A magnetite-rich Cyprus-type VMS deposit in Ortaklar: A unique VMS style in the Tethyan metallogenic belt,Gaziantep, Turkey |
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| Institution: | 1. General Directorate of Mineral Research and Exploration of Turkey, Department of Mineral Research and Exploration, Ankara 06520, Turkey;2. School of Earth and Environmental Sciences, Seoul National University, Seoul, Republic of Korea;3. Centre for Exploration Targeting, University of Western Australia, Australia;4. F?rat University, Department of Geology Engineering, 23119 Elaz??, Turkey;5. Department of Energy & Resources Engineering, Inha University, Incheon, Republic of Korea;6. Department of Geology, University of Maryland, College Park, MD 20742, USA;7. International School for Geoscience Resources, Korea Institute of Geoscience and Mineral Resources, Daejeon, Republic of Korea;1. GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen 91054, Germany;2. Department of Geology, University of Leicester, Leicester LE1 7RH, UK;3. Institut für Geologie und Paläontologie, Universität Münster, Münster 48149, Germany;1. Centro de Astrobiología — Consejo Superior de Investigaciones Científicas, Ctra Ajalvir km. 4.5., 28850 Torrejón de Ardoz, Spain;2. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada;3. Boliden Group, Exploration Department, SE-776 98 Garpenberg, Sweden;4. Luleå University of Technology, SE-971 87 Luleå, Sweden;5. c/Vilar Formoso 66, 37008 Salamanca, Spain;1. Département de Géologie et de Génie Géologique, Université Laval, Quebec, QC G1V0A6, Canada;2. Département de Génie Chimique, Université Laval, Quebec, QC G1V0A6, Canada;3. Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L3G1, Canada;4. Geological Survey of Canada, Ottawa, ON K1A0E8, Canada;5. Agnico Eagle Mines Limited, Val d''Or, Qc, Canada;1. Institute of Mineralogy, Ural Branch, Russian Academy of Sciences, Miass, Chelyabinsk District 456317, Russia;2. Department of Geology, South Urals State University, 8 Oktyabrya str. 16, Miass 456301, Russia;3. ARC Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, Australia;4. Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom;5. Institute of Oceanology, Russian Academy of Sciences, Nakhimosvsky av., 36, Moscow 117997, Russia;6. John de Laeter Centre, Department of Imaging and Applied Physics, Curtin University, GPO Box U 1987, Perth 6845, Western Australia, Australia |
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| Abstract: | The Ortaklar VMS deposit is hosted in the Koçali Complex consisting of basalts and deep sea pelagic sediments, which formed by rifting and continental break-up of the southern Neotethyan in Late Triassic. The basalts are of NMORB-type without notable crustal contamination. From the surface to depth, the Ortaklar deposit consists of a gossan zone, a thick massive ore zone and a poorly developed stockwork zone. Primary mineralisation is characterised by distinctive facies including sulphide breccias (proximal), graded beds (distal), stockworks and chimney fragments. Ore mineral abundances decrease in the order of pyrite, magnetite, chalcopyrite, and sphalerite. Two distinct phases of mineralisation, massive magnetite and massive sulphide, are present in the Ortaklar deposit. Textural evidence (e.g., magnetite replacing sulphides) and the spatial relationships with the host rocks indicate that magnetite and sulphide minerals were generated in different stages. The transition from sulphide to magnetite mineralisation is interpreted to relate to variation in H2S content of ore fluids. The 1st stage massive sulphide ore might have formed by early hydrothermal fluids rich in Fe and H2S. The 2nd stage massive magnetite might have formed by later neutral hydrothermal fluids rich in Fe but poor in H2S, replacing the pre-existing sulphide ore.The alteration patterns, mineral paragenesis, lithological features (massive ore-stockwork ore-gossan) of the Ortaklar deposit together with its trace elements, Cu-Pb-Zn-Au-Ag and REE signatures are all consistent with a Cyprus-type VMS system. The δ34S values in pyrite and chalcopyrite samples range from 2.6 to 5.7‰, indicating that the hydrothermal fluids were associated with sub-seafloor igneous activity, typical of Cyprus-type VMS deposits. However, magnetite formed later than sulphide minerals in the Ortaklar deposit, contrasting with typical Cyprus-type VMS deposits where magnetite generally occurs in lower sections. Consequently, although the Ortaklar deposit generally conforms to Cyprus-type deposits, it is distinguished from them by its late stage and high magnetite concentration. Thus, the Ortaklar deposit is thought to be an exceptional and perhaps unique Cyprus-type VMS deposit. |
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