CIEN 203 Plate Tectonics PDF

LEARNING OBJECTIVES At the end of the lecture, the student should be able to : Apply the scientific method on the Plate Tectonics hypothesis of continental drift Cite the additional evidenc...

LEARNING OBJECTIVES At the end of the lecture, the student should be able to : Apply the scientific method on the Plate Tectonics hypothesis of continental drift Cite the additional evidences used for plate tectonics Discuss the interactions of the different plates and how these explain volcanoes and earthquakes Name the different tectonic features of the Philippines Review: Layers of the Earth Lithosphere crust and uppermost mantle; rigid Asthenosphere relatively weak Topic Outline I. Continental Drift Hypothesis II. Seafloor Spreading III. Additional Evidence for Plate Motion IV. Plate Tectonics Theory V. Types of Plate Boundaries VI. Mechanisms of Plate Motions VII. Tectonic Features of the Philippines I. Continental Drift Hypothesis Alfred Wegener German meteorologist and geophysicist The Origin of Continents and Oceans: Pangaea (~200MyA) Pangaea – “all land” Laurasia: North America, Europe and Asia Gondwanaland: South America, Africa, India, Australia and Antarctica Panthalassa – “all sea” © US Geological Survey I. Continental Drift Hypothesis Evidence Continental jigsaw puzzle fit Fossil match across continents Rock type and geologic features Paleoclimatic evidence I. Continental Drift Hypothesis Evidence Continental jigsaw puzzle fit ▪ Africa and South America fits if Atlantic Ocean is closed © Tarbuck et al., 2012 I. Continental Drift Hypothesis Evidence Fossil match across continents ▪ Fossils of animals and plants that could not have travelled through the oceans: Mesosaurus, Glossopteris and Lystrosaurus © Tarbuck et al., 2012 © John Holden I. Continental Drift Hypothesis Evidence Rock Type and Geologic Features ▪ Similarities across continents (e.g. Appalachian-Caledonian Mountains) © Tarbuck et al., 2012 I. Continental Drift Hypothesis Evidence Paleoclimate ▪ Coal seams in Northern Hemisphere modified from courses.missouristate.edu with tropical trees ▪ Glacial till and striations in Southern Africa, South America, Australia and India I. Continental Drift Hypothesis Opposition Mechanism for continent movement? Tides? © Kevin Gill Continents broke through oceanic crust?  II. Seafloor Spreading Introduced by Harry Hess in the early 1960s Extensive mapping of the ocean floor during the WWII Submarine volcanoes: mid-oceanic ridges (longest chain of volcanoes), guyots, and seamounts © Center for Marine Environmental Research/University of Bre me n, Germany © Department of Ge ological and Geophysic al Sciences, Princeton Univ ersity © Nature.nps.gov II. Seafloor Spreading Earth’s crust is moving away from MORs New material is being formed along MORs Modified from N OAA © Tarbuck et al., 2012 III. Additional Evidence for Plate Motion Paleomagnetism and polar wandering Curie point – temperature at which a mineral’s magnetic properties change (e.g. magnetite 🡪 585oC) Small magnetite minerals point to the magnetic north during their birth (Paleomagnetism) © Tarbuck et al., 2012 III. Additional Evidence for Plate Motion Magnetic Reversals Magnetic strips on the ocean floor © mysciencebox.org © Tarbuck et al., 2012  III. Additional Evidence for Plate Motion Hot spot volcanism Localized; long-lasting hot regions below the lithosphere Frame of reference for tracking plate motion Age of volcanism corresponds to the time elapsed since it was on top of the hotspot/mantle plume © Tarbuck et al., 2012 III. Additional Evidence for Plate Motion Seismicity and plate boundaries Deep earthquakes (>150km): location of subducting slabs Shallow earthquakes: regions of rifting © Anne E. Egger © US Geological Survey IV. Plate Tectonics Theory Unifying theory of geology Lithosphere composed of segments (tectonic plates) Plates in constant motion relative to one another © Tarbuck et al., 2012 IV. Plate Tectonics Theory Major Plates: North American South American Pacific Eurasian Australian Indian Antarctic © US Geological Survey V. Plate Boundaries Where most movement occurs Modified from Jose F. Vigil V. Plate Boundaries Divergent boundaries (constructive) where two plates move apart creating new oceanic crust as seafloor spreading centers: oceanic ridges and continental rifts © Tarbuck et al., 2012 Adapted from wps.prenhall.com © Tarbuck et al., 2012 V. Plate Boundaries Convergent boundaries (destructive) where two plates move together forming either arcs or mountain systems forms subduction zones when oceanic lithosphere is involved © Tarbuck et al., 2012 © Tarbuck et al., 2012 OCEANIC vs OCEANIC OCEANIC vs CONTINENTAL  V. Plate Boundaries Convergent boundaries Orogenic belts form in continental vs continental Why is there no subduction? © Tarbuck et al., 2012 V. Plate Boundaries Transform boundaries (conservative) where two plates grind past each other connects oceanic ridge systems into a continuous network © Robert E. Wallace, USGS © Tarbuck et al., 2012 © Tarbuck et al., 2012  VI. Mechanisms for Plate Motion Mantle convection Due to temperature and density differences ridge push, slab pull, and mantle drag © Giphy.com © Tarbuck et al., 2012 © Rob Butler, Leeds  VII. Philippine Tectonics Volcanism Pacific ring of fire; 25 active volcanoes Earthquakes everywhere besides Palawan; why? Convergent Plate boundary Oceanic vs oceanic (mature island arc): Philippine mobile belt + Philippine Fault zone Continental vs oceanic: Palawan microcontinenal block and suture zones VII. Philippine Tectonics Plates: Eurasian Plate, Philippine Mobile Belt, and Philippine Sea Plate Trenches: West: Manila Trench, Negros Trench, Cotobato Trench, Sulu Trench East: East Luzon Trough, Philippine Trench Traces from Aurelio et al., 2016