Progress and challenges of ocean bottom seismometer exploration in the ice-covered zone of the Gakkel Ridge, Arctic Ocean

The Gakkel Ridge in the Arctic Ocean, characterized by its ultraslow spreading rate, remoteness from subduction zones and mantle plumes, and lack of transform faults, represents a unique natural laboratory for examining seafloor spreading processes. Yet, seismic investigations in this region have been severely constrained by perennial, dense ice floes. During the 12th and 14th Chinese National Arctic Research Expeditions, active-source seismic surveys were conducted across the 75°E—100°E segment of the Gakkel Ridge. A total of 43 and 19 Ocean Bottom Seismometers (OBSs) were deployed, respectively, employing large-volume airgun arrays as the seismic source. Exceptional OBS recovery rates of 98% and 100% were achieved, producing the highest-quality active-source seismic dataset obtained to date in the densely ice-covered environment. This study highlights the deployment of self-developed equipment and the application of innovative operational methodologies specifically tailored to ice-covered conditions. It further synthesizes critical experience gained in conducting seafloor seismic surveys under challenging Arctic settings and presents unprecedented data collected with maximum source energy. The results offer new constraints on the deep crustal structure of the Gakkel Ridge and provide crucial evidence to advance understanding of lithospheric accretion dynamics in ultraslow-spreading ridge systems.