| Abstract:The northern Antarctic Peninsula is located in the meeting region of the Antarctic plate, South American plate, Scotia plate and Phoenix plate, with a complex tectonic pattern. The study of its deep structural features has the potential to provide constraints for understanding issues such as plate interactions and lithospheric evolution in the region. In this paper, we conducted ambient noise tomography study using broadband continuous waveform data recorded by the China Antarctica Great Wall Station (CCZ) and 8 nearby seismic stations during 2019-2021. The one-dimensional S-wave velocity structure passing through different ray paths of each block were obtained, and the velocity differences among the blocks are compared and analyzed. The results indicate that the S-wave velocity structures of each block are clearly characterized. The S-wave velocity of crust in the Antarctic Peninsula increasing uniformly with depth, suggesting a relatively homogeneous composition of materials within the continental crust; in contrast, the S-wave velocity is lower within the crust of the Bransfield Strait, which is in the process of continental-to-oceanic crust transition, and active volcanism and magmatic activities are present in the Strait. The shallow velocity in the crust of southern South America is low, probably due to the presence of thicker sedimentary layers, and the lower velocity on the western side than that on the eastern side may reflect the effects of subduction tectonics of the Chilean Trench. The Antarctic Peninsula and South America were once connected continents, and the northern Antarctic Peninsula has higher crustal S-wave velocity, weaker seismicity, lower heat-flow values, and inactive subduction-zone tectonics relative to the southern part of South America, which suggests that the Antarctic Peninsula has a more stable crustal structure. The contrasting of the seismicity, heat-flow values, and subduction zone tectonics together reveal that the Antarctic Peninsula has a more stable crustal structure. In addition, the S-wave velocity structure of North and South Scotia Ridge are significantly different, which may be related to the different ratios of oceanic and continental crustal fragments; the velocity structure of northwest and southeast Phoenix plate are more consistent, reflecting a more homogeneous structure of the plate as a whole; the Scotia plate and Phoenix plate, which also serves as oceanic plate, have similar S-wave velocity structures, probably because they both arose from the spreading of mid-oceanic ridges. |
