Fold mechanisms in the Canton Schist: constraints on the contribution of flexural flow

Stallard, Aaron; Hickey, Kenneth A.

doi:10.1016/s0191-8141(01)00032-3

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…Today, both rotational (Prior, 1987;Chan & Crespi, 1999;Ikeda et al, 2002) and non-rotational (Fyson, 1980;Johnson, 1990;Aerden, 1995) behaviours have been documented in nature. The observed geometries of inclusion trails have been explained, for instance, by flexural flow folding (Visser & Mancktelow, 1992), coaxial deformation associated with passive folding (Ramsay, 1962;Stallard & Hickey, 2001;Timms, 2003), or deformation partitioning of bulk non-coaxial deformation into pure and simple shear components (Bell, 1981;Lister & Williams, 1983).…”

Section: Introductionmentioning

confidence: 99%

Tectono-metamorphic history recorded in garnet porphyroblasts: insights from thermodynamic modelling and electron backscatter diffraction analysis of inclusion trails

Skrzypek

Schulmann

Štípská

et al. 2011

Journal of Metamorphic Geology

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Section: Introductionmentioning

confidence: 99%

Tectono-metamorphic history recorded in garnet porphyroblasts: insights from thermodynamic modelling and electron backscatter diffraction analysis of inclusion trails

Skrzypek

Schulmann

Štípská

et al. 2011

Journal of Metamorphic Geology

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“…An essential property of this mechanism is the arrangement of principal finite strains in directions approximately parallel and perpendicular to the layer boundaries. It is further assumed that this applies also to the infinitesimal strains, so that the strain history is coaxial (Lister and Williams, 1983; Stallard and Hickey, 2001; Evins, 2005). As this mechanism is usually associated with non‐stratified layers (Ramsay, 1967; p. 397), we further assume a homogeneous material with isotropic stress–strain relationships.…”

Section: Stresses During Neutral Surface Foldingmentioning

confidence: 99%

Volumetric strains in neutral surface folding

Lisle¹,

Aller²,

Bastida³

et al. 2009

Terra Nova

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Neutral surface folding is a significant contributor to fold development. This mechanism produces contrasting strains in the inner and outer arcs of the folded layer that arise from principal stress orientations that are approximately parallel and perpendicular to the layer. We demonstrate that such stress patterns imply significant gradients of mean stress across the folding layer, being more tensional on the outer arc and more compressive in the inner arc. This could pump fluids towards the outer arc during folding and result in heterogeneous volume changes. We conclude that the neutral surface folding model should be adapted to accommodate volumetric strains, in order to explain dilatational structures (e.g. open fractures, veining) on the extrados and volume‐loss structures (e.g. pressure solution seams, stylolitic cleavages) on the intrados. This dilatation has economic implications as it allows prediction of sites of mineralization and zones of secondary permeability in fold‐related hydrocarbon traps.

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“…Porphyroblast growth and behaviour during deformation, including folding, has attracted much attention and often heated discussion over the past two decades, and are currently very interesting topics for analysis by new quantitative microstructural approaches Passchier et al, 1992;Forde & Bell, 1993;Mancktelow & Visser, 1993;Williams & Jiang, 1999;Stallard & Hickey, 2001;Kraus & Williams, 2001). Previous studies of porphyroblast inclusion trail geometry provide substantial evidence to strongly suggest porphyroblast nucleation and growth is directly related to development of crenulation cleavages (Bell, 1985;Bell et al, 1986;Bell & Hayward, 1991;Williams, 1994;Spiess & Bell, 1996;Spear & Daniel, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Growth ceases when zones of progressive shear impinge on their margins as the crenulation cleavage develops (Bell, 1985;Bell et al, 1986;. Busa & Gray, 1992;Hickey & Bell, 1999, 2001Stallard & Hickey, 2001;Bell & Chen, 2002). Porphyroblast rotation is inhibited due to the lack of shear coupling with the matrix.…”

Section: Introductionmentioning

confidence: 99%

Garnet porphyroblast timing and behaviour during fold evolution: implications from a 3‐D geometric analysis of a hand‐sample scale fold in a schist

Timms

2003

Journal Metamorphic Geology

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Detailed 3‐D analysis of inclusion trails in garnet porphyroblasts and matrix foliations preserved around a hand‐sample scale, tight, upright fold has revealed a complex deformation history. The fold, dominated by interlayered quartz–mica schist and quartz‐rich veins, preserves a crenulation cleavage that has a synthetic bulk shear sense to that of the macroscopic fold and transects the axis in mica‐rich layers. Garnet porphyroblasts with asymmetric inclusion trails occur on both limbs of the fold and display two stages of growth shown by textural discontinuities. Garnet porphyroblast cores and rims pre‐date the macroscopic fold and preserve successive foliation inflection/intersection axes (FIAs), which have the same trend but opposing plunges on each limb of the fold, and trend NNE–SSW and NE–SW, respectively. The FIAs are oblique to the main fold, which plunges gently to the WSW. Inclusion trail surfaces in the cores of idioblastic porphyroblasts within mica‐rich layers define an apparent fold with an axis oblique to the macroscopic fold axis by 32°, whereas equivalent surfaces in tabular garnet adjacent to quartz‐rich layers define a tighter apparent fold with an axis oblique to the main fold axis by 17°. This potentially could be explained by garnet porphyroblasts that grew over a pre‐existing gentle fold and did not rotate during fold formation, but is more easily explained by rotation of the porphyroblasts during folding. Tabular porphyroblasts adjacent to quartz‐rich layers rotated more relative to the fold axis than those within mica‐rich layers due to less effective deformation partitioning around the porphyroblasts and through quartz‐rich layers. This work highlights the importance of 3‐D geometry and relative timing relationships in studies of inclusion trails in porphyroblasts and microstructures in the matrix.

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Fold mechanisms in the Canton Schist: constraints on the contribution of flexural flow

Cited by 16 publications

References 20 publications

Tectono-metamorphic history recorded in garnet porphyroblasts: insights from thermodynamic modelling and electron backscatter diffraction analysis of inclusion trails

Tectono-metamorphic history recorded in garnet porphyroblasts: insights from thermodynamic modelling and electron backscatter diffraction analysis of inclusion trails

Volumetric strains in neutral surface folding

Garnet porphyroblast timing and behaviour during fold evolution: implications from a 3‐D geometric analysis of a hand‐sample scale fold in a schist

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