Plate tectonics and palinspastic reconstructions of the Anadyr‐Koryak Region, northeast USSR

The Anadyr‐Koryak region in northeastern USSR consists of a series of exotic terranes, most of which arrived from the Pacific and accreted to the Eurasian margin in Cretaceous and Tertiary times. Eight major terranes can be recognized: (1) The Kanchalan and (2) Pekulnei terranes include possible ancient blocks in their cores. The (3) Penzhina, (4) Ust' Belaya, and (5) Vaega terranes (which are parts of the Talovo‐Mainsky zone) have chaotic structure incorporating Paleozoic and early Mesozoic oceanic, island arc, continental rise, and other lithologie assemblages indicative of a subduction melange environment. The (6) Mainits and (7) Ekonai terranes (two parts of the Khatyrka megaterrane) contain late Paleozoic and Triassic island arc and back‐arc assemblages with faunas of Tethyan provenance. The (8) Olyutorsky terrane is composed mostly of Late Cretaceous island arc assemblages which accreted to the Eurasian margin in the middle Tertiary. Computed trajectories of Kula/Eurasia and Pacific/Eurasia relative motions suggest that some (or most) of these terranes traveled thousands of kilometers from the central Pacific until they eventually collided with, and were attached to, the Eurasian margin.