The Geometry of Conjugate Fold Systems

Ramsay, John G.

doi:10.1017/s0016756800059823

Cited by 82 publications

(35 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Folding is overlain in-turn by undeformed sediments indicating that deformation was syn-sedimentary. Conjugate folds form sub-parallel to oblique to the principal stress axes and their geometry reflect subtle shifts in the orientations of the primary stress field (Ramsay, 1962). These folds are interpreted to be the product of high shear stresses produced by sand-laden high-velocity currents flowing over liquefied sediment (Røe, 1987;Røe and Hermansen, 2006).…”

Section: 2mentioning

confidence: 99%

Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK

Lee

Wakefield

Phillips

et al. 2015

Quaternary Science Reviews

View full text Add to dashboard Cite

Subglacial drainage systems exert a major control on basal-sliding rates and glacier dynamics. However, comparatively few studies have examined the sedimentary record of subglacial drainage. This is due to the paucity of modern analogues, the limited recognition and preservation of upper flow regime deposits within the geological record, and the difficulty of distinguishing subglacial meltwater deposits from other meltwater sediments (e.g. glacier outburst flood deposits). Within this study, the sedimentological and structural evolution of a subglacial to subaerial (ice-marginal / proglacial) drainage system is examined. Particular emphasis is placed upon the genetic development and preservation of upper flow regime bedforms and specifically recognising them within a subglacial meltwater context. Facies attributed to subglacial meltwater activity record sedimentation within a confined, but progressively enlargening, subglacial channel system produced under dune to upper flow regime conditions. Bedforms include rare large-scale sinusoidal bedding with syn-depositional deformation produced by current-induced traction and shearing within the channel margins. Subglacial sedimentation culminated with the abrupt change to a more ephemeral drainage regime indicating channel-abandonment or a seasonal drainage regime. Retreat of the ice margin, led to the establishment of subaerial drainage with phases of sheet-flow punctuated by channel incision and anastomosing channel development under diurnal, ablation-related, seasonal discharge. The presence of extensive hydrofracture networks demonstrate that proglacial groundwater-levels fluctuated markedly and this may have influenced later overriding of the site by an ice stream.

show abstract

Section: 2mentioning

confidence: 99%

Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK

Lee

Wakefield

Phillips

et al. 2015

Quaternary Science Reviews

View full text Add to dashboard Cite

show abstract

“…On the basis of these results, in combination with field observations (e.g. Ramsay, 1962), several methods have been proposed for determining palaeostress direction from kink band geometry. This was done not only for simple, ''two-dimensional'' conjugate kink band systems (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…kink axes and intersection lineation of kink band boundaries of both sets lie in the foliation plane, such as described by Johnson, 1956), but also for the more complex ''three-dimensional'' conjugate kink band systems (conjugate sets with crossing kink axes; e.g. Ramsay, 1962;Dewey, 1965;Ramsay and Huber, 1987;Kirschner and Teixell, 1996) and even for a single set of kink bands (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Paterson and Weiss, 1962;Ramsay, 1962;Anderson, 1964;Cobbold et al, 1971). Even if a direct link between kink band geometry and palaeostress is assumed, the question can be raised whether the pre-existing local anisotropy may have influenced the (far-field) stress directions (cf.…”

Section: Introductionmentioning

confidence: 99%

“…Even if a direct link between kink band geometry and palaeostress is assumed, the question can be raised whether the pre-existing local anisotropy may have influenced the (far-field) stress directions (cf. Zandvliet, 1960;Ramsay, 1962;Cobbold et al, 1971;Donath, 1972;Murphy, 1988;Konopasek et al, 2001). This is examined by means of an analysis of contractional kink bands from two slate belts in which the orientation of the main, kinked anisotropy gradually changes on a scale exceeding that of the kink bands.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Contractional kink bands formed by stress deflection along pre-existing anisotropies? Examples from the Anglo-Brabant Deformation Belt (Belgium) and the North Dobrogea Orogen (Romania)

Debacker

Seghedi

Belmans

et al. 2008

Journal of Structural Geology

View full text Add to dashboard Cite

a b s t r a c tKink bands within two slate belts, the Anglo-Brabant Deformation Belt (Belgium) and the North Dobrogea Orogen (Romania), reveal similar problems with respect to linking kink band geometries to expected palaeostress directions. In the North Dobrogea Orogen, the two opposite kink band sets of two different systems of conjugate kink bands develop for a wide variety of cleavage orientations. In the Anglo-Brabant Deformation Belt, the occurrence of the two opposite kink band sets of a conjugate kink band system opposes the expected occurrence. In both cases, this can be attributed to stress deflection along a pre-existing anisotropy. Moreover, the presence of kink bands in the North Dobrogea Orogen with curving kink axes (and curving kink band boundaries) also puts doubt on the direct relationship between kink band geometry and stress. The idea of stress deflection along a pre-existing anisotropy and the strong control of the pre-existing anisotropy on the kink band geometry and orientation has important implications for the use of kink bands as regional palaeostress indicators. Depending on the relative intensity and relative orientation of the pre-existing fabrics (here bedding and cleavage), different mechanisms of kink band development may operate. Depending on the mechanism, different solutions in terms of inferred palaeostress direction may exist.

show abstract

Determination of the tectonic evolution from fractures, faults, and calcite twins on the southwestern margin of the Indochina Block

et al. 2015

View full text Add to dashboard Cite

In polyphase tectonic zones, integrating a study of fault and fracture with calcite twin analysis can determine the evolving paleostress magnitudes and principle stress directions that affected the area. This paper presents the results of the analyses of fractures, striated faults, and calcite twins collected within the Khao Khwang Fold-Thrust Belt in central Thailand (SE Asia). Here we attempt to reconstruct the orientation of the principal stresses that developed during the tectonic evolution of this highly deformed, polyphase orogen. Tectonic data were collected in the Permian carbonates of the Khao Khad Formation of the Saraburi Group, and five successive tectonic stages are determined that are interpreted to have developed before, during, and after, the Triassic Indosinian Orogeny. The first three stages predate the main deformation event: the first stage is interpreted as a pre-Indosinian N-S extensional stage, the second stage described a N-S strike-slip and compressional regime, largely perpendicular to the fold axes of the main structures, while the third stage is associated with an E-W compressional strike-slip phase. A further two stages took place after, or during, the main folding event and correspond to N-S compression and to an E-W composite strike-slip/contractional stage, the latter which is interpreted to represent Cenozoic deformation related to the India-Asia collision.

show abstract

The Geometry of Conjugate Fold Systems

Cited by 82 publications

References 5 publications

Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK

Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK

Contractional kink bands formed by stress deflection along pre-existing anisotropies? Examples from the Anglo-Brabant Deformation Belt (Belgium) and the North Dobrogea Orogen (Romania)

Determination of the tectonic evolution from fractures, faults, and calcite twins on the southwestern margin of the Indochina Block

Contact Info

Product

Resources

About