Pliocene to Quaternary magmatism in the Karacadağ Volcanic Complex in southeast Turkey occurred in the foreland region of the Arabia -Eurasia collision and can be divided into two phases. The earlier Karacadağ phase formed a north-south trending volcanic ridge that erupted three groups of lavas. The same range of mantle sources contributed to the younger Ovabağ phase lavas which were erupted from monogenetic cones to the east of the Karacadağ fissure. Like several other intraplate localities across the northern Arabian Plate this magmatism represents mixtures of melt from shallow, isotopically enriched mantle and from deeper, more depleted mantle. The deep source is similar to the depleted mantle invoked for other northern Arabian intraplate volcanic fields but at Karacadağ this source contained phlogopite. This source could be located in the shallow convecting mantle or may represent a metasomatic layer in the base of the lithosphere. There is no evidence for a contribution from the Afar mantle plume, as has been proposed elsewhere in northern Arabia. Melting during the Karacadağ and Ovabağ phases could have resulted from a combination of upwelling beneath weak or thinned lithosphere and restricted local extension of that weakened lithosphere as it collided with Eurasia. Tension associated with the collision focussed magma of the Karacadağ phase into the elongate shield volcano of Mt. Karacadağ. The northern end of the fissure accommodated more extensive differentiation of magma, with isolated cases of crustal contamination, consistent with greater stress in the lithosphere closest to the collision. Most magma batches of the Karacadağ and Ovabağ phases differentiated by fractional crystallisation at ~ 5 MPa, near the boundary between the upper and lower crust. Magma batches dominated by melt from garnet lherzolite show evidence for restricted amounts of differentiation at ~ 22.5 MPa, which is close to the base of the lithospheric mantle.
Siverek plateau basalts represent the Neogene activity of the Karacadağ Volcanic Complex in southeast Turkey and can be divided into two groups based on incompatible element concentrations. Group 1 is largely basaltic, containing some alkali basalts, while Group 2 consists of alkali basalts, trachybasalts and tephrites. The lavas display a range in major element concentrations that are consistent with restricted amounts of differentiation in the crust. Melts from both groups have experienced variable, small amounts of interaction with crustal rocks, which is responsible for most of the isotopic heterogeneity and caused significant Baenrichment. Neither fractional crystallisation nor crustal contamination can account for the differences in trace element enrichment observed between the two groups. Group 1 are derived mainly from the spinel lherzolite field by >1% partial melting. Group 2 lavas were derived from very similar mantle but by smaller degrees of melting and contain a larger relative contribution from garnet-lherzolite. The Siverek plateau lavas are indistinguishable from contemporaneous magmatism in the Karasu Valley of southern Turkey and in northernmost Syria. Together, these plateau basalt fields represent mantle upwelling and melting beneath the thinned and/or weakened Arabian Plate as is migrated northwards during the Neogene.
The Miocene Karamagara volcanics (KMV) crop out in the Saraykent region (Yozgat) of Central Anatolia. The KMV include four principal magmatic components based on their petrography and compositional features: basaltic andesites (KMB); enclaves (KME); andesites (KMA); and dacites (KMD). Rounded and ellipsoidal enclaves occur in the andesites, ranging in diameter from a few millimetres to ten centimetres. A non-cognate origin for the enclaves is suggested due to their mineralogical dissimilarity to the enclosing andesites. The enclaves range in composition from basaltic andesite to andesite. Major and trace element data and primitive mantle-normalized rare-earth element (REE) patterns of the KMV exhibit the effects of fractional crystallization on the evolution of the KME which are the product of mantle-derived magma.The KMA contain a wide variety of phenocrysts, including plagioclase, clinopyroxene, orthopyroxene, hornblende and opaque minerals. Comparison of textures indicates that many of the hornblende phenocrysts within the KMA were derived from basaltic andesites (KMB) and are not primary crystallization products of the KMA. Evidence of disequilibrium in the hybrid andesite includes the presence of reacted hornblendes, clinopyroxene mantled by orthopyroxene and vice versa, and sievetexture and inclusion zones within plagioclase.The KMV exhibit a complex history, including fractional crystallization, magma mixing and mingling processes between mantle and crust-derived melts. Textural and geochemical characteristics of the enclaves and their hosts require that mantlederived basic magma intruded the deep continental crust followed by fractional crystallization and generation of silicic melts from the continental material. Hybridization between basic and silicic melts subsequently occurred in a shallow magma chamber. Modelling of major element geochemistry suggests that the hybrid andesite represents a 62:38 mix of dacite and basaltic andesite. The implication of this process is that calc-alkaline intermediate volcanic rocks in the Saraykent region represent hybrids resulting from mixing between basic magma derived from the mantle and silicic magma derived from the continental crust.
The eastern Pontide tectonic belt (EPTB) contains greater than 350 identified Kuroko type volcanogenic massive sulfide deposits/mineralization/occurrences (VMSD). The deposits are associated with Late Cretaceous felsic volcanics consisting mainly of dacitic and rhyolitic lavas and pyroclastics that outcrop within a narrow zone running parallel to the eastern Black Sea coast and represent the axial zone of a paleo-magmatic arc. The Cerattepe deposit is the second-largest and is a hybrid VMS system with some epithermal features. To date, no geochemical research constrains the origin and timing of mineralization in the Cerattepe VMS deposit. Here, we provide Cu, O, H and S, isotope analysis of ores and alteration minerals to understand the hydrothermal history of the deposit and date the massive ore with Re-Os geochronology. Secondary weathering mobilized and redistributed metals in the deposit. The copper isotope signatures of shallow ores in the gossan follow patterns resulting from oxidative weathering of copper minerals with gossan Fe oxides of d65Cu = −2.59‰, enrichment zone copper sulfide of d65Cu = +2.23 and +1.73‰, and primary ores of d65Cu = +0.71 and +0.41‰. At the boundary of the enrichment zone, further cycling and migration of enrichment zone copper are evidenced by two samples having larger ranges of the d65Cu = +3.59‰, and −2.93‰. Evidence for a magmatic source for fluids and S are evidenced by the O and H isotope values from quartz veins (δ18O = +7.93‰ to +10.82‰, and δD = −78‰ and −68‰) and sulfides that possess δ34S ratios of –5 and 0‰ from drill core samples. 187Os/188Os–187Re/188Os ratios from drill core sulfide samples of Cerattepe VMS deposit yields a 62±3 Ma isochron age and a highly radiogenic Os initial ratio. This age is compatible with silicate alteration ages from a proximal deposit and clearly shows mineralization occurs at a much younger time than previously proposed for VMS mineralization in the eastern Pontides. The new Re-Os age and source of Os imply that mineralization in the area occurs at a distinctly younger interval in the back-arc basin and metals could be sourced from the surrounding host rocks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.