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- Yüksek Lisans TeziAçık Erişim2026Torul (Gümüşhane) ve civarında yer alan adakit benzeri porfirlerin petrografik, jeokimyasal ve petrolojik özelliklerinin incelenmesi
Hacer Akçay
Bu tez çalışmasında, Doğu Pontidlerin güney zonunda Mescitli yöresinde yer alan Orta Eosen yaşlı adakitik kayaçların petrografisi ve tüm-kayaç ana ve iz element jeokimyası ve petrolojisi incelenmiş, kayaçları oluşturan magmanın kökeni ve gelişimi belirlenmeye çalışılmıştır. İncelenen adakitik kayaçlar porfirik dokulu olup, genelde andezit, daha az oranda da traki-andezit ve dasit bileşimindedir. Başlıca mineraller plajiyoklas, kuvars, alkali-feldispat, amfibol, biyotit ve Fe-Ti oksit’den oluşmaktadır. İncelenen kayaçlar, orta ila yüksek-K’lu (%1.1-3.6), yüksek LaN/YbN (8.3–11.98) ve Sr/Y (34-63) oranları gösteren adakitik jeokimyaya sahiptir. Kayaçlar LREE’ce zenginleşmiş, HREE bakımından ise yataya yakın bir desen (LaN/LuN = 7.8-11.8) sunarlar ve dikkate değer bir Eu anomalisi (EuN/Eu* =0.91-0.98) göstermezler. Elde edilen tüm jeokimyasal veriler bir arada değerlendirildiğinde; adakitik karakterli bu kayaçların, delaminasyon mekanizması sonucunda mafik alt kabuk ergiyiklerinden türemiş olabilecekleri ve Orta Eosen dönemindeki çarpışma sonrası (post-collisional) tektonik rejimde litosferik manto bileşenleriyle olan muhtemel etkileşimler sonucunda geliştikleri söylenebilir.
- MakaleYalnız künye2026Scopus SJRQ1Mineralogical 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.
- MakaleAçık Erişim2023Scopus SJRQ1Geochemical 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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