Cenozoic stress evolution of the Drake Passage region (Antarctica) from morphometric and alignment analysis of volcanic seamounts

This is the authors' abstract. We don't add key points for this paper.

The Drake Passage is an oceanic corridor situated between South America and the Antarctic Peninsula connecting the Pacific and Atlantic oceans. Its geodynamic evolution commenced in the Eocene as part of the full development of the Scotia Arc. A total of 190 igneous volcanic edifices and 32 volcanic alignments have been identified on the oceanic seafloor within this region. Previous studies suggest that the elongation of volcanic edificies and volcanic alignments record the prevailing stress field, exhibiting elongation parallel to the maximum horizontal stress direction. Consequently, a regional-scale statistical analysis of the morphology and geographical and temporal distribution of these volcanic edifices offers valuable insights into the stress regime that has influenced the Drake Passage during the Cenozoic. Morphological analysis of elongated volcanic structures reveals three principal orientations of maximum horizontal stress: N000E, N046E, and N125E. The volcanic alignments show two main trends, N130E and N156E, with three secondary orientations: N042E, N070E and N101E. Recent stress field assessments based on earthquake focal mechanisms indicate a dominant orientation of N050E. The NW-SE and N-S oriented maximum horizontal stress fields are attributed to a combination of geodynamic processes, including the oceanic subduction of the former Phoenix Plate beneath the Pacific margin of the Antarctic Plate, and the right-lateral strike-slip motion between the Scotia and Antarctic plates along the South Scotia Ridge until the Tortonian to Zanclean. In contrast, the NE-SW compressional stress is associated with left-lateral strike-slip movement along the South Scotia Ridge and the South Shetland Trench, active from the Zanclean to the present-day.