Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download lab 2 -- ig rx and min
Document related concepts
Transcript
Geology 101 (20 points) Name: Other members in your group: Lab #3: Igneous Rocks Part 1: Common Igneous Rocks: Texture: 1A) Reminder: What is the definition of each texture? (If you’re not sure what coarse-grained and finegrained mean check you notes from class or read the Rock ID handout.) Coarse-grained (a.k.a. phaneritic) = Fine-grained (a.k.a. aphanitic) = Porphyritic = How big is a millimeter (mm) anyways? Draw a square with sides 1 mm in the box below: 1mm = Examine ONLY the sample of: Andesite, 2) Basalt, 3) Dacite, 4) Diorite, 5) Gabbro, 6) Granite, 7) Granodiorite, and 8) Rhyolite (Note: all of these rocks have RED labels). These rocks are located in the study room in the boxes labeled Part III: Rocks box 1 and box 2. Identify each rock listed above as either Course-grained, fine-grained, or Porphyritic in the space provide: 1B) Which 4 of these rocks are coarse-grained (a.k.a. phaneritic)? 1C) Which rocks are best described as fine-grained (a.k.a. aphanitic)? 1D) Which rock(s) is(are) porphyritic ? Describe the cooling history of this rock. 1E) List the approximate percent (%) abundance of black minerals to the nearest 10% in the spaces provided below: Granite = % Granodiorite= % Diorite = % Gabbro = % 1 Composition: Mafic, Felsic, or Intermediate 1F) List the rock NAME that best fits in the table below: Volcanic Texture Rock Name Plutonic Texture Rock Name Composition Felsic Intermediate Mafic 1G) According to your Rock ID handout, the composition of Dacite is intermediate between the composition the two volcanic rocks: & and the composition of Granodiorite is intermediate between the compositions the two plutonic rocks: & Part 2: Obsidian: Examine the sample labeled “Obsidian” (#C-11) (in Box III, Part 2) 2A) Describe the color and geologic texture of this rock. Can you see any individual mineral grains? 2B) What is the cooling history of obsidian? (circle one of each choice below). Plutonic or Volcanic? Fast Cooling or Slow Cooling? 2C) Read the discussion on pages 81 and 82 of your book and answer the questions below: Obsidian has a a high/ low silica (circle one) content, which makes it mafic/felsic (circle one) rock. 2D) Explain why you can’t use color to determine if obsidian is mafic or felsic (check page 1 or your rock handout or 81-82 in your book): 2 Part 3: Pumice (check page 81 & 82 in your book if you’re not sure of the answers below) 3A) What is the density of pumice compared to water (higher or lower)? 3B) What aspects of the texture of pumice explains its density? 3C) Based on the color, is pumice more mafic or more felsic (circle one) in composition? 3D) Is pumice more likely to form from high viscosity or low viscosity magma? Explain your reasoning. Part 4: Ultramafic Xenolith: The green minerals in this rock form a “xenolith” that was found encased in basalt (= the black rock encasing the green minerals). 4A) What is the definition of a “xenolith” (hint: check your notes or page 85 in your book). 4B) What is the cooling history of the part of this rock with the green minerals (circle one of each choice below). Plutonic or Volcanic? Fast or Slow? 4C) What is the green mineral that dominates this rock (Hint: you can check your mineral guide or the mineral self-test samples for comparison). Part 5: Mt. St. Helens Ash Examine the color of the sample provided and consider what you know about Mt St. Helens. What is the most likely chemical composition of the ash (circle one). Mafic / Intermediate / Felsic What is the name of the volcanic rock that is most similar in composition to this ash ? Describe how the ash samples Ellensburg and Mosas Lake differ? Which location was closer to the eruption? Explain your reasoning. 3 Part 6: Rock Sample Identification Examine the samples in the SC 110 boxes (Part IV, VI, & “Geology 101: Hoppe”) & fill in the chart: Cooling History Rock # Composition Texture Rock Name (circle one) (Circle one) (circle one) SQ 15 Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic SQ 17 Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic SQ 24 Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic SQ 25 Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic SQ 27 Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic SQ 30 Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic SQ 35 Rock #1* Felsic Mafic Intermediate Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Coarse-grained Fine-grained Glassy Porphyritic Rock #2* Felsic Mafic Intermediate Coarse-grained Fine-grained Glassy Porphyritic Volcanic Plutonic Volcanic Plutonic Volcanic Plutonic * Sample #s Rock-1 and Rock-2 are in the last cabinet (in the Boxes labeled “Geology 101: Hoppe”) Name the Mystery Rocks / Minerals at the front of the room: A . B. . C. 4
