Outline

Course Information

  • Instructor: Dr. Tianqi Xie

  • Course: The Earth and How It Works / Earth Processes GEOL108/121

  • Final Exam Date: December 8 (Monday) at 2:00 PM

  • Duration: 3 hours

Congratulations Message

  • Congratulations! You survived this semester!

Exam Details

  • Location: Gym

  • Items Required:

    • Student card

    • Pencil and eraser

  • Exam Format:

    • 100 multiple-choice questions

    • Single correct answer per question

    • OMR sheet for answer recording

Course Outline

  • Major Topics:

    • Plate tectonics

    • Volcanos

    • Earthquakes

    • Mountains

    • Geological time scale

    • Impact events

    • Types of rocks:

      • Igneous rocks

      • Metamorphic rocks

      • Sedimentary rocks

  • Subtopics:

    • Solar System

    • Earth and other planetary bodies

    • Geological feature formations and related rocks

    • Sedimentary processes

    • Meteorites

Slide Content Breakdown

  • Plate Tectonics (Slides 6-12)

  • Volcanism (Slides 13-35)

  • Earthquakes (Slides 36-68)

  • Mountain Building (Slides 69-79)

  • Sedimentary Processes (Slides 80-96)

  • Minerals and Rock Cycle (Slides 97-135)

  • Geological Time Scale (Slides 136-160)

  • Canadian Geology (Slides 161-185)

  • Solar System, Meteorites, Mars Rock, Moon Rock (Slides 186-198)

Plate Tectonics Overview

  • Definition: Plate tectonics is a scientific theory explaining the creation of major landforms due to Earth's subterranean movements.

  • Historical Context: Solidified in the 1960s; revolutionized earth sciences by explaining various phenomena like mountain building, volcanoes, and earthquakes.

Key Geological Features and Rocks at Plate Boundaries

  • Plate Boundary Types:

    1. Divergent Boundaries:

      • Oceanic plate separation

      • Continental plate separation

    2. Convergent Boundaries:

      • Ocean-ocean convergence

      • Ocean-continent convergence

      • Continent-continent convergence

    3. Transform-Fault Boundaries:

      • Mid-ocean ridge transform fault

      • Continental transform fault

  • Expected Geological Features:

    • Divergent Boundaries: Rift valleys, mountains, volcanoes, earthquakes

    • Convergent Boundaries: Oceanic trenches, volcanic island arcs, folded mountains, earthquakes

    • Transform Boundaries: Horizontal movement of plates, generating shallow but powerful earthquakes

Understanding the Lithosphere and Asthenosphere

  • Lithosphere: Includes the tectonic plates; consists of solid rock material

  • Asthenosphere: Layer beneath the lithosphere that is easily deformed, allowing tectonic plates to slide over it

Volcanism

  • Definition: Volcanism refers to the surface expressions of igneous processes, leading to volcano and volcanic rock formation.

  • Statistics: Approximately 1,500 potentially active volcanoes worldwide.

  • Types of Volcanoes:

    • Hotspot Volcanoes: E.g., Hawaii Islands

    • Mid-ocean Ridge: E.g., Mid-Atlantic Ridge

    • Subduction Zone Volcanoes: E.g., Indonesia’s stratovolcanoes

  • Examples of Volcanoes:

    • Yellowstone National Park (Rhyolite caldera complex)

    • Hawaii Islands (Hotspot shield volcanoes)

    • Andes Mountains (Volcanic arcs)

Types of Volcanic Eruptions

  • Effusive Eruption: Dominated by lava outpouring

  • Explosive Eruption: Characterized by violent magma fragmentation into pyroclasts

Properties of Magma

  • Viscosity: Describes how runny the magma is. Higher SiO2SiO_2 content leads to higher viscosity.

  • Gas Content: Amount of dissolved gases (e.g., water vapor, carbon dioxide) in magma influences eruption style

Types of Volcanic Rocks

  • Common Extrusive Rocks:

    • Basalt: Fine-grained, dark-colored, low silica content, characteristic of shield volcanoes and mid-ocean ridges.

    • Andesite: Intermediate silica content, often associated with stratovolcanoes at subduction zones.

    • Rhyolite: Fine-grained, light-colored, high silica content, very viscous magma, explosive eruptions.

    • Tuff: Rock composed of volcanic ash and other tephra fragments, indicating explosive eruptions.

Mountain Building (Orogenesis)

  • Definition: Orogenesis describes the processes that collectively result in the formation of mountains.

  • Processes:

    • Folding: Compression forces cause rock layers to bend and buckle, forming anticlines and synclines.

    • Faulting: Tectonic forces cause rocks to fracture and move along fault lines, leading to uplift or subsidence.

    • Volcanism: Particularly at convergent plate boundaries, volcanic activity can build significant mountain ranges (volcanic arcs).

    • Metamorphism: Intense pressure and temperature during orogenesis can transform existing rocks into metamorphic rocks.

  • Types of Mountains:

    • Folded Mountains: Formed by intense compression, typically at continent-continent convergent plate boundaries (e.g., Himalayas, Alps).

    • Volcanic Mountains: Formed by the accumulation of volcanic material (lava, ash) (e.g., Andes Mountains, Cascade Range).

    • Fault-Block Mountains: Formed when tensional forces cause large blocks of crust to uplift along normal faults (e.g., Sierra Nevada).

Earthquake Mechanics

  • Elastic Rebound Theory: Describes how energy is released in the form of seismic waves during an earthquake.

  • Key Terms:

    • Focus (Hypocenter): Origin point of seismic waves

    • Epicenter: Point on Earth's surface directly above the focus

    • Seismic Waves: Energy waves produced during earthquakes

  • Types of Seismic Waves:

    • Body Waves: P-waves (primary waves) and S-waves (secondary waves)

    • Surface Waves: More destructive waves that move on the Earth’s surface

Monitoring Earthquakes

  • Techniques:

    • Seismic activity monitoring using seismographs

    • Analysis of P-S wave interval to locate earthquakes

Earthquake Magnitude

  • Moment Magnitude (MWM_W): Calculated using seismic wave data and the physical area of rupture produced by an earthquake.

Minerals and the Rock Cycle
Minerals

  • Definition: A naturally occurring, inorganic solid with a definite chemical composition and a characteristic crystalline structure.

  • Key Properties: Include crystal form, luster, color, streak, hardness (Mohs scale), cleavage, fracture, and specific gravity.

  • Common Rock-Forming Minerals: Silicates (feldspars, quartz, micas, olivine), carbonates (calcite), oxides, sulfides, and sulfates.

The Rock Cycle

  • Definition: A continuous process by which rocks are created, destroyed, and reformed through geological processes.

  • Stages:

    1. Magma/Lava: Molten rock material.

    2. Igneous Rocks: Formed from the cooling and solidification of magma or lava.

    3. Weathering & Erosion: Break down rocks into sediments.

    4. Sediments: Loose rock fragments, minerals, or organic matter.

    5. Lithification: Compaction and cementation of sediments to form sedimentary rocks.

    6. Sedimentary Rocks: Formed from the accumulation and lithification of sediments.

    7. Metamorphism: Existing rocks are transformed by heat, pressure, or chemical alteration.

    8. Metamorphic Rocks: Formed from the alteration of other rocks.

    9. Melting: Metamorphic rocks can melt to form magma, completing the cycle.

Igneous Rocks

  • Formation: Crystallization of molten rock (magma or lava).

  • Types:

    • Intrusive (Plutonic): Formed when magma cools slowly beneath Earth's surface, resulting in large crystals (e.g., granite, gabbro).

    • Extrusive (Volcanic): Formed when lava cools rapidly on Earth's surface or under water, resulting in small crystals or glassy texture (e.g., basalt, rhyolite, obsidian).

  • Textures: Dependent on cooling rate; phaneritic (coarse-grained), aphanitic (fine-grained), porphyritic (mixed), glassy.

Metamorphic Rocks

  • Formation: Transformation of existing igneous, sedimentary, or other metamorphic rocks due to changes in temperature, pressure, or chemical environment.

  • Types of Metamorphism:

    • Contact Metamorphism: Occurs when rocks are heated by contact with hot magma.

    • Regional Metamorphism: Occurs over large areas due to intense pressure and temperature changes associated with mountain building or plate collisions.

  • Textures:

    • Foliated: Minerals are aligned perpendicularly to the direction of stress, creating layers or bands (e.g., slate, schist, gneiss).

    • Non-foliated: Minerals lack preferential alignment, typically forming massive, interlocking crystals (e.g., marble, quartzite).

Geological Time Scale and Dating Methods

  • Relative Dating Methods: Include principles like original horizontality, superposition, and cross-cutting relationships.

  • Radiometric Dating: Absolute dating based on decay of radioactive isotopes; the most accurate in igneous rocks

Fossil and Mineral Record Relationships

  • Fossil Succession: States that specific fossils indicate a certain place in geological time.

  • Correlation Techniques:

    • Lithostratigraphic Correlation

    • Biostratigraphic Correlation

Canadian Geology Overview

  • Main Regions: Canadian Shield, Interior Platform, Appalachian Orogen, Innuitian Orogen, Cordillera, and Western Canada Sedimentary Basin.

  • Significant Features: Stable tectonic province, ancient rocks, valuable mineral deposits.

  • Mining in Canada: Includes extraction of diamonds, oil sands, and other natural resources

Earth's Formative Processes

  • Ice Ages: Intervals of extensive glaciation affecting landforms and sediments.

  • Landforms: Lakes from glacial erosion, small hills, and striations visible due to past glacial activity.

Solar System, Planetary Bodies, Meteorites, and Impact Events

  • Solar System Formation: Formed approximately 4.64.6 billion years ago from a rotating cloud of gas and dust called the solar nebula.

  • Earth and Other Planetary Bodies: Comparative planetology reveals insights into Earth's processes.

    • Mars Rock: Studies of Martian meteorites and rover samples provide clues about Mars' geological history, presence of water, and potential for past life.

    • Moon Rock: Samples from Apollo missions help understand the Moon's origin, volcanic history, and impact events, informing Earth's early history.

  • Meteorites: Extraterrestrial rocks that fall to Earth.

    • Types: Chondrites (most common, primitive), achondrites (igneous, differentiated), iron, stony-iron.

    • Significance: Provide direct samples of other solar system bodies, preserving information about the early solar system's composition and conditions.

  • Impact Events: Collisions of celestial bodies (asteroids, comets) with planetary surfaces.

    • Geological Effects: Formation of impact craters (e.g., Chicxulub crater), shock metamorphism, tsunamis, widespread ejecta layers.

    • Environmental/Biological Impact: Large-scale events can cause mass extinctions, significant climate change, and widespread devastation.

Sedimentary Processes

  • Diagenesis: Changes sediments undergo after deposition, influencing their transformation into sedimentary rocks.

  • Lithification: Process converting loose sediment into solid rock through compaction and cementation.

Conclusion

  • Thank you for a good semester!