Deformation & reactions

8

Deformation and metamorphic reactions in polyphase 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

Deformation and metamorphic reactions

granodiorites / anorthosites

Introduction

The samples illustrated in photos 93 to 98 represent progressively deformed granodiorite from the Corvatsch shear zone at Corvatsch in the Engadine, Swiss Alps. Deformation occurred at 250 to 400°C (lower to mid greenschist facies conditions). Deformation in these rocks involved grain boundary sliding and/or diffusion creep, facilitated by the breakdown of plagioclase to a fine grained aggregate of albite + epidote +/- white mica +/- quartz. The grain size within this mixed-phase assemblage is 2 to 20 mm.
The anorthosite samples come from the same shear zone as the samples of naturally deformed feldspar rocks shown in chapter 4 (Jotun nappe, Norway).

further reading

8		Deformation and metamorphic reactions in polyphase rocks
8

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

Deformation and metamorphic reactions		granodiorites / anorthosites

		Introduction The samples illustrated in photos 93 to 98 represent progressively deformed granodiorite from the Corvatsch shear zone at Corvatsch in the Engadine, Swiss Alps. Deformation occurred at 250 to 400°C (lower to mid greenschist facies conditions). Deformation in these rocks involved grain boundary sliding and/or diffusion creep, facilitated by the breakdown of plagioclase to a fine grained aggregate of albite + epidote +/- white mica +/- quartz. The grain size within this mixed-phase assemblage is 2 to 20 mm. The anorthosite samples come from the same shear zone as the samples of naturally deformed feldspar rocks shown in chapter 4 (Jotun nappe, Norway).

		further reading