Late Mesozoic-Cenozoic magmatic rocks constitute the main lithological units of the Lut Block and occur in an area of 60000 km 2. Our field observation from the eastern Lut (Khur region) indicate intrusive rocks occur as dike (granitoid and mafic dikes) and shallow plutons (monzonites) in the Lut Block. Volcanic rocks (basaltic andesites, andesites, trachyandesites, dacites, rhyodacites) are also abundant and are intruded into pyroclastic rocks. U-Pb zircon ages indicate that granitic-dioritic dikes and monzonite were emplaced at 44.97 to 40.86 Ma and 41.11 Ma, respectively. Granitoid dikes are high-K calc-alkaline and metaluminous and geochemically belong to I-type granitoids. Monzonites show I-type (and rarely A-type) signatures, with typical enrichments in alkalis, Zr and Ce, high FeO t /(FeO t +MgO) ratio and depletion in Sr and Nb. Geochemical data, including major and trace elements and Sr-Nd isotopes indicate that the volcanic and intrusive rocks are products of a mantle source, presumably modified by sediment melts/fluids. The genesis of these rocks is suggested to be associated with extension above the subducting Sistan Ocean slab beneath the Lut Block. Subduction-related extension was also responsible for the high magmatic rate during Late Cretaceous-Oligocene and was associated large-scale Cu-Au mineralization in the Lut Block.
The Khur metallogenic district is located in a volcanic–plutonic belt in the central Lut Block (central eastern Iran). Mineralization occurs in Middle Eocene andesitic tuff and along four main vein systems trending northwest–southeast (Shurk, Mir‐e‐Khash, Shikasteh Sabz and Ghar‐e‐Kaftar veins). Microscopic studies reveal that the veins contain bornite, chalcocite, pyrite, tennantite together with minor sphalerite and chalcopyrite as hypogene minerals and chalcocite, digenite, covellite, valleriite, malachite, azurite, atacamite, hematite, and goethite as supergene minerals. The ore bodies are accompanied by narrow but intensely developed wall rock alterations of argillization, carbonatization and silicification. Copper content reaches 6.5, 2.4, 4.2 and 5% in Mir‐e‐Khash, Shikasteh Sabz, Ghar‐e‐Kaftar and Shurk, respectively. Microthermometric measurements of quartz‐ and calcite‐hosted fluid inclusions indicate that the mineralization might be derived from a moderately saline hydrothermal fluid at temperatures between 175–316°C. Calculated δ18O values of water in equilibrium with quartz and calcite for Khur veins suggest that the fluid might have had a magmatic source, but the 18O‐depletion was developed through mixing with meteoric water. Copper deposition in Khur veins is believed to have been largely caused by mixing, although wall rock reactions may also have occurred. The Khur veins are classified as volcanic‐subvolcanic hydrothermal‐related vein deposits.
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