The Kapan Central (Tsentral'Ni Ryudnik) copper deposit is located 2 km NNW of Kapan in the Syunik Province of southern Armenia. In contrast with the Zangezur porphyry Cu-Mo province west of Kapan dominated by Eocene through Miocene continental margin magmatic arc activity, the Kapan area is a part of the Somkhet-Karabagh “eugeoclinal” zone of Middle Jurassic submarine andesitic to bimodal volcanism and sedimentation, the result of magmatism produced by subduction of the leading edge of Gondwana beneath Laurasia. This metallogenic zone contains several VMS deposits (Kuroko-style Akhtala with barite) as well as Cu veins, stockworks and replacements (Alaverdi, Kapan-Central) in andesites believed associated with the submarine metallogenesis and possibly part of the feeder (plumbing) system of the missing (eroded?) VMS lenses.
The Somkhet-Karabagh zone can be traced, with interruptions, from Georgia (Bolnitsi district) through NE Armenia (Alaverdi, Shamlug; see LT 5032 and 5033) to the Kapan area and farther south to Iran. It is a thick sequence of repeatedly alternating andesite with local Na-altered basalt units (“spilite”) and sodic felsic volcanics (“keratophyre”) and with units of volcaniclastics and limestone on top. It is intruded by several comagmatic massifs of gabbro, diorite, monzonite and granodiorite, and by dike swarms and it is believed that the Kapan ore field is in the roof of buried Late Jurassic intrusion.
Several erosional relics of Quaternary basalt flows are in Kapan area.
The predominantly copper mineralization at Kapan ranges from stockworks to fault/fissure veins of mostly quartz with pyrite, chalcopyrite, arsenopyrite in strongly silicified (up to the “secondary quartzite” variety) and sericite-chlorite altered andesite and dacite, controlled by reactivated brittle faults. On top of the system are patches of chalcedonic silica (possibly from hot spring sinters) and massive anhydrite/gypsum.
There has been a strong supergene alteration as a result of a high proportion of pyrite in ores that has produced leached capping, Fe hydroxide infiltrations and acid waters that enter streams and accumulate in pit bottoms.
The recorded production during the Soviet era (1953-1991) is estimated at 27.8 Mt @ 1.23% Cu; the total until 2008 was ~30 Mt @ 1.3% Cu. The 2008 remaining reserves were 2.9 Mt @ 0.99% Cu, so the total endowment is approximately 419 kt Cu (that does not include the pre-1953 production). Gold content is too low and almost none has been recovered. Together with Shahumyan, the total Cu endowment for the Kapan ore field is greater than 907 kt Cu.
(Source: Peter Laznicka, September 2012)
