Diffusional crack healing in quartz

Smith, David L.; Evans, Brian

doi:10.1029/jb089ib06p04125

Cited by 262 publications

(145 citation statements)

References 31 publications

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“…C [Smith and Evans, 1984;Laubach, 1989]. The minimum depth of healing in the present study, D h , is estimated to be at least 1 km, assuming that the geothermal gradient is 50-100 C/km in the study area [Tanaka et al, 1999]; OF would have formed at a shallower depth.…”

Section: Discussionmentioning

confidence: 99%

“…Based on cross-cutting relationships between microfracture types, we suggest that HF is older than OF. HF observed in the damage zone was previously OF before becoming a healed plane of secondary fluid inclusions due to the local-scale diffusive transport of the constitutive atoms in the crystallizing minerals [Smith and Evans, 1984]. Experimental and field studies have shown that microfracture healing likely occurs at ambient temperatures above~100…”

Section: Discussionmentioning

confidence: 99%

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Microfractures within the fault damage zone record the history of fault activity

Mizoguchi

Ueta

2013

Geophysical Research Letters

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For faults without sedimentary covers, there is no robust method to obtain paleoseismic data that is crucial for the prediction of future damaging earthquake events. Sudden failure along faults during earthquakes induces off‐fault damage surrounding such basement faults. We showed that the Quaternary‐active fault has the damage zone characterized by a fracture density that decays exponentially with distance from the fault for both healed and open microfractures. In contrast, Quaternary‐inactive faults contain only healed microfracture damage zone. Cross‐cutting relationships between microfractures and a minimum healing temperature of ~100°C suggest that healed microfractures formed before, and at deeper levels, than did unhealed microfractures. The damage zone defined by open microfractures reflects the recent fault movement during exhumation, associated with erosion and regional uplift, from the maximum depth at which microfractures may remain unhealed. Microfracture analysis can therefore be used to examine the history of basement fault activity.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Microfractures within the fault damage zone record the history of fault activity

Mizoguchi

Ueta

2013

Geophysical Research Letters

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“…6). We know little of this early brittle deformation, but these fluid inclusion arrays have microstructures similar to those generated during hydrothermal diffusional healing of cracks (Smith and Evans, 1984;Beeler and Hickman, 2015). As a result, early brittle deformation, infiltration of water along open cracks, and crack healing appear to be important to the early introduction of water to quartz grain interiors (Kronenberg et al, 1986FitzGerald et al, 1991;Diamond et al, 2010;Tarantola et al, , 2012Stünitz et al, 2017).…”

Section: Wide Variations In Oh Contentmentioning

confidence: 99%

Synchrotron FTIR imaging of OH in quartz mylonites

et al. 2017

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Abstract. Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4-8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x − y stage, spectra have been collected over specimen areas of nearly 4.5 mm 2 . This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland) and Main Central Thrust (Himalayas).Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT) exhibit a large and variable 3400 cm −1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and paragneisses deformed under amphibolite conditions in the hanging wall to the Main Central Thrust (MCT) exhibit smaller broad OH bands, and spectra are dominated by sharp bands at 3595 to 3379 cm −1 due to hydrogen point defects that appear to have uniform, equilibrium concentrations in the driest samples. The broad OH band at 3400 cm −1 in these rocks is much less common. The variable water concentrations of MT quartzites and lack of detectable water in highly sheared MCT mylonites challenge our understanding of quartz rheology. However, where water absorption bands can be detected and compared with deformation microstructures, OH concentration maps provide information on the histories of deformation and recovery, evidence for the introduction and loss of fluid inclusions, and water weakening processes.

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“…For a pegmatite sheet of a thickness in the range of decimetres the thermal perturbation may have a life-time of a couple of weeks before the maximum temperature in the centre of the vein has dropped to nearly the pre-intrusive host rock temperature. Experimental studies on healing of microcracks (Smith and Evans, 1984) have revealed that the healing rate is strongly dependent on temperature. At temperatures of 300 8C, healing of microcracks in quartz is predicted to be a matter of days to weeks, and at higher temperatures it may proceed quasi-instantaneously when compared with geological time scales.…”

Section: Infiltration Of Fluid Into the Damaged Host Rock And Lifetimmentioning

confidence: 99%

Magma-driven hydraulic fracturing and infiltration of fluids into the damaged host rock, an example from Dronning Maud Land, Antarctica

Engvik

Bertram

Kalthoff

et al. 2005

Journal of Structural Geology

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Excellent outcrops in Dronning Maud Land, Antarctica, provide unique insight into the mode and extent of fluid infiltration into metamorphic and plutonic rocks in the middle crust. The fluids are liberated from pegmatitic veins and give rise to alteration halos. In the alteration halos, the conspicuous change in colour is correlated with (1) hydration mineral reactions, and (2) high density of microcracks in quartz and feldspar exceeding that observed in the unaltered host rock by an order of magnitude. The field relations indicate that the veins originated as melt-driven hydraulic fractures, sealed by pegmatite and aplite crystallising from volatile-rich melts, with the alteration halo being the wake of the process zone formed at the tip of the propagating fractures. It is proposed that (1) the size of the alteration zone and the width of the vein are correlated, resulting in higher values of both these quantities for cracks propagating at higher velocities and consequently higher crack propagation toughnesses; (2) the damage zone is characterised by a transient state of high permeability which was short-lived due to rapid healing and sealing of microcracks; (3) the infiltration and retrogression of the high-grade rocks can be considered as a quasi-instantaneous process on geologic time scales with a duration of hours to weeks. q

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Diffusional crack healing in quartz

Cited by 262 publications

References 31 publications

Microfractures within the fault damage zone record the history of fault activity

Microfractures within the fault damage zone record the history of fault activity

Synchrotron FTIR imaging of OH in quartz mylonites

Magma-driven hydraulic fracturing and infiltration of fluids into the damaged host rock, an example from Dronning Maud Land, Antarctica

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