Pressure dissolution and cleavage in the Martinsburg Shale

Wright, Thomas O.; Platt, Lucian B.

doi:10.2475/ajs.282.2.122

Cited by 146 publications

(46 citation statements)

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“…(e.g. Sibson, 1986;Wright and Platt, 1982). Each of these inelastic deformational processes slowly reduces stresses in a manner that is simulated in our models as a complete stress drop.…”

Section: Methodsmentioning

confidence: 92%

Is plane strain a valid assumption in non-cylindrical fault-cored folds?

Shackleton

Cooke

2007

Journal of Structural Geology

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Many algorithms assume plane strain to construct, model and restore fault-cored folds. Using mechanical models that allow heterogeneous transport in three dimensions, we explore the distribution and magnitude of out-of-plane transport in plunging fault-cored anticlines and provide guidelines of where plane strain should and should not be applied. We developed a new technique of incrementing infinitesimal elastic strains to produce folds with aspect ratios similar to natural folds. Map views of displacement vectors show that in general, out-of-plane displacement is localized near the lateral fold tips. Cross-sections show that out-of-plane transport is depth dependent with out-of-plane displacement increasing toward the surface. Flexural slip surfaces compartmentalize out-of-plane transport within distinct mechanical units, with the maximum outof-plane displacement near the tops of mechanical units. Two-dimensional models with additional frictionally slipping bed contacts suggest that freely slipping contacts can approximate the deformation of many frictionally slipping contacts. We show that out-of-plane transport is significant in the simplest non-cylindrical folds, and suggest that complex non-cylindrical structures should not be modeled using plane strain exclusively. We also show that flexural slip surfaces exert a significant control on the magnitude and structural position of out-of-plane transport in our models.

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“…(e.g. Sibson, 1986;Wright and Platt, 1982). Each of these inelastic deformational processes slowly reduces stresses in a manner that is simulated in our models as a complete stress drop.…”

Section: Methodsmentioning

confidence: 92%

Is plane strain a valid assumption in non-cylindrical fault-cored folds?

Shackleton

Cooke

2007

Journal of Structural Geology

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“…It is clear from the rock record that significant strains in the brittle regime are accommodated by pressure solution (e.g., Engelder 1979;Wright and Platt 1982), which is likely an important factor along brittle faults (e.g., Collettini and Holdsworth 2004;Anderson et al 2010). In contrast to other known low-to moderate-temperature deformation processes, both theoretical arguments and experimental data suggest that pressure solution in rocks and minerals has a viscous rheology (e.g., Rutter 1983;Bos and Spiers 2001).…”

Section: Introductionmentioning

confidence: 87%

Episodic Dissolution, Precipitation, and Slip along the Heart Mountain Detachment, Wyoming

Swanson

Wernicke

Hauge³

2016

The Journal of Geology

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A B S T R A C TThe Heart Mountain allochthon is among the largest landslide masses in the rock record. The basal fault, the Heart Mountain detachment, is an archetype for the mechanical enigma of brittle fracture and subsequent frictional slip on low-angle faults, both of which appear to occur at ratios of shear stress to normal stress far below those predicted by laboratory experiments. The location of the detachment near the base of thick cratonic carbonates, rather than within subjacent shales, is particularly enigmatic for frictional slip. A broad array of potential mechanisms for failure on this rootless fault have been proposed, the majority of which invoke single-event, catastrophic emplacement of the allochthon. Here, we present field, petrographic, and geochemical evidence for multiple slip events, including crosscutting clastic dikes and multiple brecciation and veining events. Cataclasites along the fault show abundant evidence of pressure solution creep. Banded grains, which have been cited as evidence for catastrophic emplacement, are associated with stylolitic surfaces and alteration textures that suggest formation through the relatively slow processes of dissolution and chemical alteration rather than dynamic suspension in a fluid. Temperatures of formation of faultrelated rocks, as revealed by clumped isotope thermometry, are low and incompatible with models of catastrophic emplacement. We propose that displacement along the gently dipping detachment was initiated near the base of the carbonates as localized patches of viscous yielding, engendered by pressure solution. This yielding, which occurred at very low ratios of shear stress to normal stress, induced local subhorizontal tractions along the base of the allochthon, raising shear stress levels (i.e., locally rotating the stress field) to the point where brittle failure and subsequent slip occurred along the detachment. Iteration of this process over geological time produced the observed multikilometer displacements. This concept does not require conditions and materials that are commonly invoked to resolve the stress paradox for low-angle faults, such as near-lithostatic fluid pressures or relative weakness of phyllosilicates in the brittle regime. Cyclic interaction of viscous creep (here by pressure solution) and brittle failure may occur under any fluid pressure conditions and within any rock type, and as such it may be an attractive mechanism for slip on "misoriented" fault planes in general.

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“…For example, Wright & Platt (1982) and Beutner & Charles (1984) have measured volume losses greater than 50% in such rocks. Deformation partitioning-that is, the distribution of progressive shearing and shortening components of deformation-can occur on a grain scale during the formation of a slaty cleavage in the classic sense (Fig.…”

Section: Dissolution and Solution Transfermentioning

confidence: 97%

Porphyroblast nucleation, growth and dissolution in regional metamorphic rocks as a function of deformation partitioning during foliation development

Bell

Rubenach

Fleming

1986

Journal Metamorphic Geology

246

194

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In regional metamorphic rocks, the partitioning of deformation into progressive shearing and progressive shortening components results in strain and strain-rate gradients across the boundaries between the partitioned zones. These generate dislocation density gradients and hence chemical potential gradients that drive dissolution and solution transfer. Phyllosilicates and graphite are well adapted to accommodating progressive shearing without necessarily building up large dislocation density gradients within a grain, because of their uniquely layered crystal structure. However, most silicates and oxides cannot accommodate strain transitions within grains without associated dislocation density gradients, and hence are susceptible to dissolution and solution transfer.As a consequence. zones of progrcssivc shearing become zones of dissolution of most minerals, and of concentration of phyllosilicates and graphite. Exceptions are mylonites, where strain-rates are commonly high enough for plastic deformation to dominate over diffusion riitcs and therefore over dissolution and solution transfer. Porphyroblastic minerals cannot nucleate and grow in zones of active progressive shearing, as they would be dissolved by the effects of shearing strain on their boundaries. However, they can nucleate and grow in zones of progressive shortening and this is aided by the propensity for microfracturing in these zones, which allows rapid access of fluids carrying the material presumed to be necessary for nucleation and growth. Zones of progessive shortening also have a number of characteristics that help to lower the activation energy barrier for nucleation, this includes a build up of stored strainenergy relative to zones of progressive shearing, in which dissolution is occuring.Porphyroblast growth is generally syndeformational. and previously accepted criteria for static growth are not valid when the role of deformation partitioning is taken into account.Porphyroblasts in a contact aureole do not grow statically either, as microfracturing, associated with emplacement, allows access of fluids in a fashion that is similar to microfracturing in zones of progressive shortening.The criteria used for porphyroblast timing can be readily accommodated in terms of deformation partitioning, reactivation of deforming foliations, and a general lack of rotation of porphyroblasts, with the spectacular exception of genuinely spiralling garnet porphyroblasts.

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Pressure dissolution and cleavage in the Martinsburg Shale

Cited by 146 publications

References 0 publications

Is plane strain a valid assumption in non-cylindrical fault-cored folds?

Is plane strain a valid assumption in non-cylindrical fault-cored folds?

Episodic Dissolution, Precipitation, and Slip along the Heart Mountain Detachment, Wyoming

Porphyroblast nucleation, growth and dissolution in regional metamorphic rocks as a function of deformation partitioning during foliation development

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