Russian Journal of Earth Sciences
Vol. 6, No. 3, June 2004
Intraplate magmatism of the De Long Islands: A response to the
propagation of the ultraslow-spreading Gakkel Ridge into the
passive continental margin in the Laptev Sea
S. A. Silantyev, O. G. Bogdanovskii,
P. I. Fedorov, S. F. Karpenko,
and Yu. A. Kostitsyn
Abstract
Synthesis of petrological, geochemical, and isotopic
data on volcanic rocks and a related suite of xenoliths in the
De Long Islands in the eastern sector of the Arctic basin is
presented with the aim of reproducing the geochemical nature of
the mantle sources of basaltic magmatism and its geodynamic
environment in the continental shelf of the Laptev Sea,
southeast of its intersection with the southern termination of
the Gakkel Ridge. The main tool of this research was the
comparative analysis of the isotopic characteristics of magmatic
products on islands of this archipelago situated at different
distances from the oceanic margin of the shelf. The
reconstructed magmatic evolution at De Long Islands implies its
close relations with the activity of a plume mantle source that
occurred beneath the continental shelf of the Laptev Sea and was
responsible for pulses of magmatic activity in this area of the
eastern sector of the Arctic over the past 124 m.y. The volcanic
activity at De Long Islands is determined to have become
systematically younger from the offshore boundary of the
continental shelf in the Laptev Sea (Bennett Island) inward the
shelf (Zhokhov Islands) and farther southeastward (Vil'kitskii
Island).