Petrogenesis and tectonomagmatic evolution of diabase dikes in a Tethyan SSZ setting: constraints from U-Pb geochronology, geochemistry and Sr-Nd-Pb isotopes
LITHOS, vol.540, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 540
- Publication Date: 2026
- Doi Number: 10.1016/j.lithos.2026.108679
- Journal Name: LITHOS
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Geobase, INSPEC, Academic Search Ultimate (EBSCO)
- Istanbul University Affiliated: Yes
Abstract
Mafic dikes within ophiolitic complexes provide critical constraints on the magmatic and tectonic evolution of supra-subduction zone (SSZ) environments. This study investigates the petrological, geochronological (titanite U-Pb), mineral-geochemical, and isotopic (Sr-Nd-Pb) characteristics of isolated diabase dikes intruding ultramafic-mafic units in the Tekirova and G & ouml;dene Zones of the Tauride Ophiolite within the Eastern Mediterranean Ophiolite Belt. The dikes are dominated by primary plagioclase (labradorite) and clinopyroxene (diopside), with opaque minerals as accessory phases. Amphibole (magnesio-hornblende) and titanite occur both as primary magmatic and secondary phases. Titanite U-Pb ages from the Tekirova dikes (89.40 +/- 13.40 and 80.47 +/- 4.77 Ma) constrain Late Cretaceous magmatism. Geochemically, the dikes are enriched in large-ion lithophile elements (LILE) and depleted in high field strength elements (HFSE), displaying pronounced Nb-Ta anomalies consistent with an SSZ arc affinity. Chondrite-normalized rare earth element (REE) patterns show light REE depletion, relatively flat heavy REE distributions, and variable Eu anomalies ((Eu/Eu*)(N) = 0.21-2.62). Sr-Nd-Pb isotopic compositions (Sr-87/Sr-86((i)) = 0.705455-0.707456; epsilon Nd-(t) = +4.5 to +8.3; Pb-206/Pb-204 = 17.89-18.91; Pb-207/Pb-204 = 15.63-16.31; Pb-208/Pb-204 = 37.96-39.88) indicate derivation from a depleted N-MORB-like mantle source variably metasomatized by subduction-derived fluids and sediments, with limited crustal contamination. There are compositional differences between the isolated dikes from the Tekirova and G & ouml;dene Zones. The Tekirova dikes exhibit closer affinities to a depleted mantle source with limited slab input, whereas the G & ouml;dene dikes record stronger metasomatic signatures, including LILE enrichment, pronounced Nb-Ta depletion, and deviation from the mantle array, indicating enhanced involvement of slab-derived components and a more evolved m & eacute;lange-related setting. Partial melting modeling indicates that the Tekirova dikes derived from a depleted spinel lherzolite source through approximately 1-10% partial melting under shallow upper mantle conditions, whereas the G & ouml;dene dikes reflect higher melting degrees (similar to 20%) from the same source, as indicated by >20 LREE systematics. These differences are attributed to mantle source heterogeneity and variable subduction-related contributions. Geothermobarometric estimates suggest shallow crustal crystallization conditions, with Tekirova samples recording slightly higher temperatures and pressures than those from G & ouml;dene. In conclusion, the systematic increase in crystallization ages from west to east along the Tauride Ophiolite Belt indicates westward younging of SSZ magmatism. This pattern is interpreted to reflect trench retreat driven by slab roll-back during Neotethys subduction, whereby progressive slab retreat and segmentation of the subduction system induced along-strike (east-west) migration of arc magmatism, resulting in the observed westward shift of magmatic activity.