Chapter 7: Problem 2

Into what metamorphic rocks will a mudrock be transformed at very low, low, medium, and high metamorphic grades?

Short Answer

Expert verified

Mudrock transforms into different metamorphic rocks depending on the metamorphic grade it experiences. At very low grade, mudrock turns into slate; at low grade, it becomes phyllite; at medium grade, it transforms into schist; and at high grade, it evolves into gneiss.

Step by step solution

Brief on Mudrock

Mudrock is a fine-grained sedimentary rock formed from the compaction and hardening of clay, silt, or mud. Mudrocks are commonly called shale, claystone, or mudstone, depending on their composition. Make sure to understand that mudrock is the starting rock type that will undergo metamorphism in this exercise.

Understand Metamorphic Grades

Metamorphic grades are classifications that describe the intensity of the metamorphic process a rock undergoes, mainly the temperature and pressure conditions. The four grades we are focusing on are: 1. Very Low Grade: Characterized by temperatures between 100 and 200 °C, and low pressures. 2. Low Grade: Characterized by temperatures ranging from 200 to 300 °C, and low-to-moderate pressures. 3. Medium Grade: Characterized by temperatures ranging from 300 to 500 °C, and moderate-to-high pressures. 4. High Grade: Characterized by temperatures exceeding 500 °C and high pressures.

Metamorphism of Mudrock at Very Low Grade

At very low metamorphic grade, mudrock transforms into a rock called "slate". Slate is characterized by its perfect cleavage along parallel planes, which allows it to split easily into thin sheets. The main minerals that form in slate are clay minerals like chlorite and muscovite, with small amounts of quartz and feldspar.

Metamorphism of Mudrock at Low Grade

At low metamorphic grade, mudrock transforms into a rock called "phyllite". Phyllite is formed at higher temperatures and pressures compared to slate and exhibits a silky sheen on its surfaces. This sheen comes from the alignment of tiny mica crystals, typically sericite or muscovite. The texture change from slate to phyllite reflects the recrystallization and growth of mica crystals.

Metamorphism of Mudrock at Medium Grade

At medium metamorphic grade, mudrock transforms into a rock called "schist". Schist is characterized by its higher content of platy minerals (e.g., biotite, chlorite) and visible foliation, a layering caused by the alignment of the mineral grains. Additionally, minerals such as garnet, staurolite, andalusite, or kyanite may also form during the metamorphic process at this stage, depending on the pressure-temperature conditions.

Metamorphism of Mudrock at High Grade

At high metamorphic grade, mudrock transforms into a rock called "gneiss". Gneiss has a distinctive banded texture with alternating light and dark bands of minerals, caused by the segregation of felsic (e.g., quartz, feldspar) and mafic (e.g., biotite, amphibole) minerals. This banded texture indicates that the rock underwent significant deformation and recrystallization due to the high temperatures and pressures experienced during metamorphism. In conclusion, the transformation of mudrock through metamorphism at different grades leads to the formation of specific metamorphic rocks: slate at very low grade, phyllite at low grade, schist at medium grade, and gneiss at high grade.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Recommended explanations on Geography Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Into what metamorphic rocks will a mudrock be transformed at very low, low, medium, and high metamorphic grades?

Short Answer

Step by step solution

Brief on Mudrock

Understand Metamorphic Grades

Metamorphism of Mudrock at Very Low Grade

Metamorphism of Mudrock at Low Grade

Metamorphism of Mudrock at Medium Grade

Metamorphism of Mudrock at High Grade

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Geography Textbooks

Living With The Physical Environment

River Landscapes

Global Resource Management

Challenges In The Human Environment

Globalisation

Sustainable Urban Development

Study anywhere. Anytime. Across all devices.