Passage I
Metamorphic rocks form when temperature and/or pressure cause changes in preexisting rock. Figure 1 shows the temperature and pressure conditions in which certain facies (categories of metamorphic rocks) are formed.
A rock’s metamorphic grade (a measure of the intensity of metamorphism) is classified on a scale of low (very similar to the original rock) to high (very different from the original rock). Table 1 lists the grades of Facies A–G from Figure 1. Figure 2 shows characteristic minerals that may be present in rocks of a given grade.
2. According to Figure 1, a Facies G rock will most likely form under which of the following pressure and temperature conditions?
Your Answer is
Correct Answer is J
Explanation
Looking at figure 1, the abscissa temperature range corresponding to Facies G is about 150°C-1000°C, and the ordinate pressure range is about 10-14 kb, so the J option is in line