Petrogenesis and geochemical evolution of mafic dikes in the Kıratlı Region (Yüksekova Complex, SE Türkiye): Evidence for tholeiitic–alkaline transition during Neo-Tethyan evolution

Öz

This study presents new petrographic and geochemical data on mafic dikes intruding the Kıratlı ophiolite (İpekyolu–Van, Eastern Anatolia), a segment of the southeastern branch of the Neo-Tethys. The dikes are mainly represented by microgabbros and diabases, composed of plagioclase and pyroxene, and display alteration features such as chloritization and sericitization. Major and trace element analyses indicate basaltic compositions that can be divided into tholeiitic and alkaline groups. Tholeiitic samples show depleted rare earth element (REE) patterns, Nb depletion, and Th enrichment, consistent with a supra-subduction zone origin, whereas alkaline samples exhibit light rare earth element (LREE)-enriched signatures and within-plate affinities, reflecting low-degree partial melting and/or crustal contamination during extensional phases. Comparisons with other ophiolitic dike suites in Türkiye suggest that the Kıratlı dikes record polyphase magmatism related to both subduction and extension. These findings provide new insights into the tectono-magmatic evolution of the southeastern Anatolian Ophiolite Belt and highlight the complex interplay of mantle heterogeneity, fractional crystallization, and tectonic processes during the closure of the Neo-Tethys.

Anahtar Kelimeler

• Eastern Anatolia
• Mafic dike
• Neo-tethys
• Tholeiitic Basalt
• Alkaline basalt

Kıratlı Bölgesi (Yüksekova Kompleksi, GB Türkiye) mafik dayklarının petrojenezi ve jeokimyasal evrimi: Neo-Tetis evrimi sırasında toleyitik–alkali geçişine kanıtlar

Öz

Bu çalışma, Doğu Anadolu'da (İpekyolu–Van) yer alan Kıratlı ofiyoliti içine sokulan mafik dayklara ait yeni petrografik ve jeokimyasal verileri sunmaktadır. Neo-Tetis’in güneydoğu koluna ait bir kesiti temsil eden bu dayklar, esas olarak plajiyoklas ve piroksen içeren mikrogabro ve diyabazlardan oluşmakta, ayrıca kloritlenme ve serisitlenme gibi alterasyon özellikleri sergilemektedir. Ana ve iz element analizleri, daykların bazaltik bileşimler gösterdiğini ve toleyitik ile alkalen olmak üzere iki gruba ayrıldığını ortaya koymaktadır. Toleyitik örnekler, nadir toprak elementlerinde (REE) tükenmiş desenler, niyobyum (Nb) azalması ve toryum (Th) zenginleşmesi ile karakterize olup, bunlar bir süpra-subdüksiyon zonu (SSZ) kökenine işaret etmektedir. Buna karşılık, alkalen örnekler hafif nadir toprak elementlerince (LREE) zengin desenler ve kıtasal iç plakaya (within-plate) benzer jeokimyasal özellikler sergileyerek, düşük dereceli kısmî erimeyi ve/veya gerilmeli tektonik evreler sırasında kabuksal kontaminasyonu yansıtmaktadır. Türkiye’deki diğer ofiyolitik dayk serileriyle yapılan karşılaştırmalar, Kıratlı dayklarının hem dalma-batma hem de gerilme rejimlerine bağlı çok evreli magmatizmayı kaydettiğini göstermektedir. Bu bulgular, Güneydoğu Anadolu Ofiyolit Kuşağı’nın tektono-magmatik evrimine dair yeni bilgiler sunmakta ve Neo-Tetis Okyanusu’nun kapanışı sırasında manto heterojenliği, fraksiyonel kristallenme ve tektonik süreçlerin karmaşık etkileşimini vurgulamaktadır.

Anahtar Kelimeler

• Eastern Anatolia
• Mafic dike
• Neo-tethys
• Tholeiitic basalt
• Alkaline basalt.

Kaynakça

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