Erosional features as indicators of thrust fault activity (Nankai Trough, Japan)
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Date
2014-10
Publication Type
Journal Article
ETH Bibliography
yes
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Abstract
A submarine channel system and basal ramps of a Quaternary mass-transport deposit (MTD) are shown to represent thrust fault activity in the Nankai accretionary wedge. Variations in channel bed slope, height and width of submarine channels and gullies indicate uplift and sediment bypass seaward from a margin-dominating out-of-sequence thrust, the megasplay fault (MSF), at < 1.67–1.46 Ma. Between ~ 1.05 and 0.85 Ma, a younger mass-transport deposit (MTD 6) was detached at different depths. Demonstrating the significant deformation observed in the study area, the direction of transport of MTD 6 differs 30°–45° from the strike of scarps and ramps at its base, which are parallel to the structural contours of thrust anticlines underneath. This character contrasts to the geometries frequently documented in frontally-emergent submarine landslides. Oblique basal ramps form significant boundaries between zones of MTD 6 with distinct acoustic and, suggestively, petrophysical properties. As a result of this study, we postulate that developed channel systems can erode the upper continental slope and lead to bypass of substantial volumes of sediment to distal parts of accretionary wedges. This process bears the potential of generating periods of more intense thrust-wedge deformation than those predicted by mathematical and physical models based on present-day taper geometries. On a regional scale, the observations in this paper are important as they indicate a more diffuse distribution of deformation in the Nankai accretionary wedge than previously assumed for the MSF region.
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Publication status
published
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Book title
Journal / series
Volume
356
Pages / Article No.
5 - 18
Publisher
Elsevier
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Continental margin; Accretionary wedge; Sediment taper; Erosion; Tectonic uplift; Seafloor deformation
Organisational unit
03931 - Strasser, M. (SNF-Professur) (ehemalig)
Notes
Funding
133481 - DYNAMITE: Dynamic Nankai Trough (Japan) and Swiss Molasse Basin: Investigating NeoTectonics, Paleo-Earthquakes and associated Geohazards (SNF)