Abstract

The article considers the history of seafloor spreading of the Eurasian Basin. The sharp decline in the spreading rate in the Eocene about 46 Ma was revealed, which is recorded in the distribution of linear magnetic anomalies. This jump in velocity is explained by a geodynamic model, but not by the northward movement of Greenland. The geodynamic processes of the Pacific subduction zone generate the upper mantle convection cell with return flow that drags the continental lithosphere of the Arctic toward this zone. The geodynamic mechanism is confirmed by seismic tomographic mantle sections of the northeastern margin of Asia and by a numerical model of upper mantle convection in the active continental margin. The plate tectonics and kinematics of the Eurasian Basin are namely influenced by the activity of the upper mantle convection return cell, which is controlled by the flow volume and ultimately by the velocity and directions of the subduction vectors of lithospheric material of the Kula and Pacific plates in the subduction zone. In the Middle Cretaceous–Middle Eocene, the return cell was active for about 73 Ma, since the Kula and Pacific plates are moving north and subducting orthogonally under the Central Arctic. After geodynamic reorganization in the Middle Eocene about 47.5 Ma, the oceanic plates in the Pacific began to move northwest. As a result, supply of Pacific Ocean lithospheric material to the Arctic convective return cell virtually ceased. Shortly after the reorganization, seafloor, spreading of the Eurasian Basin decelerated about 46 Ma to an ultraslow regime. The main tectonic and geodynamic consequences of applying the proposed geodynamic model for the Arctic in the Late Cretaceous–Cenozoic are considered.

中文翻译：

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上地幔对流细胞及相关太平洋板块俯冲对晚白垩世-新生代北极构造的影响

摘要

本文考虑了欧亚盆地海底扩散的历史。揭示了始新世约46 Ma的扩展速率急剧下降，这记录在线性磁异常的分布中。速度的跳跃是由地球动力学模型解释的，而不是由格陵兰的北移解释的。太平洋俯冲带的地球动力学过程产生了上地幔对流单元，并带有回流，将北极大陆岩石圈拖向该带。地球动力学机制由亚洲东北边缘的层析层析地幔剖面和活动大陆边缘上地幔对流的数值模型确定。即，欧亚盆地的板块构造和运动学受上地幔对流返回单元活动的影响，它受流量控制，最终受俯冲带库拉和太平洋板块岩石圈物质俯冲矢量的速度和方向控制。在白垩纪-始新世中期，由于库拉和太平洋板块向北移动并在中央北极以下垂直俯冲，因此返回单元活跃了约73 Ma。在中始新世约47.5 Ma的地球动力学重组之后，太平洋的洋洋板块开始向西北移动。结果，实际上停止了向北极对流返回池供应太平洋岩石圈物质。重组后不久，欧亚盆地的海底扩张速度降低了约46 Ma，成为超慢状态。