The ore deposits in the Kapan, Alaverdi and Mehmana mining districts are poorly understood and previous researchers named them as copper-pyrite, Cu-Au or polymetallic deposits. Different genetic origins were proposed for their formation, including VMS and porphyry-related scenarios. The ore deposits in the Kapan, Alaverdi and Mehmana mining districts are characterized by diverse mineralization styles, which include polymetallic veins, massive stratiform replacement ore bodies at lithological contacts, and stockwork style mineralization. Sericitic, argillic and advanced argillic alteration assemblages are widespread in the deposits which have intermediate to high-sulfidation state mineral parageneses that consist of tennantite-tetrahedrite plus chalcopyrite and enargite-luzonite-colusite, respectively. The ore deposits are spatially associated with differentiated calc-alkaline intrusions and pebble dykes are widespread. Published 未34S values for sulfides and sulfates are in agreement with a magmatic source for the bulk sulfur whereas published 未34S values of sulfate minerals partly overlap with the isotopic composition of contemporaneous seawater. Published mineralization ages demonstrate discrete ore forming pulses from Middle Jurassic to the Late Jurassic-Early Cretaceous boundary, indicating time gaps of 5 to 20 m.y. in between the partly subaqueous deposition of the host rocks and the epigenetic mineralization.
Most of the described characteristics indicate an intrusion-related origin for the ore deposits in Middle Jurassic rocks of the Lesser Caucasus, whereas a hybrid VMS-epithermal-porphyry scenario might apply for deposits with both VMS- and intrusion-related features.
The volcanic Middle Jurassic host rocks for mineralization and Middle to Late Jurassic intrusive rocks from the Somkheto-Karabakh Island Arc and the Kapan Zone show typical subduction-related calc-alkaline signature. They are enriched in LILE such as K, Rb and Ba and show negative anomalies in HFSE such as Nb and Ta. The ubiquitous presence of amphibole in Middle Jurassic volcanic rocks reflects magmas with high water contents. Flat REE patterns ([La/Yb]N = 0.89-1.23) indicate a depleted mantle source, and concave-upward (listric-shaped) MREE-HREE patterns ([Dy/Yb]N = 0.75-1.21) suggest melting from a shallow mantle reservoir. Similar trace element patterns of Middle Jurassic rocks from the Somkheto-Karabakh Island Arc and the Kapan Zone indicate that these two tectonic units form part of one discontinuous segmented arc. Similar petrogenetic and ore-forming processes operated along its axis and Middle Jurassic volcanic and volcanosedimentary rocks constitute the preferential host for polymetallic Cu-Au-Ag-Zn 卤 Pb, Cu-Au and Cu mineralization, both in the Somkheto-Karabakh Island Arc and the Kapan Zone.