Earth Science Lecture Notes PDF

Lec 1: Earth System Geol 100: Principles of Geology  Earth science Seeks to understand Earth and its neighbors in space Includes geology, oceanography, meteorology, astronomy Lec 1: Earth System  Earth science Branch Definit...

Lec 1: Earth System Geol 100: Principles of Geology  Earth science Seeks to understand Earth and its neighbors in space Includes geology, oceanography, meteorology, astronomy Lec 1: Earth System  Earth science Branch Definition Geology Study of the Earth Oceanography Study of oceans in all its aspects and relationships Study of the atmosphere and the processes that Meteorology produce weather and climate Astronomy Study of the universe Lec 1: Earth System  Geology Physical geology: Processes that operate on and below the Earth’s surface Historical geology: Origin of the Earth and its evolution Lec 1: Earth System  Evolution of geology 2300 years ago: Aristotle and other Greek philosophers wrote about fossils, gems, earthquakes, and volcanoes Mid- 1600s: James Ussher constructed a chronology of human and Earth history Earth created in 4004 BC 17th- 18th century: Catastrophism Earth’s landscapes had been shaped primarily by great sudden and often worldwide catastrophes Birth of Modern Geology (1795): Uniformitarianism proposed by James Hutton, popularized by Charles Lyell “The present is the key to the past.” Lec 1: Earth System  Popular writer John McPhee’s view on geologists: “They look at mud and see mountains, in mountains oceans, in oceans mountains to be. They go up to some rock and figure out a story, another rock, another story, and as the stories compile through time they connect—and long case histories are constructed and written from interpreted patterns of clues. This is detective work on a scale unimaginable to most detectives, with the notable exception of Sherlock Holmes.” Lec 1: Earth System  Natural events Geology in Economics and politics our lives Decision making Sustainable development Lec 1: Earth System Lec 1: Earth System  Scientific inquiry and method Scientific inquiry Scientific method Diverse ways to study the natural General procedure using world and propose explanations systematic observations and based on the evidence derived experiments for discovering how from studies the universe works Lec 1: Earth System  Scientific inquiry Description Example Collected through observations The sea is blue Fact and measurements to answer a Your average body temperature question is 37C Earth- centered model of the universe Tentative or untested explanation Hypothesis The Earth is billions of years old from facts and principles Burning of fossil fuels is causing global warming Well- tested and widely accepted Big Bang Theory Theory view that best explains certain Theory of Evolution observable facts General principle about how the Law of Gravitation Law universe works Law of Motion Lec 1: Earth System  Ask a question Collect data Iteration Propose new hypothesis Propose hypothesis Refine hypothesis Do more tests Test hypothesis Analyze results Results align with Results does not align with hypothesis hypothesis Report results Lec 1: Earth System Earth’s spheres Lec 1: Earth System Atmosphere Sphere of air surrounding the Earth Lec 1: Earth System Hydrosphere Sphere of water that covers ~70% of the Earth Lec 1: Earth System Biosphere Sphere of living things on Earth Lec 1: Earth System Geosphere Sphere of rock that is the Earth Lec 1: Earth System Earth’s spheres Lec 1: Earth System Earth’s spheres Lec 1: Earth System  Earth Science System Interdisciplinary approach that aims to study the Earth as a system composed of numerous interacting parts or subsystems Lec 1: Earth System  System Any size group of interacting parts that form a complex whole Lec 1: Earth System  Geosystem Lec 1: Earth System  Climate system Weather Climate Describes temperature, precipitation, Measures of how variable the cloud cover, and winds at a particular weather has been over many years location and time of observation Lec 1: Earth System  Driven by the earth’s internal heat Plate tectonic system occurs is a result from the interactions within the Earth’s interior Lec 1: Earth System  Geodynamo Involves interactions that produce a magnetic field deep inside the Earth in its liquid outer core. Lec 1: Earth System Earth System Powered by energy from external and internal processes Lec 1: Earth System  Questions? Lec 1: Earth System Lec 2: Plate Tectonics Geol 100: Principles of Geology  Earth’s interior Lec 2: Plate Tectonics Lec 2: Plate Tectonics  Why are there layers? Earth’s formation Varying densities Different temperatures and viscosities Lec 2: Plate Tectonics  How were scientists able to visualize the Earth’s interior? Lec 2: Plate Tectonics  Vibrations generated during an Seismic waves earthquake Seismic velocity: ~4-13 km/s Depends on the medium’s properties (density, compressibility, etc) Lec 2: Plate Tectonics  Primary waves Secondary waves Lec 2: Plate Tectonics  Seismic discontinuity Abrupt velocity changes and bending of waves May be due to compositional changes and/ or phase change Seismic velocity versus depth profile Lec 2: Plate Tectonics  Compositional layers Mechanical layers Based on studying the velocity of Based on studying rock rheology seismic waves that pass through (the response of rock to stress) the Earth Lec 2: Plate Tectonics  Outermost layer of the Earth Crust 30% continental, 70% oceanic Mohorovicic: seismic discontinuity between crust and mantle Criteria Continental Oceanic Composition Less mafic More mafic From mountain building, erosion and From seafloor spreading at Formation sedimentation, and continued volcanism mid-ocean ridges Thickness 25-70km 6-10km Density 2.6- 2.9 g/cm3 2.9- 3.1 g/cm3 Age Older Younger Lec 2: Plate Tectonics  Crust Lec 2: Plate Tectonics  83% of Earth’s volume Mantle Generally consists of very hot, solid rock (rich in MgO and FeO) Behaves plastically and can flow very slowly Depth (from the surface) Seismic velocity Upper mantle 400km Low (due to partial melting) Abrupt increase (due to successive Transitional zone 400-670km phase changes) Lower mantle 670-2900km Gradually increase Lec 2: Plate Tectonics  Mode of heat transfer during which hot Mantle convection material (less dense) rises, while cold material sinks (denser) Lec 2: Plate Tectonics  ~3481km diameter 16% of Earth’s volume Core Consists of iron alloy 85% Fe, 5% Ni, 8-10% lighter elements Outer core: molten material Generates Earth’s magnetic field due to convective flow Inner core: solid Lec 2: Plate Tectonics  Mechanical layers Based on studying rock rheology (the response of rock to stress) Lithosphere Asthenosphere Layers Crust and outermost mantle Rest of the mantle Rheology Strong and rigid Weak and plastic Flexural rigidity Yes No Lec 2: Plate Tectonics  Flexural rigidity Resistance to bending of flexure of a material Old, cold >>> young, warm With flexural rigidity Without flexural rigidity Lec 2: Plate Tectonics  Plate tectonics AKA lithospheric plates or plates Lithosphere breaking along plate boundaries and moving over the asthenosphere Lec 2: Plate Tectonics  Plate tectonics model 7 major plates 8 minor plates Lec 2: Plate Tectonics  Alfred Wegener Suggested Supercontinent Pangaea Continental drift hypothesis Lec 2: Plate Tectonics  Evidence 1: Fit of continents Lec 2: Plate Tectonics  Evidence 2: Fossil evidence Lec 2: Plate Tectonics Evidence 3: Geologic fit Lec 2: Plate Tectonics  Evidence 4: Ancient climate Lec 2: Plate Tectonics  The Great Debate What is the mechanism for the plates’ movement? Lec 2: Plate Tectonics  What is the mechanism for the plates’ movement? According to Wegener: (1) Gravitational forces (2) Continents broke through thinner oceanic crust Lec 2: Plate Tectonics  Seafloor spreading Process in which mantle convection pushes and pulls continents resulting in the generation of new oceanic crust Lec 2: Plate Tectonics Lec 2: Plate Tectonics  Plate boundaries Divergent Convergent Transform Lec 2: Plate Tectonics  Divergent boundary Oceanic spreading centers Continental rifting Lec 2: Plate Tectonics  Divergent: Oceanic rifting centers Lec 2: Plate Tectonics Divergent: Continental rifting Lec 2: Plate Tectonics  Divergent: Continental rifting Arabian plate African plate African plate Somalian plate East African Rift Valley Red Sea Lec 2: Plate Tectonics  Divergent: Continental rifting North American plate and Eurasian plate Lec 2: Plate Tectonics  Divergent: Continental rifting Lec 2: Plate Tectonics  Convergent boundary Lec 2: Plate Tectonics  Convergent: Continental- continental Lec 2: Plate Tectonics  Convergent: Continental- continental Mt. Everest Lec 2: Plate Tectonics  Convergent: Oceanic- oceanic Lec 2: Plate Tectonics  Convergent: Oceanic- continental Lec 2: Plate Tectonics  Convergent: Oceanic- continental Andes Mountains Lec 2: Plate Tectonics  Transform boundary Lec 2: Plate Tectonics  Transform boundary San Andreas Fault Lec 2: Plate Tectonics  Mantle convection Rising of hot matter in one area within the mantle, sinking of colder material in another Hot area: MOR, mantle plume Cold area: subduction zone Lec 2: Plate Tectonics  Mantle convection Ridge push: Slabs of lithosphere “slide down” from elevated position in the ocean ridges Lec 2: Plate Tectonics  Mantle convection Slab pull: Cold slabs of oceanic lithosphere “pulled” downward into the mantle by gravity Lec 2: Plate Tectonics  Plate boundaries form and die due to continental rifting and collision Lec 2: Plate Tectonics  History of plate movements Lec 2: Plate Tectonics Lec 2: Plate Tectonics  Via Paleomagnetism and age of seafloor: Rates of plate movements 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑓𝑟𝑜𝑚 𝑀𝑂𝑅 𝑆𝑝𝑒𝑒𝑑 = 𝑎𝑔𝑒 𝑜𝑓 𝑠𝑒𝑎𝑓𝑙𝑜𝑜𝑟 Lec 2: Plate Tectonics  Via Hotspots and Mantle Plumes Rates of plate movements Lec 2: Plate Tectonics  Hot spots Isolated volcanoes with a fixed heat source position not related to plate boundary movement Lec 2: Plate Tectonics Rates of plate movements Via Geodesy (Global Positioning System) Lec 2: Plate Tectonics Lec 2: Plate Tectonics  Grand reconstruction Pangaea reconstruction and eventual fragmentation is one of the major triumphs of Geology Lec 2: Plate Tectonics  Seafloor isochrons Lec 2: Plate Tectonics  Pangaea break-up Lec 2: Plate Tectonics  Possible future Lec 2: Plate Tectonics  Evidences from: Old mountain belts Possible past Evidences in rocks Rock types and fossils Ancient climate Paleomagnetism Lec 2: Plate Tectonics  Acceptance of Plate Tectonic Theory Lec 2: Plate Tectonics  Plate Tectonic Theory Lec 2: Plate Tectonics  Questions? Lec 2: Plate Tectonics Lec 3: Earth Materials (Minerals) Geol 100: Principles of Geology  Definition of a mineral Naturally occurring Inorganic process Homogeneous solid Definite chemical composition Ordered internal structure Lec 3: Earth Materials  Structure of matter Lec 3: Earth Materials Lec 3: Earth Materials  COVALENT BOND (sharing) Chemical bonds IONIC BOND (giving) METALLIC BOND (free exchange) Lec 3: Earth Materials  Crystal Minerals or other solids with a definite chemical composition and external shape bounded by smooth plane surfaces Lec 3: Earth Materials  Crystal Crystal faces are the external expression of the mineral’s internal atomic structure Lec 3: Earth Materials Lec 3: Earth Materials  5744 approved minerals by IMA- Mineral stats CNMNC as of May 2021 ~30 common minerals ~10 rock-forming minerals Lec 3: Earth Materials  Can minerals form here? Lec 3: Earth Materials  Can minerals form here? Lec 3: Earth Materials  Can minerals form here? Lec 3: Earth Materials  Can minerals form here? Lec 3: Earth Materials  Crystallization Lec 3: Earth Materials  Nucleation types Lec 3: Earth Materials  Crystallization process Lec 3: Earth Materials  Crystallization process Lec 3: Earth Materials Factors Rate of cooling affecting Faster rate, smaller minerals Amount of gas present mineral growth More gas, bigger minerals Magma composition More felsic, bigger minerals Lec 3: Earth Materials  Magmatic = from magma Mineral Hydrothermal = from hot fluids formation Metamorphic = from higher P-T environments Evaporite = from evaporation Sedimentary = from weathering or organisms Lec 3: Earth Materials  Magma Magmatic environment Cooling and hardening New mineral Lec 3: Earth Materials  Hydrothermal environment Classified based on T & P conditions: hypothermal, mesothermal, epithermal Hydrothermal fluid New minerals deposition Hydrothermal Interaction with pre- New minerals fluid deposition existing minerals Lec 3: Earth Materials  Pre-existing mineral High temperature and pressure conditions Metamorphic environment Crystalline structure altered New and different crystalline structure arrangement New mineral Lec 3: Earth Materials  Enriched water from stream to lake Evaporation of water Evaporite environment Concentration of soluble chemicals Precipitation and accumulation at lake bottoms New mineral Lec 3: Earth Materials Lec 3: Earth Materials  Sedimentary environment Forms minerals by weathering or biological processes through chemical alteration or concentration Lec 3: Earth Materials Chemical weathering Unstable minerals exposed to surface conditions form new minerals Lec 3: Earth Materials  Biological processes Aragonite and calcite by microorganisms Apatite by human Lec 3: Earth Materials Lec 3: Earth Materials (Mineral Classification) Geol 100: Principles of Geology  Divided based on dominant anion or anionic group Mineral Based on chemical and internal classification structure Divided into silicates and non- silicates Lec 3: Earth Materials  Average composition of continental crust 50 O 46.6 45 Si 40 Al 35 30 27.72 Fe 25 % Ca 20 Na 15 10 8.13 K 5 5 3.63 2.83 2.59 2.09 Mg 0 O Si Al Fe Ca Na K Mg ELEMENTS Lec 3: Earth Materials  NON- SILICATE GENERAL CHEMISTRY EXAMPLE Native elements 1 element Gold, iron, copper, diamond Sulfides Metal + sulfur Galena, cinnabar, pyrite Sulfosalt Metal + semi- metal Enargite Oxide Metal + oxygen Hematite, magnetite Hydorxide Metal + OH or H2O Goethite Halide Metal + halogen Fluorite, halite, sylvite Carbonate Metal + CO3 Calcite, dolomite Sulfate Metal + SO4 Gypsum Lec 3: Earth Materials  Common Rock- Forming Minerals Silicates, Carbonates, Oxides, Sulfides Lec 3: Earth Materials  Silicates Fundamental unit: SiO4 or Silica Tetrahedra 25% of known minerals 90% of earth’s crust Forms in various environments Lec 3: Earth Materials  39% 12% 12% 11% 8% 5% 5% 5% 3% PLAGIOCLASE ALKALI QUARTZ PYROXENE AMPHIBOLE MICA CLAY OTHER NON- FELDSPAR SILICATES SILICATES Silicates Non-Silicates COMMON MINERALS IN THE EARTH’S CRUST Lec 3: Earth Materials Bowen’s Reaction Dunite, Komatiite Series (ultramafic) Gabbro, Norman L. Bowen Basalt (mafic) Ranks the common silicate minerals by Diorite, temperature at Andesite which it crystallizes (intermediate) Specific minerals Granite, form at specific Rhyolite Temperatures. (felsic) Lec 3: Earth Materials  O L I V I N E (Mg2+, Fe2+)2SiO4 Nesosilicate Diagnostic properties Color: olive green Habit: saccharoidal, massive Lec 3: Earth Materials  P Y R O X E N E (NaCa)(Mg,Fe,Al)(Al,Si)2O6 Inosilicate Diagnostic properties Habit: short and stubby Cleavage: 2 direction at 90o (blocky) Lec 3: Earth Materials  A M P H I B O L E NaCa2(Mg,Fe,Al)5(Al,Si)8O22(OH)2 Inosilicate Diagnostic properties Habit: long and slender Cleavage: 2 directions at 60o and 120o Lec 3: Earth Materials  B I O T I T E K(Mg,Fe)3AlSi3O10(OH)2 Phyllosilicate Diagnostic properties Color: black Habit: foliated/ micaceous Hardness: 63% 2% High Intermediate 1000 52- 63% 3% Intermediate Mafic Up to 1200 45- 52% 4% Low Ultramafic Up to 1500 < 45% 8- 32% Low to very low Volcanism Magma types Classified based on: Temperature SiO2 content Fe-Mg content Viscosity Volcanism  Any process which causes magma composition to change Magmatic Primary magma: undifferentiated differentiation Primitive magma: underwent minimum differentiation Parental magma: least differentiated magma in a series leading to evolved rocks Volcanism  Magmatic differentiation processes Fractional crystallization, assimilation, magma mixing, liquid immiscibility Volcanism Fractional crystallization Volcanism Assimilation Volcanism Magma mixing Volcanism Liquid immiscibility Volcanism  Magma rises due to: How does Buoyancy magma move? Weight of overlying rock Magma flows due to viscosity (resistance to flow; depends on temperature) Volcanism  Controlled by: Magma Depth of intrusion solidification Shape and size of magma body Presence of circulating water Volcanism  Magma that solidifies within the earth Magma cooling Cools slowly within the earth Intrusive/ plutonic rocks Crystals visible to the eye Volcanism  Magma solidifies on the earth’s surface Magma cooling Small crystals and/or non-crystalline Extrusive/ volcanic rocks particles of various sizes Volcanism  Extrusive Intrusive  Volcanic eruption products Lava Pyroclastic deposits Gas Volcanism  Lava types Type Composition Viscosity Temperature Eruption Mafic-rich Less viscous; Effusive; flowy Basaltic High in Magnesium, 1000oC – 1200oC fast flow rate Flood basalts Iron, and Intermediate Thick lava flows; Andesitic Moderately viscous 900oC – 1000oC composition stratovolcanoes Explosive due to Felsic-rich Highly viscous; rich in silica and Rhyolitic High in Silica and 650oC – 800oC very slow flow rate volatile nature, Potassium often as pyroclastic Volcanism Pyroclastic deposits Volcanism  Gas Most abundant: water vapor (H2O) Others: CO2, H2S, SO2 Volcanism  Eruptive style Effusive eruptions Explosive eruptions Produce clouds and Produce lava flows avalanches of pyroclastic debris Volcanism  Volcanic landform: Central eruptions From a central vent Shield volcano, volcanic dome, cinder cone, stratovolcano, crater, caldera, diatreme Volcanism  Volcanic landform: Fissure eruption From nearly vertical cracks Flood basalt, ash- flow deposit Volcanism Types of eruption Volcanism  Lava flow Ash and lapilli Volcanic Blast hazards Landslide Lahar Earthquake Tsunami Gas and aerosol Volcanism  Questions? Volcanism Lec 5: Igneous Rocks Geol 100: Principles of Geology  Igneous rock From Latin word “ignis” meaning fire Rock formed by solidification of a molten magma Igneous Rocks  Magma Hot fluid or semifluid material below or within the earth's crust Composed of solid, liquid, and gas materials. Formed when there is decrease in pressure, addition of volatiles, or heat transfer from rising magma Igneous Rocks  Magma types Type Color Composition Temperature (°C) SiO2 Fe- Mg Viscosity Light-colored minerals Silicic/ High Felsic High in SiO2, K 650 – 800 > 63% 2% Rhyolitic Very slow flow rate Low in Fe, Mg Intermediate; mixed Andesitic Intermediate light- and dark-color 900 – 1,000 52- 63% 3% Moderate minerals Dark-colored minerals Low Basaltic Mafic High in Mg, Fe 1,000 – 1,200 45- 52% 4% Fast flow rate Low in SiO2, K Ultrabasic Ultramafic Olivine (+ amphibole) 1,200 – 1,500 < 45% 8- 32% Low to very low Igneous Rocks  How to classify Igneous rocks? Igneous Rocks  Composition Based on magma chemistry Classification Determines the percentage of dark- basis colored and light- colored minerals Texture Based on size, shape, arrangement and degree of crystallinity Igneous Rocks  Composition Ultrabasic, Basic, Intermediate, Silicic Remember: ultramafic, mafic, felsic are “color” terms Igneous Rocks  Silicic Intermediate Basic Ultrabasic SiO2 >66% 52- 66% 45- 52% 64mm) Bombs: Rounded clasts (>64mm) Lapilli: 2-64mm diameter Ash: < 2mm diameter Igneous Rocks  Tuff breccia Pyroclastic breccia Tuff/ ash tuff  What are some examples of Igneous rock bodies? Igneous Rocks  Igneous structures Pluton: large igneous bodies deep beneath the Earth Batholith: >100km2 Stock: Hornfels 2. Volcanic Arc Zeolite => Prehnite-Pumpellyite => Greenschist => Amphibolite => Granulite (low P-T) 3. Mountain Belts Zeolite => Prehnite-Pumpellyite => Greenschist => Amphibolite => Granulite (medium P-T) 4. Stable Continent Zeolite => Prehnite-Pumpellyite => Greenschist => Amphibolite => Eclogite (high P-T) 5. Accretionary Prism Zeolite => Blueschist => Eclogite (very high P-T)  Questions? Lec 07: Metamorphic Rocks