Influence of shear heating on microstructurally defined plate boundary shear zones

Platt, J. P.

doi:10.1016/j.jsg.2015.07.009

Cited by 34 publications

(17 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Numerical modeling and theoretical considerations indicate that only large shear zones or cataclastic fault zones can develop a persistent thermal anomaly (ΔT ~ 50–150 °C) (Burg & Gerya, ; Ben‐Zion & Sammis, ; Maino et al, ; Platt, ; Jaquet & Schmalholz, ). However, seismic deformation is expected to generate very high (ΔT 800–1500 °C), though extremely localized and transient, thermal anomalies, eventually associated with frictional melting on narrow fault planes (Bizzarri, ; Di Toro & Pennacchioni, ; Killick & Roering, ; Lachenbruch, ).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the signature of shear heating can be dissipated or masked by several factors, including (i) conductive heat loss (Platt, ), (ii) a preexisting metamorphic history, (iii) efficient heat diffusion across the shear zone, (iv) advection of high‐temperature crustal blocks from depth, (v) the lack of thermal markers recording transient thermal conditions, and (vi) upwelling of hot fluids or injection of melts (e.g., Ault et al, ; Decarlis et al, ; Gottardi et al, ; Lacroix et al, ; Mamadou et al, ; Morton et al, ; O'Neil & Hanks, ; Scholz, ; Sutherland et al, ; Torgersen & Viola, ). For these reasons, only a few field‐based studies have quantified how much mechanical heat is produced by brittle and/or ductile deformation (Ault et al, ; England et al, ; Evans et al, ; Fulton et al, ; Maino et al, ; Mori et al, ; Nabelek & Liu, ).…”

Section: Introductionmentioning

confidence: 99%

“…It is widely agreed that most of the mechanical work generated during ductile or brittle deformation is dissipated as shear heating (e.g., Brun & Cobbold, 1980;McKenzie & Brune, 1972;Scholz, 1980;Molnar & England, 1990;Mair & Marone, 2000;Nabelek et al, 2010;Burg & Gerya, 2005;Rice, 2006;Ben-Zion & Sammis, 2013;Thielmann & Kaus, 2012;Duretz et al, 2014;Schmalholz & Duretz, 2015;Platt, 2015, Mako & Caddick, 2018. The magnitude of the viscous component of shear heating (H v ) is commonly expressed as…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Time‐Dependent Heat Budget of a Thrust from Geological Records and Numerical Experiments

et al. 2020

View full text Add to dashboard Cite

We present thermometric measurements and numerical simulations of the thermal budget of a shallow thrust (5–7 km of depth). We determine the temperatures of synkinematic minerals by chlorite geothermometer and illite crystallinity index and sheared veins with stable isotope and fluid inclusion microthemometry. The fault zone attained temperature higher than the wall rocks (ΔT of ~50 °C). Some heavily damaged rocks retain a minor but systematic record of a further temperature increase up to 150 °C, and the isotopic signal of fluids indicates a proximal source localized close to the fault zone. We simulated the geological evolution with a suite of elasto‐visco‐plastic thermomechanical models using a 2‐D finite difference code that reproduces the stress, strain, temperature, and pressure variations occurring within the thrust zone. Results indicate that shear heating during distributed cataclastic flow can account for a moderate and persistent temperature increment (ΔT 5–30 °C). Transient higher temperature pulses (50–90 °C) are reproduced simulating coseismic slip along narrow fault planes localized within the broad cataclastic zone. Integration of analytical data and numerical results supports the slow creeping frictional‐viscous deformation as effective mechanism explaining the low‐T part of the thermal history. Seismic deformation equivalent to moment magnitude Mw > 6.5–7.0 earthquakes is required to fully account for the thermal signal, including the extreme peak temperature.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time‐Dependent Heat Budget of a Thrust from Geological Records and Numerical Experiments

et al. 2020

View full text Add to dashboard Cite

show abstract

“…At the most basic level, the strain gradient indicates a mechanical contrast between the margins and the core of the granite, which requires weakening (cf. Platt, 2015) from what was arguably a homogeneous granite at the outcrop scale. As noted above, microscale changes across the gradient include the proportion of recrystallized material and therefore overall average grain size, strength of the crystallographic fabric in quartz, and mineral chemistry of Fe-Mg-bearing phases and plagioclase at the granite margin (Figs.…”

Section: Strain Localization Mechanismsmentioning

confidence: 94%

“…Molnar and Dayem, 2010). However, for a zone of incipient localization to develop into mechanically and geologically significant structures such as those just mentioned, rheological weakening of an order of magnitude or more (e.g., Gerbi et al, 2010;Platt, 2015) must occur.…”

Section: Introductionmentioning

confidence: 99%

Timing and anatomy of granitic strain gradients in the Grenville Front tectonic zone, Ontario, Canada

et al. 2017

View full text Add to dashboard Cite

Observations of physical and chemical changes across strain gradients can provide information about the processes that lead to localization and therefore provide better tools for prediction of spatial and temporal strain patterns. In contrast to the many chemical and microstructural studies of natural shear zones in metapelites and mafic lithologies, few have described kilometer-scale granitic strain gradients despite the fact that granitoid bodies make up much of the orogenic crust. This study reports microstructural and compositional data across two amphibolite-facies strain gradients from middle crust of the Grenville orogen. The kilometer-scale gradients, defined by stretched enclaves and foliation intensity, form parts of the Boundary and Bad River shear zones, located along the east and west borders of the Bad River granite in the southwestern Grenville Front tectonic zone in Ontario, Canada. The granite is bounded on both sides by older orthogneiss (ca. 1720 Ma igneous crystallization age). Zircon U-Pb ages indicate that the granite crystallized from a magma at ca. 1465 Ma, with metamorphic growth at ca. 1020 Ma. Zircons in the orthogneiss record metamorphic growth during these two younger episodes. These age determinations are consistent with other regional dates and indicate that the strain gradients in the Bad River granite formed during the Grenville orogeny. Whole-rock analyses reveal minor heterogeneity in major-element distribution in the granite that can be attributed to igneous processes, and homogeneity in the trace elements, indicating that strain did not affect the bulk-rock composition. In contrast, microstructural and chemical analyses across the two strain gradients indicate some correlation with strain: slight changes in mineral compositions, development of crystallographic preferred orientations in quartz, an increase in recrystallized fraction, a reduction in recrystallized grain size, and the development of a mixed-phase matrix. However, most of these variations are subtle and occur at different positions across the gradients. The spatial distribution of the microscale changes suggests a change in deformation mechanisms toward the margin, accompanying increased localization. The rheological weakening at the Bad River granite margins was the product of microstructural, rather than mineralogical, change, in contrast to nearby shear zones in more mafic units.

show abstract

Shear zones – A review

Fossen

Cavalcante

2017

Earth-Science Reviews

328

167

View full text Add to dashboard Cite

Influence of shear heating on microstructurally defined plate boundary shear zones

Cited by 34 publications

References 74 publications

Time‐Dependent Heat Budget of a Thrust from Geological Records and Numerical Experiments

Time‐Dependent Heat Budget of a Thrust from Geological Records and Numerical Experiments

Timing and anatomy of granitic strain gradients in the Grenville Front tectonic zone, Ontario, Canada

Shear zones – A review

Contact Info

Product

Resources

About