Richard Lisle | Cardiff University (original) (raw)
Papers by Richard Lisle
Earth-Science Reviews
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Computers & Geosciences, 2015
ABSTRACT StrainModeler is a program constructed in the Mathematica™ environment that performs 3D ... more ABSTRACT StrainModeler is a program constructed in the Mathematica™ environment that performs 3D progressive strain calculations for lines and planes undergoing any sequence of homogeneous deformations. The main inputs to the system define the initial line or plane to be deformed and the deformation sequence to be applied, including combinations of simple shear, pure shear and volume change. For the deformation of lines, the output of the program is the change of attitude of the initial line, which can be represented by graphics or plotted in an equal-area projection. For the deformation of planes, the program has several outputs: i) change of attitude of the initial plane; ii) magnitudes and ratio of the semi-axes of the strain ellipse on the deformed plane; iii) orientation of the major and minor axes of the strain ellipse on the deformed plane; iv) orientations of the axial planes of the folds formed on the deformed plane, and v) area change on the deformed plane. The variation of any of these parameters can be shown against a linear parameter only linked to the number of steps involved in the deformation, as a kind of “time” line, or it can be shown against the variation of a parameter of the strain ellipsoid (e. g.: major axis/minor axis ratio). A sequence of directions can be also visualized as a curve in an equal-area plot. Three applications of the program are presented. In the first, the deformation by simple shear of a plane with any orientation is analyzed. In the second, we explore the formation of recumbent folds in layers with different initial orientations for simple shear and pure shear deformations. In the third, we use StrainModeler to analyze the deformation of a set of folds located in a ductile shear zone in the Variscan Belt of NW Spain.
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SEG Technical Program Expanded Abstracts 2008, 2008
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The Journal of Geology, 1989
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The Journal of Geology, 1999
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Terra Nova
Abstract Neutral surface folding is a significant contributor to fold development. This mechanism... more Abstract 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 ...
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Tectonophysics, 2000
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Tectonophysics, 1986
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Tectonophysics, 1977
ABSTRACT
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Quarterly Journal of Engineering Geology and Hydrogeology, 1982
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Proceedings of the Geologists' Association, 1975
ABSTRACT
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Mathematical Geology, 2005
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Mathematical Geology, 1992
Procedures are outlined for the selection of a least squares best-fit circle to data points defin... more Procedures are outlined for the selection of a least squares best-fit circle to data points defined by rectangular Cartesian coordinates. Equations are derived to allow fitting of circles centered on the x-axis as well as off-axis Mohr circles. These procedures are applicable to the estimation of second-order tensors such as stress and strain by means of Mohr's diagram.
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Journal of the Geological Society, 1996
ABSTRACT The study of minor structures in Carboniferous and Triassic sedimentary rocks at Ogmore-... more ABSTRACT The study of minor structures in Carboniferous and Triassic sedimentary rocks at Ogmore-by-Sea, Bridgend, reveals that the observed microstructures are the consequence of successive brittle deformation events. Age relationships can be deduced from sets of structures consisting of conjugate faults, oblique slip faults, tension gashes and stylolites, from which deductions can be made about the orientations of principal stresses corresponding to pre- and post-Triassic events. The demonstrable polyphase tectonic history at Ogmore and the occurrence of large numbers of striated faults at four sites allow the opportunity of testing a newly proposed strategy for palaeostress analysis from striated faults with complex stress histories. The new technique, based on the statistical procedure of cluster analysis, involves the sorting of fault-slip data into coherent dynamic sets as a preliminary stage of formal stress inversion. The fault sets separated using this technique yield stresses which are similar to those deduced from field observations. Four stress configurations are distinguished, of which two are pre-Triassic in age. Correlations with previously derived stresses are discussed.
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Journal of Structural Geology, 1998
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Journal of Structural Geology, 1995
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Journal of Structural Geology, 2009
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Journal of Structural Geology, 2010
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Journal of Structural Geology, 2004
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Journal of Structural Geology, 1987
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Earth-Science Reviews
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Computers & Geosciences, 2015
ABSTRACT StrainModeler is a program constructed in the Mathematica™ environment that performs 3D ... more ABSTRACT StrainModeler is a program constructed in the Mathematica™ environment that performs 3D progressive strain calculations for lines and planes undergoing any sequence of homogeneous deformations. The main inputs to the system define the initial line or plane to be deformed and the deformation sequence to be applied, including combinations of simple shear, pure shear and volume change. For the deformation of lines, the output of the program is the change of attitude of the initial line, which can be represented by graphics or plotted in an equal-area projection. For the deformation of planes, the program has several outputs: i) change of attitude of the initial plane; ii) magnitudes and ratio of the semi-axes of the strain ellipse on the deformed plane; iii) orientation of the major and minor axes of the strain ellipse on the deformed plane; iv) orientations of the axial planes of the folds formed on the deformed plane, and v) area change on the deformed plane. The variation of any of these parameters can be shown against a linear parameter only linked to the number of steps involved in the deformation, as a kind of “time” line, or it can be shown against the variation of a parameter of the strain ellipsoid (e. g.: major axis/minor axis ratio). A sequence of directions can be also visualized as a curve in an equal-area plot. Three applications of the program are presented. In the first, the deformation by simple shear of a plane with any orientation is analyzed. In the second, we explore the formation of recumbent folds in layers with different initial orientations for simple shear and pure shear deformations. In the third, we use StrainModeler to analyze the deformation of a set of folds located in a ductile shear zone in the Variscan Belt of NW Spain.
Bookmarks Related papers MentionsView impact
SEG Technical Program Expanded Abstracts 2008, 2008
Bookmarks Related papers MentionsView impact
The Journal of Geology, 1989
Bookmarks Related papers MentionsView impact
The Journal of Geology, 1999
Bookmarks Related papers MentionsView impact
Terra Nova
Abstract Neutral surface folding is a significant contributor to fold development. This mechanism... more Abstract 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 ...
Bookmarks Related papers MentionsView impact
Tectonophysics, 2000
Bookmarks Related papers MentionsView impact
Tectonophysics, 1986
Bookmarks Related papers MentionsView impact
Tectonophysics, 1977
ABSTRACT
Bookmarks Related papers MentionsView impact
Quarterly Journal of Engineering Geology and Hydrogeology, 1982
Bookmarks Related papers MentionsView impact
Proceedings of the Geologists' Association, 1975
ABSTRACT
Bookmarks Related papers MentionsView impact
Mathematical Geology, 2005
Bookmarks Related papers MentionsView impact
Mathematical Geology, 1992
Procedures are outlined for the selection of a least squares best-fit circle to data points defin... more Procedures are outlined for the selection of a least squares best-fit circle to data points defined by rectangular Cartesian coordinates. Equations are derived to allow fitting of circles centered on the x-axis as well as off-axis Mohr circles. These procedures are applicable to the estimation of second-order tensors such as stress and strain by means of Mohr's diagram.
Bookmarks Related papers MentionsView impact
Journal of the Geological Society, 1996
ABSTRACT The study of minor structures in Carboniferous and Triassic sedimentary rocks at Ogmore-... more ABSTRACT The study of minor structures in Carboniferous and Triassic sedimentary rocks at Ogmore-by-Sea, Bridgend, reveals that the observed microstructures are the consequence of successive brittle deformation events. Age relationships can be deduced from sets of structures consisting of conjugate faults, oblique slip faults, tension gashes and stylolites, from which deductions can be made about the orientations of principal stresses corresponding to pre- and post-Triassic events. The demonstrable polyphase tectonic history at Ogmore and the occurrence of large numbers of striated faults at four sites allow the opportunity of testing a newly proposed strategy for palaeostress analysis from striated faults with complex stress histories. The new technique, based on the statistical procedure of cluster analysis, involves the sorting of fault-slip data into coherent dynamic sets as a preliminary stage of formal stress inversion. The fault sets separated using this technique yield stresses which are similar to those deduced from field observations. Four stress configurations are distinguished, of which two are pre-Triassic in age. Correlations with previously derived stresses are discussed.
Bookmarks Related papers MentionsView impact
Journal of Structural Geology, 1998
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Journal of Structural Geology, 1995
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Journal of Structural Geology, 2009
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Journal of Structural Geology, 2010
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Journal of Structural Geology, 2004
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Journal of Structural Geology, 1987
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