Two‐dimensional models are presented for the crustal structure of the Antarctic Peninsula, a Mesozoic‐Cenozoic magmatic arc on the southeast Pacific margin. The models are constrained by measured rock properties. The West Coast Magnetic Anomaly (WCMA) is caused by a zone of mafic plutons which is 70–150 km wide and over 1500 km long. In modelling of Bouguer anomalies, isostatic compensation is maintained by crustal thickness variations. The model Moho is deepest (35 km) beneath the mid‐Cretaceous axis of the arc and shallowest (<20 km) beneath a Late Cenozoic marginal basin. Positive isostatic residual gravity anomalies are associated with the WCMA and a mafic terrane in the Mesozoic accretionary complex. Three broad areas of consistent crustal structure are identified. The junctions of these areas are sinistral fault zones which displace the curvilinear magnetic, physiographic, and gravity patterns by several tens of kilometers.

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A subduction-accretion model incorporating new geophysical data is presented to explain the geology of the Antarctic Peninsula from late Palaeozoic to Cenozoic time. According to the model, the peninsula consists of overlapping accretionary, magmatic and extensional regimes that were diachronous across the peninsula and have built the crust to its present form. The crust, which contains a small proportion of sialic basement, was mainly formed by accretionary and magmatic processes and modified to its present shape by extension. The Gondwanide Orogeny for the Antarctic Peninsula is interpreted in terms of the accretionary processes.