Состав и геодинамическая обстановка гранитоидного магматизма Алярмаутского поднятия (Западная Чукоткастатья
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Аннотация:Abstract—This paper reports the compositions of granitoids from the Alyarmaut Uplift in the western Chuk
chi Peninsula, which is interpreted as a granite–metamorphic dome. A postcollisional origin was inferred for
the granitoids. Their petrographic composition, petrochemical characteristics, and the compositions of their
biotite allowed us to assign them to highK Itype granites. The traceelement composition of the granitoids
is comparable with that of granite types associating with both collisional and suprasubduction settings, which
may reflect magma source heterogeneity generated by previous collisional processes predating dome and
granite formation. The significant scatter of εNd(T) and 87Sr/86Sr values in the granitoids is also indicative
of the heterogeneous composition of the crustal source or variable degree of magma contamination with
ancient crustal material. In addition to the dominant process of the submersion of the rim of the Chukchi
microcontinent beneath the active margin of the North Asian craton, the tectonic scenario of the formation
of the dome structure of the Alyarmaut Uplift should involve either slab detachment or delamination of the
lithospheric mantle, which causes the invasion of asthenospheric material into the base of the crust and pro
motes heat transfer necessary for the derivation of granitoid magmas.