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| Titel |
Prominent submarine mass wasting structures at the Southern Central Chilean continental margin: the Roca Slide |
| VerfasserIn |
D. Voelker, W. Weinrebe, J. Behrmann  , J. Bialas, D. Klaeschen |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025582
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| Zusammenfassung |
| Offshore Southern Central Chile (35-S-42-S), morphological expressions of voluminous
submarine mass-wasting events are documented in swath bathymetry data. The variety in
shape, water depth, runout direction and volume of these landslides points to a number of
different processes at different phases of the evolution of the Chilean continental
margin.
A blocky Olistolith deposited in the Chile Trench, probably of Holocene age was targeted
during RRS JAMES COOK Cruise JC23. The size of this feature, which was termed Roca
Slide, as well as properties such as the very steep and high headscarp, the large
runout distance and the cohesive nature of the slumped masses make it interesting in
terms of the geotechnical issue of the continental lower slope stability and tsunami
hazard.
These questions are adressed by a morphometrical description of the Roca Slide as well as
calculations of the volumes of both the missing and the dumped slump masses. Single
channel seimic reflection profiles are used to elucidate the internal structure. Gravity core
samples were retrieved in order to better date the mass wasting event, and relate it to the
subduction dynamics and climate history of this particular segment of the Chilean continental
margin. In particular, we discuss ideas regarding the nature of the possible weak layer which
formed the gliding plane of this slump.
Another, much larger and apparently older structure is observed at the middle continental
slope. This arcuate depression is interpreted as a huge rotational slide. Remarkably, there is
no present-day surface expression of slumped masses visible in the sediment-filled trench.
However, a distinct change in the reflection character of the trench fill, observed in seismic
reflection profiles across the trench may be explained by the sudden input of a very large
sediment volume, possibly due to the slump event which caused the described mid-slope
depression. |
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