows major gaps at the boundary with the Southern Apennines and becomes near vertical in the Alps‐Apennines transition zone. Tear faults accommodating opposite‐dipping subductions during Alpine convergence may represent reactivated lithospheric faults inherited from Tethyan extension. Our results suggest that the interpretations of previous tomography results that include successive slab break offs along the Alpine‐Zagros‐Himalaya orogenic belt might be proficiently reconsidered.

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Section: Downdip Slab Continuity and Implications For Cenozoic Magmatismsupporting

confidence: 68%

“…[], and Greve et al . []. These gaps match with major faults affecting the Apenninic wedge at the surface.…”

Section: Discussionmentioning

confidence: 99%

Continuity of the Alpine slab unraveled by high‐resolution P wave tomography

et al. 2016

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“…The inversion of all grid points resulted in a 3‐D model of the crust and upper mantle. The inversion was carried out using iterative damped least squares optimization based on the Levenberg‐Marquardt algorithm (Moré, ) similar to Greve et al (). The 1‐D inversion approach aimed to minimize an objective function

f

depending on measured data

boldd

and 1‐D subsurface model

boldm

that consists of three misfit terms: the data misfit, the vertical smoothness, and the norm of the perturbation from the reference model,

{boldm}_{ref}

f false(boldd, boldm false) = false‖ boldG false(boldm false) - boldd {false‖}_{2}^{2} + α false‖ \nabla boldm {false‖}_{2}^{2} + β false‖ boldm - {boldm}_{ref} {false‖}_{2}^{2}

where the first term represents data misfit.…”

Section: Methodsmentioning

confidence: 99%

Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System

Fadel

Paulssen

Meijde

et al. 2020

Geophysical Research Letters

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Rayleigh wave group and phase velocity measurements obtained from ambient noise and earthquake data at 51 broadband stations were used to construct the first 3‐D crustal and upper mantle shear wave velocity model of Botswana. The model shows low crustal velocities associated with the Passarge and Nosop sedimentary basins, whereas the Kaapvaal, Zimbabwe, Maltahohe, and Congo Cratons are recognized by high mantle velocities. The lowest upper mantle shear wave velocity, beneath northeastern Botswana, is associated with the southwestern branch of the East African Rift System. This low‐velocity mantle anomaly appears to be linked to the crust of the Okavango Rift Zone and the location of the 3 April 2017 Mw 6.5 earthquake in central Botswana. We suggest that fluids or melt at the base of the crust from the southward continuation of the East African Rift Zone triggered the intraplate earthquake in an extensional tectonic setting.

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“…Small-scale-convection (SSC) occurs in the mantle wedge at viscosities below $1.10 19 Pa s SSC thins the lithosphere, expands hydrous melting regions, and shifts dehydration boundaries The resulting 150 K trench-parallel temperature variations may contribute to arc-volcano spacing Under hydrous conditions, viscosities are likely substantially lower than those of dry mantle [e.g., Karato and Wu, 1993;Hirth and Kohlstedt, 1996], leading to small-scale convection (SSC) that is driven by gravitational instabilities from the base of the upper plate [e.g., Honda and Saito, 2003;Wirth and Korenaga, 2012;Le Voci et al, 2014]. Although some recent studies have challenged the rheological influence of water in the wedge [e.g., Fei et al, 2013;Girard et al, 2013], and furthermore, melting extracts water and, hence, may dry the wedge [e.g., Hebert et al, 2009], low seismic velocity anomalies, low seismic attenuation, and the back-arc surface topography at a number of subduction zones are most easily explained with a low-viscosity mantle wedge, potentially extending hundreds of kilometers from the trench below the back arc [e.g., Billen and Gurnis, 2001;Currie and Hyndman, 2006;Wiens et al, 2008;Greve et al, 2014].…”

Section: Key Pointsmentioning

confidence: 99%

The mantle wedge's transient 3‐D flow regime and thermal structure

Davies

Voci

Goes

et al. 2016

Geochem Geophys Geosyst

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Arc volcanism, volatile cycling, mineralization, and continental crust formation are likely regulated by the mantle wedge's flow regime and thermal structure. Wedge flow is often assumed to follow a regular corner-flow pattern. However, studies that incorporate a hydrated rheology and thermal buoyancy predict internal small-scale-convection (SSC). Here, we systematically explore mantle-wedge dynamics in 3-D simulations. We find that longitudinal ''Richter-rolls'' of SSC (with trench-perpendicular axes) commonly occur if wedge hydration reduces viscosities to Շ1 Á 10 The modulating influence of subback-arc ridges on the subarc system increases with stronger wedge hydration, higher subduction velocity, and thicker upper plates. We find that trenchparallel averages of wedge velocities and temperature are consistent with those predicted in 2-D models. However, lithospheric thinning through SSC is somewhat enhanced in 3-D, thus expanding hydrous melting regions and shifting dehydration boundaries. Subarc Richter-rolls generate time-dependent trench-parallel temperature variations of up to $150 K, which exceed the transient 50-100 K variations predicted in 2-D and may contribute to arc-volcano spacing and the variable seismic velocity structures imaged beneath some arcs.

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Shear-velocity structure of the Tyrrhenian Sea: Tectonics, volcanism and mantle (de)hydration of a back-arc basin

Cited by 19 publications

References 47 publications

Continuity of the Alpine slab unraveled by high‐resolution P wave tomography

Continuity of the Alpine slab unraveled by high‐resolution P wave tomography

Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System

The mantle wedge's transient 3‐D flow regime and thermal structure

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