Geology 101 Reading Guide for Plate Tectonics

Transcription

1 Geology 101 Reading Guide for Plate Tectonics Name The readings for plate tectonics will be in four different chapters: 2, 4, 10 and 11. If you have questions, please let me know. Chapter 2: Plate Tectonics: A Scientific Revolution Unfolds Sections 2.1 and 2.2: From Continental Drift to Plate Tectonics and Continental Drift: An Idea Before its Time (page 34) Tectonic processes are processes that. (finish the sentence): List and briefly explain the four major types of supporting types of evidence that Wegener used to support his continental drift hypothesis. 1) 2) 3) 4) Section 2.3 and 2.4: The Great Debate and The Theory of Plate Tectonics (page 38): On what basis did the critics of Wegener reject his hypothesis of continental drift? 1

2 The development of our current theory of plate tectonics happened as more was discovered about the sea floors around the world. What three types of data suggested that the oceans are dynamic and relatively young? The Earth s lithosphere consists of: What is the asthenosphere? Divergent Plate Boundaries are where plates. A current example of a divergent boundary is. Convergence of two plates of different densities creates a zone. A current example of convergent boundary is. When plates move horizontally past each other, this is termed a boundary. Please go to page 52: Sections 2.9 and 2.10: Testing the Plate Tectonic Model and How is the Plate Motion Measured? In what way did ocean drilling support the plate tectonics hypothesis? What is a hot spot and how do they support plate tectonics? How can the positions of the old volcanoes be used to determine the speed of the plate motion? 2

3 Rocks from Eurasia and North America can be tested for magnetic north. By examining rocks of different ages, we can determine the paths of the magnetic poles over time. The wanderings of the poles are really due to: Why are the polar wandering paths (for the magnetic pole) for North America and Eurasia different? In what way do the reversals of the magnetic poles support plate tectonics? How can these reversals be used to determine the speed of the plate motion? Explain briefly how the GPS system helps us determine the velocity of the plate movements. Describe the heat release mechanism called convection. Please read over the concepts called slab-pull and ridge-push in this section. To understand the various types of plate boundaries, I will ask you to read several different sections in the book. I wish all of this material was in one place in the book, but if you follow the reading guide, it should make sense by the end. Please read the following sections in the book and then answer the questions below: Sections 2.5, 4.5, 4.7, 10.2, 10.3, 10.4, 10.5, 10.6 Although these rates of seafloor production are slow on a human time scale, they are nevertheless rapid enough to have generated all of the Earth s ocean basins within the past years. 3

4 Explain why the divergent zones have a topographic ridge when the plates are being pulled apart. Based on evidence from the study of earthquake waves, we know that Earth s crust and mantle are composed of. (finish this sentence). What are the three different processes that can melt parts of the mantle and/or crust? Explain each briefly. Explain the process of partial melting. The partial melting of mantle rocks forms. Magmatic differentiation (from Bowen s Reaction Series) is a possible mechanism for the formation of magmas. It is likely that most granitic magmas originate from: What is a passive continental margin? What is an active continental margin? 4

5 What are turbidity currents? What is an accretionary wedge? Some oceanic ridges diverge at slow rates, while others have faster rates of divergence. If there is more vertical relief in the ridge, the rate of spreading is (faster/slower). What are the parts of an ophiolite complex? What does an ophiolite complex in the rock record tell us about the past? Please read sections 2.6 and 10.8 to answer the following questions: (some of the answers are in 4.7, but you should have read that section previously) With two types of crust on the lithosphere (oceanic and continental crust), there are three types of convergent boundaries: oceanic-continental, oceanic-oceanic, and continental-continental). Which of these two types creates a subduction zone? Why does oceanic lithosphere subduct? Look at the maps on page 285. Notice that the Farallon plate (this is also called the Juan de Fuca plate in one map) is getting smaller. Why? What is the eventual fate of the Juan de Fuca plate? 5

6 What is the role of water in continental-oceanic convergent boundaries? Where does the water come from? Describe how magmas are formed at oceanic-continental convergence zones: What is a modern-day example of a continental-oceanic convergent boundary? Are oceanic-oceanic convergent boundaries more similar to ocean-continental convergent zones or continental-continental convergent zones? Explain your answer. What is a modern-day example of an oceanic-oceanic convergent zone? Is volcanism common at continental-continental convergent zones? Why/Why not? What is a modern-day example of a continental continental convergent zone? 6

7 What is a transform boundary? Is volcanism common at transform plate boundaries? Give an example of a transform plate boundary. On page 45, Figure 2-17 illustrates the subduction zone along the western part of North America. Using that illustration, draw the cross section below of the subduction zone along the Washington coast. Chapter 11, Section 11.4 (page 303): What is orogenesis? Section 11.6: Collisional Mountain Belts (page 306): What is a terrane? How have terranes contributed to the development of North America? 7