Publication Date:
2017-06-23
Description:
In the Patagonian Andes erosion by temperate Pleistocene glaciers has produced a deeply incised fjord system in
which glacial and non-glacial sedimentswere deposited since the Late Glacial glacier retreat. So far, fjord bathymetry
and structures in the sediment infill were widely unexplored. Here we report the results of an investigation
of morphology and sediment characteristics of a 250 km long fjord transect across the southernmost Andes
(53°S), using multibeam and parametric echosounder data, and sediment cores. Subaquatic morphology reveals
continuity of on-land tectonic lineaments mapped using field and remote sensing data. Our results indicate that
glacial erosion and fjord orientation are strongly controlled by three major strike-slip fault zones. Furthermore,
erosion is partly controlled by older and/or reactivated fracture zones as well as by differential resistance of
the basement units to denudation. Basement morphology is regionally superimposed by Late Glacial and Holocene
subaquatic moraines, which are associated to known glacier advances. The moraines preferentially occur
on basement highs, which constrained the glacier flows. This suggests that the extent of glacier advances was
also controlled by basement morphology. Subaquatic mass flows, fluid vent sites as well as distinct Late Glacial
and Holocene sediment infills have furthermore modified fjord bathymetry. In the western fjord system close
to the Strait of Magellan subaquatic terraces occur in 20 to 30 m water depth, providing an important tag for
proglacial lake level during the Late Glacial.
Type:
Article
,
PeerReviewed
Format:
text
DOI:
10.1016/j.margeo.2013.07.015
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