The distribution and tectonic settings of structurally complex domains of generally folded and thrust-faulted, commonly allochthonous, rock assemblages, recognized in the very large (250,000 km 2 ) Koryak Upland and Chukotka regions, support the conclusion that Late Jurassic, Early Cretaceous, and Late Cretaceous shortening and, at times, accretion resulted in incorporation of the terranes into a structural collage at the northeastern Asian continental margin. The main stages of accretion and continental growth took place in the late Mesozoic during the Middle–Late Jurassic, at the Early-Late Cretaceous boundary, and in late Maastrichtian time. The Late Jurassic was the emergence time of the Oloi and Uda-Murgal volcanic belts, extending along the convergent boundaries between Siberia and the proto-Arctic and Pacific Oceans, respectively. Convergence persisted until the end of the Early Cretaceous. In Chukotka, convergence ended with collision of the Chukotka microcontinent with the active margin of Siberia that hosted the Oloi volcanic belt. During this collision, the southern passive margin of Chukotka was overthrust by tectonic nappes composed of tectono-stratigraphic units of the South Anyui terrane. Greenschists with ages of 115–119 Ma are related to accretion of oceanic- and island-arc terranes incorporated into the frontal zone of the Uda-Murgal island-arc system. The subsequent growth of the continental margin resulted from accretion of terranes of the North Koryak fold belt in the late Maastrichtian.