Mesozoic tectono-stratigraphic terranes of the Koryak-Chukotka region. Late Jurassic Margin of Laurasia – A record of Faulting Accomodating Plate Rotationстатья
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Дата последнего поиска статьи во внешних источниках: 4 декабря 2016 г.
Аннотация: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 km2) 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 Pacifi c
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.