Which mineral is commonly present in hornblende hornfels facies?
The granulite facies is the highest grade of metamorphism at medium pressure. The depth at which it occurs is not constant. A characteristic mineral for this facies and the pyroxene-hornblende facies is orthopyroxene.
What is the temperature range of hornblende hornfels facies?
Temperatures as high as 700°–800° C (1,300°–1,470° F) may be reached, depending upon the pressure at the depth of the intrusion. The minerals of the hornfels facies depend largely upon the composition of the parent rock.
What is the difference between Blueschist and greenschist facies?
As nouns the difference between blueschist and greenschist is that blueschist is (geology) a metamorphic rock containing glaucophane while greenschist is a metamorphic rock formed at low temperature and pressure, often with an abundance of green minerals such as chlorite, serpentine, and epidote.
What is the Protolith of Hornfels?
Common protoliths of hornfels include sedimentary rocks such as shale, siltstone, sandstone, limestone and dolomite; igneous rocks such as basalt, gabbro, rhyolite, granite, andesite and diabase; or, metamorphic rocks such as schist and gneiss.
What are three main agents of metamorphism?
The most important agents of metamorphism include temperature, pressure, and fluids.
What two variables are used to define metamorphic facies?
One of the two variables, temperature and pressure, is very high and the other moderate to very high. The presence of water is important in the genesis of these rocks, since rocks that are originally anhydrous may recrystallize in these facies at lower temperatures and pressures than are otherwise required.
Is the hornblende hornfels facies the same as albite epidote facies?
The hornblende-hornfels facies is a facies with the same low pressures but slightly higher temperatures as the albite-epidote facies. Though it is named for the mineral hornblende, the appearance of that mineral is not constrained to this facies. The hornblende-hornfels facies has the following mineral assemblages:
How are greenschist facies different from other facies?
The greenschist facies is at low pressure and temperature. The facies is named for the typical schistose texture of the rocks and green colour of the minerals chlorite, epidote and actinolite. Characteristic mineral assemblages are: The amphibolite facies is a facies of medium pressure and average to high temperature.
How are facies used in a metamorphic terrane?
Facies Series A traverse up grade through a metamorphic terrane should follow one of several possible metamorphic field gradients (Fig. 21.1), and, if extensive enough, cross through a sequence of facies 9 Figure 21.1.
