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6943202 
Journal Article 
TRACE ELEMENT GEOCHEMISTRY OF ALUNITE FROM THE CHELOPECH HIGH-SULPHIDATION EPITHERMAL DEPOSIT, BULGARIA: A POTENTIAL TOOL FOR EXPLORATION OF EPITHERMAL DEPOSITS 
Georgieva, S; Stefanova, E; Hikov, A; Peytcheva, I; , 
2020 
Yes 
Comptes Rendus de l'Académie Bulgare des Sciences
ISSN: 1310–1331
EISSN: 2367–5535 
PUBL HOUSE BULGARIAN ACAD SCI 
SOFIA 
73 
8 
1092-1101 
WOS:000560030100007 
Chelopech high-sulphidation epithermal (Cu-Au) deposit with its well-characterized hydrothermal footprint is a perfect object to test whether the geo-chemical features of alunite could be used as a reliable exploration tool. Trace element geochemistry of alunite mineralization from two locations in a suite of samples with well-preserved advance argillic alteration was studied: Sharlo Dere area (a remote easternmost part of the deposit - present day surface, elevation 750 m, with uneconomic mineralization) and exploration block 151 (Western sector of the deposit, deeper levels, elevation 100-150 m, ore productive zone). Both locations are set about 2 km apart from each other. The advanced argillic mineral assemblage consists of quartz, dickite/kaolinite, aluminium phosphate-sulphate minerals, alunite, rutile/anatase and pyrite. Based on cross-cutting relationships and petrographic observations two alunite generations were recognized in the exploration block 151: pre-ore alunite (G1) and post-ore alunite (G2). LA-ICP-MS analyses of alunite from both locations show that the contents of Sr, REE, Th, U, Ba, P and Sr/Pb and La/Pb ratios are higher in deeper levels alunites compared to the distal Sharlo Dere alunites. A remarkable enrichment of Ga and V is established in Sharlo Dere alunites. This enrichment of both elements could be explained by a hydrothermal fluid pass through coal-bearing stratigraphic sequences. Our data indicate that alunite chemistry could be used with caution for vectoring to the intrusive centre, having in mind the possibility of wall rock influence. 
geochemical exploration tools; alunite; advanced argillic alteration