The geological structure of the Gakkel Ridge: in the light of new geological and geophysical data

Abstract

In 2011‒2020 the significant amount of seismic lines was carried out in the Eurasian Basin of the Arctic Ocean, which made it possible to study the structure of the junction zones of the Gakkel Ridge with the Nansen and Amundsen basins on a number of profiles. During 2019‒2020 15 sections of the Gakkel Ridge and its rift valley were studied using a sub-bottom profiler and seismo-acoustic profiling. New data on the relief of the basement, as well as the use of databases of bathymetry, gravity and magnetic anomalies updated at VNIIOkeangeologia, made it possible to calculate the magnetization of the rocks of the Gakkel Ridge along a number of profiles crossing the ridge, and to perform the model calculations of the Earth’s crust structure using a complex of geological and geophysical data in the area of the southeastern termination of the ridge. The Gakkel Ridge is a structure, the isolation of which refers to the time interval of Early Oligocene (34 Ma)–Early Miocene (23 Ma), in the process of radical restructuring of the spreading kinematics in the already existing ocean basins in the regions of the North Atlantic and the Arctic. The values of the calculated magnetization of the magnetic layer of the Earth’s crust show that this layer is partly composed of oceanic basalts, but mainly of deep-originated rocks, gabbro and peridotites, brought to the surface during detachment accompanying spreading. The Laptev Sea continuation of the rift valley of the Gakkel Ridge, to the south of the caldera, passes above many kilometers of sediments, at the base of which sedimentary rocks of Cretaceous and Late Jurassic age occur.