Table of Contents for the Journal of GEOsciences. List of articles from the latest print issue.https://www.jgeosci.orgen-US https://www.jgeosci.org/img-system/jgeosci_cover.jpghttps://www.jgeosci.org Aysal Nı, Şişman Tükel F; Vol. 70, issue 4, pages 199 - 209
AI-based algorithms have increasingly found applications across various fields of geology, emerging as robust alternatives to conventional thermobarometric calibration strategies. In this study, the compatibility, distinctions, and reliability of these novel AI-driven approaches were assessed through a comparative analysis with conventional methods. Focusing on three representative case-study samples from the Oligo-Miocene plutons in northwestern Turkey, the pressure-temperature (P-T) conditions governing clinopyroxene, amphibole, and biotite crystallization were evaluated.
The comparative analysis revealed significant methodological divergences. Conventional clinopyroxene barometers yielded widely scattered and often petrologically unrealistic pressure estimates (frequently >10 kbar), whereas AI-based algorithms provided tightly clustered results consistent with shallow-to-mid crustal emplacement (2-4 kbar). For hydrous phases, while conventional methods indicated only shallow crystallization depths (<2 kbar), AI-based models for amphibole and biotite consistently revealed deeper, mid-crustal crystallization conditions (˜5-6 kbar). These findings suggest that the studied plutons underwent polybaric crystallization, a history that is effectively captured by AI algorithms but partially obscured by conventional calibrations. Consequently, while AI-based approaches offer superior resolution for complex magmatic systems, the observed discrepancies highlight the necessity of integrating whole-rock geochemistry with mineral chemistry for robust geological interpretations. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.405 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.405 Omang BO, Lohmeier S, Vishiti A, Suh CE, Lehmann B, Ijunghi AK, Shuster J, Kave G, Azah MV, Ereh OP, Southam G; Vol. 70, issue 4, pages 211 - 228
This study evaluates panned alluvial gold grains recovered from the Uneme-Dangbala drainage systems and the Lom river basin, both located within the Pan-African metasedimentary belts that define the mobile belt zone between the West African Craton and the Congo Craton, to infer their source rocks and the evolution of the gold grains during their transport into their depositional surficial environment. The Lom grains lack inclusions. They possess secondary gold precipitates, and evidence of amalgamation and bacterial growth in crevices. Gold grains from the Igarra schist belt contain Bi-Te bearing mineral inclusions such as hedleyite, sulphotsumoite, and aleskite with variable contents of Pb, S, and Au. Their drop-like shapes and multimineral composition suggest precipitation from a Bi-Te-Pb-Au melt. Compositionally, the inclusions vary from Bi-Te-Pb-S, Pb-S-Bi-Te, Bi-Te-Au-Pb-S, Pb-S-Bi, Pb-S, Bi-Te, Bi-Au to Au-Bi. The characteristic Bi-Pb-Te-S cluster indicates an oxidized calc-alkaline magmatic-hydrothermal origin. Thus, granitoids that intrude the metasedimentary rocks are the potential source of the hypogene gold mineralization. Gold from both schist belts, although derived from granitoids, has a different composition. The detrital gold particles from both areas correspond primarily to an Au-Ag alloy, although grains from the Lom basin reveal traces of Cu. Average gold finenesses of 884 in the Igarra schist belt and 925 in the Lom basin is lower than that of gold from most orogenic deposits. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.406 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.406 Turunç Oğ, Demirbilek M; Vol. 70, issue 4, pages 229 - 252
The studies on mineral resources modelling and reserve estimation require a rigorous methodological framework and a multidisciplinary analytical infrastructure to ensure that quantitative assessment results accurately reflect geological reality and are presented reliably. The uncertainties inherent in reserve estimation, production planning, and economic valuation processes necessitate the characterization of project risks based on scientific facts. In this context, our study aims to evaluate the resource potential of the Şamlı Iron Ore Deposit through three-dimensional geological modelling and geostatistical methods. The studied ore deposit, located in the north of Balıkesir, western Turkey, exhibits skarn/iron oxide copper-gold (IOCG) type mineralization. The study integrated data from 161 diamond core drillholes, totaling 16,283.40 m, using Leapfrog Geo, Snowden Supervisor, and Datamine Studio RM software. Four main mineralization zones were defined, and solid models were constructed and integrated with block modelling. Geostatistical analyses revealed that iron (Fe) grade exhibits moderate spatial continuity with an influence range of 150 meters and a nugget effect accounting for 8 % of the total structural variance. According to the Ordinary Kriging method with optimized parameters, the estimated resource potential of the deposit, at a cut-off grade of 28 % Fe, was determined to be 2,031,657 tons with an average grade of 48 % Fe. The high reconciliation level (92.3 %) between the predicted grades of mined blocks and the actual production data confirms the operational accuracy of the model. These results reveal that the adopted methodology provides a reliable framework for evaluating iron deposits in similar geological settings and can significantly mitigate project risks. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.0041.25 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.0041.25 Kalashnikova SA, Gurzhiy VV; Vol. 70, issue 4, pages 253 - 262
Single crystals of a new uranyl carbonate (NH₄,Na)₄[UO₂(CO₃)₃] (1) have been prepared by evaporation at room temperature from aqueoussolution. The structure was solved by direct methods [orthorhombic, Cmcm, a = 15.712(3), b = 9.039(2), c = 8.915(3) Å, V = 1266.2(6) ų and Z = 4] and refined to R₁ =0.0314 (wR₂ = 0.0704). The crystal structure of the novel compound is based on pseudo-layered complexbuilt by [(UO₂)(CO₃)₃]^4- uranyl tricarbonate clusters (UTC) linked together through Na⁺ and NH₄⁺ ions. Such layered complexes of UTC are typical for a number of uranyl compounds of both natural and synthetic origin, including čejkaite. However, the relative arrangement of layers in 1 is distinct due to the specific interlayer content and can be described as a novel polytype. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.0063.26 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.0063.26