Fluid inclusion and Pb-O isotope constraints on the genesis of the Jurassic Karaburun VMS deposit (Central Pontides, Türkiye)
Periodico di Mineralogia, cilt.95, sa.1, ss.25-50, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 95 Sayı: 1
- Basım Tarihi: 2026
- Doi Numarası: 10.13133/2239-1002/19139
- Dergi Adı: Periodico di Mineralogia
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Sayfa Sayıları: ss.25-50
- Anahtar Kelimeler: Central Pontides, fluid inclusion, Karaburun VMS, Pb-O isotope geochemistry, pelitic-mafic type
- Ankara Üniversitesi Adresli: Evet
Özet
The Jurassic Karaburun deposit of the Central Pontides represents one of the largest known volcanogenic massive sulphide (VMS) systems in Turkiye, comprising ∼125 Mt of ore with average grade 1.16 wt% Cu, 0.25 wt% Zn, and 0.05 wt% Co. Mineralization is hosted by low-grade greenschist-facies rocks of the Çangaldaǧ Metamorphic Complex (CMC), where volcaniclastic and detrital successions interlayered with deep-marine sediments are intruded by mafic dikes and sills. Ore occurs mainly as stratiform, sheet-like to tabular bodies, expressed by disseminated, banded, pyritic clastic, semi-massive, and massive sulphide textures. To constrain ore-fluid evolution and metal provenance, we investigate primary fluid inclusions in ore-stage quartz and combined microthermometry with quartz δ18O and massive-sulphide Pb isotopes. Two-phase inclusions yield eutectic temperatures of -26 to -11 °C and lack clathrate formation, indicating a dominant H2O-NaCl system. Homogenization temperatures of 178-301 °C, corrected for ∼160 bar hydrostatic pressure, imply trapping at 223±25 °C; ice-melting temperatures correspond to 1.4-11.1 wt% NaCl equiv. (mean 6.5 wt%). Moderately elevated salinity and the absence of boiling features support seawater-derived fluids modified by subseafloor circulation, with limited magmatic input. Quartz δ18O values (11.79 ‰ to 14.40 ‰ VSMOW) require isotopically evolved fluids, giving δ18O(fluid) of ∼3-6‰ at FI-constrained temperatures. Pb isotope ratios (208Pb/204Pb=37.463-37.751; 207Pb/204Pb=15.424-15.503; 206Pb/204Pb=18.079-18.431) are weakly radiogenic and narrowly variable, consistent with a predominately mantle-derived Pb source. Collectively, these constraints indicate formation in a Jurassic ensimatic arcback- arc basin undergoing rifting, with chiefly seawater hydrothermal fluids modestly overprinted by magmatic volatiles.