Seismic facies changes along a nearly continuous 24° latitudinal transect: the fjords of Chile and the northern Antarctic Peninsula

Abstract

High-resolution seismic reflection profiles and piston cores from bays, fjords, and straits of the inland passage of Chile and the northern Antarctic Peninsula region were used to examine changes in seismic facies along a nearly continuous 24 ° latitudinal transect that encompasses temperate, subpolar, and polar climatic regimes. These climatic regimes are characterized by differences in seismic facies. Eight seismic facies are recognized on the basis of reflection character, intensity of acoustic contrast at bounding surfaces, and external shape of the unit. The northern and central Chilean fjord region is a temperate maritime setting characterized by thick ice-proximal and ice-distal glacial-marine strata and a variety of morainal features. The southern inland passage and the South Shetland Islands of Antarctica represent transitional (sub-polar) glacial-marine settings. These areas are characterized by relict ice-proximal glacialmarine facies and relatively thin ice-distal glacial-marine facies. Morainal ridges occur in bays and fjords of Chile. The northern Antarctic Peninsula is a polar climatic setting. The straits, bays, and fjords of the region have been virtually scraped clean of sediments. A thin, draping glacial-marine unit occurs locally in these areas.