Stibnite microstructures as imprints of fault movement

Jean-Philippe Bellot (1, 2) , Laurent Bailly (2) , Catherine Lerouge (2) , Vincent Bouchot (2)

1 ISTEEM - Institut des Sciences de la Terre, de l'Environnement et de l'Espace de Montpellier
2 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

The natural deformation of stibnite in relation to the kinematic history of a regional fault is resolved using microstructural analysis of massive stibnite along the Biards Fault in the Massif Central (France). Stibnite underwent intra-crystalline deformation associated with a strong linear and planar anisotropy. Lepidoblastic textures, undulatory extinction of oriented grains, growth of antimony between these grains, and a colour change of stibnite from white to black, result from dynamic recrystallisation. A range of asymmetric microstructures indicate non-coaxial deformation and a left-lateral sense of shear, related to the movement of the fault zone. The computed displacement corresponds to the geological offsets measured along the fault. We conclude that stibnite has microstructurally recorded the bulk kinematics of its host fault zone.

Domaines: Sciences de la Terre

Jean-Philippe Bellot, Laurent Bailly, Catherine Lerouge, Vincent Bouchot. Stibnite microstructures as imprints of fault movement. Mineralium Deposita, 2004, 39 (5-6), pp.576-582. ⟨10.1007/s00126-004-0432-1⟩. ⟨hal-03794460⟩