| Summary: | 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. This work interpreted an apparent left-lateral offset of the Pacific Margin Anomaly (PMA) visible in aeromagnetic anomaly data as evidence for a component of left lateral strike-slip motion along segment boundaries. An ERS-l SAR mosaic was created of the entire AP and combined with aeromagnetic anomaly data and mapped geologic data to study how the process of fracture zone subduction modified AP structure. Our approach was to compare lineaments derived from the SAR mosaic with aeromagnetic lineations and mapped geologic 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. Based on this relation, the Graham Land-Palmer Land Transition Zone (TZ) was examined in detail. Correlation between the SAR and aeromagnetic lineaments suggests both mark crustal structures in the TZ. Differences between trends of mapped geologic features and SAR lineaments within the TZ and to the north of the TZ argue that the TZ is structurally unique within the AP. A model invoking left lateral fault motion can explain the lineament patterns. Correlation between lineament trends and fracture zone traces suggests that faulting reflects the response of the AP crust to fracture zone subduction. European Space Agency for the ERS-1 SAR data. This project was supported by a grant from the Antarctic Geology and Geophysics Program, Office of Polar Programs, National Science Foundation.
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