ppt made by ashish and rohit and ankit for best explain of civil engineering

1. Dr.Subhash Technical
Campus
 ASHISH.K. RADADIYA=150830106040
 ROHIT.c.NAGANI=150830106038
 Butani ankit =150830106040
Guided by.
Prof.d. parmar
petrology

2. Introduction to Metamorphic Petrology

3. Overview of Metamorphic Petrology
• What is metamorphism and why do we care?
• Metamorphism and tectonics
• Metamorphic textures and what they tell us about
conditions of formation
• P-T environments
• Metamorphic reactions, equilibrium
• Controls on metamorphic reactions
• Types of metamorphic rocks

4. Review: The Rock Cycle
• What is the rock cycle?
• Idea that a rock (igneous, sedimentary,
metamorphic) is not permanent. Igneous rocks
erode to become sedimentary; sedimentary get
subducted and melted…..
• How do metamorphic rocks form?

5. What is Metamorphism?
Meta = change
Morph = form
Process by which mineralogical and/or textural change occurs in the solid state as a
result of a change in P, T

6. Why Study Metamorphism?
• Interpretation of the conditions and evolution of
metamorphic bodies, including mountain belts,
subduction zones, cratons
• Metamorphic rocks may retain enough inherited
information from their protolith to allow us to interpret
much of the pre-metamorphic history as well

7. The motion of these plates is dictated largely by metamorphic
petrology--principally the pressure-induced transformation of relatively
low density minerals into high density minerals.

8. How do We Study Metamorphism?
• Use chemistry and physics to interpret textures and compositions of minerals
 field studies involve mapping, field interpretation of structure and petrology, and
collection of samples
 laboratory investigations include crystal structure and orientation studies by
diffraction of x-rays, electrons, and neutrons; texture studies by electron
microscopy; and compositional studies using electron microprobe
 theory is based on chemistry and physics, particularly thermodynamics and kinetics
 experiments use high-P, high-T equipment, such as laser-heated diamond-anvil cells
to mimic Earth's interior

9. Some Background
• Metamorphism is continuum between
diagenesis and melting
 Melting is high T end (migmatite)
 Diagenesis is low T end

10. Gneiss/Migmatite
• High-temperature limit grades into melting
• Over the melting range solids and liquids coexist
• Xenoliths, restites, and other enclaves?
• Migmatites (“mixed rocks”) are gradational

11. The various plate-tectonic regimes of the Earth cause rocks to
experience a broad range of pressures and temperatures, which leads
to a broad range of metamorphic minerals and metamorphic rock
types.

13. stable cratons (green): cratons are stable and relatively cold, with 'normal'
thermal gradients of ~20 K/km.
magmatic arcs (red-orange): magmatic arcs are sites where heat is
transported to shallow levels, producing low P metamorphism.

16. continental rifts (orange): crustal extension via normal faulting leads to
transport of heat to shallow levels, followed by cooling to a normal thermal
gradient.

18. subduction zones (blue): rapid subduction transports cold material into the mantle,
producing high P metamorphism.

20. Protolith!!!
• What is the definition of protolith?
• What are some common protoliths?
We’ll return to this question in a lecture or two…….

21. A metamorphic facies is a set of metamorphic mineral assemblages each for a specific
rock compositions, that form over a specific range of P and T.

22. a
b
Metamorphic Rocks

23. Figure 22-1c. Garnet muscovite schist. Muscovite crystals are visible and silvery, garnets occur as large dark porphyroblasts.
Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.
Metamorphic Rocks

24. Metamorphic Rocks

25. THANK YOU