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Journals / Yerbilimleri / 2026 / Cilt: 47 Sayı: 1

Petrological and Geochemical Characteristics of Isotropic Gabbros in the South of Lake Van (Gevaş–Dokuzağaç) and Their Geodynamic Setting in the Bitlis–Zagros Suture Zone

Van Gölü Güneyindeki (Gevaş–Dokuzağaç) İzotrop Gabroların Petrolojik ve Jeokimyasal Özellikleri ve Bitlis–Zagros Kenet Zonu İçerisindeki Jeodinamik Konumu

Tijen Üner(VAN YÜZÜNCÜ YIL ÜNİVERSİTESİ)0000-0001-6059-9148
Pages
92–109
Publication Date
2026-05-02
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

These results suggest that the isotropic gabbros represent plutonic equivalents of SSZ-related magmatism developed during the closure of the southern Neo-Tethys and record the regional continuity of subduction-controlled oceanic crust formation along the Bitlis–Zagros Suture Zone.

📌 3 Key Takeaways

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Objective & Hypothesis:The isotropic gabbros exposed within the ophiolitic units south of Lake Van (Gevaş) provide important constraints on the Late Cretaceous evolution of the southern branch of the Neo-Tethys Ocean.
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Key Findings & Data:The gabbros display subalkaline affinities, characterized by low–moderate TiO₂ contents, pronounced Nb–Ta negative anomalies and enrichment in large ion lithophile elements (LILE; Ba, Sr) on N-MORB-normalized multi-element diagrams.
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Conclusion & Impact:These results suggest that the isotropic gabbros represent plutonic equivalents of SSZ-related magmatism developed during the closure of the southern Neo-Tethys and record the regional continuity of subduction-controlled oceanic crust formation along the Bitlis–Zagros Suture Zone.
🔬Design:Araştırma Makalesi
📍Scope:Comprehensive Sample
⚙️Variables:Dalma batma zonu · izotrop gabro · Bitlis–Zagros Sütur Zonu

Abstract

The isotropic gabbros exposed within the ophiolitic units south of Lake Van (Gevaş) provide important constraints on the Late Cretaceous evolution of the southern branch of the Neo-Tethys Ocean. In this study, major oxide, trace element and rare earth element (REE) analyses of the gabbroic rocks were carried out and evaluated within a regional geodynamic framework. The gabbros display subalkaline affinities, characterized by low–moderate TiO₂ contents, pronounced Nb–Ta negative anomalies and enrichment in large ion lithophile elements (LILE; Ba, Sr) on N-MORB-normalized multi-element diagrams. Their REE patterns generally show slight LREE enrichment or nearly flat distributions without significant HREE depletion, suggesting partial melting within the spinel-peridotite stability field. These geochemical features indicate derivation from a depleted mantle source that was metasomatized by subduction-related fluids, followed by moderate degrees of partial melting. Systematic trends observed in major and trace element variation diagrams point to fractional crystallization processes involving olivine ± clinopyroxene ± plagioclase during magma evolution. The geochemical characteristics of the Gevaş gabbros are consistent with those reported from the northern belt ophiolites of southeastern Anatolia and the suprasubduction zone (SSZ) ophiolites of the Zagros belt in Iran. These results suggest that the isotropic gabbros represent plutonic equivalents of SSZ-related magmatism developed during the closure of the southern Neo-Tethys and record the regional continuity of subduction-controlled oceanic crust formation along the Bitlis–Zagros Suture Zone.

Özet

Van Gölü’nün güneyinde (Gevaş) yüzeylenen ofiyolitik birimler içerisinde yer alan izotrop gabroların petrolojik ve jeokimyasal özellikleri, Neo-Tetis Okyanusu’nun güney kolunun Geç Kretase’deki kapanım sürecine ilişkin önemli veriler sunmaktadır. Bu çalışma kapsamında gabro örneklerinin ana oksit, iz element ve nadir toprak element (NTE) analizleri gerçekleştirilmiş ve elde edilen veriler bölgesel jeodinamik çerçevede değerlendirilmiştir. Gabrolar subalkalin karakterde olup düşük–orta TiO₂ içerikleri ve N-MORB’a normalize edilmiş çok element diyagramlarında belirgin Nb–Ta negatif anomalileri ile LILE (Ba, Sr) zenginleşmeleri sunmaktadır. NTE desenleri genel olarak hafif LREE zenginleşmesi veya düz paternler göstermekte ve belirgin granat-kontrollü HREE tükenmesi içermemektedir. Bu özellikler, tükenmiş fakat dalma-batma bileşeni ile metasomatize edilmiş bir üst manto kaynağından spinel-peridotit stabilite alanında gerçekleşen orta dereceli kısmi ergimeyi işaret etmektedir. Majör oksit ve iz element diyagramlarında gözlenen sistematik eğilimler, olivin ± klinopiroksen ± plajiyoklaz fraksiyonasyonunun magmatik evrimde önemli rol oynadığını göstermektedir. Jeokimyasal özellikler, Güneydoğu Anadolu’daki kuzey kuşak ofiyolitleri ve İran Zagros kuşağındaki dal batma zonu karakterli ofiyolitlerle paralellik sunmaktadır. Bu veriler, Gevaş izotrop gabrolarının Neo-Tetis’in güney kolunun kapanımı sırasında gelişen dalma batma zonu magmatizmasının plütonik temsilcileri olduğunu ve Bitlis–Zagros Kenet Zonu boyunca dalma-batma kontrollü okyanusal kabuk gelişiminin bölgesel sürekliliğini yansıttığını ortaya koymaktadır.

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Cite This Article

Üner, T. (2026). Petrological and Geochemical Characteristics of Isotropic Gabbros in the South of Lake Van (Gevaş–Dokuzağaç) and Their Geodynamic Setting in the Bitlis–Zagros Suture Zone. Yerbilimleri, Cilt: 47 Sayı: 1, 92–109. https://doi.org/10.17824/yerbilimleri.1897139

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