Geological Structures: a Practical Introduction

Waldron, John W.F.; Snyder, Morgan

doi:10.29173/oer3

Cited by 6 publications

(4 citation statements)

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“…(1) Two features with the same age on opposite sides of the fault allowing geologists to reconstruct how much motion there must have been for the large strike-slip faults (e.g., Cather 1999). These features can be sedimentary units, intrusive bodies, orogenic belts, basins, facies changes, and paleo-shorelines (Cather et al, 2006;Waldron and Snyder, 2020); (2) Linear features such as fences, stream channels, roads, etc., that are offset by surface ruptures in earthquakes (Rockwell, 1988;Avouac and Tapponnier, 1993;Lavé and Avouac, 2000); (3) Constructed lines, such as isopachs, lithofacies lines, and traces of axial surfaces with bedding (e.g., Crowell, 1959).…”

Section: Piercing Pointsmentioning

confidence: 99%

“…In general, these conditions hold depending on the scale of analysis; competent rocks most likely fulfill the requirements of the geometric models in scales from decimeters to several hundred meters at shallow crustal levels. Diverse solutions have been proposed for calculating the net slip: graphic methods (Ragan, 2009;Babín-Vich and Gómez-Ortiz, 2010;Lisle and Walker, 2013;Waldron and Snyder, 2020), simple trigonometric equations (Xu et al, 2007;Nieto-Fuentes et al, 2014) and vector equations (Yamada and Sakaguchi, 1995;Nieto-Fuentes et al, 2022).…”

Section: Case Of Knowing Slip Direction and One Separation On A Faultmentioning

confidence: 99%

“…The slip of a fault is a measure of its true displacement. It is the relative displacement of formerly adjacent points on opposite sides of the fault, measured on the fault surface (e.g., Bates and Jackson, 1987;Waldron and Snyder, 2020). Typically, it has components parallel to dip (dip-slip) and parallel to strike (strike-slip), as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative determination of fault slip magnitude: a review

Xu¹,

Nieto-Samaniego²,

Xu³

et al. 2023

revmexcg

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In geology, a fault is a rock fracture with perceptible relative displacement of the opposite sides of the fracture. Quantitatively obtaining the activity history of faults depends mainly on the estimation of fault slip and the study of markers, which can be used to understand and analyze the tectonic evolution of the faulted regions. Fault slip is calculated by restoring points that were originally adjacent before the deformation, those points are named piercing points. In this paper, we review some published methods to determine fault slip, using: (1) the offset of contours on structural contour maps; (2) offset on seismic reflection sections; (3) a known slip vector (fault striae) and one marker; (4) two known markers. Cases (3) and (4) are commonly applied to field work and geological maps.

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Section: Piercing Pointsmentioning

confidence: 99%

Section: Case Of Knowing Slip Direction and One Separation On A Faultmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantitative determination of fault slip magnitude: a review

Xu¹,

Nieto-Samaniego²,

Xu³

et al. 2023

revmexcg

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“…Unlike the principal curvatures that depend on both the gradient and the Hessian of the of the prospective local surfaces, the most positive and most negative curvatures only depend on the Hessian (Roberts, 2001;Chopra and Marfurt, 2010b). Geologic structures can be studied at a variety of scales and generally exhibit curvatures of different wavelengths (Waldron and Snyder, 2020). In particular, the most positive and most negative curvatures can be both short-wavelength and long-wavelength Marfurt, 2010a, 2015;Hunt et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Hypersurface curvatures of geological features

Ravve

Tertois

Ribet

et al. 2023

Geophysical Journal International

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Summary Reflector-normal angles and reflector-curvature parameters are the principal geometric attributes used in seismic interpretation for characterizing the orientations and shapes, respectively, of geological reflecting surfaces. Commonly, the input dataset for their computation consists of fine 3D grids of scalar fields representing either the seismic-driven reflectivities (e.g. amplitudes of 3D seismic migrated volumes) or model-driven reflectivities, computed, for example, from the derived elastic impedance parameters. Conventionally, the computation of curvature parameters at each grid point is based on analyzing the local change in the inline/crossline dips, considering the potential existence of a local quadratic reflecting surface in the vicinity of that point. This assumption breaks down for subsurface points in the vicinity of either complex reflecting surfaces (e.g. brittle/rough/tilted synclines/anticlines, ridges/troughs, and saddles) and/or sharp, discontinuous geological features (e.g. fault edges/tips, pinch-outs, fracture systems, channels, and small geobodies), where the values of the computed curvature become extremely high. However, while these high values can indicate the existence of non-reflecting objects, they do not deliver their specific geometric characteristics. In this study we present a novel method that better characterizes the shapes of these complex geological features by extending the assumption of local surfaces (2D surfaces in 3D space) into local hypersurfaces (3D hypersurfaces in 4D space), with their corresponding (three rather than two) principal (and effective) curvature parameters. We demonstrate the advantages of our method by comparing the conventional dip-based surface curvature parameters with the hypersurface curvature parameters, using a synthetic model/image with different types and shapes of geological features and a seismic image of real data containing a complex fault and hidden buried channels.

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