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Geology 370 - Elementary Petrology |
| University of Wisconsin-Madison Spring 2000 |
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Geology 370 - Elementary Petrology |
| University of Wisconsin-Madison Spring 2000 |
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HOMEWORK PROBLEM #1 - GEOLOGY 370 DUE: MONDAY IN LECTURE FEB. 14, 2000 ***** NO EXCEPTIONS ! ***** Part 1 of 2: Constructing the Binary Diagrams and Equilibrium Processes Below are "experimental data" for three binary phase diagrams that mimic real systems; the approach here is very similar to how an experimental petrologist would construct the diagrams. Hint: trace amounts of something probably mean you are close to the liquidus. Note that diagram #1 is a system that has some solid solution (when this occurs, it is noted by the subscript "SS"); this first system also is water saturated (V phase). The second and third diagrams are the same system (no solid solution) at different pressures; #2 is for low pressure, equivalent to upper crustal pressures, and #3 is for high pressure, equivalent to lower crustal pressures. Draw your diagrams with Temp on the Y-axis, composition labeled on the X-axis. Plot on detailed graph paper such as mm-lined paper, and fill the page as much as possible (one diagram per page). Be sure to label the melting temperatures of the pure phases, the liquidus and solidus lines, all phase fields, and any minimums, eutectics, or peritectics you discover. Check that you have labeled ALL of these items before you turn it in. 1. The system A-B (a solid solution system) Composition A: 8% B 800oC Liq + V 92% A 760oC Liq + Trace ASS + V 740oC Liq + ASS + V 720oC ASS + Trace Liq + V 680oC ASS + V 600oC ASS + V 590oC ASS + BSS + V Composition B: 24% B 800oC Liq + V 76% A 760oC Liq + V 730oC Liq + Trace ASS + V 720oC Liq + ASS + V 700oC Liq + ASS + BSS + V 600oC ASS + BSS + V Composition C: 32% B 800oC Liq + V 68% A 760oC Liq + V 730oC Liq + Trace BSS + V 720oC Liq + BSS + V 700oC Liq + ASS + BSS + V 600oC ASS + BSS + V Composition D: 48% B 800oC Liq + V 52% A 790oC Liq + Trace BSS + V 720oC Liq + BSS + V 700oC Liq + ASS + BSS + V 600oC ASS + BSS + V Composition E: 63% B 880oC Liq + V 37% A 830oC Liq + V 810oC Liq + BSS + V 760oC Liq + BSS + V 705oC BSS + V + Trace Liq 690oC BSS + V 650oC ASS + BSS + V First phase diagram continued: Composition F: 88% B 880oC Liq + V 12% A 840oC Liq + BSS + V 790oC Liq + BSS + V 760oC BSS + V 650oC BSS + V 510oC BSS + V 490oC ASS + BSS + V Questions for first diagram: 1A) What is the maximum % B component in ASS? What is the maximum % A component in BSS? 1B) Describe in detail the equilibrium crystallization and cooling path of a system of Composition F, from 900oC to 400oC, noting specific temperatures and solid and liquid compositions (note as XB) at pertinent points in the evolution of the system. 1C) Can you guess what geologically common binary system the A-B system is? (it is in your text)
2. The system X-Y-Z at Low Pressure. NO solid solution. Note: Y is a mineral with a composition of 21% Z, 79% X. Draw this on the X-axis immediately. Keep in mind that the bulk compositions below are cast only in terms of the endmember components X and Z for convience, but it should become clear to you as you construct the diagram what areas contain the phases X, Y, and Z. Composition A: 10% Z 1645oC Liq 90% X 1615oC Liq + X 1340oC Liq + X 1305oC Liq + X 1160oC Liq + X 1140oC X + Y 1110oC X + Y Composition B: 35% Z 1340oC Liq 65% X 1305oC Liq + X 1160oC Liq + X 1140oC Liq + Y 1110oC Liq + Y 1010oC Liq + Y 990oC Y + Z Composition C: 45% Z 1160oC Liq 55% X 1140oC Liq 1110oC Liq + Y 1010oC Liq + Y 990oC Y + Z
Composition D: 60% Z 1160oC Liq 40% X 1140oC Liq 1110oC Liq + Trace Z 1010oC Liq + Z 990oC Y + Z
Second phase diagram continued: Composition E: 70% Z 1340oC Liq 30% X 1305oC Liq + Trace Z 1160oC Liq + Z 1140oC Liq + Z 1110oC Liq + Z 1010oC Liq + Z 990oC Y + Z Composition F: 90% Z 1615oC Liq 10% X 1570oC Liq + Z 1160oC Liq + Z 1140oC Liq + Z 1110oC Liq + Z 1010oC Liq + Z 990oC Y + Z Questions for second diagram: 2A) Describe in detail the equilibrium crystallization and cooling path of a system of Composition B, from 1700oC to 900oC, noting specific temperatures and liquid compositions (note as XZ) at pertinent points in the evolution of the system. 2B) Describe in detail the equilibrium MELTING path of a system of Composition A, from 900oC to 1700oC, noting specific temperatures and liquid compositions (note as XZ) at pertinent points in the evolution of the system. 2C) Can you guess what TWO geologically common systems the X-Y-Z system could be? (one you have seen in lecture many times, the other you have not, nor is it in the book)
3. The system X-Y-Z at High Pressure. Composition A: 5% Z 1330oC Liq 95% X 1320oC Liq + Trace X 1310oC Liq + X 1160oC Liq + X 1140oC X + Y 1010oC X + Y 990oC X + Y Composition B: 10% Z 1160oC Liq 90% X 1140oC X + Y 1010oC X + Y 990oC X + Y
Composition C: 15% Z 1200oC Liq + Trace Y 85% X 1160oC Liq + Y 1140oC X + Y 1010oC X + Y 990oC X + Y
Third phase diagram continued: Composition D: 21% Z 1220oC Liq 79% X 1200oC Y 1160oC Y 1140oC Y 1010oC Y 990oC Y Composition E: 30% Z 1200oC Liq 70% X 1190oC Liq + Y 1010oC Liq + Y 990oC Y + Z
Composition F: 53% Z 1010oC Liq 47% X 990oC Y + Z
Composition G: 70% Z 1280oC Liq 30% X 1260oC Liq + Z 1010oC Liq + Z 990oC Y + Z
Composition H: 90% Z 1410oC Liq 10% X 1400oC Liq + Z 1010oC Liq + Z 990oC Y + Z
Questions for third diagram: 3A) Describe in detail the equilibrium crystallization and cooling path of a system of Composition E, from 1300oC to 900oC, noting specific temperatures and liquid compositions (note as XZ) at pertinent points in the evolution of the system. 3B) Describe in detail the equilibrium MELTING path of a system of Composition C, from 900oC to 1300oC, noting specific temperatures and liquid compositions (note as XZ) at pertinent points in the evolution of the system. |
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