Late Triassic-Early Jurassic I-type leucogranites and quartz diorites from the Kaçkar Batholith (Eastern Pontides, NE Turkiye): Implications for the generation of highly evolved felsic magmas at convergent plate boundaries
LITHOS, cilt.540, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 540
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.lithos.2026.108654
- Dergi Adı: LITHOS
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Geobase, INSPEC, Academic Search Ultimate (EBSCO)
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
This study examines Late Triassic-Early Jurassic I-type leucogranites and quartz diorites from the Ka & ccedil;kar Batholith (NE T & uuml;rkiye) to constrain the origin of highly evolved felsic magmas at convergent plate boundaries. Zircon UPb ages indicate crystallization of the Yedig & ouml;l quartz diorites and S & imath;rakonaklar leucogranites at similar to 210-207 Ma, whereas the Alt & imath;parmak leucogranites record a younger felsic event at similar to 192 Ma, documenting episodic magmatism across the Triassic-Jurassic transition. The quartz diorites are calc-alkaline and metaluminous, displaying positive zircon Ce anomalies without Eu depletion, consistent with oxidized, hydrous, mantle-influenced magmas and limited plagioclase fractionation. In contrast, the leucogranites are evolved, weakly peraluminous, and characterized by very low Sr contents and pronounced negative Eu anomalies in both whole-rock and zircon chemistry, reflecting strong feldspar-controlled internal differentiation. The leucogranites include perthite- and antiperthite-bearing varieties, recording contrasting KNa feldspar systematics during magma evolution. All lithologies display mantle-influenced Sr-Nd-Pb and zircon LuHf isotopic signatures consistent with an I-type, juvenile-dominated origin, excluding derivation from metasedimentary sources. Geochemical constraints indicate that the leucogranites did not form through simple fractional crystallization of quartz diorite magmas, but instead originated from feldspar-retentive partial melting of meta-igneous lower crust, driven by sustained thermal input from mantle-influenced magmatism within a vertically coupled arc system and followed by feldspar-dominated differentiation. Enrichment in Nb, Ta, Th, and U reflects magmatic fertility and late-stage accessory mineral concentration rather than economically significant rare-metal mineralization. Overall, the results highlight episodic felsic magma generation above a south-dipping subduction zone during Late Triassic-Early Jurassic.