Deformation of granitoids at low metamorphic grade. I: Reactions and grain size reduction

Gerald, J. D. Fitz; Stünitz, Holger

doi:10.1016/0040-1951(93)90163-e

Cited by 308 publications

(146 citation statements)

References 93 publications

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“…Recrystallization by formation and migration of high-angle grain boundaries seems to be more effective in highly strained zones, whereas recovery predominates elsewhere (e.g. Fitz Gerald and Stünitz, 1993;Trimby et al, 1998;Passchier and Trouw, 2008;Stipp and Kunze, 2008;Druiventak et al, 2012). Accordingly, zones of intense crystal-plastic deformation resulting from the kick experiment are replaced by small new grains during the creep experiment.…”

Section: Recrystallizationmentioning

confidence: 99%

Short-wavelength undulatory extinction in quartz recording coseismic deformation in the middle crust – an experimental study

Trepmann

Stöckhert

2013

Solid Earth

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Abstract. Deformation experiments are carried out on natural vein quartz in a modified Griggs-type solid medium apparatus to explore the preservation potential of microfabrics created by crystal-plastic deformation at high stress, overprinted during subsequent creep at lower stress. A corresponding stress history is expected for the upper plastosphere, where fault slip during an earthquake causes quasiinstantaneous loading to high stress, followed by stress relaxation. The question is whether evidence of crystal-plastic deformation at high stress, hence an indicator of past seismic activity, can still be identified in the microstructure after overprint by creep at lower stresses. First, quartz samples are deformed at a temperature of 400 • C and constant strain rate of 10 −4 s −1 ("kick"), and then held at 900 to 1000 • C at residual stress ("creep"). In quartz exclusively subject to high-stress deformation, lamellar domains of slightly differing crystallographic orientation (misorientation angle < 2 • ) and a few tens of micrometres wide occur. In the transmission electron microscope (TEM), these areas show a high density of tangled dislocations and cellular structures. After "kick and creep" experiments, pronounced short-wavelength undulatory extinction (SWUE) is observed in the polarization microscope. The wavelength of SWUE is up to 10 µm, with oscillatory misorientation of up to a few degrees. TEM inspection reveals domains with high density of dislocations and differing diffraction contrast bound by poorly ordered dislocation walls. Only zones with exceptional damage generated during high-stress deformation are replaced by small new grains with a diameter of about 10 to 20 µm, forming strings of recrystallized grains. For large original grains showing SWUE, the Schmid factor for basal a glide is found to be high. SWUE is taken to reflect high-stress crystal-plastic deformation, the modified microstructure being sufficiently stable to be recognized after subsequent creep as an indicator of past seismic activity.

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Section: Recrystallizationmentioning

confidence: 99%

Short-wavelength undulatory extinction in quartz recording coseismic deformation in the middle crust – an experimental study

Trepmann

Stöckhert

2013

Solid Earth

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“…If the temperature increases or the strain rate decreases, grain boundary migration is dominant. The plastic behavior of quartz points to a minimum temperature condition of *270°C (Fitz Gerald and Stünitz 1993;van Daalen et al 1999). In a recent detailed study of the eastern Tonale Fault, Stipp et al (2002) established that in quartz, the transition from subgrain rotation to grain boundary migration recrystallization occurs at *500°C.…”

Section: Lithologiesmentioning

confidence: 99%

The Sierra Ballena Shear Zone in the southernmost Dom Feliciano Belt (Uruguay): evolution, kinematics, and deformation conditions

Oyhantçabal

Siegesmund

Wemmer

et al. 2009

Int J Earth Sci (Geol Rundsch)

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The Sierra Ballena Shear Zone (SBSZ) is part of a high-strain transcurrent system that divides the Neoproterozoic Dom Feliciano Belt of South America into two different domains. The basement on both sides of the SBSZ shows a deformation stage preceding that of the transcurrent deformation recognized as a high temperature mylonitic foliation associated with migmatization. Grain boundary migration and fluid-assisted grain boundary diffusion enhanced by partial melting were the main deformation mechanisms associated with this foliation. Age estimate of this episode is [658 Ma. The second stage corresponds to the start of transpressional deformation and the nucleation and development of the SBSZ. During this stage, pure shear dominates the deformation, and is characterized by the development of conjugate dextral and sinistral shear zones and the emplacement of syntectonic granites. This event dates to 658-600 Ma based on the age of these intrusions. The third stage was a second transpressional event at about 586 to \560 Ma that was associated with the emplacement of porphyry dikes and granites that show evidence of flattening. Deformation in the SBSZ took place, during the late stages, under regional low-grade conditions, as indicated by the metamorphic paragenesis in the supracrustals of the country rocks. Granitic mylonites show plastic deformation of quartz and brittle behavior of feldspar. A transition from magmatic to solid-state microstructures is also frequently observed in syntectonic granites. Mylonitic porphyries and quartz mylonites resulted from the deformation of alkaline porphyries and quartz veins emplaced in the shear zone. Quartz veins reflect the release of silica associated with the breakdown of feldspar to white mica during the evolution of the granitic mylonites to phyllonites, which resulted in shear zone weakening. Quartz microstructures characteristic of the transition between regime 2 and regime 3, grain boundary migration and incipient recrystallization in feldspar indicate deformation under lower amphibolite to upper greenschist conditions (550-400°C). On the other hand, the mylonitic porphyries display evidence of feldspar recrystallization suggesting magmatic or high-T solid-state deformation during cooling of the dikes.

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“…The infiltration of fluids along microcracks (e.g. Fitz Gerald and Stünitz, 1993) induced mineral reactions combined with a grain size reduction. Paulsson (2003) has found no marked change in composition or oxidation state correlated with the alteration at the locality of Trollslottet investigated in the present paper.…”

Section: Fluid Infiltration Causing Alterationmentioning

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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Deformation of granitoids at low metamorphic grade. I: Reactions and grain size reduction

Cited by 308 publications

References 93 publications

Short-wavelength undulatory extinction in quartz recording coseismic deformation in the middle crust – an experimental study

Short-wavelength undulatory extinction in quartz recording coseismic deformation in the middle crust – an experimental study

The Sierra Ballena Shear Zone in the southernmost Dom Feliciano Belt (Uruguay): evolution, kinematics, and deformation conditions

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

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