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

Abstract

The work examined the tectonics and stratigraphy of the Eurasian basin in pre-Quaternary times based on the results of interpretation of the ARC1407A seismic profile and calculations of the theoretical position of linear magnetic anomalies. The sedimentary packages identified on the seismic profile and their stratigraphic adjustments are close to similar studies in the western parts of the Nansen and Amundsen basins. The age assignment of sedimentary strata corresponds to the results of drilling ACEX wells and the main stages of development of the Eurasian basin. The reference horizon of ~34 million years old, previously identified in some scientific works and associated with the cessation of spreading in the western part of the North Atlantic and the entry of the Greenland Plate into the North American Plate, has not been established, which is similar to studies in the western parts of the basins of the Eurasian Basin. For the western part of the Nansen Basin, a reference horizon with an age of ~38 Ma was identified for the first time, previously traced in the western part of the Amundsen Basin, the appearance of which is associated with one of the stages in the development of the Eurekan Orogeny. Also, for the western part of the Nansen Basin, within the ARC1407A section, a reference horizon with an age of ~26 Ma, previously traced in the western part of the Amundsen Basin, is established. The appearance of this boundary is associated with the beginning of unstable spreading in the westernmost segment of the Eurasian basin between the Yermak Plateau and the Morris Jesup Rise. The end of the long stratigraphic hiatus from 44.4 to 18.2 Ma in the ACEX well section clearly correlates with the appearance of sedimentary strata with an age of ~19.6‒18.3 Ma, which confirms the point of view about the beginning of the formation of the deep-sea connection between the North Atlantic and Eurasian basins. This event coincides with a fundamental stage in the restructuring of the movements of the Eurasian and North American plates, expressed in a change in the general direction of migration of the instantaneous opening poles from north-northwest to south-southeast. It is assumed that thick sedimentary deposits in the Nansen Basin and in the rift valley of the Gakkel ridge, observed on seismic section ARC1407A are glaciomarine Late Pliocene-Quaternary in age 2.7 Ma. Apparently these deposits are making up a significant volume of sediment in the eastern part of the Eurasian Basin and the Gakkel Ridge.