Abstract
Vein-type Pb-Ni-Bi-Au-Ag mineralization at the Clemence deposit in the Kamariza and “km3” in the Lavrion area, was synchronous with the intrusion of a Miocene granodiorite body and related felsic and mafic dikes and sills within marbles and schists in the footwall of (and within) the Western Cycladic detachment system. In the Serpieri deposit (Kamariza area), a porphyry-style pyrrhotite-arsenopyrite mineralized microgranitic dike is genetically related to a garnet-wollastonite bearing skarn characterized by a similar base metal and Ni (up to 219 ppm) enrichment. The Ni–Bi–Au association in the Clemence deposit consists of initial deposition of pyrite and arsenopyrite followed by an intergrowth of native gold-bismuthinite and oscillatory zoned gersdorffite. The zoning is related to variable As, Ni, and Fe contents, indicating fluctuations of arsenic and sulfur fugacity in the hydrothermal fluid. A late evolution towards higher sulfur fugacity in the mineralization is evident by the deposition of chalcopyrite, tennantite, enargite, and galena rimming gersdorffite. At the “km3” locality, Ni sulfides and sulfarsenides, vaesite, millerite, ullmannite, and polydymite, are enclosed in gersdorffite and/or galena. The gersdorffite is homogenous and contains less Fe (up to 2 wt.%) than that from the Clemence deposit (up to 9 wt.%). Bulk ore analyses of the Clemence ore reveal Au and Ag grades both exceeding 100 g/t, Pb and Zn > 1 wt.%, Ni up to 9700 ppm, Co up to 118 ppm, Sn > 100 ppm, and Bi > 2000 ppm. The “km3” mineralization is enriched in Mo (up to 36 ppm), Ni (>1 wt.%), and Co (up to 1290 ppm). Our data further support a magmatic contribution to the ore-forming fluids, although remobilization and leaching of metals from previous mineralization and/or host rocks, through the late involvement of non-magmatic fluid in the ore system, cannot be excluded.
Highlights
The Lavrion district in Greece is part of the Attic-Cycladic metamorphic core complex, and contains a variety of ore types including porphyry Mo-W, skarn Fe-Cu-Bi-Te, carbonate-replacementPb-Zn-Cu-As-Sb-Ag ± Au-Bi, and vein/breccia Pb-Zn-Cu-As-Sb-Ag-Au-Ni-Bi [1,2,3,4,5,6,7]
The present study describes the mineralogy and geochemistry of intrusive bodies in the Kamariza area and describes a new occurrence of skarn and porphyry-style mineralization in the Serpieri deposit, which is spatially associated with a felsic dike intruding marbles [6,9]
Forty-three thin and polished sections of host-rocks, skarn, and sulfide mineralization were studied by optical microscopy and a JEOL JSM 5600 scanning electron microscope, equipped with backscattered imaging capabilities, at the Department of Mineralogy and Petrology, University of Athens
Summary
The Lavrion district in Greece is part of the Attic-Cycladic metamorphic core complex, and contains a variety of ore types including porphyry Mo-W, skarn Fe-Cu-Bi-Te, carbonate-replacementPb-Zn-Cu-As-Sb-Ag ± Au-Bi, and vein/breccia Pb-Zn-Cu-As-Sb-Ag-Au-Ni-Bi [1,2,3,4,5,6,7]. Dominated by base metal sulfides, nickel- and to a lesser extent cobalt-bearing metallic minerals have been described from several sites in the Lavrion district, for example, at the Kamariza, Plaka and “km3” deposits. Gersdorffite, rammelsbergite, nickeline, and safflorite were described from the “km3” site by Marinos and Petraschek [1], Wendel and Markl [8], and Rieck et al [9]. Gersdorffite related to sulfides and fluorite was found along the detachment fault in the Villia deposit and in chimneys from the Jean. Kolitsch et al [6] described the following Ni and Co minerals at Plaka (145 Adit), associated with pyrrhotite-bearing skarn: cattierite, cobaltite, pentlandite, polydymite, siegenite, ullmannite, and violarite. Polydymite, ullmannite, vaesite, and violarite were detected at “km3”
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