1. The geological setting of volcanogenic sulphide orebodies in Albanian ophiolites.
- Author
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Hoxha L., Eyre J.M., Scott P.W., Hoxha L., Eyre J.M., and Scott P.W.
- Abstract
Cu-Fe sulphides with minor Zn, Au and Ag occur as massive, disseminated and vein mineralisations in volcanosedimentary rocks, volcanics and occasionally associated intrusions of a sheeted dyke complex in ophiolites in Albania. The ophiolites form two sub-parallel units, the Western Ophiolite and Eastern Ophiolite Belts, stretching across the country from north-west to south-east, and have mid-ocean-ridge and island-arc (boninite supra-subduction type) affinities, respectively. The Western Ophiolite Belt comprises a volcano-sedimentary series, pillow basalts, ultramafic rocks, gabbros and plagiogranites. The orebodies with massive chalcopyrite-pyrite ores vary in shape occurring between haematised radiolarian chert and tholeiitic basalt pillow lavas. The Eastern Ophiolite Belt consists of a basalt-andesite-rhyolite series cut by a sheeted dyke complex and underlain by quartz diorite-plagiogranite, gabbro, gabbronorite and harzburgite. Massive sulphide ores underlain by disseminated veins and stockworks are hosted by a Middle-Upper Jurassic lower basalt-andesite succession. Alteration includes chloritisation, epidotisation, silicification, argillisation, zeolitisation and carbonatisation. The Upper Jurassic, upper dacite volcanoclastic, andesite-dacite, boninite succession hosts massive pyrite-chalcopyrite-sphalerite ore underlain by few or no disseminated veins or stockworks. The Eastern Ophiolite Belt offers the greatest potential for locating future orebodies, possibly beneath thrust planes., Cu-Fe sulphides with minor Zn, Au and Ag occur as massive, disseminated and vein mineralisations in volcanosedimentary rocks, volcanics and occasionally associated intrusions of a sheeted dyke complex in ophiolites in Albania. The ophiolites form two sub-parallel units, the Western Ophiolite and Eastern Ophiolite Belts, stretching across the country from north-west to south-east, and have mid-ocean-ridge and island-arc (boninite supra-subduction type) affinities, respectively. The Western Ophiolite Belt comprises a volcano-sedimentary series, pillow basalts, ultramafic rocks, gabbros and plagiogranites. The orebodies with massive chalcopyrite-pyrite ores vary in shape occurring between haematised radiolarian chert and tholeiitic basalt pillow lavas. The Eastern Ophiolite Belt consists of a basalt-andesite-rhyolite series cut by a sheeted dyke complex and underlain by quartz diorite-plagiogranite, gabbro, gabbronorite and harzburgite. Massive sulphide ores underlain by disseminated veins and stockworks are hosted by a Middle-Upper Jurassic lower basalt-andesite succession. Alteration includes chloritisation, epidotisation, silicification, argillisation, zeolitisation and carbonatisation. The Upper Jurassic, upper dacite volcanoclastic, andesite-dacite, boninite succession hosts massive pyrite-chalcopyrite-sphalerite ore underlain by few or no disseminated veins or stockworks. The Eastern Ophiolite Belt offers the greatest potential for locating future orebodies, possibly beneath thrust planes.