Quartz mylonite from the Simplon fault zone

5.1

ORIENTATION IMAGES OF NATURALLY DEFORMED ROCKS

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Quartz mylonite from the Simplon fault zone

(Christian Pauli)

This particular c-axis orientation image is the first one we ever produced.

The thin section is from a quartz mylonites of the Simplon fault zone (SFZ). The regional geology of the SFZ, the c-axis pole figures and X-ray textures of many deformed quartz veins have been described and determined in detail by Mancktelow (1985, 1987, 1990). Specimen SP 178 is from the Simplon Pass area, where the deformation occurred under conditions of greenschist-facies metamorphism overprinting earlier amphibolite facies assemblages.

SP178 was collected from a strongly deformed quartz vein near the Simplon Line itself. Its c-axes (determined with the U-stage) lie on a slightly kinked single girdle. The microstructure consists of elongate to ribbon shaped 'old grains', with a dispersed development of elongate subgrains and new grains of an average grain size of approximately 80 µm. A shape fabric due to elongate subgrains, new grains and asymmetric grain boundary bulges is developed.

Reference:

Panozzo Heilbronner, R. and C. Pauli (1993). "Integrated spatial and orientation analysis of quartz c-axes by computer-aided microscopy." J. Struct. Geol. 15(3-5): 369-382.

Pauli, C., PhD thesis, Dept. of Geosciences, Basel University (http://www.unibas.ch/earth/)

5.1	ORIENTATION IMAGES OF NATURALLY DEFORMED ROCKS
	top / contents / section 5 / pages -- 5.1 -- 5.2 -- 5.3 -- 5.4 -- 5.5 -- 5.6

		Quartz mylonite from the Simplon fault zone (Christian Pauli)
		This particular c-axis orientation image is the first one we ever produced. The thin section is from a quartz mylonites of the Simplon fault zone (SFZ). The regional geology of the SFZ, the c-axis pole figures and X-ray textures of many deformed quartz veins have been described and determined in detail by Mancktelow (1985, 1987, 1990). Specimen SP 178 is from the Simplon Pass area, where the deformation occurred under conditions of greenschist-facies metamorphism overprinting earlier amphibolite facies assemblages. SP178 was collected from a strongly deformed quartz vein near the Simplon Line itself. Its c-axes (determined with the U-stage) lie on a slightly kinked single girdle. The microstructure consists of elongate to ribbon shaped 'old grains', with a dispersed development of elongate subgrains and new grains of an average grain size of approximately 80 µm. A shape fabric due to elongate subgrains, new grains and asymmetric grain boundary bulges is developed. Reference: Panozzo Heilbronner, R. and C. Pauli (1993). "Integrated spatial and orientation analysis of quartz c-axes by computer-aided microscopy." J. Struct. Geol. 15(3-5): 369-382. Pauli, C., PhD thesis, Dept. of Geosciences, Basel University (http://www.unibas.ch/earth/)