Intra-Stratal Flow and Convolute Folding

Williams, Emyr

doi:10.1017/s0016756800061380

Cited by 52 publications

(13 citation statements)

References 4 publications

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“…The key to determining whether convolute bedding is surficial in õrigin or is truly intrastratal lies with the upper contaet relationships (Miller 1922;Williams 1960); without evidence of structural involvement of the superjacent layers, a confident interpretation of intrastratal deformation is difficult to support. This is true also at the scale of observation that concerns us.…”

Section: 875mentioning

confidence: 99%

Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles

O’Leary

Laine

1996

Geo-Marine Letters

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Intrastratal deformation of marine strata is ordinarily recorded in high-resolution seismic reflection profiles as acoustically transparent or "chaotic" intervals marked by hyperbolic echoes. Intrastratal deformation is easily confused with buried slump or slide deposits formed initially at the sea ftoor. Correct identification of intrastratal deformation depends on the presence of a warped continuously reflective layer overlying a chaotic/transparent layer. Decollement is the key criterion for identification in seismic reflection profiles. Other criteria inctude intrusive structures or faults rooted in a chaotic/transparent layer and thickening and thinning of a chaotic/transparent layer with transitions to reflective intervals.

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Section: 875mentioning

confidence: 99%

Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles

O’Leary

Laine

1996

Geo-Marine Letters

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“…The concept of intrastratal flow can be used to explain convolute lamination (Williams 1960). Chough and Chun (1988) adapted this concept to explain the ripping of overlying sediments by liquefied sediments beneath it (''rip-down clasts'').…”

Section: Introductionmentioning

confidence: 99%

Sediment Flow and Deformation (SFD) Layers: Evidence for Intrastratal Flow in Laminated Muddy Sediments of the Triassic Osawa Formation, Northeast Japan

Kawakami¹,

Kawamura²

2002

Journal of Sedimentary Research

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Thin chaotic layers containing abundant intraformational mud clasts are found in the offshore laminated mudstone of the Triassic Osawa Formation in northeast Japan. The geometry and internal structures of the layers are somewhat similar to those of slump/slide or debris-flow deposits, however, the layers have both upper and lower erosional contacts. Projections of host sediments and mud clasts with planed surfaces are identified beneath the upper contact of the layers. Closely packed sheet-form or ellipsoidal mud clasts are embedded in a poorly sorted fine-to coarse-grained sandy matrix. Some mud clasts are tightly folded, or show imbricated stacking. Internal layering structures are also well developed in the layers.The above features strongly suggest soft-sediment deformation as horizontal displacement of sand and mud under buried conditions. Here, we term these layers ''sediment flow and deformation (SFD) layers.'' Deformation layers with similar attributes have been identified by some prior authors, as in the case of flow of liquefied and/or fluidized host sand and clastic sill intrusion. However, the SFD layers described herein have more complex structure indicating advanced deformation.Occurrence of the SFD layers is stratigraphically limited to the uppermost part of the Osawa Formation, which is overlain by sand-rich submarine-fan deposits (the Fukkoshi Formation). It suggests that the stress field caused by differential loading of overlying deposits facilitated intrastratal flow and sill intrusions of sand. The vertical confinement was also controlled by the anisotropy in physical properties, such as tensile strength of laminated mud and/or conditions of gentle slope.

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“…In other words, this fold owes its development to the shearing mechanism, not to the buckling process. In this way, the similar type of recumbent fold was formed by the mechanism of shear slip (laminar flow) movement across an original set of planar cross-beds as suggested by Williams (1960). to the direction of laminar flow and parallel to the axial surface (Fig.…”

Section: Discussionmentioning

confidence: 92%

Microfabrics of a recumbent fold in cross-bedded sandstones

Yagishita

Morris

1979

Geol. Mag.

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Plates 1-2)Summary. A thin-section study of the orientation of long-axes of quartz grains was conducted for a similar type fold of overturned cross-bedding in Carboniferous sandstones. Preferred orientation of detrital grains of the fold shows that (a) apparent long-axes of grains are parallel to the axial plane in a plane normal to the fold axis, {b) long-axes of grains in the axial plane are oriented in a high angle to the fold axis, and (c) grains are aligned parallel to the fold axis in a plane perpendicular to the other two directions. From the dimensional orientation of quartz grains in this sample, it is concluded that the overturned fold was made by a shear mechanism immediately following sedimentation in which the original quartz grains were reorientated by small-scale slippage along the shear planes.

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Intra-Stratal Flow and Convolute Folding

Cited by 52 publications

References 4 publications

Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles

Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles

Sediment Flow and Deformation (SFD) Layers: Evidence for Intrastratal Flow in Laminated Muddy Sediments of the Triassic Osawa Formation, Northeast Japan

Microfabrics of a recumbent fold in cross-bedded sandstones

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