Model of Formation of the Sedimentary System of the Eurasian Basin, the Arctic Ocean, as a Basis for Reconstructing Its Tectonic Evolution

摘要

For the first time tectonic reconstructions was carried out along the entire seismic dataset, including both Russian and international seismic lines. Based on the analysis of the sedimentary cover of the Eurasian Basin (Arctic Ocean), four stages of evolution of the sedimentation system were identified. During the first, Cretaceous-Paleocene stage, vast axisymmetric epicontinental Amundsen and Nansen paleo basins were formed on the shoulders of the continental rift. Similar rifting environments of the second half of the Cretaceous were recorded along the entire periphery of the Arctic Ocean from Greenland and Svalbard to the Chukchi Borderland. The second (Eocene) stage was characterized by gradual expansion of the sedimentary basin up to its present-day size, caused by accretion of oceanic crust in the Gakkel Ridge and seafloor spreading. The Eurican orogeny, which formed dextral De-Geer transform zone, was suggested as a main tectonic driver of the spreading stage. The third (Oligocene-Miocene) stage corresponds to the accumulation of undisturbed veneer of hemipelagic sediments of 300-600 meter thick, which covered the entire Eurasian Basin. Accumulation of undisturbed sediment sequence throughout the Eurasian Basin indicates the cessation of seafloor spreading in the Gakkel Ridge and the establishment of a tectonic dormancy regime untill the neotectonic stage onset. The similar tectonic regime is recorded along the entire periphery of the Arctic Basin. The resumption of the seafloor spreading in the Gakkel Ridge occurred during the fourth (Pliocene-Quaternary) stage. We suggest that the re-spreading process in the Eurasian basin has tectonically been triggered by the activation of the similar process in the Norwegian-Greenland Basin. Propagation of the tectonic stresses along the Gakkel Ridge toward the Siberian segment of the Eurasian Basin explains both the distinct morphological segmentation of the Gakkel Ridge into the Siberian and Atlantic segments, and the anomalously high tectonic, volcanic and hydrothermal activity of the Gakkel Ridge.