Angouran is one of the most significant non-sulphide zinc deposits world wide with 17.3 Mt non-sulphide ore containing 28.5 % Zn and 5.5 % Ph plus an additional 4 Mt of high grade Zn-Pb sulphide ore. The deposit is situated within the Tertiary Urumieh-Dokhtar volcanic belt at the active continental margin of the Zagros in northwestern Iran. The non-sulphide zinc ore is hosted by the upper carbonate rock member of a metamorphic core complex of Neoproterozoic age with schists and serpentinised ultramafic rocks in the hangingwall, all folded into an anticlinal structure. The metamorphic basement is strongly faulted and has been uplifted and, subsequent to the alpine orogenesis, thrusted towards the west. Pliocene basaltic-andesitic domes have intruded the anticline that is flanked by a thick cover of andesites and volcanosedimentary rocks of Miocene age. The volcanic activity continued with the sub-recent deposition of travertine at the mine site, indicating geothermal activity within the mineralised area to the present day. The sulphide protore is non-defortned and post-metamorphic and occurs at the contact between the footwall schists and the overlying marble unit. The sulphide ore consists predominantly of sphalerite, subordinate galena with minor amounts of pyrite ( As), arsenopyrite, Pb-sulfosalts, and Cd-sulfide. The oxide ore directly overlies the sulphide ore on an uneven surface and has a thickness of about 200 in. The non-sulphide ore occurs in strongly tectonised and karstified hangingwall carbonate rocks in chaotically reworked and mixed units with schist clasts in a matrix of soft clayey material and non-sulphide ore minerals. The ore consists mainly of massive smithsonite with hemimorphite, hydrozincite, quartz, cerrusite, late mimetite, Pb-oxides, and Fe- and Mn- oxyhydroxides. Textural evidence suggests a post-metamorphic (post-Proterozoic) sulphide ore that probably formed from ore fluids connected with the Tertiary hydrothermal activity. A subsequent, oxidising stage of the hydrothermal activity might have also promoted the formation of the non-sulphide Zn ores by oxidation of the protore.
