Mantle Dynamic Processes Investigation beneath the Eastern Arctic Gakkel Ridge based on Submarine Seismic Observations

Mantle flow movement is one of the core aspects of the investigation of mid-ocean ridge dynamics. Previous studies have demonstrated that there are significant differences in the asthenospheric mantle flow movements as well as the patterns of magma supply and migration depending on the plate spreading rate. Compared with the fast-, middle-, and slow-spreading ridges, the mantle dynamics of the ultraslow-spreading mid-ocean ridges are less studied. The mantle dynamics of the Arctic Gakkel Ridge, which has the slowest spreading rates on Earth, have almost no relevant studies because of the constraints imposed by harsh weather and dense ice cover. In this study, we used approximately 300 teleseismic data collected from 42 OBS deployed during the 12th Chinese Arctic Scientific Expedition to establish the anisotropic structure of the upper mantle in the eastern part of the Gakkel Ridge based on the shear wave splitting method. A total of ~100 pairs of splitting parameters and 6 null measurements were obtained, showing complex anisotropy patterns along the Gakkel ridge axis and on both sides near the axis beneath the North American and Eurasian plates. The results may reflect the horizontal complicated mantle flows along and normal to the mid-ocean ridge and a vertical upwelling mantle flow, revealing a three-dimensional model of distinctive upper mantle dynamic processes of the slowest-spreading Gakkel Ridge.