PlateBoundaries-Activity-Sp21

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101

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Geology

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Dec 6, 2023

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Plenge Sp21 Tectonic Boundaries (30 pts) Your name Poojha Palle Group # ______ ---------------------------------------------------------------------------------------------------------------------------------------------------------------- Purpose: To use observational evidence to find plate boundary, and to correlate specific types of evidence to specific types of plate movement. Materials: (1) Case study maps and key (available in class and on Sakai), (2) This worksheet, (3) etext and/or notes from Chapter 4.5, (4) Reading on boundary types (available on Sakai) Part 1. Match features with boundaries (5 pts). Instructions: 1. Use chapter 4 from text and “Notes of boundary types” to describe plate boundaries in Table 1 (pg. 1). Describe each boundary in terms of data you could collect (e.g., seafloor age, elevation) rather than processes we infer (e.g., subduction). Table 1. (5 pts) Fill out the box for each boundary using the words provided and/or descriptions as needed. You only need to write something if you can get useful information about that plate boundary from that piece of evidence. If not, write “N/A” Associated with Boundary type Volcanoes? (yes or no) & describe Earthquakes (shallow, deep, or both) High elevation? (yes or no) & describe Low elevation? (yes or no) & describe Crustal age? (young or different ages, N/A) O-O Divergent No Yes, shallow Relatively high, yes No Young O-C Convergent Yes, very active volcanic activity near island chains Yes, varies from shallow to deep Low elevation Yes, relatively low on oceanic crust Medium O-O Convergent Yes, active volcanic activity. Caldera, stratavolcanoes, lava domes. Yes, varies from shallow to deep Low elevation at trenches High at volcanic islands Old C-C Convergent No Yes, varies from shallow to deep Relatively high elevation due to mountains No N/A C-C Divergent No Yes, shallow; moderate volcanic activity, strata, shield, and caldera volcanoes. Low elevation Relatively low N/A Part 2. Identifying boundaries based on features (20 pts) 1
1. Work with your group to make observations about each case study. Use the key, and complete Table 2 by choosing the best answers to describe each boundary. More than one answer can be chosen! Example: if you see a high elevation features that is next to a plate boundary, but traces the general shape of the plate boundary, you would choose “high elevation parallel to the boundary.” 2
3 (5 pts) Case Study I: Boundary Type: Divergent Volcanoes a. Are found right on top of the plate boundary b. Are found parallel to the plate boundary c. Are not really useful in drawing the plate boundary Earthquakes a. Are found on top plate boundary b. Are found parallel to the plate boundary c. Are not useful in drawing the plate boundary a. All earthquakes are shallow b. Some earthquakes are shallow, and some are deep c. All earthquakes are deep Topographic a. High elevation on the plate boundary (relatively low on both sides) b. Low elevation on the plate boundary (relatively high on both sides) c. High elevation parallel to the plate boundary on one side d. Low elevation parallel to the plate boundary on one side e. Elevation is high on one side of the boundary and low on the other f. The relative elevation does not seem useful in drawing the plate boundary Crustal age (for oceanic boundaries) a. The crust is uniformly young on top of the plate boundary, and gets older moving away b. The crust is uniformly old on top of the plate boundary, and gets younger moving away c. The age of the crust is not useful in determining the location of the plate boundary (5 pts) Case Study II: Boundary Type: O-C Divergent Volcanoes a. Are found right on top of the plate boundary b. Are found parallel to the plate boundary c. Are not really useful in drawing the plate boundary Earthquakes a. Are found on top plate boundary b. Are found parallel to the plate boundary c. Are not useful in drawing the plate boundary a. All earthquakes are shallow b. Some earthquakes are shallow, and some are deep c. All earthquakes are deep Topographic a. High elevation on the plate boundary (relatively low on both sides) b. Low elevation on the plate boundary (relatively high on both sides) c. High elevation parallel to the plate boundary on one side d. Low elevation parallel to the plate boundary on one side e. Elevation is high on one side of the boundary and low on the other f. The relative elevation does not seem useful in drawing the plate boundary Crustal age (for oceanic boundaries) a. The crust is uniformly young on top of the plate boundary, and gets older moving away b. The crust is uniformly old on top of the plate boundary, and gets younger moving away c. The age of the crust is not useful in determining the location of the plate boundary (5 pts) Case Study III: Boundary Type: O-O Convergent Volcanoes a. Are found right on top of the plate boundary b. Are found parallel to the plate boundary c. Are not really useful in drawing the plate boundary Earthquakes a. Are found on top plate boundary b. Are found parallel to the plate boundary c. Are not useful in drawing the plate boundary a. All earthquakes are shallow b. Some earthquakes are shallow, and some are deep c. All earthquakes are deep Topographic a. High elevation on the plate boundary (relatively low on both sides) b. Low elevation on the plate boundary (relatively high on both sides) c. High elevation parallel to the plate boundary on one side d. Low elevation parallel to the plate boundary on one side e. Elevation is high on one side of the boundary and low on the other f. The relative elevation does not seem useful in drawing the plate boundary Crustal age (for oceanic a. The crust is uniformly young on top of the plate boundary, and gets older moving away b. The crust is uniformly old on top of the plate boundary, and gets younger moving away
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Part 3. Questions (5 pts) ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The cross section shows an ocean-continental convergent boundary. 1. (3 pts) A specific relationship can be drawn between earthquake depth and distance from a subduction-zone boundary. Explain this relationship, and why this relationship exists. Use the diagram to help you. The Wadati Benioff zone. The descending plate bends and fractures as it is pulled down into the mantle causing shallow earthquakes to occur. Earthquakes happen only in the cool and brittle lithosphere. The lithosphere eventually loses its brittle nature as it warms up as it descends into the hotter mantle. This is where deeper earthquakes occur due to increasing temperature and pressure of mantle. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 2. (1 pts) Which 2 features should you look for when looking for an ocean-ocean divergent boundary? a. Oceanic ridge b. young crust 3. (1 pt) Which of the diagrams below accurately shows the movements (arrows) associated with the surface features shown in the diagram? You may select your choice by deleting the incorrect choices 4