The seismostratigraphic and structural analysis of the whole length of the Magellan Strait, from the Atlantic to the
Pacific entrance is for first time illustrated on the basis of multichannel seismic (MCS) profiles. The Strait crosses
a geologically complex region that includes different morphotectonic provinces, and has been subdivided into
three distinct segments, eastern (Atlantic), central, and western (Pacific), being each segment characterized by
peculiar sedimentary and tectonic architectures. The MCS profiles shed light on the subsurface of the region in
particular on the Quaternary and Tertiary features. In the foreland basin province, the MCS profiles imaged an
almost undeformed structural and stratigraphic frame with very thick Cretaceous to Tertiary package. Seismic evidence
of deformation of the foreland units occurs in the fold-and-thrust belt province. Along the Cordillera
province, the Magallanes-Fagnano transform fault exerts an important morpho-tectonic control that strongly conditions
its bathymetric profile. The seismic profiles also highlighted a number of depositional features linked to the
up to 150 m thick sedimentary record of the glacial cycles. Whereas the eastern segment (outer foreland province)
is devoid of significant glacial-related deposits, the central segment (inner foreland and fold-and-thrust belt
provinces) shows evidence of repeated advances and retreats of the Magellan glacier. An important moraine ridge
complex, probably corresponding to the glacial advance “D” of Clapperton et al., has been seismically imaged in
the central segment, as well as an older, large bank of ice-distal sediments that have been interpreted as proglacial
lake deposits, which show evident signs of repeated glacial erosions. Ice-contact features in the form of frontal
moraine complexes made up of dipping foreset strata are present in the fjord-like, western segment of the Strait
(Cordillera province), along with their related ice-proximal and ice-distal facies. Eventually, the occurrence of preglacial
sediments tectonized by the Magallanes-Fagnano transform fault has been reported in the same segment.
This fact, which is supported by small outcrops reported in the updated geologic map, if substantiated by further
investigations (i.e. advanced seismic reprocessing, sea bottom samplings), would prove the relatively young age
(Late Miocene?) of the Magallanes-Fagnano transform fault.
