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Late Cretaceous to Middle Eocene calc-alkaline to alkaline magmatic rocks emplaced within the southeastern Anatolian orogenic belt, the most extensive magmatic belt in Turkey, result from the complex collision between the Afro-Arabian and Eurasian plates and the subduction of the southern and northern Neotethyan oceanic basins beneath the Eurasian continental margin during the Alpine–Himalayan orogeny. In a transect in east-central Turkey extending from Baskil (Elazig) to Divrigi (Sivas) to the north, and from Copler (Erzincan) to Horozkoy (Nigde) to the SW, these magmatic rocks vary in time, spatial distribution, and composition. 40Ar/39Ar ages supplemented by a few U–Pb ages geochronology from major plutons demonstrate a general younging of magmatism in the transect from c. 83 Ma in the south (Baskil) to c. 69 Ma in the north (Divrigi-Keban), followed by a c. 44 Ma scattered magmatic complex now found along a NE trending arcuate belt between Copler and Horoz. In general, trace element and rare earth element (REE) geochemistry in the magmatic rocks suggest two main sources for the melts: (1) a mantle-wedge and subducted oceanic lithosphere producing arc-type magma; and (2) metasomatized lithospheric mantle modified by subduction producing magmatic rocks with more metasomatized mantle and within plate signatures. The combination of geochemical and geochronological data presented herein provides a basis to reconstruct the temporal and spatial transition from subduction-related to post-collision and to late-orogenic magmatism in the eastern Mediterranean region. Subduction-related magmatism is rooted to closure of the Neo-Tethyan Ocean whereas post-collision and late orogenic-within plate-related magmatism is driven by the collision of a northern promontory of the SE Anatolian orogenic belt with northerly derived ophiolitic rocks. The magmatic transition occurs regionally in northerly to northwesterly trending belts in the southeastern Anatolian orogenic belt. The magmatism exhibit a clear shift from deep seated arc-type to late-orogenic from south (Baskil) to more deeply eroded mid-crustal plutons at the north (Divrigi), then to magmatism related to incipient slab-rupture from northeast (Copler, Kabatas, Bizmisen-Calti) to SW (Karamadazi and Horoz). The age progression follows a south-to-north geochemical trend of decreasing crustal input into mantle-derived magmas, and is explained as a consequence of slab roll-back after the collision/obduction of northerly ophiolites followed by slab steepening and incipient rupture leading to transtensional block faulting and subsidence, and thus to the preservation of near-surface magmatic products along a NE trending belt.

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Hydrothermal iron ores at Divriği, east Central Anatolia, are contained in two orebodies, the magnetite-rich A-kafa and the limonitic B-kafa (resources of 133.8 Mt with 56% Fe and 0.5% Cu). The magnetite ores are hosted in serpentinites of the Divriği ophiolite at the contact with plutons of the Murmano complex. Hydrothermal biotite from the Divriği A-kafa yield identical weighted mean plateau ages of 73.75 ± 0.62 and 74.34 ± 0.83 Ma (2σ). This biotite represents a late alteration phase, and its age is a minimum age for the magnetite ore. Similar magnetite ores occur at Hasançelebi and Karakuz, south of Divriği. There, the iron ores are hosted in volcanic or subvolcanic rocks, respectively, and are associated with a voluminous scapolite ± amphibole ± biotite alteration. At Hasançelebi, biotite is intergrown with parts of the magnetite, and both minerals formed coevally. The weighted mean plateau ages of hydrothermal biotite of 73.43 ± 0.41 and 74.92 ± 0.39 Ma (2σ), therefore, represent mineralization ages. Hydrothermal biotite from a vein cutting the scapolitized host rocks south of the Hasançelebi prospect has a weighted mean plateau age of 73.12 ± 0.75 Ma (2σ). This age, together with the two biotite ages from the Hasançelebi ores, constrains the minimum age of the volcanic host rocks, syenitic porphyry dikes therein, and the scapolite alteration affecting both rock types. Pyrite and calcite also represent late hydrothermal stages in all of these magnetite deposits. The sulfur isotope composition of pyrite between 11.5 and 17.4‰ δ34S(VCDT) points towards a non-magmatic sulfur source of probably evaporitic origin. Calcite from the Divriği deposit has δ18O(VSMOV) values between +15.1 and +26.5‰ and δ13C(VPDB) values between −2.5 and +2.0‰, which are compatible with an involvement of modified marine evaporitic fluids during the late hydrothermal stages, assuming calcite formation temperatures of about 300°C. The presence of evaporite-derived brines also during the early stages is corroborated by the pre-magnetite scapolite alteration at Divriği, and Hasançelebi-Karakuz, and with paleogeographic and paleoclimatic reconstructions. The data are compatible with a previously proposed genetic model for the Divriği deposit in which hydrothermal fluids leach and redistribute iron from ophiolitic rocks concomitant with the cooling of the nearby plutons

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