Moho Depth along the Antarctic Peninsula and Crustal Structure across the Landward Projection of the Hero Fracture Zone

Abstract

Results of deep seismic soundings collected during four Polish Geodynamical Expeditions to West Antarctica between 1979 and 1991 were synthesised to produce a map of Moho depth beneath the NW coast of the Antarctic Peninsula. In this paper, we present a new interpretation of the deep landward projection of the Hero Fracture Zone based on two seismic transects. On each transect we found high velocity bodies with Vp>7.2 km s−1, similar to ones we detected previously in Bransfield Strait. However, these bodies are not continuous; they are separated by a zone of lower velocities located SW of Deception Island. In Bransfield Strait an asymmetric “mushroom”-shaped high velocity body was found at a depth interval from 13–18 km down to the Moho boundary at a depth of ca. 30 km. As a summary of results, we present a map of Moho depth along the coast of the Antarctic Peninsula, prepared using previous seismic 2D models. The map shows variations in crustal thickness from 38–42 km along the Antarctic Peninsula shelf in the southern part of the study area to 12–18 km beneath the South Shetland Trench.