Ore petrology and metamorphic history of Zn-Pb ores,Monteneve, Tyrol,N. Italy

Bands of sphalerite, pyrrhotite, galena, and chalcopyrite are found within and conformable with two distinctive stratigraphic horizons of the metasedimentary Breonie Metalliferous series of northern Italy. Banding is attributable to deposition and metamorphism. Gangue minerals and ore minerals are intergrown and of comparable grain size. Sulfide textures, an older and a younger generation, are metamorphic in origin. Older textures include porphyroblasts, coarse grain, annealing twins, and concentrations of selected minerals along grain boundaries and in fold hinges. Younger generation textures include minute fractures, breccia, mylonite, mineral preferred orientation, deformation twins, linear arrays of small grains, grain size reduction of an order of magnitude, and pressure shadows. The younger deformation textures were slightly modified by syntectonic and posttectonic recrystallization, annealing, and grain growth. Metamorphic textures combined to erase original depositional features except for the layering and conformability inherited from an early sedimentary sulfide setting.Work carried out within the "Progetto Finalizzato Geodinamica", subproject 4, Operative Unit 4. 2. 3., C. N. R. contracts nos. 78. 00821, 79. 00509, 80. 01380. Publication No. 422 of the "Progetto Finalizzato Geodinamica"