Metamorphic Rock Analysis and Interpretation Activity 7.3 Date: Name: les of sed
ID: 288472 • Letter: M
Question
Metamorphic Rock Analysis and Interpretation Activity 7.3 Date: Name: les of sedimentary limestone and metamorphic marble in Fig. A7.3.1 I. These rocks are both comnposed of the same mineral. What is it) What sest could you perform on the rocks to be sure? 2. How is the sesture of these two rocks differen? marble Figure A7.3.1 BFigure A7.3.2 shows three metamorphic rocks that had a mudstone or shale protolith and that display excellent foliation. The three specimens represent different metamorphic grades. Higher-grade types can also be formed from protoliths other than mudstone, but we are going to think about a progression from mudstone through successively more intense metamorphism I. Describe the change in grain size from slate to schist. 2. How does the texture of phyllite differ from that of schist? S. Why do you think that the micas (flat minerals) in these rocks are all parallel, or nearly so, to one another? phylite schist slate 1 cm 1 cm 1 cm A7.3.2 white layers in this metamorphic rock-a gneiss-were originally flat, parallel layers Analyze the rock sample in Fig- 7.5A. The that were later folded during metamorphism. Describe a process that could account for folded without breaking during regional metamorph how this strong, dense gneiss was Analyze the foliated metamorphic rock sample in Fig. A7.3.3. 1. What mineral defines the foliation in this rock? 2. Notice that the rock consists mostly of muscovite but also contains scattered garnet crystals What is the name for tdhi kind of texture?Explanation / Answer
Activity 7.3
A. 1. Calcite. It can be tested simply by pouring acid( generally dil. HCl) which gives effervescence.
2. Limestone is composed of fine grains along with calcareous shells of some fossils. Marble is formed by high grade regional metamorphism and thus have granoblastic texture( coarse equidimensional grains)
B. 1. Grain size increases from slate to phyllite to schist.
2. Phyllite is foliated but the foliations are less developed and subparallel while in schist foliations are well developed closely spaced and parallel.
3. Slate , phyllite and schist are formed by the action of directed pressure so the micas are arranged parallel to each other in a direction perpendicular to the direction of pressure.
C. Figure 7.5A not given in question.
D. 1.muscovite
2.porphyroblastic texture
3.garnetiferrous micaschist
4.argillaceous protolith
E.1. This rock is foliated as we can see alternate green and white bands.
2.granitic gneiss
3. Quartzofeldspathic/ granitic protolith
Activity 7.5
A.central sillimanite zone is highest grade metamorphosed rock.
B.1. Sillimanite zone has metamorphosed at high pressure and temperature because it is just adjacent to the granitic intrusion.
2. Maximum temperature would be around 800degree C
C.1.A. Blueschist
B.pumpelliyte- prehnite
C.chlorite amphioble( green schist)
D. Eclogite