Tectono-Geodynamic Settings in the Conjugation Zone of the Lomonosov Ridge, Eurasian Basin,and Eurasian Continental Margin

摘要

Interpretational analysis of new seismic data allowed us to reconstruct the geodynamic settings that led to the formation of an ensemble of tectonic structural elements in the conjugation zone of the Eurasian Basin, Lomonosov Ridge, and Eurasian continental margin (Laptev and East Siberian seas). The presence of the Khatanga-Lomonosov fracture zone (KhLFZ), adapted to the conjugation zone of the continental margin, structures of the Eurasian spreading basin, and the Lomonosov Ridge, is substantiated. The representation of the KhLFZ in anomalous geophysical fields and wave pattern in seismic sections is analyzed to reveal the nature of kinematic relationship between the KhLFZ and adjacent tectonic elements. Shear displacements along the KhLFZ ceased in the Early Cenozoic (similar to 46 Ma ago) simultaneously with the transition to the ultraslow spreading phase of the Gakkel Ridge. Our analysis of the geological and geophysical data shows that in the southern segment of the Eurasian Basin, where regular narrow magnetic anomalies are absent, the base of the sedimentary cover is predominantly represented by highly stretched blocks of the continental basement. The formation of the Gakkel Ridge's axial spreading zone in this segment took place in three stages: (i) rifting in the Aptian-Albian, (ii) telescoped development in the Late Cretaceous-Paleocene-Eocene, and (iii) inherited formation of the rift valley during the late interval of the neotectonic stage. The evolution of the Severny Basin, located in the conjugation zone of the Lomonosov Ridge and continental margin, has a formation scenario similar to pull-apart basins; its formation was interrelated with the simultaneously opening of the adjacent southeasternmost segment of the Amundsen Basin (part of the Eurasian Basin).