New U–Pb Ages of the Volcano–Plutonic Association of the Oloi Belt (Alazeya–Oloi Folded System, Western Chukotka)

Abstract

The Egdygkych hypabyssal rocks of the Nichan and Vuknei massifs, as well as the host volcanites and tuffs of the Oloi volcanic belt of the Alazeya–Oloi folded system have been dated by U–Pb (SIMS and LA–ICP–MS). The obtained ages of the Egdygkych complex correspond to the Early Cretaceous (Berriasian–Valanginian), while those of their host rocks range from the Late Jurassic (Tithonian) to the beginning of the Early Cretaceous (Berriasian). These new U–Pb geochronological data confidently suggest a unity of the volcanic–plutonic association of the Late Jurassic (Tithonian)–Early Cretaceous (Berriasian–Valanginian) age of the Oloi volcanic belt. The data obtained refine the age range of Au–Mo–Cu ores confined to the contacts between the Egdygkych complex rocks and host volcano-sedimentary deposits or contacts of individual intrusive phases within the complex.