Oxygen Isotope Composition of the Silicate Minerals and Chrome Ores in the Guleman Ophiolite in Southeastern Türkiye

• Published in: Doklady earth sciences Vol. 515; no. 2; pp. 722 - 733
• Main Authors: Ertürk, Mehmet Ali, Kara, Hatice, Kalender, Leyla
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.04.2024; Springer Nature B.V
• Subjects: Chemical composition; Chromite; Dunite; Earth and Environmental Science; Earth Sciences; Fractional crystallization; Gabbro; Geochemistry; Isotope composition; Isotopes; Low temperature; Minerals; Ocean floor; Olivine; Ophiolites; Ores; Oxygen; Oxygen isotopes; Rock; Rocks; Sediment samples; Serpentinization; Silicate minerals; Silicates; Stable isotopes; Turkey; silicate minerals; chromite deposit; Guleman ophiolite; oxygen isotopes
• ISSN: 1028-334X; 1531-8354
• DOI: 10.1134/S1028334X23602651

Oxygen crystallising was obtained from olivine, chromite separates from host rock samples, and gabbro from ultramafic cumulates, harzburgite, and dunite samples collected from tectonites of the Guleman ophiolites. The study includes the oxygen isotope compositions from the Guleman ophiolite and the evolutionary scenarios of geochemical and isotopic signatures. The olivine and chromitite δ 18 O olivine/chromite and δ 18 O melt values point out these minerals and melt isotopic compositions similar to mantle values and rich, heavy stable isotopes. The highest δ 18 O chromite isotopic composition values indicate that as the heavy isotope in the melt increases, the concentration in the mineral increases. Excluding a dunite sample, the values of the δ 18 O whole rock of the dunite and pyroxenite samples are similar to mantle values. The gabbro samples have higher δ 18 O whole rock values than the two harzburgites. Hereby, the chromite formations are the later fractional crystallisation products than olivine and dunites due to the lowering of δ 18 O. The lower oxygen isotopic composition in studied samples than the normal mantle values, and these values point out subducted hydrothermally alteration. The higher δ 18 O isotopic compositions could be explained by serpentinization on the ocean floor at low temperatures.