Evidence for the tectonic segmentation of the Antarctic Peninsula from integrated ERS-1 SAR mosaic and aeromagnetic anomaly data

Abstract

The Antarctic Peninsula (AP) is a Mesozoic-Cenozoic Andean-type magmatic arc resulting from subduction of Pacific Ocean lithosphere beneath its western margin. During the past 60 million years discrete segments of the Pacific-Phoenix spreading ridge have successively collided with the western margin of the AP diachronously from south to north in a series of ridge-crest collision episodes. Previous work suggested that the AP (upper plate) was tectonically segmented due to subduction of discrete ridge-crest segments, with segments bounded by the projection of oceanic fracture zones (OFZ). An ERS-1 SAR mosaic was created over the Graham Land-Palmer Land Transition Zone (TZ) and combined with aeromagnetic anomaly and mapped geologic data to study how the process of OFZ subduction modified AP structure. Good correlation of SAR lineament trends and mapped fault trends on Alexander Island provide evidence that some of the SAR lineaments are structurally controlled. Correlation between the SAR and aeromagnetic lineaments suggests both mark crustal structures in the TZ. A model invoking distributed left-lateral fault motion can produce that tight dextral curvature across the TZ and explain the lineament patterns. Correlation between lineament trends and OFZ traces suggests that faulting reflects the response of the AP crust to OFZ subduction.