Аңдатпа
Abstract Accessory zircon extracted from serpentinized dunite and harzburgite of the Tekturmas Zone of Central Kazakhstan, which is one of the largest ophiolite zones in the western part of the Central Asian Belt, has been studied for the first time. A U–Th–Pb (SIMS) geochronological study of this zircon was carried out and the age of its crystallization was estimated at 467 ± 3 Ma, which corresponds to the boundary between the Dapingian and Darriwilian stages of the Middle Ordovician. The presence of accessory Middle Ordovician zircon in dunite and harzburgite is most likely a reflection of the last stage of ultramafic depletion associated with melting of mafic rocks that form the upper parts of the ophiolite section in the northern part of the Tekturmas Zone.