Earth Systems Lecture Notes - Endogenic, Exogenic, Geologic Time Scale, Anthropocene - PDF

Lecture 3 Endogenic and Exogenic Systems, Geologic Time scale, Anthropocene Copyright © 2019 Pearson Canada Inc. 1-1  Lecture 3 will focus on:  Geosystems, geology, geomorphology  Endogenic and exogenic systems and their driving forces  The time spans, into...

Lecture 3 Endogenic and Exogenic Systems, Geologic Time scale, Anthropocene Copyright © 2019 Pearson Canada Inc. 1-1  Lecture 3 will focus on:  Geosystems, geology, geomorphology  Endogenic and exogenic systems and their driving forces  The time spans, into which Earth’s geologic history is divided, the Anthropocene  Guiding principles laws in geology  The principles of uniformitarianism and superposition  Earth’s Structure and Internal Energy  Earth Materials and the Rock Cycle Copyright © 2019 Pearson Canada Inc. 1-2 Introduction  Why we need to understand the Natural Environment?  Human dependence on natural environment,  Resolution of environmental issues,  Intrinsic interest.  The Natural Environment: Four spheres (Atmosphere, Hydrosphere, Lithosphere, Biosphere)  Dynamic system, Strahler, A. and Strahler, A., 2005. Physical Geography, Wiley, NY.  Array of subsystems,  Multitude of interconnected processes,  Diverse spatial and temporal scales. Copyright © 2019 Pearson Canada Inc. 1-3 Two Broad Earth Systems Earth’s endogenic and exogenic systems: 1) Endogenic system: encompasses internal processes that produce flows of heat and material from deep below Earth’s crust.  Energy source: heat from pressure (gravity) and radioactive decay,  Related branch of science: Geology. 2) Exogenic system: consists of external processes at Earth’s surface that set into motion air, water, and ice.  Energy source: solar energy and the energy of motion (air, water, ice),  Related branch of science: Geomorphology Copyright © 2019 Pearson Canada Inc. 1-4 Two Broad Earth Systems Copyright © 2019 Pearson Canada Inc. 1-5 Two Broad Earth Systems Copyright © 2019 Pearson Canada Inc. 1-6 THE GEOLOGIC TIME SCALE: Absolute Dating The Geologic Time Scale  Eon > Era > Period > Epoch  Overall > 4.567 billion years (Ga = Giga annum)  88.3% - Precambrian Eon  Last 2 Ma (Mega annum) -0.04% of the time. Copyright © 2019 Pearson Canada Inc. 1-7 THE GEOLOGIC TIME SCALE: Absolute Dating The Geologic Time Scale  The Sun and its Solar System (including Earth) ~4.6 billion years B.P.  Holocene (Present Epoch, ,postglacial) ~ 11,500 years B.P.  ‘Anthropocene’ (proposed) ‘the human epoch’ ~ (??) 250 –6000 years B.P. 1-8 Anthropocene:  Human activity affects the Earth’s systems greater than natural forces  Human activity affects the earth’s systems faster than natural forces  Anthropocene’: ‘the human epoch’ ~ (??) 250 – 6000 years B.P.(Before Present)  Novel stratigraphic signatures support the formalization of the Anthropocene at the Epoch level (from Waters et al. 2016) 1-9 Anthropocene: 1 - 10 GUIDING PRINCIPLES LAWS IN GEOLOGY: Dating 1) Absolute Time  Actual number of years (BP)  Scientific methods to determine absolute age (e.g. radiometric dating). 2) Relative Time  Sequence of events — what happened in what order  Relative dating is based on the relative positions of rock strata (layers) above or below each other (stratigraphy)  Two facts: The oldest rock on Earth is about 4.0 billion years, The oldest fossil is about 3.5 billion years.  Radiometric Dating: Half-life, the decay-rate, is the time required for one-half of the unstable atoms in a rock sample to decay into “daughter” isotopes. Copyright © 2019 Pearson Canada Inc. 1 - 11 GUIDING PRINCIPLES IN GEOLOGY: Dating Some history:  1669 –Steno, N.: Law of superposition  Hooke, R.: Fossils as dating instrument  1786 –Cuvier: Extinctions  1799 –Smith, W. : Law of faunal succession, extinction  1841: First global geological record  20th century: Radio-dating sync palaeo and geological records Copyright © 2019 Pearson Canada Inc. 1 - 12 GUIDING PRINCIPLES IN GEOLOGY: Dating Stratigraphy: is the overall study of rock layers, including the principles, types of stratigraphic units (like formations and structure) and their interpretation. Relative dating: is one of the tools used within stratigraphy to place these rock layers and events in a chronological sequence Stratigraphy principles: 1) Principle of Original Horizontality 2) Principle of Lateral Continuity 3) Principle of Superposition 4) Principle of Cross-Cutting Relations 5) Law of Inclusions 6) Law of Faunal Succession Copyright © 2019 Pearson Canada Inc. 1 - 13 GUIDING PRINCIPLES IN GEOLOGY: Dating Copyright © 2019 Pearson Canada Inc. 1 - 14 GUIDING PRINCIPLES IN GEOLOGY: Dating Superposition and Uniformitarianism: Youngest layers  Superposition: Rock and sediment are always arranged with the youngest bed (stratum) “superposed” toward the top Relative Dating of a rock formation and the oldest at the base, if they have not been disturbed.  Uniformitarianism: The same physical processes active in the environment today have been operating throughout the geologic time (Earthquakes, volcanic eruptions, landslides, orogenesis). Oldest layers Copyright © 2019 Pearson Canada Inc. 1 - 15 GUIDING PRINCIPLES IN GEOLOGY: Unconformities Unconformity: is a pattern that you look for in a group of rocks that tells you erosion has taken place, involve sedimentary rocks, changes in sea level, and/or uplift from an orogeny. Copyright © 2019 Pearson Canada Inc. 1 - 16 GUIDING PRINCIPLES IN GEOLOGY: Unconformities Unconformity Types: 1) A disconformity: Is an erosional surface where the rocks below the unconformity are much older than the rocks above. 2) A nonconformity: forms when igneous or metamorphic bedrock is eroded, and then horizontal layers of sedimentary rock are deposited directly on top of it. 3) An angular unconformity: is created when horizontal layers of sedimentary rock lie on top of tilted and uplifted layers of older sedimentary rocks. 4) A paraconformity: is very similar to a disconformity, except the evidence for erosion is not present, and instead, there was only a pause in sediment deposition. Radiometrically dated reveal a large gap in time. Copyright © 2019 Pearson Canada Inc. 1 - 17 GUIDING PRINCIPLES IN GEOLOGY: Unconformities Copyright © 2019 Pearson Canada Inc. 1 - 18 GUIDING PRINCIPLES IN GEOLOGY: Dating Copyright © 2019 Pearson Canada Inc. 1 - 19 Earth’s Structure and Internal Energy  Earth from nebula 4.6 billion Crust years ago.  Silica and iron are two dominant materials.  As temperature decreased, Earth solidified and gravity sorted materials by density.  Core mass = 1/3 of Earth’s Mantle mass. Outer Core  Core volume = 1/6 of Earth’s volume. Inner Core Strahler, A. and Strahler, A., 2002. Physical CopyrightGeography. Wiley,Canada © 2019 Pearson NY. Inc. 1 - 20 Earth’s Structure and Internal Energy Earth’s Magnetism Crust  Magnetic poles and geographic poles are different!  The fluid outer core generates 90% of Earth’s magnetic field, because it is made of liquid molten metallic iron.  Migration of the north Mantle magnetic pole (NMP), NMP Outer Core now is at 85.1°N, 134°W. Inner Core Strahler, A. and Strahler, A., 2002. Physical CopyrightGeography. Wiley,Canada © 2019 Pearson NY. Inc. 1 - 21 Earth’s Structure and Internal Energy  Each layer distinct in either composition or temperature.  Heat energy migrates outward by conduction as well as by convection in the plastic, or fluid, layers.  Seismic tomography - identify the boundaries  Density changes could induce reflection and refraction of seismic waves  Earth’s Mantle: 80% Earth’s total volume, density is 4.5g/cm3. The boundary between the uppermost mantle and the crust above is called the Mohorovicic ( or Moho) discontinuity. Copyright © 2019 Pearson Canada Inc. 1 - 22 Earth’s Structure and Internal Energy The Asthenosphere and Lithosphere  The asthenosphere: Between the upper mantle and the uppermost mantle, a plastic-like layer, flow when a force is present. A rigid layer will instead bend or break.  The Lithosphere consists of the crust and the uppermost mantle.  Average thickness of oceanic crust is 5 km, and 30 km for continental crust. Copyright © 2019 Pearson Canada Inc. 1 - 23 Earth’s Structure and Internal Energy  Continental crust low in density (or 2700 kg/m3), granite, called sial(dominanted by silica and aluminum).  Oceanic crust is denser (or 3000 kg/m3), basalt, called sima (dominanted by silica and magnesium). Copyright © 2019 Pearson Canada Inc. 1 - 24 Earth’s Structure and Internal Energy The Buoyancy and Isostasy  Buoyancy (physics) tells us that something less dense (e.g., wood, ice) floats in something denser (e.g., water).  Earth’s crust floats on the denser (elastic) layers beneath it.  The crust is in a constant state of compensating adjustment, or Isostasy.  Where the load is greater, the crust tends to sink, or ride lower in the asthenosphere. Without load, the crust rides higher, in a recovery uplift known as isostatic rebound. Copyright © 2019 Pearson Canada Inc. 1 - 25 Earth’s Structure and Internal Energy The Isostatic Adjustment Principle:  Isostatic (iso = “equal,” static = “standstill”) refers to the state of gravitational equilibrium between the lithosphere and asthenosphere such that the tectonic plates “float” at an elevation that depends on their thickness and density.  Is the balance between the buoyancy and gravitational forces, explain the vertical movements of Earth’s crust. Copyright © 2019 Pearson Canada Inc. 1 - 26 Earth’s Structure and Internal Energy  Isostatic adjustment in Canada: Copyright © 2019 Pearson Canada Inc. 1 - 27 Earth’s Structure and Internal Energy Copyright Strahler, A. and Archibold, O.W., 2011. © 2019 Physical PearsonWiley, Geography. CanadaNY.Inc. 1 - 28 Earth’s Structure and Internal Energy Copyright © 2019 Pearson Canada Inc. 1 - 29  TheStructure Earth’s and InternalElements Most Abundant Energy of Elements of Earth’s theCrust Crust Metalloid, does not act as a base or an acid Copyright Strahler, A. and Archibold, O.W., 2011. © 2019 Physical PearsonWiley, Geography. CanadaNY.Inc. 1 - 30 Earth Materials and the Rock Cycle Minerals and Rocks:  A mineral is an inorganic (nonliving) natural compound having a specific chemical composition and possessing a crystalline structure.  A rock is an assemblage of minerals bound together, or a mass of a single mineral, or undifferentiated material, or even solid organic material (such as coal). § Three basic rock types: Igneous (fire-formed, from molten material), Sedimentary (from settling out), Metamorphic (altered)  Three basic rock types: Igneous (fire-formed, from molten material), Sedimentary (from settling out), Metamorphic (altered) Copyright © 2019 Pearson Canada Inc. 1 - 31 Earth Materials and the Rock Cycle Rocks: three types according to the processes that formed them: 1) Igneous (Most abundant class, formed from molten material)  Rapid cooling fine texture.  Slow cooling coarse texture  Intrusive igneous - cool magma below the surface, granite  Extrusive igneous rock - cool lava on the surface, basalt 2) Sedimentary (formed by lithification of sediment via cementation, compaction, dehydration, or heating),  Sediment can be clastic, chemically precipitated, or organic, Shells (lime stones) or organic matter (coal), or precipitation of minerals (lime stones) 3. Metamorphic (altered 1 and 2 by heat, pressure, compression and shear). Copyright © 2019 Pearson Canada Inc. 1 - 32 Earth Materials and the Rock Cycle More silica Less silica Copyright © 2019 Pearson Canada Inc. 1 - 33 Earth Materials and the Rock Cycle Copyright © 2019 Pearson Canada Inc. 1 - 34 Earth Materials and the Rock Cycle  Pluton are any intrusive igneous body, it includes: 1) Batholith 2) laccolith 3) Sills 4) Dikes Copyright © 2019 Pearson Canada Inc. 1 - 35 Earth Materials and the Rock Cycle Sedimentary Rocks: 1) Clastic Sedimentary Rocks:  Formed from fragments broken off a pre-existing parent rock,  Produce by Lithification (compaction and cementation by minerals, drying and heating),  Can be classified by size of the sediment (shale, sandstone, conglomerate) 2) Chemical Sedimentary Rocks:  Produce from shells or by chemical precipitation i.e. inorganic mineral compounds derived from a saline solution,  Forming karst topography, hydrothermal deposits and salt deposits; Ex.: halite and potash. 3) Biogeochemical sedimentary rocks:  Formed from organic deposits, i.e. material produced by plants and animals.  Ex.: chalk (skeletons and shell fragments) and coal (peat + compaction). Copyright © 2019 Pearson Canada Inc. 1 - 36 Earth Materials and the Rock Cycle Sedimentary Rocks: 1) Clastic Sedimentary Rocks:  Formed from fragments broken off a pre-existing parent rock,  Produce by Lithification (compaction and cementation by minerals, drying and heating),  Can be classified by size of the sediment (shale, sandstone, conglomerate) 2) Chemical Sedimentary Rocks: 3) Biogeochemical sedimentary rocks: Copyright © 2019 Pearson Canada Inc. 1 - 37 Earth Materials and the Rock Cycle Sedimentary Rocks: 1) Clastic Sedimentary Rocks:  Formed from fragments broken off a pre-existing parent rock,  Produce by Lithification (compaction and cementation by minerals, drying and heating),  Can be classified by size of the sediment (shale, sandstone, conglomerate) 2) Chemical Sedimentary Rocks: 3) Biogeochemical sedimentary rocks: Copyright © 2019 Pearson Canada Inc. 1 - 38 Earth Materials and the Rock Cycle Sedimentary Rocks: 1) Clastic Sedimentary Rocks: 2) Chemical Sedimentary Rocks:  Produce from shells or by chemical precipitation i.e. inorganic mineral compounds derived from a saline solution,  Forming karst topography, hydrothermal deposits and salt deposits; Ex.: halite and potash. 3) Biogeochemical sedimentary rocks: Copyright © 2019 Pearson Canada Inc. 1 - 39 Earth Materials and the Rock Cycle Sedimentary Rocks: 1) Clastic Sedimentary Rocks: 2) Chemical Sedimentary Rocks:  Produce from shells or by chemical precipitation i.e. inorganic mineral compounds derived from a saline solution,  Forming karst topography, hydrothermal deposits and salt deposits; Ex.: halite and potash. 3) Biogeochemical sedimentary rocks: Copyright © 2019 Pearson Canada Inc. 1 - 40 Earth Materials and the Rock Cycle Sedimentary Rocks: 1) Clastic Sedimentary Rocks: 2) Chemical Sedimentary Rocks: 3) Biogeochemical sedimentary rocks:  Formed from organic deposits, i.e. material produced by plants and animals.  Ex.: chalk (skeletons and shell fragments) and coal (peat + compaction). Copyright © 2019 Pearson Canada Inc. 1 - 41 Earth Materials and the Rock Cycle  Sedimentary Rocks: Copyright © 2019 Pearson Canada Inc. 1 - 42 Earth Materials and the Rock Cycle Metamorphic rocks: Formed by physical alteration of a pre-existing rock via:- high pressure - compression and/or shear(foliation)- extreme heat- both, More resistant to weathering and erosion  Contact metamorphism, when rocks cooked by intrusion magma  Regional metamorphism, when a large areal extent of rock is subject to metamorphism  Foliated rocks has a banded  Nonfoliated rocks Copyright © 2019 Pearson Canada Inc. 1 - 43 Earth Materials and the Rock Cycle Contact and regional metamorphism:  Contact metamorphism occurs in the upper crust when rising magma “cooks” adjacent rock.  Regional metamorphism occurs deep in the lithosphere. Copyright © 2019 Pearson Canada Inc. 1 - 44 Earth Materials and the Rock Cycle Coal Formation:  Peat + compaction → lignite (a.k.a. brown coal).  Lignite + compaction and dehydration → bituminous coal (a.k.a. soft coal).  Bituminous coal + heat and pressure → anthracite (a.k.a. hard coal). Copyright © 2019 Pearson Canada Inc. 1 - 45 Earth Materials and the Rock Cycle  The Rock Cycle: Two cyclic systems drive the rock cycle: 1) The hydrologic cycle: at and above Earth’s surface, powered by sun 2) The tectonic cycle: below Earth’s surface powered by internal heat, Copyright © 2019 Pearson Canada Inc. 1 - 46  Earth Materials and the Rock Cycle k Transformation ck eing by Copyright Strahler, A. and Strahler, A., 2002. Physical © 2019 Wiley, Geography. Pearson Canada Inc. NY. 1 - 47 Thank you  1 - 48