GSU GEOL 1122K - Chapter 2 Visual Quiz (8 pages)

During subduction one tectonic plate is forced beneath another In this image an oceanic plate is subducting under another oceanic plate What geologic feature is being created in the image a forearc basin a backarc basin a mid ocean ridge a volcanic island arc Subduction commonly leads to volcanism In this case new volcanic islands have been produced This type of activity has given rise to the island nation of Japan as well as the Aleutian Islands extending off the southwest coast of Alaska In the following figure the magnetic anomaly pattern is mirrored on either side of the central ridge What is responsible for this pattern Seafloor spreading builds new crust equally on both sides of the ridge The magnetic anomalies follow a repetitious pattern in mantle convection The anomalies follow El Ni o La Ni a cycles The anomalies follow Milenkovich cycles based on orbital dynamics This image is of a mid ocean ridge These are divergent plate boundaries meaning that new material is created at the ridge As the material spreads away from the central ridge any changes in the Earth s magnetic field will be mirrored almost exactly Multiple types of plate boundaries can often be found in close proximity to one another Below is an image of the Juan de Fuca plate subducting beneath Washington and Oregon in the American Northwest Match the type of plate boundary with the correct letter on the image A Convergent B Divergent C Transform A Divergent B Transform C Convergent A Transform B Divergent C Convergent A Transform B Convergent C Divergent The Juan de Fuca plate is subducting beneath the North American plate at the Cascade trench Spreading centers are indicated by the red bars off shore Arrows show the shear motion of the transform boundaries between spreading centers Paleoenvironmental reconstructions of Pangea indicate that regional climates during the Paleozoic were significantly different than they are today Looking at the following figure which statement about climate and associated rock deposits from the Paleozoic is FALSE Desert sands were deposited in South America Coal swamps were present along the east coast of the United States India was partially glaciated Coral reefs were found in North America Europe and Asia Though South America had both glaciated areas and coal swamps sand dunes were not common to the continent That is very different from today where Peru is home to the Atacama Desert the driest place on Earth The constant motion of tectonic plates leads to convergent divergent and transform plate boundaries Which type of structure is shown in the figure below a subduction zone a mid ocean ridge a passive margin a strike slip fault The image shows where two plates are being pulled apart leading to volcanic activity and faulting This is a submarine divergent plate boundary The distribution of various geological features can be used to recreate what the world looked like millions of years ago This figure shows the location and direction of glacial striations which are indicators of the direction of glacial movement Based on this information where was the pole located Antarctica North America Australia Southern Africa The continents of South America Antarctica Africa and Australia can be reconstructed to form the polar region of Earth from 260 280 Mya The glacial striations radiate away from southeastern Africa suggesting it was the pole The following figures show what happens when two continents collide In the upper figure oceanic crust is being subducted until the continents collide The bottom figure shows the collision What happens to the subducting plate when continents collide The subducting plate is uplifted into a volcanic island arc The subducting plate becomes detached and the convergent boundary sutures become closed leaving a single plate The subducting plate creates a transform plate boundary The subducting plate creates a backarc basin Continent to continent collisions lead to extensive mountain building and the eventual end of the convergent boundary as two plates fuse into one This result occurs because continental crust is too buoyant to be subducted The lithosphere is the rigid part of the mantle while the asthenosphere is the relatively more fluid portion The following figure shows the spatial relationship between the Earth s crust lithosphere and asthenosphere Which of the following statements regarding the figure is FALSE Continental lithosphere is thinner than oceanic lithosphere The asthenosphere is denser than the lithosphere Oceanic crust is thinner than continental crust Oceanic lithosphere sinks deeper into the asthenosphere than continental lithosphere Continental lithosphere is much thicker than oceanic lithosphere As a result of the extra mass the continental lithosphere settles deeper into the relatively softer asthenosphere much like a heavily loaded boat will settle deeper into the sea This figure shows the mid Atlantic ridge south of Iceland The arrows show the orientation of Earth s magnetic field as it has reversed several times over the last 180 Million Years What information can be determined based on the width of the different anomaly rock units the severity of the magnetic anomaly the relative duration of the anomaly the rate of crustal uplift the depth of the ocean at the time the anomaly was created Because new crust is being formed at the mid ocean ridge at a fairly constant rate we can surmise that wider anomaly units represent longer durations of time Through plate tectonics plates move about the Earth slamming into pulling away from and sliding past one another Match the images from the figure below with the appropriate boundary name A Convergent B Divergent C Transform A Transform B Convergent C Divergent A Divergent B Convergent C Transform A Divergent B Transform C Convergent Divergent boundaries are found at ocean ridges and continental rift zones Convergent boundaries occur where plates collide Subduction and mountain building commonly result Transform boundaries occur where plates slide past one another such as at the San Andreas Fault in California