Structural Connection of the Chukchi Borderland and the Chukchi Sea Shelf: 3D Geophysical Modelling of the Earth Crust

Abstract

A 3D model of the crustal structure of the region, which includes the Chukchi Borderland with the adjacent ocean and the Chukotka‒Alaska Shelf, has been compiled and calculated. The peculiarity of the crustal structure is the three-sided isolation of the Chukchi Borderland and presence of a transitional area from the south connecting the Chukchi Borderland with the Chukotka‒Alaska Shelf. The connection between the Chukchi Borderland and the Wrangel Rise of the Chukchi Shelf is traced through the North Chukchi Rise located between the North Chukchi Trough and the Hanna Trough. A clockwise rotation of the Chukchi Borderland began in the Early Cretaceous, because basalts at the bottom of the sedimentary strata sections along the eastern and southern boundaries of the Chukchi Basin have a reversed magnetization, i.e., their outpouring occurred before the beginning of the Cretaceous superchron, earlier than 121 Ma. Near the upper boundary of the Neocomian, there was a large-scale shear displacement of crustal blocks along the eastern boundary of the Chukchi Rise, which had a thrust pattern before that. The 3D model demonstrates that the Chukchi Borderland and the Chukchi Basin are the natural components of the continental margin, as they have a strong geological connection with the continental masses of the Chukchi Shelf.