Crystallographic preferred orientation, seismic velocity and anisotropy in roofing slates

Cárdenes, V.; López-Sánchez, Marco A.; Barou, Fabrice; Olona, Javier; Llana‐Fúnez, Sergio

doi:10.1016/j.tecto.2021.228815

Cited by 9 publications

(20 citation statements)

References 56 publications

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“…Christensen, 1985;Guo et al, 2014). In the case of slates from the WALZ, recent laboratory data have shown that the magnitude of the anisotropy increases with the decrease of confining pressure, as the orientation of the microcracks is strongly controlled by the shape fabric in very well foliated slates (Cárdenes et al, 2021).…”

Section: Radial Anisotropymentioning

confidence: 99%

“…CC BY 4.0 License. metamorphic conditions, which imposes a strong mostly planar mechanical anisotropy to the propagation of seismic waves (Cárdenes et al, 2021).…”

Section: Upper Crustal Domains In the Study Areamentioning

confidence: 99%

“…However, this means that another origin must be invoked to produce the RA magnitude increment at higher depths. As it is minerals, such as phyllosilicates, are common in the composition of these rocks, so the alignment of minerals and grains (Wenk et al, 2020;Cárdenes et al, 2021) seems to be the most likely mechanism controlling the anisotropy in the WALZ and at depths > 8 km.…”

Section: Radial Anisotropymentioning

confidence: 99%

“…Firstly, to apply the ANI method to learn differences in architecture in relation to two orogenic events with contrasting kinematics (therefore orientation of structures). For this reason, we extended the area of observations to include parts of the Iberian crust with stronger Variscan imprint, incorporating domains with strong tectonic fabric susceptible to produce seismic anisotropy (Cárdenes et al, 2021) and with contrasting orientation to Alpine structures (Figs. 1a and b).…”

Section: Introductionmentioning

confidence: 99%

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Radial anisotropy and S-wave velocity depict the internal to external zones transition within the Variscan orogen (NW Iberia)

Acevedo

Fernández‐Viejo

Llana‐Fúnez

et al. 2021

Preprint

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Abstract. The cross-correlation of ambient noise records registered by seismic networks has proven to be a valuable tool to obtain new insights into the crustal structure at different scales. Based on 2- to 14-s-period Rayleigh and Love dispersion data extracted from the seismic ambient noise recorded by 20 three-component broadband stations belonging to two different temporary experiments, we present the first i) upper crustal (1–14 km) high-resolution shear wave velocity and ii) radial anisotropy variation models of the continental crust in NW Iberia. The area of study represents one of the best exposed cross-sections along the Variscan orogen of western Europe, showing the transition between the external eastern zones towards the internal areas in the west. Both the 2-D maps and an E-W transect reveal a close correspondence with the main geological domains of the Variscan orogen. The foreland-fold and thrust-belt of the orogen, the Cantabrian Zone, is revealed by a zone of relatively low shear wave velocities (2.3–3.0 km/s), while the internal zones generally display higher homogeneous velocities (> 3.1 km/s). The boundary between both zones is clearly delineated in the models, depicting the arcuate shape of the orogen grain. The velocity patterns also reveal variations of the bulk properties of the rocks that can be linked to major Variscan structures, such as the basal detachment of the Cantabrian Zone or the stack of nappes involving pre-Variscan basement; or sedimentary features such as the presence of thick syn-orogenic siliciclastic wedges. Overall, the radial anisotropy magnitude varies between −5 and 15 % and increases with depth. The depth pattern suggests that the alignment of cracks is the main source of anisotropy at < 8 km depths, although the intrinsic anisotropy seems to be significant in the West-Asturian Leonese Zone, the low-grade slate belt adjacent to the Cantabrian Zone. At depths > 8 km, widespread high and positive radial anisotropies are observed, caused by the presence of subhorizontal alignments of grains and minerals in relation to the internal deformation of rocks either during the Variscan orogeny or prior to it.

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Section: Radial Anisotropymentioning

confidence: 99%

“…CC BY 4.0 License. metamorphic conditions, which imposes a strong mostly planar mechanical anisotropy to the propagation of seismic waves (Cárdenes et al, 2021).…”

Section: Upper Crustal Domains In the Study Areamentioning

confidence: 99%

Section: Radial Anisotropymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radial anisotropy and S-wave velocity depict the internal to external zones transition within the Variscan orogen (NW Iberia)

Acevedo

Fernández‐Viejo

Llana‐Fúnez

et al. 2021

Preprint

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“…It should be noted that measurements of P-wave velocity anisotropy in one plane give a little information about the anisotropic structure of a refractor (Backus 1962;Crampin and Bamford 1977;Crampin et al 1980;Crampin and Kirkwood 1981). In recent years, the behavior of transversely isotropic rocks, e.g., gneiss, schist, slate, phyllite, shale, mudstone, and layered sandstone, has attracted increased attention (Cardenes et al 2021;Xu et al 2017;Li et al 2017;Sarout and Gueguen 2008;Barton 2007). The anisotropy is one of the most distinct features that must be considered in this kind of rock, and is widely encountered in civil, mining, petroleum, geothermal, and geoenvironmental engineering (Ma et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Development of a New Empirical Relation to Assess P-wave Velocity Anisotropy of Rocks

Moomivand

Nikrouz

et al. 2021

Geotech Geol Eng

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Wave velocity as a simple nondestructive method is used for various applications in geotechnical engineering. Several physical parameters and anisotropy related to rock textural arrangements, schistosity and weakness planes such as cracks and joints affect the P-wave velocity (VP). First, VP anisotropy of quartz-mica schist as a common type of widespread metamorphic rock was compared with VP anisotropy of jointed homogeneous limestone specimens to clarify effect of these two different types of anisotropies. The results showed that the VP anisotropy of quartz-mica schist texture is stronger than the VP anisotropy of jointed limestone, because all body of quartz-mica schist specimens have VP anisotropy behavior. Many rocks are anisotropic and degree of anisotropy varies from one rock to another.Several investigations have been carried out on VP anisotropy but there is not a unique comprehensive relation to represent the influence of different degrees of anisotropy on the VP for different rocks. The relation between VP and angle () between the axis of symmetry (perpendicular to weakness planes) with the wave propagation direction was analyzed for a wide range of anisotropy degree using the results of nine different types of rocks including: Angouran quartz-mica schist, Golgohar mica schist, amphibole schist, mica-quart schist, Marcellus shale, Withby shale WUK47B, WUK70 and WUK2, and Veroia-Polymylos gneiss. A new simple empirical relation fitted to all groups of results was obtained to assess VP for different degrees of anisotropies with a good correlation of determination (R 2 = 0.937), low RMSE (RMSE = 320 m/s) and low CV (CV = 7.0%). P wave velocity anisotropy can simply be predicted by the developed relation using only two parameters of VP0 and VP90. A VP anisotropy classification diagram was also developed based on the different values of .

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Crystallographic and shape preferred orientation producing anisotropy in slates from Northern Spain

Wenk

Huang

Devoe

et al. 2022

Journal of Structural Geology

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Crystallographic preferred orientation, seismic velocity and anisotropy in roofing slates

Cited by 9 publications

References 56 publications

Radial anisotropy and S-wave velocity depict the internal to external zones transition within the Variscan orogen (NW Iberia)

Radial anisotropy and S-wave velocity depict the internal to external zones transition within the Variscan orogen (NW Iberia)

Development of a New Empirical Relation to Assess P-wave Velocity Anisotropy of Rocks

Crystallographic and shape preferred orientation producing anisotropy in slates from Northern Spain

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