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Plate Tectonics - The Engine That Drives the Rock Cycle. Jim Miller Dept of Geological Sciences Precambrian Research Center University of Minnesota- Duluth. Earth Materials. Geological Processes. SEDIMENTARY ROCKS. Melting 2. Compaction & Cementation. MAGMA. Cooling &
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Plate Tectonics - The Engine That Drives the Rock Cycle Jim Miller Dept of Geological Sciences Precambrian Research Center University of Minnesota- Duluth
Earth Materials Geological Processes SEDIMENTARY ROCKS Melting 2 Compaction & Cementation MAGMA Cooling & Crystallization VOLCANIC ROCKS Tectonic Uplift Erosion, Transportation & Deposition SEDIMENT INTRUSIVE ROCKS Weathering Melting 1 METAMOPHIC ROCKS Subduction Heat & Pressure SOIL Precipitation
Rock Cycle Limestone Quartz + Clay+Lithics Clay+Lithics Qtz Sandstone Basalt Graywacke Shale Rhyolite Quartzite Greenstone Slate Marble Gabbro Granite Amphibolite Schist Gneiss Migmatite Felsic Mafic
Overview of Plate Tectonics Jim Miller
Plate Tectonic Theory The Earth’s outer shell (lithosphere) is composed of rigid plates that are moving relative to one another.
Physical and Chemical Structure of the Earth Lithospheric Mantle Compositional Components of the Lithosphere Continental Crust– ~62% SiO2, low density rocks , “felsic” Oceanic Crust - ~ 48% SiO2, high density rocks , “mafic” Lithospheric Mantle - ~ 40% SiO2, very high density rocks , “ultramafic” Chemical Layers Physical Layers
Plate Tectonics drives 2 Stages of Crust-making 1. Mantle partially melts to make ocean crust 2. Ocean crust melts to make continental crust
What moves the Plates? Slab Pull - densification of subducted plate pulls the plate into the mantle Mantle Push - Upwelling of the asthenospheric mantle pushes the plates apart Ridge Slide – Thermal upwelling at ridges causes plates to separate by sliding downhill (by gravity) Problem - we are not sure how the mantle is structured.
Divergent Plate Boundaries Mid-ocean Ridges Where Stage 1 Crust is Made
Youthful Oceanic Crust 200 100 0 Ma
Basalt – Rock Type of the Oceanic Crust Remember: Melting the Mantle Makes Mafic Magma!! Always
Continental Rifting The creation of new ocean basins
Continental Rifting and The Break-up of Pangea
Convergent Boundaries Making 2nd Stage Crust Ancient Continental Crust
Convergent Boundaries- Where the Action Is!! Ocean - Ocean Earthquakes Ocean- Continent Volcanoes Continent - Continent
Consequences of Convergence Explosive Volcanism Mt. St. Helens May 18, 1980
Consequences of Convergence Mountain Building and Rock Deformation
Consequences of Convergence - Earthquakes 1326 Aftershocks
OROGENESIS The Culmination of Convergence
Transform Boundaries Connects other Boundaries San Francisco Earthquake April 18, 1906 Mag 7.8
Mantle Plumes (Hotspots) Creation of overthickened oceanic crust
Famous Hotspots Yellowstone Hawaii Iceland
Plate Tectonics - The Engine That Drives the Rock Cycle Use Illustrations as Rock Cycle Story Starters