Facies Analysis of the Volcano-Sedimentary Host Rocks of the Cretaceous Madneuli Massive Sulphide Deposit, Bolnisi District, Georgia

The Cretaceous Madneuli barite-gold-copper-pollymetallic deposit is a major deposit of the Georgian Bolnisi mining district, located in the Artvin-Bolnisi zone. This contribution presents a detailed lithofacies analysis of volcanic host rocks of the Madneuli deposit, including detailed mapping of six outcrop sections, hand samples studies and thin section observations. The rhyolitic volcanoclastic host rocks can be divided ino three groups: (1) massive breccias interpreted as massive breccia flows, (2) stratified tuff and lapilli tuff (including ignimbrites, rhyolite and rhyodacite pyroclastic flows), and (3) turbiditic tuff. On the northern level of the deposit two ignimbrite horizons were singled out. One of them (columnar jointed ignimbrite) was first seen and described by the authors. The same should be said about the association of ignimbrite with rhyolitic pyroclastic lava flows and dacitic hyaloclastic rocks. (author)