Experimental qtz-fs

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Experimentally deformed quartzo-feldspathic rocks

TOP

1-

Experimentally deformed quartz aggregates

2-

Naturally deformed quartz-rich rocks

3-

Experimentally deformed feldspar aggregates

4-

Naturally deformed feldspar rocks

5-

Experimentally deformed quartzo-feldspathic rocks

6-

Naturally deformed quartzo-feldspathic rocks

7-

Experimentally deformed pyroxenite and diabase

8-

Deformation and metamorphic reactions in polyphase rocks

Experimentally deformed quartzo- feldspathic rocks

starting material & regime1 / regime 2 / annealing & melting

Introduction

Most crustal rocks consist of two or more phases, which have quite different strengths or even different deformation mechanisms at a given set of conditions. Thus the strengths and microstructures in such rocks depend on the proportions as well as the arrangement of the various phases, as well as their individual flow laws. This chapter illustrates the microstructures developed in a natural fine-grained granite (aplite) deformed over a range of conditions from lower temperatures where the feldspar is semi-brittle whereas the quartz deforms by regime 1 dislocation creep, to somewhat higher temperatures where the feldspar undergoes regime1 dislocation creep but the quartz deforms by regime 2 dislocation creep.
Most of the samples were deformed in axial compression, with strains ranging up to 85% shortening, at which point the microstructures are almost identical to some natural mylonites, with feldspar augen and quartz ribbons. The microstructures developed in simple shear are illustrated in a few photos, and the effects of static annealing following deformation are illustrated in one pair of photos.
Most of the samples were deformed at conditions where very little if any melt was involved. However, one pair of photos illustrates how a few percent melt can switch the deformation from crystal plasticity to cataclastic flow.
In this chapter, the distinction between regimes 1 and 2 in the headings for the different sections refers to the deformation behavior of quartz, not feldspar.

further reading

5		Experimentally deformed quartzo-feldspathic rocks
5

TOP	1-	Experimentally deformed quartz aggregates	2-	Naturally deformed quartz-rich rocks
	3-	Experimentally deformed feldspar aggregates	4-	Naturally deformed feldspar rocks
	5-	Experimentally deformed quartzo-feldspathic rocks	6-	Naturally deformed quartzo-feldspathic rocks
	7-	Experimentally deformed pyroxenite and diabase	8-	Deformation and metamorphic reactions in polyphase rocks

Experimentally deformed quartzo- feldspathic rocks		starting material & regime1 / regime 2 / annealing & melting

		Introduction Most crustal rocks consist of two or more phases, which have quite different strengths or even different deformation mechanisms at a given set of conditions. Thus the strengths and microstructures in such rocks depend on the proportions as well as the arrangement of the various phases, as well as their individual flow laws. This chapter illustrates the microstructures developed in a natural fine-grained granite (aplite) deformed over a range of conditions from lower temperatures where the feldspar is semi-brittle whereas the quartz deforms by regime 1 dislocation creep, to somewhat higher temperatures where the feldspar undergoes regime1 dislocation creep but the quartz deforms by regime 2 dislocation creep. Most of the samples were deformed in axial compression, with strains ranging up to 85% shortening, at which point the microstructures are almost identical to some natural mylonites, with feldspar augen and quartz ribbons. The microstructures developed in simple shear are illustrated in a few photos, and the effects of static annealing following deformation are illustrated in one pair of photos. Most of the samples were deformed at conditions where very little if any melt was involved. However, one pair of photos illustrates how a few percent melt can switch the deformation from crystal plasticity to cataclastic flow. In this chapter, the distinction between regimes 1 and 2 in the headings for the different sections refers to the deformation behavior of quartz, not feldspar.

		further reading