Resumen de Fenómenos de contacto en Los Mármoles de Alta Gracia, La Calera y Malagüeño, provincia de Córdoba
Contact phenomena in the marbles of Alta Gracia, La Calera and Malagueño (province of Córdoba).- The author describes contact phenomena in the marbles of various quarries in the zones around Alta Gracia, La Calera and Malagueño (province of Córdoba), and clear distinction is made between the mineral asemblages which are the results of the regional metamorphism and those which occur between marbles and intrusive rocks.
The contact phenomena are, in general, very little developed in the Sierra of Córdoba, but they show clearly, althoug in small scale, the same develop- ment which is formed in the large classic zones of contact metamorphism.
The mineral assemblages are zoned and trend to built monomineral bands. The origin of the latter is explained by the contact metasomatism process which acts in two ways (Korzhinsky's bimetasomatism): an acid siliceous and aluminous front migrates towards the marble, and a basic calcic front moves to the intrusive, forming endomorphic and exomorphic zones.
The process has in general, three genetic phases: 1) a magmatic stage represented by anhidrous and high-temperature assemblages; 2) postmagmatic stage, where appear new rich assemblages in volatile elements, which replace the formers; 3) a postskarn stage, where mineral assemblages of low temperature, and with OH in their composition, replace the mineral of the first and second stage.
One of the most important phenomena which are described, are the formation of scapolite by replacement of the endomorphic plagioclase. Two calcium-silicate metasomatites are described, althoug they do not bear any direct conection with intrusive bodies.
