Back to Abstract Index
Paper Number: 84
Complex
gold mineralizing system of the Plavica deposit, R. Macedonia
Serafimovski,
T.1 and Tasev, G.1
1Department
of Mineral deposits, Faculty of Natural and Technical Sciences,
University “Goce Delcev”-Stip, str. Goce Delcev 89, The Republic of
Macedonia; todor.serafimovski@ugd.edu.mk.
___________________________________________________________________________
The geological setting of the
Plavica deposit, a part of the complex Kratovo-Zletovo volcanic area
[1], comprises ignimbrite, stratified volcanic tuff and breccia, dacitic
andesite and their pyroclasts, and quartz latites. In addition to large
faults, there are abundant ring-like structures and structures hosting
intrusive dikes produced during episodic Tertiary magmatism.
High-sulfidation epithermal gold has been identified and studied in the
Plavica deposit. Epithermal gold and associated mineral phases have been
determined in silicified tuff, secondary quartzite,
quartz-pyrite-enargite veins, and mainly disseminated within an altered,
but mostly silicified volcanic sequence. Higher Au concentrations at the
Plavica deposit are related to the silica bodies, which is
characteristic of numerous high-sulfidation epithermal deposits around
the world, and the orebodies at Plavica are particularly similar to
those at the Summitville deposit in the USA [2], especially in regards
to their variable geometry with depth. Presence of an advanced argillic
alteration indicates a low pH of the ore fluid and intense leaching.
Sericitic alteration is present at the Plavica deposit, but its
occurrence is separate from the advanced argillic alteration at greater
depths and in the central parts of the deposit. An advanced argillic
alteration and massive silica bodies, which enclose sericitized zones in
the Plavica deposit, suggest a genetic model similar to that at the
Rodalquilar deposit (Spain), where hydrothermal fluid became cooler and
more acidic (by inclusion of dissociated magmatic SO2)
upwards [3]. High-sulfidation deposits are typically located at the top
of porphyry copper deposits (e.g., Lepanto-Phillipines) and it is thus
not accidental that fluids in those systems are brines and sometimes
rich in CO2 (Figure 1). Fluid-inclusion data from the Plavica
deposit provide evidence for direct inflow of a magmatic fluid between
boiling episodes of the hydrothermal fluid [4]. Exploration drill holes
at Plavica intersect Cu-sulfides, magnetite, and traces of molybdenite
in areas of sericitic alteration, and geophysical data justify the
concept that the deeper parts of the Plavica system lie adjacent to a
porphyry copper system (Figure 1).
Figure 1: Schematic genetic model of the Cu-Au-polymetallic
deposit Plavica
The model for the Plavica deposit suggests that at higher volcanic
levels the stuctural-lithological setting allowed transport of magmatic
fluids from magmatic reservoirs, through zones of crushing, brecciation,
intense faulting, and fracturing, up to sub-volcanic and volcanic
levels. This formed classic vein type high sulfidation epithermal Cu-Au
mineralization and shallower disseminated gold zones related to
“vuggy”-sinter quartzites. Copper and polymetalic vein mineralization at
certain hypsometric levels (Figure 1) are also products of the evolution
of the magmatic-hydrothermla system.
References:
[1] Serafimovski, T. (1990) Metallogeny of the Lece-Chalkidiki zone.
PhD thesis, Fac. Mining-Geology,Stip,380 p.
[2] Bethke, P. et al., (2005) Chem. Geol. .215: 281–315.
[3] Arribas, A. et al., (1995) Econ. Geol. 90: 795–822.
[4] Serafimovski, T., et al., (2014) Elaborate of detailed geological
study, with calculation of geological ore reserves, of copper and gold
in the Plavica, Kratovo locality. Genesis Resources Int., Skopje, 431 p.
(in Macedonian).
