Exam 3 study guide/notes

Exam 3 study - Convergent Boundaries Mountain Building Orogenesis – the processes producing mountains Location of mountain building activity

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Unformatted text preview: Convergent Boundaries Mountain Building Orogenesis – the processes producing mountains Location of mountain building activity? Earth’s Major Mountain Belts Convergent Boundaries Types of convergent boundaries? What happens at each type? Anatomy of Subduction Zones SLIDE 6 Plate Tectonics and Magma Generation Subduction Zone Activity SLIDE 8 Trench rollback Extension – RESULT OF TRENCH ROLL BACK Tensional stress Subduction Zone Activity 9 Volcanic Island Arc 10 Continental Volcanic Arc 11 and 12 Continental Collisions 13 What happens to oceanic crust? Accretionary wedge? Forearc basin? Volcanic arc? All oceanic crust destroyed Sutures – line that separates the 2 former crusts Fold-and-Thrust belt —can behave ductile and brittle Terranes and Accretion Terranes – small crustal fragments with different history than adjacent crust Accretion – addition of terranes to continental crust by movement of plates Terrane Formation show on slide 17 Forming a Divergent Boundary slide 18 Mountains from Divergent Boundaries? Fault-block mountains • Can form elongate ridges • Type of faulting? Vertical Movement of Crust Isostasy – concept of floating crust in gravitational balance Glacial Isostasy Vertical Movement of Crust Mantle convection -- HEAT MOVING UP, NOT TO MELT, JUST TO EXPAND • Buoyancy of hot mantle material – accounts for upwarping in lithosphere • (and in the opposite case, cooled material can subside) *when could all this first happen? Heat on inside, outside cool enough to be solid Origin of Continental Crust When could plate tectonics first occur? Tectonic Settings Orogenic belts Craton – old stable Shield – igneous/metamorphic rocks at surface Platform – shield covered by sedimentary rock To know about oldest you look at shield? DIVERGENT BOUNDARY Geo-- Mapping the Ocean Floor Weighted lines -- measure depth Sonar Reflects sound from ocean floor Invented in the 1920s Satellites – tells about shape of the floor Measure subtle differences of the ocean surface Variations reflect gravitational pull and features on the seafloor Major Ocean Provinces I) Continental margin II) Deep-Ocean Basin III)Mid-Ocean Ridge I) Continental Margins Passive • Not associated with plate boundaries Active Continental Margin- pacific west coast Continental shelf and slope • Active • Associated with plate boundaries Passive Continental Margin – eastern Atlantic coast A) Continental Shelf All features on land can see on shelf Average 80 km wide Low angle 0.1* To ~200 m deep Light can hit the sea floor, (life can exist) Continental Shelf Sediment Sands and clays Plants and animals disturb its B) Continental Slope Average 20 km wide Lower angle at bottom Boundary between continental and oceanic crust C) Continental Rise Thick accumulation of sediment Turbidity currents deposit sediment to form deep-sea fans...
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This note was uploaded on 05/01/2008 for the course GEOL 1100 taught by Professor Ruez during the Spring '08 term at Auburn University.

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Exam 3 study - Convergent Boundaries Mountain Building Orogenesis – the processes producing mountains Location of mountain building activity

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