On August 21, the international top journalNature published a paper entitled “Highly variable magmatic accretion at the ultraslow-spreading Gakkel Ridge” with Academician Li Jiabiao from the SIO as the corresponding author and Zhang Tao as the first author. This achievement has overturned the long-held view in the international ocean academic community for more than half a century that the magma supply at ultra-slow spreading mid-ocean ridges is extremely scarce, and proved the characteristics of its overall highly variable and locally unusually abundant magmatic activity for the first time, greatly enriching and improving the theory of dynamic evolution of global mid-ocean ridges, and making the voice of Chinese scientists in the field of global plate tectonics.

The deep mid-ocean ridge is the longest submarine mountain range on Earth’s surface, and the magma continuously upwells and erupts along the central rift valley, forming new oceanic crusts and nurturing abundant mineral resources. The icy Arctic, where the slowest-spreading mid-ocean ridge in the world develops, has always been a blind spot for deep Earth exploration. Against the last piece of the puzzle in plate dynamics observations, Academician Li Jiabiao first initiated the JASMInE international scientific cooperation program and led a team to carry out China’s 12th Arctic Expedition to the Gakkel Ridge in the Arctic in 2021. They independently developed polar seabed exploration equipment, established the technical process for dense ice areas, battled the ice and cold for 79 days, overcame the unfavorable conditions of over 80% sea ice coverage and an average operating water depth of over 3,500 meters in the operating sea area, deployed 43 sea seismographs under the coldest weather conditions in history, and achieved a recovery rate of 97.7%. A large-scale sub-ice sea seismic detection in the Arctic was carried out for the first time in the world, breaking the international assertion that sea seismograph detection could not be carried out in the high-latitude densely ice-covered areas in the Arctic.

Based on this deep seabed detection and comprehensive survey, Academician Li Jiabiao’s team discovered the surprisingly extremely abundant and highly variable magma supply at the ultra-slow spreading mid-ocean ridge in the Arctic, and established a new dynamic mechanism of active mantle upwelling through systematic analysis and simulation of the ultra-slow spreading mid-ocean ridge. By further comparing the observation data of mid-ocean ridges with different spreading rates worldwide, they proposed a new theory that the global mid-ocean ridge system is controlled by both active and passive mantle upwelling mechanisms. The passive mantle upwelling mode dominates in the fast and slow spreading mid-ocean ridges, while the active mantle upwelling mode dominates in the ultra-slow spreading mid-ocean ridge.

Depending on the spreading rates, global mid-ocean ridges are also divided into three types: fast spreading (>80mm/yr), slow spreading (20-80mm/yr), and ultra-slow spreading (<20mm/yr). The traditional passive mantle upwelling theory well explains the crustal accretion from fast-spreading to slow-spreading mid-ocean ridges. However, there is a significant deviation between theoretical predictions and actual observations at ultra-slow spreading mid-ocean ridges. The new findings challenge the classic theory of traditional oceanic crust accretion, reveal the universality of locally large-scale magmatic activity at ultra-slow spreading mid-ocean ridges and propose a dual-control theory of passive and active mantle upwelling for global mid-ocean ridges. This achievement also theoretically re-examines the material basis and resource prospects for the formation of hydrothermal sulfides, and will bring a new pattern for global seabed resource research, exploration and development.