The fluid chemical evolution of the Elatsite porphyry Cu-Au-PGE deposit, Bulgaria

摘要

The Panagyurishte ore district hosts late Cretaceous porphyry-type ore deposits, among which the Cu-Au-PGE monzodioritic to granodioritic intrusion-related deposit Elatsite is the most prominent one. Four successive mineral stages can be distinguished. During the first Mt-Bn-Cp stage, characterized by high concentrations of Au and PGE and significant Cu, the minerals crystallized from high-salinity aqueous fluids with 60 ― 42 wt.% NaCl_(equiv). The next three, Q-Cp-Py , Q-Py and Q-Gn-Sp, stages are precipitated from progressively cooler and less saline fluids (44 ― 20 wt.% NaCl_(equiv.)). LA-ICPMS fluid chemical data demonstrate that the pre-ore fluid of the Mt-Bn-Cp stage contained up to 4 wt.% Cu and elevated other base metal contents. Work is in progress to characterize the chemical evolution of the fluid through the depositional sequence of the mineralization in order to confine chemical processes responsible for the formation of the deposit.