Modification of fluid inclusions in quartz by deviatoric stress. II: experimentally induced changes in inclusion volume and composition

Diamond, Larryn W.; Tarantola, Αlexandre; Stünitz, Holger

doi:10.1007/s00410-010-0510-6

Cited by 57 publications

(65 citation statements)

References 42 publications

(55 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

View full text Add to dashboard Cite

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.

show abstract

Section: Wide Variations In Oh Contentmentioning

confidence: 99%

Synchrotron FTIR imaging of OH in quartz mylonites

et al. 2017

View full text Add to dashboard Cite

show abstract

“…This article describes the modifications of shapes and microstructures observed in the experiments (''microstructure'' is used herein as an equivalent of the traditional petrological term ''texture''). A companion article (Diamond et al 2010) reports the changes in fluid inclusion volumes and composition in the same set of experiments.…”

Section: Introductionmentioning

confidence: 99%

Modification of fluid inclusions in quartz by deviatoric stress I: experimentally induced changes in inclusion shapes and microstructures

Tarantola

Diamond

Stünitz

2010

Contrib Mineral Petrol

Self Cite

View full text Add to dashboard Cite

Fluid inclusions in quartz are known to modify their shapes and microstructures (textures) during weak plastic deformation. However, such changes have not been experimentally demonstrated and criteria are not available to relate them to paleostress conditions. To address these issues, quartz crystals containing natural CO 2 -H 2 O-NaCl fluid inclusions have been experimentally subjected to compressive deviatoric stresses of 90-250 MPa at 700°C and *600 MPa confining pressure. Strains of up to 1% cause the inclusions to develop irregular shapes and to generate microcracks in crystallographic planes oriented subperpendicular to the major compression axis, r 1 . The uniform alignment of the microcracks imparts a planar fabric to the samples. The microcracks heal and form swarms of tiny satellite inclusions. These new inclusions lose H 2 O by diffusion, thereby triggering plastic deformation of the surrounding quartz via H 2 O-weakening. Consequently, the quartz samples deform plastically only in domains originally rich in inclusions. This study shows that fluid inclusions deformed by deviatoric stresses may indeed record information on paleostress orientations and that they play a key role in facilitating crystal-plastic deformation of quartz.

show abstract

“…Diffusion is assumed to be the mechanism of H 2 O transport through the quartz crystal according to specific fugacity gradients. However, the boundary conditions, i.e., the parameters that control diffusion, are not always well defined in re-equilibration experiments and are often only theoretically deduced [28]. The experimental work in the present study reveals a different type of H 2 O transport through the quartz crystal, which is not triggered by fugacity gradients, but by hydrostatic pressure gradients.…”

Section: Preferential H 2 O Lossmentioning

confidence: 69%

“…The experiments illustrate that H 2 O can also diffuse against specific H 2 O fugacity gradients, and this process can be characterized as a crystal-recovery process, in which the included fluid is expelled from the crystal through migration of fluid pockets away from the inclusion. The results of this crystal-recovery process have been described in only a few studies on re-equilibration of fluid inclusions, both natural and synthetic [5,[26][27][28][29], whereas other work revealed only textural evidence of the occurrence of this process [6]. A direct consequence of this process would be the formation of a halo of relatively small H 2 O-rich inclusions around the original larger fluid inclusion and the recrystallization and inward growth of inclusion walls into a highly irregular pattern.…”

Section: Preferential H 2 O Lossmentioning

confidence: 99%

See 1 more Smart Citation

Re-Equilibration Processes in Fluid Inclusion Assemblages

Bakker

2017

Minerals

View full text Add to dashboard Cite

Post-entrapment modifications reduce the reliability of fluid inclusions to determine trapping conditions in rock. Processes that may modify fluid inclusion properties are experimentally identified in this study using synthetic fluid inclusions in quartz with a well-defined composition and density. Modifications are characterized with microthermometry (homogenization and dissolution temperatures) and Raman-spectroscopy in binary fluid systems H 2 O-D 2 O and H 2 O-NaCl. Three distinct processes were identified in this study: (1) diffusion of H 2 O and D 2 O; (2) crystal-recovery, expulsion of H 2 O and accumulation of quartz in inclusions (preferential H 2 O loss); (3) irreversible total volume increase at the α-β quartz transition. Diffusion is caused by H 2 O fugacity gradients and can be modelled according to classical diffusion models. The variability of re-equilibrated properties in fluid inclusion assemblages depends on time, temperature, diffusion distance and the size of fluid inclusions. Negative pressure gradients (internal under-pressure) induce the crystal-recovery process, in which H 2 O is preferentially extracted from inclusions that simultaneously shrink by the inward growth of quartz. This process reduces the H 2 O concentration and increases the fluid density by total volume loss. Temperature and time are also controlling factors of this process, which is able to transport H 2 O against fugacity gradients.

show abstract

Modification of fluid inclusions in quartz by deviatoric stress. II: experimentally induced changes in inclusion volume and composition

Cited by 57 publications

References 42 publications

Synchrotron FTIR imaging of OH in quartz mylonites

Synchrotron FTIR imaging of OH in quartz mylonites

Modification of fluid inclusions in quartz by deviatoric stress I: experimentally induced changes in inclusion shapes and microstructures

Re-Equilibration Processes in Fluid Inclusion Assemblages

Contact Info

Product

Resources

About