The paper presents new data on the isotopic age and chemical composition of volcanic rocks from the Tytyl'veem and Mangazeika basins of western Chukotka superposed on Mesozoides of the Verkhoyansk-Chukotka Tectonic Region. The results of SIMS U-Pb zircon dating (121.4 +/- 2.8 and 118.0 +/- 2.0 Ma) corroborate the Aptian age of the Tytyl'veem Formation. This age, in turn, indicates its formation after closure of the South Anyui ocean (Neocomian), but before origination of the Okhotsk-Chukotka Belt (Albian-Campanian). Post-collisional Aptian igneous rocks are widespread in the northern Verkhoyansk-Chukotka Tectonic Region; the legth of the corresponding igneous province is no less than 1400 km. In geochemical characteristics, the post-collisional volcanic rocks occurring in Western Chukotka are similar with the rocks from Andean-type igneous belts.