Deformation and seismic anisotropy of the subcontinental lithospheric mantle in NE Spain: EBSD data on xenoliths from the Catalan Volcanic Zone



Fernandez-Roig, Merce, Galan, Gumer and Mariani, Elisabetta ORCID: 0000-0002-0585-5265
(2017) Deformation and seismic anisotropy of the subcontinental lithospheric mantle in NE Spain: EBSD data on xenoliths from the Catalan Volcanic Zone. TECTONOPHYSICS, 698. pp. 16-37.

[thumbnail of ManuscriptFdzRoig_R2.docx] Text
ManuscriptFdzRoig_R2.docx - Author Accepted Manuscript

Download (151kB)
[thumbnail of Figures.pdf] Text
Figures.pdf - Author Accepted Manuscript

Download (17MB)

Abstract

Mantle xenoliths in Neogene-Quaternary basaltic rocks related to the European Cenozoic Rift System serve to assess the evolution of the subcontinental lithospheric mantle beneath the Catalan Volcanic Zone in NE Spain. Crystallographic preferred orientations, major element composition of minerals, and temperature and pressure estimates have been used to this end. The mantle consists of spinel lherzolites, harzburgites and subordinate websterites. Protogranular microstructures are found in all peridotites and websterites, but lherzolites also display finer-grained porphyroclastic and equigranular microstructures. The dominant olivine deformation fabric is [010] fiber, but subordinate orthorhombic and [100]-fiber types are also present, especially in porphyroclastic and equigranular lherzolites. The fabric strength (J index = 10.12–1.91), equilibrium temperature and pressure are higher in xenoliths with [010]-fiber fabric and decrease in those with orthorhombic and [100]-fiber type. Incoherence between olivine and pyroxene deformation fabric is mostly found in porphyroclastic and equigranular lherzolites. Seismic anisotropy, estimated from the crystal preferred orientations, also decreases (AVp = 10.2–2.60%; AVs max = 7.95–2.19%) in porphyroclastic and equigranular lherzolites. The olivine [010]-fiber fabric points to deformation by simple shear or transpression which is likely to have occured during the development of late-Hercynian strike-slip shear zones, and to subsequent annealing during late Hercynian decompression, Permian and Cretaceous rifting. Also, it cannot be excluded that the percolation of mafic magmas during these extensional events provoked the refertilization of the lithospheric mantle. However, no clear relationship has been observed between fabric strength and mineral mode and composition. Later transtensional deformation during late Alpine orogenesis, at higher stress and decreasing temperature and pressure, transformed the earlier fabric into orthorhombic and [100]-fiber type. Comparison of seismic anisotropy estimates with the available SKS-wave splitting data suggests that most of the measured seismic anisotropy would be explained by the lithospheric contribution, if the lithospheric mantle fabrics record mainly transpression and transtensional deformation.

Item Type: Article
Additional Information: publisher: Elsevier articletitle: Deformation and seismic anisotropy of the subcontinental lithospheric mantle in NE Spain: EBSD data on xenoliths from the Catalan Volcanic Zone journaltitle: Tectonophysics articlelink: http://dx.doi.org/10.1016/j.tecto.2016.12.023 content_type: article copyright: © 2017 Elsevier B.V. All rights reserved.
Uncontrolled Keywords: Lithosphere, Mantle, Olivine, Pyroxene, Deformation fabric, Seismic anisotropy
Depositing User: Symplectic Admin
Date Deposited: 27 Feb 2017 15:13
Last Modified: 19 Jan 2023 07:19
DOI: 10.1016/j.tecto.2016.12.023
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3005644