Influence of stress, temperature, and strain on calcite twins constrained by deformation experiments

Rybacki, E.; Evans, Brian; Janssen, C.; Wirth, Richard; Dresen, Georg

doi:10.1016/j.tecto.2013.04.021

Cited by 73 publications

(127 citation statements)

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“…Twinning is associated with strain hardening of the samples (e.g., Barnhoorn et al, 2004;Rybacki et al, 2013). The average twin densities (number of twins/mm), measured on thin sections of samples CMHT8, 3, 4 and CMHT5 in successive 1 mm steps in front of the inclusions, asymptotically decrease from ≈ 67 twins/mm directly adjacent to the inclusion to ≈ 35 twins/mm 5 mm apart, irrespective of the imposed bulk shear strain.…”

Section: Stress Concentrationmentioning

confidence: 99%

Strain localization during high temperature creep of marble: The effect of inclusions

et al. 2014

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The deformation of rocks in the Earth's middle and lower crust is often localized in ductile shear zones. To better understand the initiation and propagation of high-temperature shear zones induced by the presence of structural and material heterogeneities, we performed deformation experiments in the dislocation creep regime on Carrara marble samples containing weak (limestone) or strong (novaculite) second phase inclusions. The samples were mostly deformed in torsion at a bulk shear strain rate of ≈ 1.9x10 -4 s -1 to bulk shear strains γ between 0.02 and 2.9 using a Paterson-type gas deformation apparatus at 900°C temperature and 400 MPa confining pressure. At low strain, twisted specimens with weak inclusions show minor strain hardening that is replaced by strain weakening at γ > 0.1 -0.2.Peak shear stress at the imposed conditions is about 20 MPa, which is ≈8% lower than the strength of intact samples. Strain progressively localized within the matrix with increasing bulk strain, but decayed rapidly with increasing distance from the inclusion tip.Microstructural analysis shows twinning and recrystallization within this process zone, with a strong crystallographic preferred orientation, dominated by {r} and (c) slip in .Recrystallization-induced weakening starts at local shear strain of about 1 in the process zone, corresponding to a bulk shear strain of about 0.1. In contrast, torsion of a sample containing strong inclusions deformed at similar stress as inclusion-free samples but do not show localization. The experiments demonstrate that the presence of weak heterogeneities initiates localized creep at local stress concentrations around the inclusion tips. Recrystallizationinduced grain size reduction may only locally promote grain boundary diffusion creep. Accordingly, the bulk strength of the twisted aggregate is close to or slightly below the lower (isostress) strength bound, determined from the flow strength and volume fraction of matrix and inclusions.

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Section: Stress Concentrationmentioning

confidence: 99%

Strain localization during high temperature creep of marble: The effect of inclusions

et al. 2014

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“…Fontos azonban megemlíteni, hogy a kristályos karbonátkőzetekkel kapcsolatban -azok ásványtani egy szerűsége és relatíve könnyű deformálhatósága következ tében -számos kőzetdeformációs tanulmány született (pl. KOROKNAI 2004, NÉMETH & MÁDAI 2004, RYBACKI et al 2013.…”

Section: Bevezetésunclassified

“…Egy szerű nyírás során az alakváltozás sebességének növe -kedésével az ikerlemezek sűrűsége jellemzően növekszik, vele párhuzamosan pedig az ikerlemezek vastagsága csök -ken, az így kialakuló ikerlamellák nem sorolhatók be egyértelműen a BURKHARD (1993) által meghatározott típu sokba. Ezzel ellentétben a deformáció sebességének csök ke né -sével növekvő vastagságú és kisebb sűrűségű iker le me zek alakulnak ki a kalcitban (RYBACKI et al 2013). …”

Section: Deformációs Ikresedésunclassified

“…A klasztokban a felülbélyegző ikerlemezek sűrűségének növekedésével párhuzamosan azok vastagsága lecsökkent (III. tábla, G), ami az alakváltozás sebességének egyértelmű növekedését jelzi (RYBACKI et al 2013). RYBACKI et al (2013) ezt az ikertípust egyszerű nyí -rásos alakváltozáshoz kötik, ami már ~150 °C-on is kialakulhat.…”

Section: Táblázat a Vizsgált Minták Petrográfiai Jellemzőiunclassified

“…tábla, G), ami az alakváltozás sebességének egyértelmű növekedését jelzi (RYBACKI et al 2013). RYBACKI et al (2013) ezt az ikertípust egyszerű nyí -rásos alakváltozáshoz kötik, ami már ~150 °C-on is kialakulhat. A klasztok erőteljes át -alakulása, finomszemcsés halma zokká történő átkristá lyoso dása, a kőzet képlékeny deformációja szintén a fluidum gyengítő hatásával magya rázható (LIU et al 2002).…”

Section: Táblázat a Vizsgált Minták Petrográfiai Jellemzőiunclassified

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A dorozsmai márvány (Tiszai-főegység) kőzettani újravizsgálata: deformáció és fluidum hatása a mikroszerkezet fejlődésére

Papp¹,

Varga²,

Mészáros³

et al. 2017

Földt. Közl.

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Detailed petrographic studies on marbles are rare in the Hungarian geological literature. Determination of the mineral phases and their grain size, examination of the grain boundaries as well as deformation microstructures, however, can provide a comprehensive information about the metamorphic evolution and the deformation history of a marble unit.The metamorphic basement block near the village of Dorozsma contains a few-meter-thick marble zone within the Békés-Codru Zone. A petrographic study of archive thin sections representing this marble zone was carried out from the boreholes Dorozsma-4, Dorozsma-7 and Dorozsma-54.The fine-grained marble samples show heteroblastic texture with a composition of carbonate + quartz + muscovite + Mg-chlorite ± talc. The carbonate crystal boundaries are dominantly sutured, embayed and rarely curved. All the morpho logical types of deformation twins appear in the samples, but dominantly twin types II and IV are present. The characteristic features of the samples are small dissolution cavities filled with fine crystalline carbonate, blocky quartz and, in some cases, with saddle dolomite. In the samples from the borehole Dorozsma-4 small inclusion free carbonate grains substitute the deformation twins of the large carbonate crystals. In addition, small carbonate neoblasts and Mgchlorite flakes can be found among the large carbonate crystals. Characteristic microstructures of the samples from the well Dorozsma-7 are large sigmoid carbonate clasts in a very fine-grained matrix. The deformation twins of the carbonate clasts can be easily identified and show the signs of recrystallization. These samples beside the carbonate clasts also contain irregularly shaped polycrystalline quartz grains with dissolved edges, undulose extinction and signs of incipient dynamic recrystallization.The microstructures presented above suggest a polyphase deformation. The D 1 deformation event took place above 250 °C based on the relict microstructures. The subsequent D 2 ductile deformation event was a low-temperature dynamic recrystallization with a simple shear component, which could be the result of a hydrolitic weakening effect of hydrothermal fluids during deformation of the Dorozsma marble.Keywords: Dorozsma, marble, petrography, ductile deformation, metasomatism Összefoglalás A márványok petrográfiai vizsgálata napjainkig alárendelt szerepet kapott a hazai földtani szakirodalomban. A már -ványt felépítő ásványfázisok, valamint azok szemcsemérete és a szemcsehatár jellegének meghatározása (kőzetszövet), illetve a deformációs bélyegek feltárása és értelmezése révén azonban átfogó képet kaphatunk a kőzet metamorf fejlő dé -séről és deformációtörténetéről, ami független bizonyítékokkal szolgálhat a befoglaló metamorf kőzettest korreláció -jához.A Békés-Codrui-egységen belül elhelyezkedő, Dorozsma környéki kristályos aljzatban egy maximum néhányszor tíz mé ter vastagságú, markáns töréses deformációt szenvedett márványzóna található. Tanulmányunkban az e zónát mintázó Dorozsma-4, -7 és -54 fúrá...

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Rate‐ and strain‐dependent brittle deformation of rocks

et al. 2014

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Key Points:• Deformation by brittle creep requires less energy than by imposed strain rate • An empirical relation between creep rate and energy deficit is exhibited • A relation between our empirical law and stress corrosion laws is determined Abstract We develop a unifying framework to quantify rate-dependent deformation in the brittle field and establish links between the microscale time-dependent crack growth processes and the macroscopically observed rate dependency. Triaxial deformation experiments have been performed under both constant strain rate and constant stress (creep) conditions on three types of sandstone. The measured relative evolution of P wave speeds as a function of inelastic axial strain is similar for both types of test, despite differences in strain rate of up to 3 orders of magnitude. This similarity indicates that there exists a direct, time-independent link between the microstructural state (as reflected by the variations in P wave speed) and the inelastic axial strain. Comparison of applied stresses between constant strain rate and creep experiments as a function of inelastic strain indicates that creep deformation requires less mechanical work to bring the sample to failure. This energy deficit corresponds to a stress deficit, which can be related to a deficit in energy release rate of the microcracks. We establish empirically that the creep strain rate is given bẏ∝ exp(ΔQ∕ * ), where ΔQ is the stress deficit (negative) and * is an activation stress. This empirical exponential relation between creep strain rate and stress deficit is analogous to rate-and-state friction law. We develop a micromechanical approach based on fracture mechanics to determine the evolution of an effective stress intensity factor at crack tips during creep deformation and estimate the activation volume of the stress corrosion reaction responsible for brittle creep.

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Influence of stress, temperature, and strain on calcite twins constrained by deformation experiments

Cited by 73 publications

References 59 publications

Strain localization during high temperature creep of marble: The effect of inclusions

Strain localization during high temperature creep of marble: The effect of inclusions

A dorozsmai márvány (Tiszai-főegység) kőzettani újravizsgálata: deformáció és fluidum hatása a mikroszerkezet fejlődésére

Rate‐ and strain‐dependent brittle deformation of rocks

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