Deformation Twins in Hornblende

Rooney, Thomas P.; Riecker, Robert E.; Ross, Malcolm

doi:10.1126/science.169.3941.173

Cited by 55 publications

(14 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous experimental studies focused on the deformation mechanisms of calcic amphibole (hornblende), which are considered to be important in determining the mechanical properties of the lower continental crust. For example, under very high strain rates (~10 −5 s −1 ), natural clinoamphiboles normally deform by (101) mechanical twinning, together with (100)[001] dislocation glide (even at 600–750°C) without dynamic recrystallization [ Rooney et al , , ; Dollinger and Blacic , ]. Dislocation glide, incipient dynamic recrystallization, fracturing, and partial melting of experimentally deformed amphibole were reported in high‐temperature deformation experiments (>600°C) [ Hacker and Christie , ].…”

Section: Discussionmentioning

confidence: 99%

“…Calcic amphibole may have a similar deformation behavior to glaucophane, given their similar crystal structures and chemistry. Previous experimental studies focused on the deformation (100)[001] dislocation glide (even at 600-750°C) without dynamic recrystallization [Rooney et al, 1970[Rooney et al, , 1975Dollinger and Blacic, 1975]. Dislocation glide, incipient dynamic recrystallization, fracturing, and partial melting of experimentally deformed amphibole were reported in high-temperature deformation experiments (>600°C) [Hacker and Christie, 1990].…”

Section: Deformation Mechanisms Of Glaucophane and Lawsonite In Expermentioning

confidence: 99%

See 1 more Smart Citation

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

et al. 2015

View full text Add to dashboard Cite

A series of simple-shear experiments on blueschist was performed at 400-500°C and 1-2.5 GPa to understand the deformation of seismically active, subducting oceanic crust. The experiments show that brittle microstructures are mainly found at pressures of 1-2 GPa, whereas ductile microstructures form at 2.5 GPa. J-indices (a measure of fabric intensity) of glaucophane crystal preferred orientations change systematically with changing shear strain and confining pressure, and the angle between the slip plane and the shear direction of samples deformed at >2 GPa is similar to that of a strain ellipsoid. These results, together with the variable orientations of fine grains in a selected area electron diffraction image at 2 GPa, indicate that the brittle-ductile transition for glaucophane occurs at~2 GPa. In contrast to this, lawsonite in the experiments show abundant fracturing in most specimens and a poor correlation between the J-index, shear strain, and confining pressure. This demonstrates that lawsonite deformed by brittle failure under all experimental conditions. In the case of a starting material that has a strong fabric and deformed under dry experimental conditions, the brittle-ductile transition zone of glaucophane will be much shallower than 2 GPa. Therefore, our initial experimental results on the deformation behavior of blueschist indirectly support the dehydration embrittlement of subducting oceanic crust (glaucophane) as an important factor in the origin of intraplate earthquakes.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Deformation Mechanisms Of Glaucophane and Lawsonite In Expermentioning

confidence: 99%

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

et al. 2015

View full text Add to dashboard Cite

show abstract

“…[100] and [010] Burgers vectors (9.885 A and 18.169 A, respectively) were thought to be too long to be activated (Rooney et al 1970).…”

Section: Deformation Mechanisms Of Amphibolementioning

confidence: 99%

“…Many studies document crystal plastic deformation of hornblende with a dominant (100) [001] slip system from experiments and natural rocks (e.g. Rooney et al 1970;Cumbest et al 1989a, b;Hacker & Christie 1990). Volume diffusion rates are, however, slow in amphiboles (e.g.…”

mentioning

confidence: 99%

Contrasting microstructures and deformation mechanisms in metagabbro mylonites contemporaneously deformed under different temperatures ( c. 650 °C and c. 750 °C)

Baratoux

Schulmann

Ulrich

et al. 2005

View full text Add to dashboard Cite

Deformation mechanisms of amphibole and plagioclase were investigated in two metagabbroic sheets (the eastern and western metagabbros from the Stars M~sto belt, eastern Bohemian Massif), using petrology, quantitative microstructural and electron backscattered diffraction methods. After the gabbroic pyroxene was replaced by amphibole, both gabbroic bodies became progressively deformed. The eastern metagabbros were deformed under temperature of c. 650 ~ and the western metagabbros under c. 750 ~ Subgrain rotation and dislocation creep, characterized by strong crystallographic and shape preferred orientations, operated in plagioclase of the eastern belt during the early stages of deformation. Subsequent randomizing of plagioclase crystallographic preferred orientation is interpreted to be due to grain boundary sliding in the mylonitic stage. Large (50-150 ixm) grain sizes during the mylonitic stages are interpreted to be due to low strain rates. Amphibole is stronger and deforms cataclastically, leading to important grain size reduction when the bulk rock strength drops substantially. In the western belt, plagioclase deformed by dislocation creep accompanied by grain boundary migration (possibly chemically induced) while heterogeneous nucleation and syndeformational grain growth in conjunction with dislocation creep were typical for amphiboles.

show abstract

“…in plagioclase feldspars (Starkey, 1963(Starkey, , 1967Heard, 1969, 1970;Marshall and McLaren, 1977) and in clinoamphiboles (Buck and Paulitsch, 1969;Buck, 1970;Rooney, et al, 1970;Rooney and Riecker, 1973;Rooney et al 1974Rooney et al , 1975Dollinger and Blacic, 1975;Kirby and Christie, 1977).…”

Section: Stresses For Twinning In Minerals and Their Aggregatesmentioning

confidence: 99%

Proceedings of Conference IX; Magnitude of deviatoric stresses in the Earth's crust and upper mantle

Andriese¹

1980

Open-File Report

View full text Add to dashboard Cite

Deformation Twins in Hornblende

Cited by 55 publications

References 4 publications

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

Deformation microstructures of glaucophane and lawsonite in experimentally deformed blueschists: Implications for intermediate‐depth intraplate earthquakes

Contrasting microstructures and deformation mechanisms in metagabbro mylonites contemporaneously deformed under different temperatures ( c. 650 °C and c. 750 °C)

Proceedings of Conference IX; Magnitude of deviatoric stresses in the Earth's crust and upper mantle

Contact Info

Product

Resources

About