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The arditurri Pb-Zn-F-Ba deposit (Cinco Villas massif,Basque Pyrenees): A deformed and metamorphosed stratiform deposit
Authors:A Pesquera  F Velasco
Institution:(1) Dpto. de Mineralogía y Petrología, Universidad del País Vasco., Apdo. 644, E-48080 Bilbao, Spain
Abstract:Stratiform banded and massive Pb-Zn-F-Ba mineralizations in metasediments of the Westphalian Cinco Villas formation (Basque Pyrenees) show several features related to Hercynian deformation and low-grade regional metamorphism. However, some primary depositional textures and structures are preserved. Minerals like pyrite reveal preregional metamorphic textures (framboidal-colloform pyrite with automorphic overgrowths, dendritic and atoll textures), typical of rapid precipitation from supersaturated solutions during hydrothermal-sedimentary activity. Deformation and subsequent micro- and mesoscale remobilization have caused morphological and textural changes in the mineralizations producing folding, mineral foliation, transposition, boudinages, piercements, etc., as well as the development of veinlike orebodies. Pyrite shows a general tendency toward cataclasis whereas sphalerite, galena, and chalcopyrite exhibit a variety of microstructures (subgrains, twining, recrystallization, etc.) indicative of ductile deformation. Microscopy suggests the deformation of more plastic sulfide occurred mainly by a dislocation-type mechanism at low temperatures (350°C), which are compatible with the regional metamorphism recorded in the host rocks.
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