GEO 101 1st Edition Lecture 5 Outline of Last Lecture 1 Minerals Building blocks of rocks 2 What is a mineral 3 Composition of Minerals 4 Chemistry Refresher a Structure of Atom b Chemical Bonding i Ionic ii Covalent iii Metallic iv Van Der Walls 5 Structure of Minerals 6 How do we Identify Minerals a Diagnostic Properties i Crystal Form Shape ii Luster iii Color iv Streak v Harness vi Cleavage vii Fracture viii Specific Gravity ix Other Properties 7 Mineral groups 8 Categories of Silicate Minerals 9 Non Silicate Minerals Outline of Current Lecture 1 Divergent Plate Boundaries 2 Divergent Plate Boundaries Rifting 3 Driving Mechanisms 4 Testing the Theory Evidence 5 Importance 6 The Rock Cycle These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Current Lecture Plate Tectonics The New Paradigm Divergent Plate Boundaries Oceanic ridges and seafloor spreading o Seafloor spreading occurs along oceanic ridge system Spreading rates and ridge topography o Ridge systems exhibit topographic differences o Differences controlled by spreading rates Divergent Plate Boundaries Rifting Why is there continental rifting Why did Pangaea break up Lithosphere thickness impedes flow of heat Driving Mechanisms Density variations of plates overlying mobile fluid asthenosphere drive Plate Tectonics Forces that drive plate motion o Slab pull o Ridge push o Slab suction Models of plate mantle convection o Acceptable model must be consistent with observed physical and chemical properties of mantle o Models 1 Layering at 660 kilometers Accounts for physical properties layering 2 Whole mantle convection Tries to account for physical properties layering 3 Deep layer model Testing the Theory Evidence Hot spots and mantle plumes o Caused by rising plumes of mantle material o Volcanoes can form over them Hawaiian Island chain o Mantle plumes Long lived structures Originate at great depth mantle core boundary Paleomagnetism and plate motions o Plate motions determined from paleomagnetism stored in rocks Direction Rate Measuring plate velocities from space o Establishing exact locations on opposite sides of a plate boundary and measuring relative motions o Method Global Positioning System Importance Provides explanations for o Earth s major surface processes o Distribution of earthquakes volcanoes and mountains o Distribution of ancient organisms and mineral deposits Problem o Plate Mantle interactions convection models not well known Provides framework for GEO 101 concepts o Think of plate tectonics for remainder of course The Rock Cycle What is a Rock o Has to be natural Not man made such as concrete or brick o Solid Coherent i e held together o Made of minerals or less commonly glass 3 Basic Types of Rocks o Igneous Rocks Usually very hard very solid Cooling and solidification of magma Granite and basalt o Sedimentary Rocks o Layered Accumulate in layers at Earth s surface Sediments derived from weathering of preexisting rock Compaction and precipitation Sandstone and limestone Metamorphic Rocks Swirly and hard Formed by heat and pressure Changing preexisting igneous sedimentary of other metamorphic rock Heat and pressure Gneiss