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Plavica |
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Macedonia |
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Au Cu
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Plavica Cu-Au deposit is located within the Republic of Macedonia, around 50 km east of the city of Skopje and 4 km south of the town of Kratovo.
The deposit is situated in the Kratovo-Zletovo volcanic field, one of a number of Tertiary igneous centres which occupy a NW-SE trending belt which extends for several hundred kilometres through Serbia, Macedonia and Greece. Mineralisation is closely associated with many of these igneous complexes and a distinct belt of mineral deposits that constitute the Lece/Sumadija-Chalkidiki metallogenic zone extends from the Lece district in Serbia through Macedonia and into the Chalkidiki district of Greece and possibly extending across the Aegean into western Turkey to near Izmir. This zone of volcanics and associated mineralisation occurs as two elongate, geological terranes, the Vardar zone and the Serbo-Macedonian zone, sandwiched between the Carpatho-Balkanides in the east and the Dinarides-Hellenides to the west. The geology of the region is part of the early stages of the Alpine orogeny, related to the closure of the Tethyan Ocean as the African plate converged with, and was subducted below, the Eurasian plate in an ENE direction.
The Plavica deposit is hosted by Oligo-Miocene, calc-alkaline, volcanic rocks of the 1200 sq. km. Kratovo-Zletovo volcanic field which was developed as a series of NW-trending, linked basins overlying the boundary between the Vardar and Serbo-Macedonian zones. The Plavica deposit is located in the Probistip fault controlled basin. The basement in district comprises Precambrian and Palaeozoic schists and amphibolites of the Serbo-Macedonian zone which are unconformably overlain by Upper Cretaceous and Eocene-Oligocene sediments and igneous rocks.
The Probistip basin is filled with around 1 km of sediments and volcanics which are dominantly early to mid Miocene to Pleistocene in age exhibiting several cycles of extrusive volcanic rocks (mostly lava flows), volcanogenic sediments (tuffs, ignimbrites) and some shallow water, lacustrine, clastic sediments. The volcanic rocks are predominantly intermediate and high K trachyandesite (latite) with subordinate andesite, basaltic trachyandesite, dacite and trachyte, occuring as lavas, stocks, dykes, ignimbrites, breccias and tuffs. Plutonic igneous bodies are not common, although some monzonite, quartz monzonite and diorite bodies are mapped. Geophysics suggest that plutons underlie the region at depths of 2 to 5 km.
Concentric, arcuate fractures around the Plavica deposit have been interpretted to indicate it lies within a small ~1.5 km diameter caldera, supported by the circular form of the outcrop patterns and geomorphology surrounding the deposit, with abundant NW-SE, ENE-WSW and E-W trending fractures with some indication of a radial distribution. The fractures in the central parts of the suggested caldera structure host the mineralisation.
Mineralisation occurs in four distinct settings, namely:
i). stockwork and disseminated Cu-Au (-Mo, Ag), which occurs in the central and deepest part of the system and is present over an area of 5 to 6 sq. km and has been reported at depths of 950 m below surface
ii). veins of quartz, pyrite, sphalerite and enargite (±Au) which occur at intermediate levels and appear to be superimposed on the stockwork mineralisation. Old workings in the Zlatica area followed these enargite veins for distances up to 200 m with thicknesses from 0.7 to 5 m containing around 2% Cu and 1 g/t Au.
iii). silica bodies which occur peripheral to the central zone and consist of quartz plus some opal and are sub-vertical in orientation. Both massive and 'vuggy' silica are recorded. These bodies have a maximum development at depths of <100 m but extend to greater depths where they taper out (usually at around 400 m). They contain elevated gold levels (up to 1 to 10 ppm) as well as alunite, jarosite, native sulphur and kaolinite. The silica bodies follow EÐW fractures and crosscut both the stockwork mineralisation and enargite veins. Locally, the silica bodies are cut by breccias containing angular silica clasts
iv). small veins, locally enriched in Pb and Zn (up to 1% combined Pb+Zn) found around the margins of the caldera.
The vein-type and disseminated mineralisation is dominated by pyrite, together with sulphides and sulphosalts of copper, zinc and arsenic. Alteration of the volcanic rocks is intense and consists of advanced argillic alteration in association with massive silica replacement bodies; these overly zones of sericitic alteration.
The mineralised zone at Plavica contains ~0.2% Cu, 0.3 g/t Au and 5 to 10 g/t Ag and extends over an area of 4 sq. km and is known to depths of >1000 m. The main mineralised body covers an area of close to 1 sq. km with vertical extent of around 200 m (Alderton and Serafimovski, 2007).
The deposit is currently considered uneconomic, although the close magmatic association suggests a porphyry Cu deposit may be present at depth.
The most recent source geological information used to prepare this decription was dated: 2007.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Alderton D H M and Serafimovski T, 2007 - The geology and genesis of the Plavica copper-gold deposit, Macedonia : in Trans. IMM (incorp. AusIMM Proc.), Section B, Appl. Earth Sc. v116 pp 94-105
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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