Figure 47

Naturally deformed feldspar aggregates

Figure caption

Naturally deformed feldspar rocks

regime 1 / regime 2 low deformation / regime 2 moderate-high deformation

47

Anorthosite deformed to low strain at granulite grade, with mechanical twinning.

Low strain anorthosite metamorphosed in the granulite facies, Ceilidh Hill, central Australia. In natural deformation of feldspars, the transition from regime 1 to regime 2 occurs at much higher temperatures than quartz, requiring at least upper amphibolite conditions. The bytownite plagioclase grains exhibit polysynthetic twins that terminate within the grains, defining them as secondary twins. (CH 1)

		Naturally deformed feldspar aggregates
		Figure caption

	Naturally deformed feldspar rocks	regime 1 / regime 2 low deformation / regime 2 moderate-high deformation


47		Anorthosite deformed to low strain at granulite grade, with mechanical twinning. Low strain anorthosite metamorphosed in the granulite facies, Ceilidh Hill, central Australia. In natural deformation of feldspars, the transition from regime 1 to regime 2 occurs at much higher temperatures than quartz, requiring at least upper amphibolite conditions. The bytownite plagioclase grains exhibit polysynthetic twins that terminate within the grains, defining them as secondary twins. (CH 1)