Abstract:
A combined fluid inclusion and microstructural study was carried out in beryl crystals from the San Cayetano Nb-Ta-bearing pegmatite (San Luis, Argentina). Primary aqueous-carbonic fluids (T0) were subsequently re-trapped during shearing, resulting in en-échelon microfractures. The more brittle behaviour of beryl compared to quartz makes this mineral more suitable for the preservation of fluid inclusions and microstructures. The primary inclusions T0 are preserved in strain-free domains, whereas the pseudo-secondary T1-to T3-type inclusions occur in domains showing intracrystalline deformation. CO2 was relatively immobile or reacted to form carbonate in early T1-type inclusions, whereas H2O preferentially migrated along microfractures and was trapped as T2-and T3-type inclusions. Short intragranular trails of fluid inclusions, representing en-échelon healed microfractures, resulted from progressive strain localization. Contrary to previous proposals, this new model implies the progressive thickness reduction of intracrystalline micro-shear zones. Besides, hydrolytic weakening linked to dislocation glide is the most likely mechanism to explain the evolution of fluid inclusions, with intracrystalline deformation enhancing anisotropic diffusion. This study highlights the potential of combined fluid inclusion and microstructural studies in order to understand the interaction between fluid activity and deformation. In this way, valuable insights can be provided into the progressive development of overprinted fabrics and low-to medium-temperature deformation mechanisms of minerals. © 2018
Registro:
Documento: |
Artículo
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Título: | Development of sigmoidal en-échelon microfractures in beryl and the role of strain localization evidenced by fluid inclusions |
Autor: | Sosa, G.M.; Oriolo, S.; van den Kerkhof, A. |
Filiación: | Geoscience Center of the University of Goettingen, Goldschmidtstrasse 3, Goettingen, D-37077, Germany CONICET - Universidad de Buenos Aires. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires (IGEBA), Intendente Güiraldes 2160, Buenos Aires, C1428EHA, Argentina
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Palabras clave: | Crack initiation; Fluid inclusions; Fluid-deformation interaction; Healed microfractures; Hydrolytic weakening; Shear zone thickness; Crack initiation; Deformation; Dislocations (crystals); Mineralogy; Silicate minerals; Deformation interactions; Fluid inclusion; Hydrolytic weakening; Microfractures; Shear zone; Diffusion in liquids; beryl; crack propagation; deformation; en echelon structure; fluid inclusion; fracture; shear zone; strain; Chelon |
Año: | 2018
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Volumen: | 115
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Página de inicio: | 297
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Página de fin: | 303
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DOI: |
http://dx.doi.org/10.1016/j.jsg.2018.04.005 |
Título revista: | Journal of Structural Geology
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Título revista abreviado: | J. Struct. Geol.
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ISSN: | 01918141
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Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01918141_v115_n_p297_Sosa |
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Citas:
---------- APA ----------
Sosa, G.M., Oriolo, S. & van den Kerkhof, A.
(2018)
. Development of sigmoidal en-échelon microfractures in beryl and the role of strain localization evidenced by fluid inclusions. Journal of Structural Geology, 115, 297-303.
http://dx.doi.org/10.1016/j.jsg.2018.04.005---------- CHICAGO ----------
Sosa, G.M., Oriolo, S., van den Kerkhof, A.
"Development of sigmoidal en-échelon microfractures in beryl and the role of strain localization evidenced by fluid inclusions"
. Journal of Structural Geology 115
(2018) : 297-303.
http://dx.doi.org/10.1016/j.jsg.2018.04.005---------- MLA ----------
Sosa, G.M., Oriolo, S., van den Kerkhof, A.
"Development of sigmoidal en-échelon microfractures in beryl and the role of strain localization evidenced by fluid inclusions"
. Journal of Structural Geology, vol. 115, 2018, pp. 297-303.
http://dx.doi.org/10.1016/j.jsg.2018.04.005---------- VANCOUVER ----------
Sosa, G.M., Oriolo, S., van den Kerkhof, A. Development of sigmoidal en-échelon microfractures in beryl and the role of strain localization evidenced by fluid inclusions. J. Struct. Geol. 2018;115:297-303.
http://dx.doi.org/10.1016/j.jsg.2018.04.005