Radková P., Mikuš T., Bakos F., Koděra P. & Luptáková J., 2019: A new type of carbonate-hosted Au mineralization at Dúbrava near Rochovce, Western Carpathians. Acta Geologica Slovaca, 11, 2, 103–118.

A new type of carbonate-hosted Au mineralization at Dúbrava near Rochovce, Western Carpathians

Pavlína Radková¹, Tomáš Mikuš², František Bakos¹, Peter Koděra³ & Jarmila Luptáková²

ŕ¹Rodinia, s.r.o., Mostová 2, 811 02 Bratislava, Slovakia; pavlina@rodinia.sk, fbakoss@yahoo.com
²Earth Science Institute, Slovak Academy of Sciences, Ďumbierska 1, 974 01 Banská Bystrica, Slovakia; mikus@savbb.sk, luptakova@savbb.sk
³Department of Geology of Mineral Deposits, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15 Bratislava, Slovakia; kodera@fns.uniba.sk

Abstract

A unique metallogenic type of Au mineralization was discovered in Mesozoic carbonates belonging to the Bôrka nappe accretion mélange near Rochovce. The mineralization is structurally controlled by faults formed during several stages of Alpine deformation. Widespread dolomitization, along with sericite and pyrite alteration of marbles, indicate extensive hydrothermal activity along the Lubeník-Margecany thrust fault. The earlier period of Au mineralization is linked to N–S structures, hosting coarse-grained zonal gold accompanied by minor silicification. This indicates that the mineralization differs from typical Carlin style deposits. Zonal textures of gold with inward Ag diffusion, together with aurostibite inclusions, indicate a sulphur-deficient environment during the late stages of hydrothermal evolution. Later base-metal mineralization is related to the NE–SW fault zones displacing the Au-bearing structures. The presence of various assemblages of Pb-Zn-Sb-As secondary minerals (segnitite, mimetite, oxyplumboroméite, arsendescloizite, austinite) originated from slightly acidic fluids as a result of pyrite oxidation. The studied locality is geochemically similar to other gold and polymetallic occurrences within 5 km of the Rochovce granite, which can be interpreted as intrusion-related and/or heat energy driven types of mineralization. However, this type of mineral association in carbonate host rock with specific alterations is quite unusual.

Key words: Western Carpathians, Rochovce granite, gold, aurostibite, adelite group minerals, roméite group minerals, mimetite, segnitite

Manuscript received: 2019-09-30

Revised version accepted: 2019-12-03