Phyllosilicate preferred orientation in relation to strain path determination in the lower Paleozoic Stavelot-Venn Massif (Ardennes, Belgium)

Sintubin, Manuel

doi:10.1016/0040-1951(94)90256-9

Cited by 23 publications

(17 citation statements)

References 12 publications

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“…Oriented electron micrographs of a shale (Figure 2) illustrate this overall axial symmetry with the planes of the clay platelets primarily horizontally oriented. However, nonlithostatic tectonic deformation produces orthorhombic texture [e.g., Oertel , 1983; Sintubin , 1994b] consistent with longstanding deformation models. O'Brien et al [1987] have found even more complex deformation in a series of X‐ray goniometry measurements on metamorphic phyllites.…”

Section: Texture and The Orientation Distribution Functionsupporting

confidence: 59%

“…One final possible reason for the discrepancy between the muscovite aggregate and the laboratory observations in Figure 10 may relate to the assumption that many phyllitic rocks, and particularly shales, will be transversely isotropic. However, phyllite mineral ODFs are not necessarily axially symmetric as indicated by Oertel [1983], O'Brien et al [1987], and Sintubin [1994b] with varying degrees of orthorhombicity apparent in materials that have undergone some tectonic straining. The peaks of an ODF need not even necessarily be perpendicular to the foliation, O'Brien et al [1987] show a biotite [001] ODF from a mylonite that displays a nearly Gaussian distribution the peak of which, however, is shifted nearly 10° from X 3 .…”

Section: Discussionmentioning

confidence: 99%

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Intrinsic elasticity of a textured transversely isotropic muscovite aggregate: Comparisons to the seismic anisotropy of schists and shales

Cholach

Schmitt

2006

J. Geophys. Res.

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[1] The anisotropic properties of phyllosilicate rocks are investigated through the modeling of the pore-free ''intrinsic'' elasticity of a textured muscovite aggregate. The elastic constants were calculated for textures, as defined using orientation distribution functions (ODFs), ranging from perfectly aligned to completely random. The ODFs were described using a Gaussian distribution, the width of which is controlled by the standard deviation of the orientations of the crystal c axis with respect to the sample foliation plane under the assumption that the sample has hexagonal (transversely isotropic) symmetry. The values were obtained using the widely used Voigt-Reuss-Hill averaging techniques as well as the geometric mean average (GMA). The GMA is more physically meaningful in that it requires that the elastic constants determined in either the stiffness or the compliance domains be invertible. Comparisons between these different averages indicate that, strictly, the Voigt and Reuss values do not necessarily provide the limiting bounds as is expected for the isotropic case. Despite this, some characteristics of the elastic wave P wave anisotropy are only weakly dependent on the averaging procedure employed. The calculated elastic constants are converted to the anisotropic e, d, and g parameters in order to allow for comparison to existing measurements in the literature. However, these ''intrinsic'' results are not intended to provide a measure of the properties of phyllites per se but to provide a reference against which more sophisticated models that incorporate porosity, layering, and composition may be constructed.

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Section: Texture and The Orientation Distribution Functionsupporting

confidence: 59%

Section: Discussionmentioning

confidence: 99%

Intrinsic elasticity of a textured transversely isotropic muscovite aggregate: Comparisons to the seismic anisotropy of schists and shales

Cholach

Schmitt

2006

J. Geophys. Res.

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“…Ordovician and Silurian pole figures result from the superposition of a less penetrative cleavage fabric and a differently orientated compaction fabric. While the Cambrian pole figures indicate an oblate strain ellipsoid (Sintubin, 1994), the Ordovician and Silurian pole figures suggest a prolate strain ellipsoid.…”

Section: D X-ray Texture Fabricsmentioning

confidence: 97%

“…The degree of preferred orientation of phyllosilicates results from the structural history, the strain path and the lithology (Sintubin, 1994). Because of the complex interaction the following discussion focuses on the qualitative interpretation of the pole figures and on their relationship with the cleavage fabric.…”

Section: D X-ray Texture Fabricsmentioning

confidence: 99%

The Caledonian deformation of the Brabant Massif and the Early Palaeozoic in northeast Germany: compared

Giese

Katzung²,

Walter

et al. 1997

Geol. Mag.

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The Caledonian deformation of the Brabant Massif and the Rügen Early Palaeozoic has been compared by structural analysis including strain determinations, X-ray texture analysis, illite crystallinity and vitrinite reflectivity. Both areas have experienced weak internal deformation under anchimetamorphic to very low-grade metamorphic conditions. The deformation of the Brabant Massif is characterized by (a) a pronounced diagenetic foliation which resulted from compaction and weak extensional tectonics; (b) tilting or weak folding of the Cambrian strata around the Cambrian/Ordovician boundary without internal deformation; (c) a main phase of Caledonian deformation in the Lower Devonian which was associated with open folding and an axial-plane pressure solution cleavage; (d) bending of Caledonian structures from northwest-southeast to northeast-southwest. The internal deformation appears homogeneous with decreasing strain values towards upper structural levels. The strain ellipsoid is predominantly prolate with the main axis of extension parallel to the bedding-cleavage intersection lineation. It is interpreted as the result of superposition of compaction, tectonic shortening and volume loss through pressure solution. The Rügen Early Palaeozoic is less deformed and less metamorphosed under anchizonal conditions. While the upper structural level is almost undeformed, towards the deeper structural levels a spaced and then a continuous slaty cleavage is developed which is successively crenulated by a fracture cleavage. The internal deformation appears inhomogeneous due to several thrust zones with somewhat higher strain values. Outside the thrust zones strain values increase towards lower structural levels, but not significantly. The strain ellipsoid is prolate with a strongly varying orientation of the X-axis. The structural inventory of both areas is comparable with other fold-and-thrust belts. While the Rügen Palaeozoic represents an imbricated thrust-fan of an upper structural level with discrete thrusts and inhomogeneous strain, the Brabant Massif represents a deeper structural level dominated by folding and more homogeneous internal deformation.

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“…and chloritoid (20.9 m.r.d.) is extremely high with respect to other slates, such as very low-grade to low-grade metamorphic shales and slates in the Palaeozoic of the BrabantArdenne area (Belgium, France;Sintubin, 1994;Debacker and Sintubin, 2008) and in the high-strain Cambrian slate belt of Wales (Wood and Oertel, 1980). Experimental studies of fabric formation in fine-grained sediments have shown that mechanical rotation of pre-existing grains is only capable of producing fabrics up to about 10 m.r.d.…”

Section: Discussionmentioning

confidence: 99%

Preferred mineral orientation of a chloritoid-bearing slate in relation to its magnetic fabric

Haerinck

Wenk

Debacker³

et al. 2015

Journal of Structural Geology

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a b s t r a c tA regional analysis of the anisotropy of the magnetic susceptibility on low-grade metamorphic, chloritoid-bearing slates of the Paleozoic in Central Armorica (Brittany, France) revealed very high values for the degree of anisotropy (up to 1.43). Nonetheless, high-field torque magnetometry indicates that the magnetic fabric is dominantly paramagnetic. Chloritoid's intrinsic degree of anisotropy of 1.47 ± 0.06, suggests that chloritoid-bearing slates can have a high degree of anisotropy without the need of invoking a significant contribution of strongly anisotropic ferromagnetic (s.l.) minerals. To validate this assumption we performed a texture analysis on a representative sample of the chloritoid-bearing slates using hard Xray synchrotron diffraction. The preferred orientation patterns of both muscovite and chloritoid are extremely strong (~38.6 m.r.d. for muscovite, 20.9 m.r.d. for chloritoid) and display roughly axial symmetry about the minimum magnetic susceptibility axis, indeed suggesting that chloritoid may have a profound impact on the magnetic fabric of chloritoid-bearing rocks. However, modeling the anisotropy of magnetic susceptibility by averaging single crystal properties indicates that the CPO of chloritoid only partially explains the slate's anisotropy.

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Phyllosilicate preferred orientation in relation to strain path determination in the lower Paleozoic Stavelot-Venn Massif (Ardennes, Belgium)

Cited by 23 publications

References 12 publications

Intrinsic elasticity of a textured transversely isotropic muscovite aggregate: Comparisons to the seismic anisotropy of schists and shales

Intrinsic elasticity of a textured transversely isotropic muscovite aggregate: Comparisons to the seismic anisotropy of schists and shales

The Caledonian deformation of the Brabant Massif and the Early Palaeozoic in northeast Germany: compared

Preferred mineral orientation of a chloritoid-bearing slate in relation to its magnetic fabric

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