Igneous and Metamorphic Petrology

GEOL-4711  Spring 2014

Review for Lecture Final

 

Comprehensive Material: Approximately 30-40% of the final will be taken from Lecture Exams #1 and #2.  The questions will be identical except for a possible phase diagram questions that use the same diagram with a different starting compositions.  The remaining 60-70% will be new material covered by the following review questions.

 

Alkaline Magmatism (Chapter 19)

1) List and describe the important petrographic, mineralogic and geochemical characteristics of alkaline magma.  List and describe the common rock types associated with alkaline magma? 

2) Describe the general abundance and tectonic/geographic distribution of alkaline magma.  Give geographic examples of each of these.

3) List and describe the evidence that indicates a deep mantle origin for alkaline magma.  Why are they believed to form by low degrees of partial melting of the mantle?  Describe the evidence that indicates measurable crystal fractionation occurs in alkaline magma.

4) Define the following terms: hawaiite, mugearite, trachyte, and basanite.

 

Nature of Metamorphism (Chapters 21, 22 and 25)

1) Give a concise definition for metamorphism.

2) List and describe the three major agents of metamorphism.  Give numeric estimates of the geothermal and geobaric gradients.  What is the cause of these increases in temperature and pressure.  Explain how and why both change with substantial depth.  List and describe the effects of increased temperature on rocks and minerals.

3) List and describe the three major types of directed pressure. 

4) What is the composition and source of chemical fluids involved in metamorphism?  List and describe the three major fluid-related metamorphic processes.

5) What are the conditions and effects of contact metamorphism?  Why does epizonal metamorphism alter rocks more than katazonal?  What are some typical metamorphic minerals that form during contact metamorphism?

6) Describe the conditions and effects of subseafloor metamorphism.  Which elements are lost or gained during the process?  What is a spilite and how can it be distinguished from an alkaline olivine basalt or MORB?

7) Describe the conditions and effects of burial metamorphism.  At what depths does it occur? Why does it only form low-grade metamorphic rocks with granoblastic textures?

8) Describe the conditions and effects of dynamic metamorphism.  Explain why cohesive solid-(ductile) state flow occurs instead of brecciation.  How are individual crystals changed by this process?  How are mylonites defined and recognized?

9) Describe the conditions and effects of regional metamorphism.  Along which plate tectonic boundaries does it occur?  Explain why the geothermal gradient is usually increased during the process.  Which type of rocks are formed during this type of metamorphism?   

10) Compare and contrast ductile and cataclastic flow.  Name and describe some of the crystallographic processes that are associated with plastic or ductile flow.

11) Name and describe the three major types of solid-state crystal growth or recrystallization associated with metamorphism.  Give examples of each. 

12) Define and illustrate how granoblastic fabric develops in a metamorphic rock.  What is the Crystalloblastic Series?  List two mineral examples for each of the following crystalloblastic series (most euhedral, intermediate euhedral and least euhedral).

13) Define, compare and contrast porphyroclasts and porphyroblasts.  Describe how each are recognized. 

14) Compare, contrast and give examples of pretectonic, syntectonic and post-tectonic crystal growth.  Describe how each is recognized.

15) Describe how metamorphic grade is used to describe metamorphic processes and materials.  How is each grade recognized?  What is the difference between prograde and retrograde metamorphism?  How is each recognized?

16) What is a metamorphic zone?  How are they recognized?  Define and describe isograds.  What are some of the problems in using metamorphic zones?

17) Define and describe metamorphic facies.  Explain why they are considered the best classification of metamorphic rocks.  List at least two of the metamorphic minerals that characterize each of the following metamorphic facies: zeolite, prehnite-pumpellyite, greenschist, amphibolite; granulite, blueschist and eclogite.  Describe the conditions under which each forms.

18) What is a chemographic diagram?  How and why are they used?  Be able to draw and interpret an Escola or ACF Diagram.  Why is this diagram only used for certain types of rocks?  Explain how the rock data are plotted on this diagram. 

19) What are the controlling factors that determine which metamorphic minerals form in a rock?

20) Define the following terms: effective stress, contact aureole, hornfel, metasomatism, spilites, mylonite, cataclastic, ductile flow, granoblastic, poikiloblasts, porphyroclasts, and augen.