The Pre-Quaternary Evolution of the Eurasia Basin: The Results of Interpretation of Seismic Profile ARC1407A

Abstract

This paper presents the results of a study of the pre-Quaternary tectonics and stratigraphy of the Eurasia Basin (EB) according to the interpretation of the ARC1407A seismic profile and calculations of the theoretical positions of linear magnetic anomalies. The sedimentary sequences are recognized in seismic profiles and their stratigraphic position is similar to that of sedimentary sequences in the western parts of the Nansen and Amundsen basins. The age indexation of sedimentary sequences corresponds to the ACEX drilling results and the main evolution stages of the EB. No previously recognized reference horizon with the age of ~34 Ma, which is related to the termination of spreading in the western part of North Atlantic and amalgamation of the Greenland and North American plates, is recognized, as is supported by our studies in the western parts of the EB. In the western part of the Nansen Basin we identified a reference horizon with the age of 38 Ma for the first time, which was previously traced in the western part of the Amundsen Basin, whose formation is related to the evolution stage of the Eurekan Orogen. A reference horizon with the age of ~26 Ma, which has been traced in the western part of the Amundsen Basin before, is also distinguished in the western part of the Nansen Basin within ARC1407A. This geological boundary is related to the beginning of unstable spreading in the western segment of the EB between the Yermak Plateau and Morris Jessup Rise (Plateau). The end of a long stratigraphic hiatus between 44.4 and 18.2 Ma in the section of ACEX boreholes is clearly correlated with the formation of a sedimentary sequence of ~19.6‒18.3 Ma, which is the age of the beginning of the formation of a deep-water gateway between the North Atlantic and Eurasian sedimentary basins. This event coincides with the main reconstruction stage of movements of the Eurasia and North America plates, which led to a change in the direction of migration of momentary opening poles from the NNW to SSE. It is suggested that the thick sedimentary sequences in the Nansen Basin and the rift valley of the Gakkel Ridge that are observed in seismic section ARC1407A include Late Pliocene–Quaternary (<2.7 Ma) glaciomarine rocks, which compose a significant volume of sediments in the eastern part of the EB and the Gakkel Ridge.