Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026/r/munzur/4767
  Geological Formation Environments of Rare Earth Elements: Examples from Around the World and Turkiye

  Çimen, Okay; Dönmez, Cahit

  Rare earth elements (REEs) are critical raw materials used in strategic fields such as defense, energy, electronics, lasers, and sensor technologies, and particularly in the production of permanent magnets including NdFeB and SmCo types. Since the early 2000s, the global supply of rare earth elements has become dominated by China for mining, beneficiation, and separation processes, as non-Chinese producers have lost competitiveness due to high capital requirements and the costs imposed by environmental regulations. This review addresses the geological formation environments, deposit types, and global reserve-resource distributions of REEs within an integrated framework. REE mineralization occurs within primary geological sources such as carbonatites, alkaline magmatic systems, and iron oxide copper-gold (IOCG) deposits, as well as in secondary sources including ion-adsorption clays, placers, and lateritic formations. Primary sources are generally enriched in light REEs and are characterized by high-cost production processes, whereas heavy REEs are predominantly obtained from secondary sources. Globally, REE reserves are estimated to be approximately 90-120 Mt, while potential resources are on the order of similar to 480 Mt, with China occupying a leading position in terms of both reserves and resources. In Europe, Greenland, Sweden, Finland, Norway, Germany, and Turkiye are among the regions with significant REE potential. In Turkiye, the principal REE areas defined at the deposit scale are the Eski & scedil;ehir-K & imath;z & imath;lcaoren (Beylikova) and Malatya-Kuluncak districts. These districts are associated with alkaline magmatism and display enrichment particularly in Nd and Pr (beyond La and Ce), rendering them strategically important for NdFeB permanent magnet production. Recent studies conducted by Eti Maden indicate that the Eski & scedil;ehir-K & imath;z & imath;lcaoren area hosts a large-scale resource of approximately 694 Mt with total REE grades of1.5-1.8%. The Eski & scedil;ehir-K & imath;z & imath;lcaoren area is related to the extensional tectonic regime of Western Anatolia, whereas the Malatya-Kuluncak area is associated with post-collisional alkaline magmatism of Late Cretaceous-Early Paleocene age developed within the Central Anatolian Crystalline Complex. The presence of similar alkaline systems across Turkiye indicates significant potential for REE exploration and critical mineral strategies. This synthesis provides a comprehensive geological reference framework for the development of REE exploration strategies, the diversification of global supply chains, and evaluation of Turkiyes'REE potential.

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• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/1331
  Geochemical signature, detrital zircon U–Pb, and mica Ar–Ar age systematics from the Karadere Basement Unit of the İstanbul-Zonguldak Terrane (NW, Türkiye): evidence for an Avalonian-Cadomian active continental margin

  Çimen, Okay; Gücer, Mehmet Ali; Göncüoğlu, Mehmet Cemal; Akal, Cüneyt; Arslan, Mehmet; Simonetti, Antonio; Karaoğlan, Fatih

  The İstanbul-Zonguldak Terrane is located in northwest Anatolia and includes several outcrops with pre-Cambrian basement units. The Karadere Basement Unit represents the easternmost basement of this terrane and is composed of paragneiss, quartzite, and orthogneiss. The paragneiss and quartzite are cut by orthogneisses and disconformably overlain by Lower Ordovician to Middle Devonian cover units. Its pre-Cambrian to Palaeozoic tectonic evolution remains poorly understood, and therefore, this study reports whole-rock trace element signatures, detrital zircon U–Pb, and muscovite Ar–Ar age data for samples of paragneiss, quartzite, amphibolite, and orthogneiss. The whole-rock geochemical data indicate that the protoliths of the paragneiss and quartzite samples investigated here could have been derived from arc-related felsic magmatic units located in an active continental margin. The protoliths of amphibolites and orthogneiss samples are gabbro and granite, respectively, and their geochemical signatures are akin to those from continental arc igneous suites. The detrital zircon U–Pb data are characterized by predominantly Mesoproterozoic (84%) and lesser amount of Palaeoproterozoic and Neoproterozoic ages and suggest an early Tonian (youngest peak age of 915 ± 18 Ma) maximum depositional age. Moreover, zircon U–Pb dating analyses from an orthogneiss sample yielded an age of 603 ± 2 Ma, indicating the occurrence of mid-Ediacaran arc magmatism. This represents one of the oldest Ediacaran ages obtained from the metamagmatic basement rocks of the İstanbul-Zonguldak Terrane. Ar–Ar dating of muscovite from ortho- and paragneiss samples yielded ages of 533 ± 25 Ma and 530 ± 9 Ma, respectively, which are interpreted as early Cambrian cooling ages. Overall, the combined results reported here reveal that the Karadere Basement Unit is markedly different from NE African basement units but displays similarities to the basement rocks of both Avalonian and Amazonian terranes. It may have been formed and metamorphosed in an Avalonian–Cadomian active continental margin during the mid- to late Neoproterozoic and early Cambrian.

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• MakaleAçık Erişim2026Scopus SJRQ4/r/munzur/1305
  Petrography, geochemistry and formation of the Sarıçimen (Van, eastern Türkiye) Fe-Ni-Co laterite deposit

  Çimen, Okay

  The Sarıçimen Fe-Ni laterite deposit is located in eastern Türkiye (Van province) and represents one of the important Ni and Co-enriched lateritic mineralizations formed in the ophiolitic occurences. This study aims to decipher the petrographic and geochemical signatures of the laterite horizon in order to better figure out the processes controlling Fe-Ni-Co mineralization and the genesis of the deposit. In this study, field and petrographic observations, and whole-rock geochemical data have been used to characterize the mineralogical and geochemical evolution of the lateritic horizon. Petrographic studies indicate that the protolith of the laterite zone is mostly composed of serpentinized ultramafic rocks including relics of Cr-spinel and chromite grains. This lateritic zone is characterized by hematite-and magnetite-rich zones formed above saprolitic levels that may have been derived from the weathering of ultramafic parent rocks. Whole rock geochemical analyses indicate that Fe₂O₃ and SiO₂ are the dominant oxides, and Ni concentrations vary between 0.33 and 1.01 wt.%. Also, Co values are ranging between 330 ppm and 600 ppm in the laterite samples investigated here. More importantly, correlation analyses exhibit a positive relationship between Ni and Fe₂O₃ and this may be attributed to a close association with Fe-oxide minerals during the lateritization. In contrast, a negative correlation between Ni and SiO₂ may indicate the presence of silica depletion during chemical weathering. The geochemical trends investigated here reveal that the laterite zone developed through intense lateritic weathering of ultramafic rocks, which is characterized by the removal of relatively mobile elements such as Si and Ca and the residual enrichment of Fe, Ni, and Co. The presence of Cr-spinel relics once again confirms the ultramafic origin of the parental rocks. Overall, the Sarıçimen deposit represents a Fe-Ni-Co laterite derived from nearby ultramafic sources within the ophiolitic sequence. The occurrence of Fe-Ni-Co laterite deposits at both the southwestern and northeastern segments of the Southern Neotethys Suture Zone suggests that this tectonic belt may represent a promising metallogenic area for lateritic Fe-Ni-Co mineralization in the southern Türkiye.

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• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/764
  Mineralogical and geochemical controls on Co-V-Pt-Ni enrichment in manganese mineralization: evidence from the Dilli deposit, Eastern Türkiye

  Gücer, Mehmet Ali; Çimen, Okay; Aktağ, Alican; Keskin, Serdar

  The growing demand for critical minerals driven by the global energy transition and advanced technologies highlights the importance of unconventional metal reservoirs. This study investigates the Ni-, Co-, V-, and Pt-enriched Dilli manganese deposit (Kemaliye-Erzincan, Eastern Türkiye) to constrain the mineralogical, geochemical, and genetic controls on critical metal enrichment in Mn oxide mineralization. An integrated approach combining field observations, petrography, X-ray diffraction (XRD), whole-rock geochemistry, mineral chemistry, and stable C-O isotope analysis was applied to better understand the potential origin of critical mineral enrichments. The mineralization is dominated by Mn4+-bearing oxides, principally pyrolusite and hollandite, accompanied by minor rhodochrosite. High MnO (39-64 wt%) and very low Al2O3 and Fe2O3 contents indicate chemical precipitation with negligible detrital input. Discrimination diagrams and trace-element systematics consistently support a structurally controlled hydrothermal origin. Chondrite-normalized REE patterns display low total REE and very low Nd contents comparable to typical hydrothermal deposits, whereas neutral to slightly positive Ce anomalies and non-chondritic Y/Ho ratios suggest limited oxidative interaction with surface-derived fluids rather than primary marine hydrogenetic growth. Stable C–O isotope compositions of co-genetic calcite are inconsistent with a purely marine depositional environment and indicate precipitation from low-to moderate-temperature hydrothermal fluids. Mineral chemistry reveals strong phase-specific partitioning: hollandite preferentially incorporates V and Ba, whereas pyrolusite is enriched in Ni. Cobalt occurs in both phases, whereas Pt may also be present in both Mn oxide phases, suggesting that trace-element distribution is influenced by both crystallochemical and physicochemical controls. The enrichment of Ni, Co, and Pt is most plausibly linked to hydrothermal fluid circulation through ultramafic units, which likely acted as the primary metal source prior to precipitation. The Dilli deposit thus represents a structurally controlled hydrothermal Mn system enriched in critical metals, emphasizing the exploration relevance of Mn oxide mineral chemistry in identifying alternative sources of critical metals in Türkiye.

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/2123
  Geochronological and isotopic data from the adakitic Dodurga Pluton (Central Pontides, N Türkiye): new insights for the geodynamic evolution of the northern Neotethys

  Çimen, Okay; Gücer, Mehmet Ali; Simonetti, Antonio; Karaoğlan, Fatih

  The Dodurga Pluton is located within the Central Pontides (northern Türkiye), has a SW–NE elongation, and consists of granodiorite and dacite porphyry. Previous studies have suggested that this pluton is Triassic in age, and its whole-rock geochemical systematics is consistent with that from adakitic magmatic occurrences rather than the classic arc granitoid suite. This study reports for the first time in situ/whole-rock radiogenic isotopic (Sr, Nd, and Pb) and mica/amphibole Ar–Ar age data to evaluate better its petrogenetic/geodynamic evolution and the chemical nature of mantle source(s). Unlike previous data, combined new in situ zircon U–Pb yield Late Cretaceous crystallization ages of 84.2 ± 0.9 Ma and 86.9 ± 0.9 Ma, and the Ar–Ar age data along with apatite fission track measurements suggest magma cooling extending to 82.3 ± 0.4 Ma and 85.4 ± 0.4 Ma, respectively. The apatite fission track (AFT) dating results also reveal that this pluton was buried at a depth of 2.5–3 km following a fast-cooling period during the Late Cretaceous and cooled/exhumed over ~2 km during the Middle–Late Miocene (15–10 Ma) in a slow cooling phase. The overall data reported here suggest that the Dodurga Pluton represents melts derived from an enriched/metasomatized mantle source that interacted with lower crustal mafic rocks in an active continental margin as a result of northward subduction of the northern branch of the Neotethys Ocean.

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• MakaleAçık Erişim2024Scopus SJRQ4/r/munzur/6327
  Erken Eosen yaşlı adakitik andezitler (Gümüşhane, KD Türkiye) içerisindeki mikrogranüler anklavların jeokimyasal karakteristikleri

  Çimen, Okay; Gücer, Mehmet Ali; Güner, Abdulkadir Murat

  Doğu Sakarya Zonu’ndaki (KD Türkiye) erken Senozoyik magmatizması, bölgesel tektonomagmatik gelişime dair önemli veriler sağlamaktadır. Bölgede, adakit veya adakitik intrüzif/ekstrüzif kayaçlar Geç Paleosen’den Pliyo-Kuvaterner döneme kadar yaygın olarak gözlenmektedir. Çalışma alanında, Erken Eosen adakitik andezitler, genellikle 10 km2’den küçük mostralar halinde gözlenmektedir. Adakitik bileşimli bu andezitler bol miktarda mikrogranüler anklav içermekte olup bu çalışmada petrografik/jeokimyasal özellikleri ve ana kayaç ile olan petrolojik ilişkileri irdelenmiştir. Ana kayaca kıyasla nispeten bazik bileşimli anklavlar, küreselden elipsoidala kadar değişen şekillerde ve birkaç cm ile 20 cm arasında değişen boyutlarda gözlenmektedir. Anklavlar mikrolitik yer yer porfirik dokulu olup başlıca plajiyoklas, hornblend, klinopiroksen, ortoklas ve opak minerallerden meydana gelmektedir. Gerek petrografik gerekse petrokimyasal özellikleri anklavların bazaltik andezit türünde olduğunu ve sub-alkalin bir magmadan türemiş olabileceğini göstermektedir. Ana ve iz element değişimleri, gelişimlerinde fraksiyonel kristallenmenin etkili olduğunu ve plajiyoklas, piroksen, hornblend, magnetit ve apatit ayrımlaşmasının büyük ölçüde rol oynadığını göstermiştir. Anklav ve ana kayaçların benzer iz element davranışları felsik ve mafik magmaların karışması esnasındaki etkileşim süreçlerini işaret edebilir. NTE dağılımları ise gelişimlerinde hornblend fraksiyonlaşmasının önemli rol oynadığını, buna karşılık plajiyoklas ayrımlaşmasının etkili olmadığını işaret etmektedir. Petrokimyasal veriler, anklavların ana magmasının, kuzey Neotetis Okyanusu’nun tamamen kapanmasından hemen sonra; genleşmeli tektonik rejimin başlangıç aşamalarında, amfibol-eklojit fasiyesi koşullarında okyanusal bazaltların kısmi erimesi ile üretildiğini göstermektedir.

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• MakaleAçık Erişim2024/r/munzur/4894
  Geochemical and petrological features of Carboniferous granites from the Güneydere (Bayburt) area

  Gücer, Mehmet Ali; Delimehmet, Zeynep; Çimen, Okay

  Middle-Late Carboniferousgranitic rocks are widely observed in larger outcrops in the Eastern Pontide orogenic belt of the Eastern Sakarya Zone. This tectonic belt is an important part of the Anatolian plate in terms of containing igneous rocks with a wide age and composition range. This study presents new petrochemical-petrological data on Carboniferous granites in the G & uuml;neydere and surrounding area of Bayburt (NE Turkey). The granitic rocks, which include an area of approximately 5 km, represent the pre-Jurassic basement in the study area. Besides, they are unconformably overlain by Early- Middle Jurassic volcano-clastics units and Late Jurassic- Early Cretaceous limestones. They mainly consist ofgranite, granite porphyry and aplite, to a lesser extent granodiorite and quartz monzonite. Rocks have high SiO2 contents (60.43-75.51%) and high K calc-alkali to shoshonitic affinities and have been derived from an I-type source. The granitic rocks are metalumine-peralumine in character and are similar to postcollisional volcanic arc granitoids. Whole-rocks major and trace element trends show that plagioclase, hornblende, biotite, apatite, and Fe-Ti oxide mineral fractionations play an important role in the formation of the rocks. It has been revealed that fractional crystallization and assimilation+magma mixing processes play a role in the development of granites. Also, the saturation temperatures calculated from the whole-rock zircon values reflect lower initial magma temperatures. All results obtained indicate that parental magma of studied granitic rocks have evolved from lower/middle crust- derived melts as a result of partial melting and differentiated and emplaced in the continental magma chamber.

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• MakaleYayıncıda açık erişim2024Scopus SJRQ1/r/munzur/1794
  Revisiting the depositional age and provenance characteristics of metasedimentary rocks from the basement units in the Central Pontides (N Turkey): New constraints for tectonic evolution of the southern Black Sea region

  Çimen, Okay; Ali Gücer, Mehmet; Akal, Cüneyt; Cemal Göncüoğlu, Mehmet; Arslan, Mehmet; Simonetti, Antonio; Karaoğlan, Fatih

  The pre-Jurassic tectonic evolution of the Central Pontides in northern Turkey is still poorly understood due to the lack of detailed geochemical and geochronological data from the basement units. Therefore, this study reports for the first time combined whole rock geochemistry, trace element data and U-Pb ages for detrital zircons, and Ar-Ar geochronological data from the metasedimentary rocks of the Devrekani Massif, Geme Complex, and the Serveçay Unit to better understand their provenance, depositional age characteristics, and tectonic evolutions. The detrital zircon U-Pb data of metasedimentary units from the Devrekani Massif, Geme Complex, and the Serveçay Unit yield ca. 191, 185 and 298 Ma maximum depositional ages (youngest age peaks), respectively. The Devrekani Massif is dominated by Permo-Carboniferous-aged detrital zircons (67 %), whereas Neoproterozoic and Devonian-aged detrital zircons are more common in the Geme Complex (47 %) and the Serveçay Unit (53 %). These distinct age distributions clearly indicate that the Devrekani Massif may has been deposited in a dissimilar location compared to the Geme Complex and the Serveçay Unit. Furthermore, in contrast to the Devrekani Massif, the source area of the metasedimentary rocks from the Geme Complex is comparable with that of the Serveçay Unit. Lastly, the obtained detrital zircon U-Pb and mica Ar-Ar ages suggest that the Devrekani Massif and the Geme Complex were deposited and metamorphosed during the Early and Middle Jurassic, respectively. The Serveçay Unit was deposited and metamorphosed in the Permian.

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• MakaleYayıncıda açık erişim2023Scopus SJRQ1/r/munzur/2255
  Geochemical and radiometric data for mafic rocks from the Guleman Ophiolite (SE, Turkey): New insights on the geodynamic evolution of the southern Neo-Tethyan ocean

  Sapancı, Özgür; Tokat, Gürkan; Eraslan, Nuh Kadri; Karakaya, Abdullah Onur; Gücer, Mehmet Ali; Çimen, Okay

  The Guleman Ophiolite is located in the southeast of Turkey and mainly consists of harzburgites and dunites hosting economically viable chromitite bodies, and lesser amounts of cumulate and isotropic gabbro, diabase dykes, pyroxenite and locally plagiogranite. This study reports the combined whole-rock geochemical and radiogenic isotope (Sr and Nd) data for gabbro and diabase dykes, and in-situ zircon U-Pb geochronological data for plagiogranite and gabbro from the Guleman Ophiolite. Two different geochemical groups were determined based on immobile minor and trace elements, and radiogenic isotope characteristics of gabbro and diabase dykes investigated here. The first group is represented by boninites and displays highly depleted elemental patterns compared to NMORB, and spoon-shaped rare earth element profiles. Contrarily, the second group resembles back-arc basin basalts and is characterized by NMORB-like rare earth element patterns associated with negative Nb anomalies. The boninitic samples are characterized by less radiogenic 143Nd/144Nd(i) (0.51229 to 0.51267; ƐNd = −4.8 to +2.7) and more radiogenic 87Sr/86Sr(i) (0.70549 to 0.70758) isotope compositions compared to the back-arc basin basalt-like samples (143Nd/144Nd(i) = 0.51289 to 0.51296; ƐNd = +7.0 to +8.4; 87Sr/86Sr(i) = 0.70496 to 0.70629), indicating derivation from distinct and/or heterogeneous mantle source regions within a supra-subduction zone. The LA–ICP–MS zircon U-Pb analyses yielded concordant late Cretaceous ages for gabbro (82 ± 2.9 Ma) and plagiogranite (79.9 ± 0.8 Ma) samples. The overall geochemical, isotopic and geochronological data presented here suggest that the Guleman Ophiolite consists of forearc and initial back-arc spreading sections of oceanic crust, which may have been formed in an intra-oceanic subduction zone within the Berit Ocean (northern branch of the southern Neo-Tethyan ocean). Moreover, the generation of continental arc magmatism (i.e. Baskil and Esence Granitoids) was well-documented on the active margin of the Malatya-Keban Metamorphics to the north. Therefore the closure of this oceanic basin should have resulted in multiple coeval northward subduction events during the late Cretaceous.

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• MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2861
  Geochemical, isotopic and U-Pb geochronological investigation of the late Cretaceous Karaçayır carbonatite (Sivas, Turkey): Insights into mantle sources within a post-collisional tectonic setting

  Çimen, Okay; Ağrılı, Haşim; Kuebler, Corinne; Simonetti, Antonio; Corcoran, Loretta; Simonetti, Stefanie; Çolak, Turgut; İnal, Sedat; Dönmez, Cahit

  The Karaçayır carbonatite is located within the northeastern edge of the Central Anatolian Crystalline Complex, and represents one of the significant rare earth element (REE) mineralizations in Turkey. The carbonatite intrudes the associated syenite as dikes and veins, and is mainly composed of medium- to coarse-grained calcite, and lesser amounts of apatite, mica, amphibole, pyroxene, and magnetite. This study reports new and combined geochemical, radiogenic (Sr, Pb), stable (O and C), and for the first time B and Nd isotopic ratios and in-situ U-Pb age data from the Karaçayır carbonatite. The carbonate separates from the Karaçayır carbonatite are characterized by high Ba (30 to 484 ppm), Sr (613 to 9106 ppm) and total rare earth element (TREE) concentrations (172 to 2892 ppm), which are consistent with geochemical signatures for mantle-derived carbonate melts. The combined δ18OV-SMOW (+10.7 to +19.0 ‰), δ13CV-PDB (−2.9 to +1.8 ‰) and δ11B (−13.9 to −2.9 ‰) data for a majority of the carbonate separates investigated here in contrast indicate that they are the result of open system behavior involving contamination by the country rock (marble), and/or sub-solidus, low temperature alteration. Based on the combined stable and radiogenic isotopic signatures for the least altered/contaminated samples, the carbonatite magma at Karaçayır most likely represents a low-degree partial melt of an isotopically heterogeneous (metasomatized) mantle source containing EM (enriched mantle)-like components and recycled crustal carbon; the latter finding is consistent with those recorded for young (<300 Ma old) carbonatites worldwide. A weighted mean 206Pb/238U age of 69.3 ± 1.7 Ma is obtained for apatite from the Karaçayır carbonatite, and indicates its emplacement within a post-collisional tectonic setting during the late Cretaceous.

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