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- MakaleYalnız künye2025Scopus SJRQ1Identification and source provenance of jadeite-bearing jade axes from Ulucak Höyük, Western Anatolia
Sayit, Kaan; Çevik, Özlem; Aktağ, Alican; Erdoğu, Burçin; Bamyacı, Onur; Vuruşkan, Osman; Sivil, Coşkun
The jades from Ulucak Höyük (İzmir, Turkey) are green-colored in hand specimen, and combined petrographic, XRD, and whole-rock analyses indicate that they mainly comprise jadeitic clinopyroxene, characterizing them as jadeite-bearing jades. Primitive mantle (PM)-normalized multi-element patterns reveal two distinct chemical groups. Both groups display depletion in Th and U; however, Group 1 shows a narrower elemental range and marked positive Pb anomaly. The second group, on the other hand, displays a wide elemental range in most elements and strong negative anomalies in Zr and Hf ([Nd/Zr]PM = 1.6–4.2; [Sm/Hf]PM = 1.8–3.5). Regarding REE systematics, both groups are characterized by weak positive slopes ([La/Yb]Ch = 1.7–5.3). However, whereas Group 1 shows coherent LREE-enriched trends, Group 2 displays flat- to LREE-enriched patterns with a wide range in Eu. When the geochemical features of Ulucak jades are compared with the high-pressure (HP) metamorphic rocks from Turkey and Greece, the similar multi-element patterns of Syros eclogites (Greece) to Group 2 Ulucak jades make Syros a possible source area for the Ulucak artefacts. On the other hand, the geochemical resemblance of the Sifnos jadeite-bearing gneisses to Group 1 Ulucak jades may raise the possibility of this island being another source for the Ulucak jades.
- MakaleAçık Erişim2019Scopus SJRQ2Geochemistry of the post-collisional Miocene mafic Tunceli Volcanics, Eastern Turkey: Implications for the nature of the mantle source and melting systematics
Aktağ, Alican; Önal, Ayten Öztüfekçi; Sayit, Kaan
The East Anatolian Accretionary Complex (EAAC) comprises an ideal example of post-collisional volcanism within the Africa-Eurasia collision zone. The Miocene mafic Tunceli Volcanics, as a part of this post-collisional volcanic system, are located in the western termination of EAAC. The mafic Tunceli Volcanics are characterized by mildly alkaline and tholeiitic basalts, in which olivine, clinopyroxene and plagioclase characterize the main mineralogy. The role of fractional crystallization (FC) and assimilation combined with fractional crystallization (AFC) processes appear to be negligible in the petrogenesis of the primitive mafic Tunceli Volcanics. Relative enrichment in large ion lithophile elements (LILE), Th and La over high field strength elements (HFSE) and heavy rare earth elements (HREE) suggest contribution from a metasomatized mantle source. The wide range of ratios displayed by these elements also calls for some asthenospheric input for the genesis of these volcanics. The metasomatizing agents can be attributed to a past subduction event, probably during the closure of Neotethys. Considering also the geophysical constraints, which limits the lithospheric thickness to about 70–75 km around the region, a melt mixing between lithospheric and asthenospheric melts generated at different depths appear to be an important process in the petrogenesis of these lavas. The combined geochemical and geophysical data, therefore, necessitate a geodynamic model with some remnant lithospheric mantle underlying the Eastern Anatolian region.
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