Assemblage of glacial and related landforms in the fjords of southern Chile

J. A. Dowdeswell; E. K. Dowdeswell; C. Rodrigo; J. Diaz

doi:10.1144/M46.139

At 42–55° S (Fig. 1a), the fjords of southern Chile are one of the lowest-latitude and mildest regions in which glaciers reach the sea today (Dowdeswell & Vásquez 2013). The Andean ice caps and glaciers of the Darwin Cordillera in Tierra del Fuego are of high mass throughput with precipitation often metres per year and, to balance this, very high rates of surface melting. These ice masses either reach the sea at fjord heads or feed braided-river systems that flow into the fjords. Large volumes of meltwater and glacial sediment are therefore delivered to Chilean fjords either directly from subglacial streams beneath tidewater glaciers or indirectly by glacifluvial processes. At the Last Glacial Maximum (LGM) the Patagonian Ice Cap expanded to fill these fjords, which were re-occupied by ocean waters as deglaciation proceeded.

Fig. 1.

Sun-illuminated multibeam-bathymetric images of submarine landforms in the fjords of Chilean Patagonia. Acquisition system Atlas Fansweep. Frequency 200 kHz. Grid-cell size 20 m. (a) Location of study area (red box; map from GEBCO_08). (b) Terminal moraine ridge and other transverse ridges produced by Tempano Glacier, inner Iceberg Fjord. S, streamlined lineations. (c) Hummocky but otherwise largely flat seafloor beyond Pio XI Glacier in Eyre Fjord. H, hummocky glacial debris. (d) Swath-bathymetric image of 100 m high recessional moraine in Europa Fjord. (e) Glacifluvial delta in Iceberg Fjord fed from an associated braided river. (f) Glacifluvial delta in Bernardo Fjord, showing a braided river and the adjacent Bernardo Glacier. (g) Small fluvial delta in Eyre Fjord. Images modified after Dowdeswell & Vásquez (2013). We thank the Servicio Hidrografico y Oceanografico de la Armada de Chile (SHOA) for allowing use of their swath-bathymetric data.

Description

Many Chilean fjords have experienced tidewater-glacier advance during the cool Little Ice Age (approximately sixteenth–nineteenth centuries), followed by retreat over the past century …

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