Arc evolution: a magnetic perspective from the Antarctic Peninsula

The Antarctic Peninsula is a Mesozoic–Cenozoic magmatic arc built on Palaeozoic and younger basement. It was formed by processes related to the subduction of Pacific ocean floor at its western margin, although subduction has now ceased along most of its length. The peninsula features all the tectonic components commonly associated with a developing arc system: basement, accretionary complex, magmatic arc, arc-related basins, intra-arc extension and post-subduction volcanism. Seventeen thousand kilometres of high resolution aeromagnetic data have recently been collected in a transect across part of the arc, covering an area 290 by 230 km and incorporating examples of most of the above tectonic components. The new map reveals distinct magnetic signatures, which can now be related to each of these components in a way that was not possible with reconnaissance data sets. A characteristic magnetic anomaly pattern for each component is described and comparisons drawn with magnetic studies of other arc regions.