Lecture 5: Plate Tectonics II and Principles of Geology PDF

Lecture 5: Plate Tectonics II and Principles Student Accessibility of Geology Services ©JoAnna Wendel Reminder: Quiz 2 Unlimited attempts Due 11:59 pm on Friday Objectives for Today Last class: continental drift...

Lecture 5: Plate Tectonics II and Principles Student Accessibility of Geology Services ©JoAnna Wendel Reminder: Quiz 2 Unlimited attempts Due 11:59 pm on Friday Objectives for Today Last class: continental drift hypothesis & unifying Theory of Plate Tectonics Today: Learn the three types of plate boundaries Understand the main tenet of geology: uniformitarianism Recognize the basic principles of geology Fig 3.12 6 The Three Types of Plate Boundaries 7  Types of Plate Boundaries 1. Divergent Boundaries two tectonivcinta a Formation of new lithosphere Most often found in ocean ridges e.g., Mid-Atlantic Ridge Fig 3.13 8  Volcanic activity Stepped Art Magma Continental crust Rift valley Fig 3.14 9 Fig 3.15 10  Volcanic activity Stepped Art Magma I Continental crust Rift valley Coastal mountain range I Narrow fault-bounded sea eventually Fig 3.14 11  Volcanic activity Magma Continental crust Rift valley Coastal mountain Narrow fault-bounded sea range Continental “seaboard” (coastal mountains gone) Wide ocean Stepped Art 12 Fig 3.14  Types of Plate Boundaries 2. Convergent Boundaries two platesmovin Three types: lithosphora Oceanic-oceanic Ocean trench Oceanic-continental Subduction zone Continental-continental Mountains form Cause of: Deformation Volcanism Mountain building Metamorphism Earthquakes Valuable mineral deposits 13 NASA  2. Convergent Boundaries a pl Oceanic-Oceanic Plate Boundary density higher Fig 3.16 metteata det riss 14 2. Convergent Boundaries Oceanic-Continental Plate Boundary denser bushednew Fig 3.16 as creates masma 15 2. Convergent Boundaries Continental-Continental plate Boundary up force eachother or no little range mountain no subducting melting - > ↳ creates : no volcanism S Fig 3.16 16 Types of Plate Boundaries 3. Transform Plate Boundaries cause +sunami or earthquake can when they get stuck on eachother Fig 3.18 17 Fig 3.19 18 Plate Tectonics and the Rock Cycle createerode mountending Plate tectonics play a role in the rock cycle Convergent plate boundaries create mountains Mountains erode, producing sediments Sediments are transported, buried, and lithified Earth's internal heat and pressure melts material, producing igneous rocks Sedimentary and igneous rocks are altered forming metamorphic rocks 20 Geologic Principles  Uniformitarianism Uniformitarianism is a main tenet of geology States that the laws of nature have remained ( synonymous unchanged through time and that the processes observed today also operated in the past The present is the key to the past - Lyell that to understand use processes happen today as a way the past Actualism Application of modern processes to ancient systems I same process happens , but not at uniform rate  Examples of Actualism Modern ripples, PEI Permian ripples in cross-section, TX Modern and ancient sedimentary structures Precambrian ripples, Red Rock Canyon, AB Permian Modern mudcracks, TX mudcracks, TX Images: J. Hawthorn  Stratigraphy layered rocks = strata A branch of geology concerned with Steno composition, origin, age relationships, and geographic extent of layered (stratified) rocks Mostly deals with sedimentary rocks Sequences of rocks interpreted using principles outlined by Steno (1669) Principle of superposition Principle of original horizontality Principle of original lateral continuity Images: J. P. Trap via commons.wikimedia.org, Betty Crocker Steno’s Principles 1) Principle of Superposition Oldest strata are at the bottom in an undisturbed sequence of strata Image: Stanley (2009) Steno’s Principles 1) Principle of Superposition Oldest strata are at the bottom in an undisturbed sequence of strata Image: pancakesfromscratch.com Steno’s Principles youngest 1) Principle of Superposition ? Oldest strata are at the bottom in an undisturbed sequence of strata oldest Steno’s Principles some force later acts on it to 2) Principle of Original Horizontality change the shape All strata are horizontal when they form Image: Stanley (2009) Steno’s Principles 2) Principle of Original Horizontality All strata are horizontal when they form Images: alamarra.com; commons.wikimedia.org  Steno’s Principles 2) Principle of Original Horizontality All strata are horizontal when they form y Fig. 4.4 Steno’s Principles 3) Principle of Original Lateral Continuity Strata originally are unbroken flat expanses Can be interrupted by erosion Image: Stanley (2009) Steno’s Principles 3) Principle of Original Lateral Continuity Strata originally are unbroken flat expanses Can be interrupted by erosion Image: 4.bp.blogspot.com Steno’s Principles 3) Principle of Original Lateral Continuity Strata originally are unbroken flat expanses Can be interrupted by erosion  Other geological principles Cross-cutting relationships Principle of Cross- Cutting Relationships (Hutton) -Intrusive igneous rocks or faults are younger older always younger than the rock they invade insidee ↑ rock faulting Fig 4.5 Other geological principles: Cross-cutting relationships Principle of Cross-Cutting Relationships -Intrusive igneous rocks or faults are always younger than the rock they invade Image: midstatemills.files.wordpress.com Other geological principles Inclusions and Components Principle of Inclusions & Components (Charles Lyell) – Rock fragments within another body of rock are older than the including body of rock Fig 5.2 Other geological principles Inclusions and Components Principle of Inclusions & Components (Charles Lyell) – Rock fragments within another body of rock are older than the including body of rock Image: 4.bp.blogspot.com Other geological principles: Unconformities periods of erosion or nondeposition Substantial interval of time when erosion occurred rather than deposition Angular unconformity Image: Stanley (2009)  Other geological principles: Unconformities Angular unconformity Disconformity T - deposited difference 3 in time ↓ to Sedimentary rock Sedimentary rock erosional event surface 2 Hi - between. 1. deposited Tilted sedimentary rock Sedimentary rock Nonconformity in time diff. with overlayed X sedimentary Sedimentary rock igneous Igneous rock [ metamorphic Images: Stanley (2009)