Mineralogía y geoquímica de pegmatitas del Grupo Pocho, Distrito Altautina (Córdoba).

COLOMBO, FERNANDO; SFRAGULLA, JORGE; VERDECCHIA, SEBASTIÁN O.; GONZÁLEZ DEL TÁNAGO, JOSÉ; PANNUNZIO MINER, ELISA VICTORIA

Cordoba

Congreso; XIII Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogénesis; 2019

Asociación Mineralógica Argentina y Asociación Geológica Argentina

Granitic pegmatites belonging to the Pocho Group (western Córdoba Province) are lens-shaped, deformed zoned bodies that are hosted by paragneisses and migmatites of the Piedras Rosadas Complex. Major minerals are those typical for granitic pegmatites (quartz, potassic feldspar, plagioclase, muscovite and biotite). Accessory species include beryl (yellow prisms), garnet (almandine-spessartine-pyrope solid solution, with Alm>Sp) and tourmaline (schorl-dravite series). Iron-rich chrysoberyl is very scarce. Phosphate nodules show compositions spanning the fields of beusite-(Ca), beusite-(Mn) and graftonite-(Ca). They contain inclusions of chladniite, Mn-rich fluorapatite and fillowite. Manganese-rich wagnerite was found at the Cerrito Blanco de la Huerta pegmatite. REE minerals are represented by monacite-(Ce) and xenotime-(Y). Hydrothermal phases, derived from graftonite-group minerals, are jahnsite-(CaMnMg), mitridatite and triploidite. Other very scarce accessories include gahnite (inclusions in beryl), bornite and Cu sulfides, and bertrandite. These pegmatites belong to the Rare-Element class, REL-Li subclass, beryl type, beryl-columbite-phosphate subtype (LCT petrogenetic family). Geochemically, they are characterized by the presence of B, Be and P and reduced to negligible contents of F and HFSE, but the most outstanding feature is the abundance of Mg. It is possible that these pegmatites are closely related to anatectic melts, without extensive differentiation in magmatic chambers.