Fluid Evolution of the Čukaru Peki Cu-Au Porphyry System (East Serbia) inferred from a fluid inclusion study

Miloš Velojić,Vladica Cvetković,Rade Jelenković

doi:10.4154/gc.2020.14

Abstract

Čukaru Peki is a recently discovered copper-gold deposit in the Bor metallogenic zone in east Serbia. Three types of mineralization can be distinguished in this ore deposit: porphyry, high-sulphidation, and transitional epithermal type. This research was focused on fluid inclusion analysis of genetically different veins from the porphyry and the transitional zones of Čukaru Peki with an aim of better understanding the fluid evolution and mineralization processes in this system. Seven types of veins were identified in the porphyry zone of Čukaru Peki and four of these veins contained transparent minerals which were suitable for fluid inclusion analysis. Eight types of inclusion assemblages were distinguished in these veins: type 1 – primary inclusions with homogenization temperatures above 550°C and high salinity, type 2a- scattered polyphase inclusions two salt crystals, type 2b-polyphase inclusions with two salt crystals in crystal growth zones, type 3- brine inclusions with one salt crystal in crystal growth zones, type 4- vapour-rich inclusions, type 5- primary inclusions in anhydrite, and types 6 and 7- secondary low-temperature inclusions This research suggests that saline fluids (30-40% wt.% NaCl eq.) were the most important ones for the formation of porphyry-type mineralization and that the mineralization was formed at temperatures between 350 and 450°C and pressures between 100 and 500 bars. The epithermal stage was characterized by cooler low-salinity fluids with temperatures between 150-350°C, and salinity between 0 and 7 wt.% NaCl eq.

Highlights

Čukaru Peki is a copper-gold ore deposit, discovered in 2012 by Rakita Exploration, 5km south of the mining town of Bor in eastern Serbia (JELENKOVIĆ, 2014)
Eight types of inclusion assemblages were distinguished in these veins: type 1 – primary inclusions with homogenization temperatures above 550°C and high salinity, type 2a – scattered polyphase inclusions with two salt crystals, type 2b-polyphase inclusions with two salt crystals in crystal growth zones, type 3 – brine inclusions with one salt crystal in crystal growth zones, type 4 – vapourrich inclusions, type 5 – primary inclusions in anhydrite, and types 6 and 7 – secondary lowtemperature inclusions This research suggests that saline fluids (30–40% wt.% NaCl eq.) were the most important ones for the formation of porphyry-type mineralization and that the minerali zation was formed at temperatures between 350 and 450°C and pressures between 100 and 500 bars
According to GOLDSTEIN & SAMSON (2003), a fluid inclusion assemblage comprises a discriminated group of petrographically associated fluid inclusions, which are assumed to be trapped coevally

Summary

Introduction

Čukaru Peki is a copper-gold ore deposit, discovered in 2012 by Rakita Exploration, 5km south of the mining town of Bor in eastern Serbia (JELENKOVIĆ, 2014). BANJEŠEVIĆ & LARGE (2014) state that this ore deposit can be genetically classified as a high-sulphidation epithermal and porphyry copper-gold deposit. This ore deposit belongs to the Bor metallogenic zone, which is spatially and genetically related to the Timok magmatic complex (JANKOVIĆ, 1990). It is elongated in an approximate N-S direction and stretches from the town of Majdanpek in the north to Tupiznica mountain in the south It is part of the eastern segment of the Cretaceous magmatic and metallogenic arc named the Apuseni-Banat-TimokSrednogorje belt, which was formed during the closure of the Neotethyan ocean (e.g., NEUBAUER, 2002; GALLHOFER et al, 2015).

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