Abstract—The results of U–Th–Pb-isotope dating of accessory zircons from basalts of the Goitkh volcanic region (GVR) in the West Caucasus are presented. A sample for isotope dating was taken from basalt porphyrites of the Chataltopa volcanic complex at the Tuapse River basin. Isotope geochronology using an ion probe showed that the basalts of this complex in the GVR were discharged during the Jurassic at the Aalenian–Bajocian boundary (169 Ma) within the period of the tectonic transformation of an axial trough in the rifting basin of the Greater Caucasus. Zircons in the basalts are characterized by a low Th/U ratio that is peculiar to rocks of an acidic composition; this indirectly confirms that the evolution of Jurassic rifting magmatism in the Caucasus proceeded via the assimilation of continental crust.

摘要— 介绍了西高加索 Goitkh 火山区 (GVR) 玄武岩副锆石的 U-Th-Pb 同位素测年结果。同位素测年样品取自 Tuapse 河流域的 Chataltopa 火山复合体的玄武岩斑岩。使用离子探针的同位素年代学表明，GVR 中该杂岩的玄武岩在侏罗纪期间在大高加索裂谷盆地中的一个轴向槽的构造转变期间在 Aalenian-Bajocian 边界（169 Ma）排出. 玄武岩中的锆石具有酸性成分岩石特有的低 Th/U 比的特点；这间接证实了高加索侏罗纪裂谷岩浆作用的演化是通过大陆地壳的同化作用进行的。