Sulfide Polymetallic Ores of the Filizchay Deposit: Lithology, Stratigraphy, Tectonics (Azerbaijan)

The Filizchay deposit, located in the Karabchay anticline, presents a stratigraphic sequence dominated by sedimentary rocks. The Filizchay Series (J₁p₂), composed of dark gray to black clay shales interbedded with sandy flyschoid beds, hosts a compact, lens-shaped polymetallic ore body of massive pyrite with sphalerite, galena, chalcopyrite, and pyrrhotite. Overlying this, the Gubakh Series (J₁t₁+₂) includes sandstone-shale and clay shale units, the latter containing dispersed pyrrhotite concretions. The hanging wall exposes the Murovdag Series (J₁t₁) with two members: phyllitized silty-clay shales rich in pyrite, and alternating sandstone-shale beds truncated by the Kekhnamedan thrust. These lithological and structural features clarify the geological setting and mineralization processes, with implications for regional metallogeny and exploration. The deposit reflects stable facies and flyschoid rhythms, with increasing sulfide enrichment and metamorphism from Pliensbachian to Toarcian. Stratiform pyrite occurs in the third clay shale bed of the Filizchay Series. Structurally, it lies at the junction of the northern limb of the Karabchay anticline and the deformed Kekhnamedan crush zone, further complicated by the Balakhanchay transverse uplift. Mapping shows folds and thrusts, including second-order anticlines and drag folds reaching up to 700 m in amplitude, with dips of 45–80°. The northern limb is strongly deformed, hosting en echelon folds and thrusts linked to the Filizchay thrust. In the Kekhnamedan zone, the Murovdag Series shows intense compression, steep axial planes, and strong cleavage. Mineralogically, the mixed ore zone beneath the oxidized horizon contains primary and secondary sulfides. Loose ores with fine-grained aggregates occur in fractures. Pyrite dominates, with secondary lead and copper enrichment: chalcocite, covellite, bornite, anglesite, and cerussite. These results improve understanding of ore formation in highly deformed terrigenous complexes and provide insights for metallogenic models and exploration.