Gültekin Topuz

The East Anatolian Plateau is a major collisional feature within the Tethyan realm formed as a late‐stage result of the collision between East Anatolia and the Arabian Platform. The timing of this collision is highly debated, with estimates from the Late Cretaceous to the Miocene. This study presents new biostratigraphic and detrital zircon U–Pb–Hf data from upper Campanian and Danian siliciclastic rocks of the Arabian Foreland Basin, ∼40 km south of the Bitlis Suture. Upper Campanian rocks contain a dominant zircon age cluster (100–83 Ma) with εHf(t) values ranging from −7 to +6, whereas overlying Danian sandstones yield broader age spectra with clusters at 100–65 Ma, 750–500 Ma, and 1,100–800 Ma. The absence of Late Cretaceous magmatism on the Arabian Plate indicates derivation from the magmatic arc north of the Bitlis Suture. The late Campanian–Danian provenance shift likely reflects erosion of the upper arc and exhumation of metamorphic massifs representing middle‐ to lower‐crustal levels of the magmatic arc and the subducted Arabian margin, indicating that the Arabia–Eastern Anatolia collision began in the late Campanian (∼74–71 Ma). Reassessment of published detrital zircon data from the Iranian foreland suggests later collision along the Zagros Suture (Maastrichtian‐early Paleocene in the Kermanshah and Khorramabad areas). Final Eurasia–Arabia suturing occurred along the İzmir–Ankara–Erzincan and Zagros sutures, linked across West Azerbaijan (Iran), providing a coherent explanation for the pronounced Mesozoic–early Cenozoic geological contrasts between Eastern Anatolia and NW Iran.

The so-called Harmancık “purple jade” from the Bursa region of northwestern Türkiye has attracted attention as a gemstone; however, its geological characteristics and provenance have long remained uncertain. This short communication presents new field observations along with mineralogical and petrological data concerning the provenance, metamorphic evolution, and geoarchaeological relevance of this unique rock type. The rock occurs as loose boulders scattered across cultivated fields in the villages of Akpınar, Kocapınar, and Gedikören, where it was previously interpreted either as part of Neogene sedimentary successions or as a high-pressure metamorphic rock affected by contact metamorphism. Our detailed mapping and field observations suggest that the present distribution of the blocks reflects Quaternary reworking, whereas their primary source lies within the Late Cretaceous ophiolitic mélange of the Tavşanlı Zone. An apparently in situ exposure demonstrates a direct association between blueschist and felsic jadeite-bearing metavolcanic rocks. Mineral assemblages dominated by jadeite (40–60 vol. %), K-feldspar, albite, lawsonite, and relic aegirine, together with locally preserved volcanic microtextures and whole-rock geochemical signatures, indicate that the rocks represent blueschist-facies metatrachyte, locally grading into minor metaphonolite rather than true jadeitite jade formed by metasomatic processes. The purple to lavender coloration is largely restricted to fluid pathways. These rocks constitute a rare example of alkaline felsic volcanic protoliths metamorphosed under blueschist-facies conditions, most plausibly as part of an accreted seamount. Moreover, the occurrence of Neolithic polished stone tools produced from this rock type demonstrates its prehistoric exploitation and underscores its geoarchaeological importance.

The Qaradagh Batholith in northwestern Iran, adjacent to the Meghri–Ordubad pluton (MOP) within the South Armenian Block, is dominated by granodiorite, which represents its earliest intrusive phase. Both the Qaradagh Batholith and the MOP formed in a subduction‐to‐post collisional setting linked to the closure of Neo‐Tethys Ocean between middle Eocene and early Miocene. U–Pb zircon dating of the granodiorite was conducted to constrain its emplacement age, yielding a ²⁰⁶ Pb/ ²³⁸ U weighted mean age of 43.81 ± 0.18 Ma and a U–Pb concordia age of 44.04 ± 1.00 Ma, placing intrusion in the middle Eocene, earlier than previously suggested Oligocene ages. In situ zircon Lu–Hf isotope analyses, conducted to determine magma source characteristics, yielded ε _Hf ( t ) values between +8.7 and +11.1, indicating derivation from a depleted, juvenile mantle source with minimal crustal contamination. This is supported by low initial ⁸⁷ Sr/ ⁸⁶ Sr (0.7037–0.7041), positive ε _Nd (i) (+2.69) and low zircon U and Th contents relative to Miocene intrusions in NW Iran, which have higher crustal contribution. Model T _DM ages of zircons (256–354 Ma) indicate a Carboniferous–Permian source material, consistent with late Paleozoic subduction. These results place the Qaradagh granodiorite among the earliest manifestations of Paleogene magmatism in the region.

The paradigm of plate tectonics holds that ocean plates are rigid during drift and only experience tectonic deformation at subduction zones, but new findings from the Pacific challenge this idea. Geological and geophysical evidence from the Ontong Java, Shatsky, Hess, and Manihiki oceanic plateaux indicates that extensional deformation during plate drift is a widespread phenomenon across the Pacific plate. These anomalously thick oceanic plateaux are weaker regions of the ocean lithosphere and more prone to tectonic deformation. Numerical geodynamic models demonstrate that a slab pull force from distant subduction plate boundaries can be effectively transmitted to oceanic plateaux through strong ocean lithosphere and cause substantial extension during plate drift. Our findings reveal that a wide expanse of the Pacific has experienced syn‐drift plate tectonics linked to pull from the western Pacific subduction factory.

The Sakarya Zone of northern Turkey contains a well-preserved Early–Middle Jurassic and Late Cretaceous submarine magmatic arc constructed over pre-Jurassic bedrocks that are considered to be the eastward extension of the Armorican Terrane Assemblage in Europe. In this study, we present U-Pb-Hf isotopic data from the detrital zircons of middle Permian and Lower Jurassic sandstones to reveal episodes of Paleozoic–early Mesozoic magmatic flare-ups. Detrital zircon ages, together with data from the literature, define three major age groups at 400–380 Ma, 326–310 Ma, and 250–230 Ma, which indicates three distinct magmatic flare-ups. In addition, there are minor age clusters at 460–430 Ma and 215–195 Ma. Initial εHf values of the detrital zircons indicate significant juvenile input during the Triassic flare-up, the involvement of significantly reworked crustal material during the late Carboniferous magmatic flare-up, and both juvenile and reworked crustal material during the Middle Devonian magmatic flare-up. Within the pre-Jurassic continental basement rocks of the Sakarya Zone, the late Carboniferous igneous rocks are well documented and most voluminous, and the Middle Devonian rocks are known locally, while the Triassic igneous rocks—apart from those in Triassic accretionary complexes—are hardly known. Because the Sakarya Zone is a Gondwana-derived continental block that was later involved in the Variscan and Alpine orogenies, these magmatic flare-ups cannot be explained by subduction-related processes along a single subduction zone. We propose that the Sakarya Zone rifted from the northern margin of Gondwana during the Late Ordovician–Silurian, the Devonian magmatic flare-up (400–380 Ma) was related to the southward subduction of the Rheic Ocean beneath the Sakarya Zone during its northward drift, the late Carboniferous magmatic flare-up (326–310 Ma) occurred following the collision of the Sakarya Zone with Laurussia, and the Triassic flare-up (250–230 Ma) resulted from northward subduction of the Tethys Ocean beneath the Sakarya Zone. Comparison with data from the literature shows that the Triassic and late Carboniferous magmatic flare-ups are also characteristic features of neighboring Armorican domains, such as the Balkans and the Caucasus; however, the Middle Devonian flare-up appears to be restricted to the Sakarya Zone. Along with the late Carboniferous flare-up, the Late Ordovician–Silurian flare-up, which is locally recorded in the Sakarya Zone, is typical of the Armorican Terrane Assemblage as a whole.

Figure S1: Comparative columnar sections of the Anatolide-Tauride Block and the Sakarya Zone. Figure S2: Field pictures. Figure S3: Thin-section micrographs showing microtextural features of the sandstone samples studied. Figure S4: CL images of dated zircon grains. Figure S5: REE patterns of the dated zircon grains. Figure S6: Variation of U/Th, U/Yb, and Nb/Yb ratios of the detrital zircon grains dated with age. Figure S7: U-Pb detrital zircon age histograms and probability density curves for literature data. Table S1: Coordinates of the dated samples. Tables S2–S3: U-Pb and Hf metadata. Table S4: U-Pb-Th isotopic data and trace-element compositions of zircons. Table S5: Hf isotopic data of zircons.

Figure S1: Comparative columnar sections of the Anatolide-Tauride Block and the Sakarya Zone. Figure S2: Field pictures. Figure S3: Thin-section micrographs showing microtextural features of the sandstone samples studied. Figure S4: CL images of dated zircon grains. Figure S5: REE patterns of the dated zircon grains. Figure S6: Variation of U/Th, U/Yb, and Nb/Yb ratios of the detrital zircon grains dated with age. Figure S7: U-Pb detrital zircon age histograms and probability density curves for literature data. Table S1: Coordinates of the dated samples. Tables S2–S3: U-Pb and Hf metadata. Table S4: U-Pb-Th isotopic data and trace-element compositions of zircons. Table S5: Hf isotopic data of zircons.