The Madneuli copper-gold polymetallic deposit is the major ore deposit of the Georgian Bolnisi mining district in the Artvin-Bolnisi belt in the southeastern part of Georgia, Lesser Caucasus. Numerous ore deposits occur in the Bolnisi region connected with Upper Cretaceous explosive volcanic events. This investigation is based on physical volcanology and facies architecture of the host rocks, and was applied for the first time in this region. Our study shows that the predominant part of the host rock sequence of the Madneuli polymetallic deposit was deposited under submarine conditions, which is in agreement with volcanogenic massive sulfide models or transitional, shallow submarine magmatic to epithermal models that were proposed by previous studies.