184k views
1 vote
Which of the following might represent the best rock of a pelitic protolith?

a. biotite
b. quartz arenite
c. limestone
d. tonalite
e. NOA

1 Answer

4 votes

Final answer:

Biotite is the best rock to represent a pelitic protolith due to its common occurrence in metamorphosed shale, indicating moderate to high-grade metamorphism typical of pelites.

Step-by-step explanation:

The best rock to represent a pelitic protolith would be biotite. This is because during the metamorphism of a shale protolith, which is rich in clay minerals and typically forms in a sedimentary environment, new minerals that indicate the metamorphic grade can form.

Biotite, a mica mineral, is a common product of metamorphism in pelitic rocks along with other minerals such as chlorite, garnet, and several types of alumino-silicate minerals like kyanite, sillimanite, and andalusite. The presence of biotite suggests that the rock has undergone moderate to high-grade metamorphism typical of pelites. This answer excludes options like quartz arenite, which is a type of sandstone, limestone, which is a carbonate rock, and tonalite, an intrusive igneous rock. The option 'NOA' (Nephrite, Omphacite, and Albite) refers to a different category of metamorphic rock.

User RhysC
by
7.6k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories