Tectonics and hydrogeology of accretionary prisms: role of the décollement zone

Moore, J. Casey

doi:10.1016/0191-8141(89)90037-0

Cited by 196 publications

(125 citation statements)

References 34 publications

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“…The bulk of the compaction apparently occurred in response to tectonic thickening and increased vertical loads. A small amount of additional compaction also appears to have resulted from lateral compressive stresses (Moore, 1989). However, these lateral compressive effects appear to be relatively small and, given the large scatter in the porosity data, it is hard to judge their significance.…”

Section: Summary and Significance Of Resultsmentioning

confidence: 98%

Mechanisms of Accretion and Subsequent Thickening in the Barbados Ridge Accretionary Complex: Balanced Cross Sections across the Wedge Toe

Brown¹,

Mascle²,

Behrmann³

1990

Proceedings of the Ocean Drilling Program

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Detailed analysis of ODP Leg 110 cores provides evidence for a complex structural evolution of the frontal thrust system of the Barbados Ridge accretionary wedge. Thrust faulting and back rotation are the dominant thickening mechanisms within 5 km of the toe of the wedge. Folding and duplex formation are only secondary thickening processes at this point. Estimates of shortening across the frontal 5 km of the wedge vary depending on the balancing technique used. Ignoring the affects of compaction, line-balanced sections suggest 26-36% tectonic shortening, whereas simple volume balanced sections indicate 32% shortening. When a potential average 14% volume loss is considered, the volume-balance estimates of shortening rise to nearer 40%.By 12 km from the front (Site 673), large-scale folding, with the development of overturned sections, becomes a significant thickening process. This folding is followed by the development of low-angle faults that cut out stratigraphic section at around 18 km from the toe (Site 674). These faults are interpreted as out-of-sequence thrusts that cross-cut and dismember an already complexly deformed wedge. The out-of-sequance thrusts are found in a region of the wedge where arc-dipping, low-angle reflectors become prominent on seismic reflection profiles.The current basal decollement zone (to the east of Site 674) lies in the lower Miocene section. Oligocene and Eocene strata are thrust undeformed beneath the wedge for at least 12-18 km (and perhaps farther). The presence of Oligocene and Eocene material within the wedge is, therefore, evidence of a different basal decollement geometry in the past. This different geometry could have entailed either: (1) an earlier phase of frontal off-scraping, with a decollement zone at a lower stratigraphic level; or (2) duplex formation and underplating of part of the Oligocene and Eocene section. We suggest that a mechanism of underplating is the best explanation for the general structural configuration observed at Site 674. If this is the case, then on ODP Leg 110 we made the first penetration of an underplated section in ODP or DSDP history.The overall progression in structural style across the accretionary wedge reflects the need for continuous shape adjustments to maintain a stable critical taper during progressive accretion. Erosion of material from the slope of the wedge at Sites 673 and 674 may have had an important affect on the structural development of the wedge. It is important to note that erosion becomes significant in the region of the wedge where underplating and out-of-sequence thrusting is proposed to have occurred.

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Section: Summary and Significance Of Resultsmentioning

confidence: 98%

Mechanisms of Accretion and Subsequent Thickening in the Barbados Ridge Accretionary Complex: Balanced Cross Sections across the Wedge Toe

Brown¹,

Mascle²,

Behrmann³

1990

Proceedings of the Ocean Drilling Program

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“…Convergence rates faster than dewatering may cause hydrofracturing of the basal front of the upper plate. Consequently, an upward migration of the d6collement to a level of minimal efficient friction will favour tectonic erosion, as discussed by Von Huene and Lee (1983), Platt (1989) and Moore (1989).…”

Section: Discussionmentioning

confidence: 99%

Tectonic regime of the southern Kurile Trench as revealed by multichannel seismic lines

et al. 1995

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The analysis of the two multichannel seismic reflection records P-855 and P-856 reveals the complexity of the tectonic structure of the Kurile margin. The absence of trench fill and the relatively constant thickness of the subducted sediments on top of the oceanic basement shows that little or no accretion is occurring at present. The lower slope is characterized by active thrusting within a small accretionary prism. The toe of the middle slope is a more consolidated unit that constitutes an efficient buttress. A piggy back basin, possibly filled by sediments that have drifted down slope, has formed on top of this unit. A narrow high marks the transition to the edge of the continental terrace. Furthermore, the upper slope reveals an unconformity marking the top of the basement. The similarity of this unconformity and its sedimentary cover with the well documented data acquired around DSDP Legs 56-57 suggests that northern Japan and the southern Kurile forearcs may have experienced a similar Cenozoic vertical history.

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“…The low acoustic impedance can be explained by high porosity sustained by high fluid pressure [Moore et al, 1990]. This pore fluid pressure, far higher than hydrostatic, can account for the weak coupling along the décollement [e.g., Moore, 1989]. The prominent reverse-polarity décollement seismic reflection extends from beneath the accretionary prism to $8 km seaward of the deformation front [Bangs et al, 2004].…”

Section: Geologic Settingmentioning

confidence: 99%

Initiation of plate boundary slip in the Nankai Trough off the Muroto peninsula, southwest Japan

Tsuji

Matsuoka

Yamada

et al. 2005

Geophysical Research Letters

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To investigate variations in physical properties accompanying the development of the décollement, we used a neural network analysis of seismic attributes derived from 3D seismic reflection data gathered in the Nankai Trough convergent margin off the Muroto peninsula of southwest Japan. This analysis resulted in a detailed map of the geological features along the décollement and revealed a drastic change in physical properties at the sole of the proto‐thrust. Ocean Drilling Program (ODP) data suggest that the décollement physical property change coincides with the initiation of slip. Furthermore, changes in the structure of the accretionary prism and reorganization of the décollement geometry also attend the initiation of plate boundary slip.

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Tectonics and hydrogeology of accretionary prisms: role of the décollement zone

Cited by 196 publications

References 34 publications

Mechanisms of Accretion and Subsequent Thickening in the Barbados Ridge Accretionary Complex: Balanced Cross Sections across the Wedge Toe

Mechanisms of Accretion and Subsequent Thickening in the Barbados Ridge Accretionary Complex: Balanced Cross Sections across the Wedge Toe

Tectonic regime of the southern Kurile Trench as revealed by multichannel seismic lines

Initiation of plate boundary slip in the Nankai Trough off the Muroto peninsula, southwest Japan

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