Geodynamic Significance of the Early Triassic Karaburun Granitoid (Western Turkey) for the Opening History of Neo-Tethys

Authors: CÜNEYT AKAL, OSMAN ERSİN KORALAY, OSMAN CANDAN, OBERHAENSLI ROLAND, FUKUN CHEN

Abstract: The Karaburun Peninsula, which is considered part of the Anatolide-Tauride Block of Turkey, contains clastic and carbonate sequences deposited on the northern margin of Gondwana. The Palaeozoic clastic sequence, which is intruded by the Early Triassic granitoid and tectonically overlies a Mesozoic mélange sequence, can be divided into three subunits: a lower clastic subunit consisting of a sandstone-shale alternation, an upper clastic subunit consisting of black chert-bearing shales, sandstone and conglomerate, and a Permo-Carboniferous carbonate subunit. The lower Triassic Karaburun I-type granitoid has a high initial ^8^7Sr/^8^6Sr ratio (0.709021-0.709168), and low ^1^4^3Nd/^1^4^4Nd ratio (0.512004-0.512023) and \epsilonNd (-5.34 to -5.70) isotopic values. Geochronological data indicate a crystallization (intrusion) age of 247.1±2.0 Ma (Scythian). Geochemically, the acidic magmatism reflects a subduction-related continental-arc basin tectonic setting, which can be linked to the opening of the northern branch of Neo-Tethys as a continental back-arc rifting basin on the northern margin of Gondwana. This can be related to the closure through southward subduction of the Palaeotethys Ocean beneath Gondwana.

Keywords: Karaburun, Neo-Tethys, Palaeo-Tethys, diorite, Triassic, magmatism

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