Preprint Article Version 2 This version is not peer-reviewed

Crystallographic and Seismic Anisotropies of Calcite at Different Depths: A Study Using Quantitative Texture Analysis by Neutron Diffraction

Version 1 : Received: 3 November 2019 / Approved: 6 November 2019 / Online: 6 November 2019 (05:09:01 CET)
Version 2 : Received: 22 December 2019 / Approved: 24 December 2019 / Online: 24 December 2019 (11:03:19 CET)

A peer-reviewed article of this Preprint also exists.

Zucali, M.; Chateigner, D.; Ouladdiaf, A.B. Crystallographic and Seismic Anisotropies of Calcite at Different Depths: A Study Using Quantitative Texture Analysis by Neutron Diffraction. Minerals 2020, 10, 26. Zucali, M.; Chateigner, D.; Ouladdiaf, A.B. Crystallographic and Seismic Anisotropies of Calcite at Different Depths: A Study Using Quantitative Texture Analysis by Neutron Diffraction. Minerals 2020, 10, 26.

Journal reference: Minerals 2019, 10, 26
DOI: 10.3390/min10010026

Abstract

Eight samples of limestones and marbles were studied by neutron diffraction to collect 2 Quantitative Texture (i.e., Crystallographic Preferred Orientations or CPO) of calcite deforming at 3 different depths in the crust. We studied the different Texture patterns developed in shear zones at 4 different depth and their influence on seismic anisotropies. Samples were collected in the French and 5 Italian Alps, Apennines, and Paleozoic Sardinian basement. They are characterized by isotropic to 6 highly anisotropic (e.g., mylonite shear zone) fabrics. Mylonite limestones occur as shear zone horizons 7 within the Cenozoic Southern Domain in Alpine thrust-and-fold belts (Italy), the Briançonnais domain 8 of the Western Alps (Italy-France border), the Sardinian Paleozoic back-thrusts or in the Austroalpine 9 intermediate units. The analyzed marbles were collected in the Carrara Marble, in the Austroalpine Units 10 in the Central (Mortirolo) and Western Alps (Valpelline). The temperature and depth of development of fabrics vary from < 100C, to 800C and depth from <10 km to about 30 km, corresponding from upper 12 to lower crust conditions. Quantitative Texture Analysis shows different types of patterns for calcite: 13 random to strongly textured. Textured types may be further separated in orthorhombic and monoclinic 14 (Types A and B), based on the angle defined with the mesoscopic fabrics. Seismic anisotropies were 15 calculated by homogenizing the single crystal elastic tensor, using the Orientation Distribution Function 16 calculated by the Quantitative Texture Analysis. The resulting P- and S-waves anisotropies show a wide 17 variability due to the textural types, temperature and pressure conditions, and dip of the shear planes.

Subject Areas

calcite; seismic anisotropy; texture; CPO; thrust; shear zone; neutron diffraction; crust

Comments (1)

Comment 1
Received: 24 December 2019
Commenter: Michele Zucali
Commenter's Conflict of Interests: Author
Comment: reviewed version December
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