Origin of Th–U and REE enrichment in the Early Miocene Kestanbol Magmatic Complex, Western Anatolia: constraints on source heterogeneity and magmatic evolution
Contributions to Mineralogy and Petrology, cilt.181, sa.10, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 181 Sayı: 10
- Basım Tarihi: 2026
- Doi Numarası: 10.1007/s00410-026-02370-5
- Dergi Adı: Contributions to Mineralogy and Petrology
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Artic & Antarctic Regions, Chemical Abstracts Core, Environment Index, Geobase, Academic Search Ultimate (EBSCO), Natural Science Collection (ProQuest), Earth, Atmospheric, & Aquatic Science Collection (ProQuest), Engineering Source (EBSCO), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Anahtar Kelimeler: High-K magmatism, Kestanbol Magmatic Complex, Northern Aegean, Th-U-REE enrichment, Türkiye, Western Anatolia, Zircon O-Hf isotopes
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
The Early Miocene Kestanbol Magmatic Complex (KMC) in the SW Biga Peninsula, Western Anatolia, is an unusual, high-K post-collisional plutonic-volcanic system comprising coexisting plutonic, hypabyssal, and volcanic lithologies. These lithologies show pronounced enrichments in rare earth elements (REE), Th, and U relative to adjacent Oligo-Miocene plutons and regional high-K suites. Whether this system-wide enrichment primarily reflects progressive magmatic differentiation or inheritance from an enriched mantle source remains debated. Here, we integrate whole-rock geochemistry, mineral chemistry, zircon trace-element thermometry, zircon O-Hf isotopes, and available geochronological constraints to evaluate the origin and evolution of the KMC and the associated Th–U–REE enrichments. Comparatively elevated Th–U–REE abundances occur across compositionally distinct KMC lithologies, including silica-undersaturated high-K and locally ultrapotassic rocks, and therefore cannot be attributed solely to late-stage differentiation of felsic melts. Thermodynamically constrained FC and AFC models reproduce divergent evolutionary paths toward silica-undersaturated and silica-saturated to silica-oversaturated compositions and show that differentiation can further concentrate Th and U. However, neither process reproduces the highest observed concentrations or the overall enrichment pattern. Whole-rock Sr–Nd and zircon O–Hf isotope systematics further argue against progressive crustal assimilation as the principal control on isotopic variability, although localized crustal modification cannot be excluded. Together, these results indicate that the elevated Th–U–REE budget was largely inherited from enriched mantle-derived high-K magmas and subsequently redistributed by fractional crystallization, variable crustal assimilation, and magma interaction within a shallow reservoir. Thermometric, petrographic, and field relations indicate that the Kestanbol pluton formed as an epizonally emplaced, dynamically replenished crystal mush closely linked to coeval subvolcanic and volcanic activity. The KMC therefore provides an important example of how enriched mantle domains and upper-crustal hybridization together generate potassic and actinide-rich post-collisional magmatic systems in the northern Aegean region.