Preliminary data on the mineral chemistry of garnet from the skarn alteration associated with the Elatsite porphyry-copper gold deposit, Bulgaria

Abstract

The skarn alteration is poorly preserved at the Elatsite, restricted to the hornfelses from the East, Southeast and Southern part of the deposit. The rocks are defined as exoskarns, with a mineral composition including garnets, epidote, pyroxene, amphiboles, carbonates, prehnite, quartz, sulphides. The newly formed minerals occur in poorly preserved layers. The garnet grains are subhedral with inclusions of epidote and quartz, while some of them are corrode with carbonate and zeolites formed in the fractures. The garnets are grossular-andradite type, with higher values for HREE over LREE, and low values for Rb, Sr, Ba, Pb and U. The skarn formation is related with the intrusion of the magma which causes the heating of the metamorphic rocks (rich in carbonate material – chlorite-sericite-carbonite, sericite-carbonate schists, etc.) from the low-grade metamorphic rocks. The Fe+3–Al+3 exchanges in the cores of the garnets indicate their formation from fluids with high oxygen fugacity.