Albititas metasomáticas y venas de cuarzo en los leucogranitos de Burguillos del Cerro (España). Modelo de evolución hidrotermal basado en el estudio de inclusiones fluidas

Abstract

Slightly peraluminous to metaluminous leucogranites are common as dyke swarms in the Burguillos del Cerro Plutonic Complex. They show superimposed hydrothermal alterations consisting of quartzrich albitites and Au-bearing quartz veins. Several types of fluid Inclusions have been distinguished in the alteration. They belong to the system H20-NaCI-KCI-MgCI2-CaCI2 and range from high salinity to low salinity types. In any type, a trend of decreasing salinity concomitant to a decrease of minimum P and T trapping conditions is found. An evolutive model is proposed consisting in the repetitive mixing of hot saline waters, initially of probable magmatic derivation, with a cold low salinity meteoric fluid, in several discrete episodes of hydrofractunng, under declining regional temperature conditions. Albitites and quartz veins seem to be temporally and genetically related