The petrogenesis and geodynamic setting of the late cretaceouse plutonic and volcanic rocks from Çaykara magmatic complex (Araklı/ Trabzon, NE Turkey)

Abstract

The study area situated in the eastern of Black Sea region, south of Araklı (Trabzon) district and occupied the western part of the Kaçkar Batholith. The aim of this study is to study petrological, geochronological and isotopically properties of volcanic and plutonic rocks. SHRIMP U-Pb age analysis, the emplacement age is 92.5 ±2 Ma (Turonian) for Taşlıyayla volcanic rock, 85.0 ±2.4Ma (Santonian) for Gündoğdu plutonic rocks, 83.1±2 Ma (Campanian) for Boğalı plutonic rocks. Petrographically the Taşlıyayla volcanic rocks consist of basaltic and andesitic rocks, Gündoğdu Pluton and Boğalı Pluton varies from granite to monzogranite. Differences in chemical properties of Taşlıyayla volcanic rocks indicate to the importance of FC as a primary process during the magma generation with magma mixing and indicating to magma products of a shallow mantle source (i.e. MORB-like spinel-lherzolite). The isotopic ratios of 87Sr/86Sr143Nd/144Nd and 206Pb/204Pb of the rocks belonging to the Gündoğdu Pluton are between 0.703552 to 0.711929, 0.512222 to 0.512084 and 17.986 to 18.534, respectively. The isotopic ratios of 87Sr/86Sr143Nd/144Nd and 206Pb/204Pbfor the Boğalı Pluton range from 0.706097 to 0.706657, 0.512279 to 0.512341 and 18.247 to 18.718, respectively. Chemical feauters of Gündoğdu and Boğalı pluton rocks indicate to dominant the FC, and magma mixing with minor amount of crustal contamination during the magma generation. The Taşlıyayla volcanic rocks formed during the first stage of closure of the Neotethyan Ocean. The Gündoğdu and Boğalı Plutons were formed during the last stage closure of the Neotethyan Ocean as result as a result of extensional arc and slab-roll back model.