Geological framework and metallogenic evolution of the Demirli Cu-Mo porphyry system, Lesser Caucasus, Azerbaijan

Namad Pashayev¹, Saida Ibrahimova¹, Murad Abdulla-zada¹

¹Azerbaijan State Oil and Industry University, Baku, Azerbaijan

Min. miner. depos. 2026, 20(3): 121-133

https://doi.org/10.33271/mining20.03.121

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ABSTRACT

Purpose. The Demirli Cu-Mo porphyry system, hosted within Jurassic volcanic-volcaniclastic successions and spatially associated with the Janyatag granitoid pluton (Lesser Caucasus, Azerbaijan), represents a key target for reassessing its residual mineral potential using legacy exploration data and results from renewed exploration initiated in 2024.

Methods. We integrated legacy geological mapping and exploration datasets (1965-1989 and subsequent campaigns) with digitized drilling and sampling archives, 1:1000-scale lithologic-structural mapping covering 1.97 km², systematic sampling of alteration zones and mine-related materials, reverse-circulation drilling conducted in 2024, and 3D geological modeling using Leapfrog Geo and Micromine. Historical geophysical and geochemical datasets, including magnetic surveys, electrical methods such as induced polarization, and lithochemical data, were used to constrain the subsurface geometry of the mineralized system.

Findings. Mineralization is concentrated within the apical and marginal domains of a multiphase hypabyssal intrusive complex. It is localized along NW-SE- to near-N-S-trending fault corridors linked to the Gylyataq deep fault system. Hydrothermal alteration comprises extensive silicification (secondary quartzites) and quartz-sericite, quartz-kaolinite, and quartz-chlorite assemblages, accompanied by stockwork veinlets and disseminated sulfides. Surface and mine-related samples commonly yield Cu concentrations of approximately 0.1-0.7%, with locally elevated Mo values. Legacy datasets indicate a vertically extensive mineralized interval of approximately 200-300 m and a broad anomaly footprint consistent with porphyry-style veinlet and disseminated mineralization.

Originality. The study provides an integrated reinterpretation linking intrusive evolution, structural reactivation, alteration architecture, and 3D geological modeling, thereby refining the exploration model for the Demirli Cu-Mo porphyry system.

Practical implications. The results support step-out drilling along the principal fault corridors and within apical intrusive and alteration domains, and identify alteration patterns that can serve as exploration vectors in resource-definition programs.

Keywords: porphyry Cu-Mo; Lesser Caucasus; Lok-Karabakh zone; hypabyssal pluton; induced polarization; hydro-thermal alteration; stockwork; 3D geological modeling

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