The structural state of the former lower continental crust in Calabria (S. Italy)

Kruhl, Jörn H.; Huntemann, Torsten

doi:10.1007/bf01829367

Cited by 64 publications

(34 citation statements)

References 13 publications

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“…Hornblende has a strong crystallographic-preferred orientation or texture, with an orthorhombic symmetry. The [001] direction is parallel to the lineation (X), and (100) planes are parallel to the foliation, while [010] direction defines a maximum centered around the Y-axis and elongated in Z, which correlates well with previous studies of amphibole textures (e.g., Gapais and Brun 1981;Siegesmund et al 1989Siegesmund et al , 1994Kruhl and Huntemann 1991;Barroul and Kern 1996;Ivankina et al 2005;Díaz Azpiroz et al 2007;Tatham et al 2008). Textural analyses from EBSD result in sharper distributions but patterns are equivalent to those obtained using neutron diffraction ( figs.…”

Section: Texturesupporting

confidence: 82%

Fabric Development in a Middle Devonian Intraoceanic Subduction Regime: The Careón Ophiolite (Northwest Spain)

Barreiro

Catalán²,

Prior³

et al. 2010

The Journal of Geology

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Section: Texturesupporting

confidence: 82%

Fabric Development in a Middle Devonian Intraoceanic Subduction Regime: The Careón Ophiolite (Northwest Spain)

Barreiro

Catalán²,

Prior³

et al. 2010

The Journal of Geology

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“…Fig. 2(a); (c) sample Kr3270B; both Hercynian lower crust of Calabria, lower and upper part, respectively; histograms after Kruhl & Huntemann (1991); (d) sample A16, (e) sample T87; both Mozambique Belt, peak conditions and retrograde overprint, respectively; (f ) sample TIR21, Bohemian Massif; part of the measured pattern is shown in Fig. 2(e).…”

Section: Scottish Highlands (1)mentioning

confidence: 99%

“…The grain size of the studied quartz ranges from #1 to several millimetres. The subgranulite facies peak conditions of metamorphism (Kruhl & Huntemann, 1991 ). However, the chessboard grains of the chessboard patterns reach diameters of 50-300 mm.…”

mentioning

confidence: 99%

“…crust (Field 4a2) predominantly prismatic SGBs occur ( Fig. 2b) (Kruhl & Huntemann, 1991), with a distinct unimodal frequency distribution (Histogram c, Fig. 3 ).…”

mentioning

confidence: 99%

“…Field 2 in Fig. 3 represents the maximum stability field of the different phases present during facies rocks (Kruhl & Huntemann, 1991;Masberg et al, 1992 ). In addition, basal SGBs and chessboard shearing of the granitic dykes.…”

mentioning

confidence: 99%

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Prism‐ and basal‐plane parallel subgrain boundaries in quartz: a microstructural geothermobarometer

Kruhl

1996

Journal Metamorphic Geology

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462

340

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A B S TR A CT Empirical data on quartz subgrain patterns from various metamorphic rocks show that, at least up to 10 kbar in the stability field of low-quartz, prismatic subgrain boundaries are dominant whereas basal subgrain boundaries are not developed. In the high-quartz stability field, both prismatic and basal subgrain boundaries occur and form typical rectangular ('chessboard') patterns. The likely reason behind the different occurrence of these subgrain patterns is that in high-quartz prismatic glide becomes as easy as, or probably even easier than, basal glide. The two types of subgrain patterns can be clearly distinguished by optical microscopy. Consequently, the occurrence of chessboard subgrain patterns in quartz represents a practicable geothermobarometer. The possibilities of its application are far reaching and include the specification of deformation conditions at high-grade metamorphism, the recognition of syntectonic intrusions and the distinction between pluton emplacement at lower and at higher crustal levels.

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Quartz grain boundaries as fluid pathways in metamorphic rocks

2013

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[1] TEM and SEM/FIB sequential imaging of quartz grain boundaries from contact and regional metamorphic rocks show that most of the grain boundaries are open on the nanometer scale. Three types of voids occur. (i) Roughly 40-500 nm wide open zones parallel to the grain boundaries. They are suggested to be caused by general volume reduction as a result of anisotropic cooling contraction at temperatures decreasing below ca. 300 C, the threshold temperature of diffusion in quartz and of decompression expansion at pressures decreasing below several hundred MPa. (ii) Cavities of variable shape and up to micrometer size along the open grain boundaries and (iii) cone-shaped, nanometer-sized depressions at sites where dislocation lines meet the open grain boundaries. The latter two types are generated by dissolution-precipitation processes. Open grain boundaries, cavities, and depressions form a connected network of porosity, which allows fluid circulation and may affect physical properties of the rocks. The same process is suggested to occur along grain and phase boundaries in other rocks as exemplified in this study, and it should be expected along intracrystalline cracks or cleavage planes.

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The structural state of the former lower continental crust in Calabria (S. Italy)

Cited by 64 publications

References 13 publications

Fabric Development in a Middle Devonian Intraoceanic Subduction Regime: The Careón Ophiolite (Northwest Spain)

Fabric Development in a Middle Devonian Intraoceanic Subduction Regime: The Careón Ophiolite (Northwest Spain)

Prism‐ and basal‐plane parallel subgrain boundaries in quartz: a microstructural geothermobarometer

Quartz grain boundaries as fluid pathways in metamorphic rocks

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