Planet Earth Part 1 PDF

1 Introduction to Geosciences 1. Planet Earth – Part 1 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1. Planet Earth: Overview 2 Chapter 1 – Content Part 1: 1.1 The earth and our solar system 1.1.1. Planetary systems...

1 Introduction to Geosciences 1. Planet Earth – Part 1 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1. Planet Earth: Overview 2 Chapter 1 – Content Part 1: 1.1 The earth and our solar system 1.1.1. Planetary systems 1.1.2. Our solar system 1.1.3. The earth in our solar system 1.2 The earth‘s interior 1.2.1. Internal structure of the earth 1.2.2. Chemical composition of the earth 1.2.3. Thermal gradients in the earth Part 2: 1.3 Plate tectonics 1.4 History of the earth Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 3 A planetary system consists of - a central star - one or more planets that are bound to this central star by gravitation … and sometimes additional objects, e.g. - dust clouds - moons - comets - asteroids (planetoids) - protoplanets („planet embryos“) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 4 Star: any astronomic object that consists of light-emitting plasma Planet: any astronomic object that orbits a star and has its own gravity Dust cloud: small particles of cosmic dust („stardust“), typically 0.1 µm or smaller Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 5 Moon: any astronomic object that orbits around a planet. One planet can have several moons (Saturn has 62). Comet: any icy object that releases gases when close to the sun Asteroid: a minor planet (often a fragment of an astronomic object, 1m to 1000 km in diameter). More than 14,000 NEAs (near earth asteroids) are known. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 6 In total, there are more than 3,700 known planets – but probably many more in our galaxy alone, the „Milky Way“. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 7 1. How many planets are there in our galaxy? 2. What is the local group? Film 1.1.1. 3. How many galaxies exist in total? The Milky Way Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 8 1. How many planets are there in our galaxy? Film 1.1.1 2. What is the local group? The Milky Way 3. How many galaxies exist in total? 1. at least 100 billion planets 2. a group of around 50 galaxies around ours (the Milky Way) 3. at least 170 billion galaxies Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.1 Planetary Systems 9 A planetary system consists of any of the following elements: - a central, light-emitting star - one or more planets that are bound to the central star by gravitation - dust clouds (consisting of small particles) - moons that orbit around planets - comets (icy astronomic bodies that emit gas when they come near hot stars) - asteroids (planetoids), i.e. minor planets (which may crash with other planets) - protoplanets („planet embryos“) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 10 Our solar system was formed around 4.6 billion years ago. There are 8 planets plus Pluto (which is considered a planetoid due to its small size) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 11 The following sentence helps you to memorize the names of the planets: Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune (Pluto) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 12 Terrestrial planets consist mostly of iron and silicate rocks. They include… Mercury Venus Earth Mars Iron is typically concentrated in the inner core, silicates dominate the mantle and crust. Example: The earth‘s crust contains about 60.2% SiO 2 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 13 The giant planets are not dominated by rocks and can be differentiated into two groups: Gas giants are dominated by hydrogen and helium gas (Jupiter, Saturn) Ice giants are dominated by frozen water, ammonia and methane (Uranus and Neptune) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 14 1. How many solar systems exist in our galaxy? Film 1.1.2 2. How are the groups of the gas giants and the ice giants also called? Our solar system 3. Which planet is the largest in our solar system? 4. What is the Kuiper Belt? Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 15 1. How many solar systems exist in our galaxy? Film 1.1.2 2. How are the groups of the gas giants and the ice giants also called? Our solar system 3. Which planet is the largest in our solar system? 4. What is the Kuiper Belt? 1. around 500 solar systems (but some without planets) 2. the Jovian planets (Jovian means Jupiter-like) 3. Jupiter 4. an icy belt around Neptune that contains many asteroids and Pluto („dwarf planet“) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.2 Our solar system 16 Our solar system consists of the sun as the central star, 8 planets and one dwarf planet. - The terrestrial planets Mercury, Venus, Earth and Mars are closest to the sun and consist mostly of iron and silicates. - The jovian planets can be classified as gas giants (Jupiter, Saturn) consisting mostly of hydrogen and helium, and ice giants (Uranus, Neptune) consisting mostly of frozen water, ammonia and methane Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 17 Revolution of the moon around the earth Duration: 27.32 days Distance from earth: about 385,000 km Distance travelled: 2.4 mill. km Travel speed: 1,022 km/h Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 18 Revolution of the earth around the sun Duration: 365.256 days Distance from sun: about 150 mill. Km Distance travelled: 940 mill. km Travel speed: 108,000 km/h Revolution of the moon around the earth Duration: 27.32 days Distance from earth: about 385,000 km Distance travelled: 2.4 mill. km Travel speed: 1,022 km/h Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 19 4.6 billion years ago, the sun began to form from dust and gases Energy Output of the Sun: 3.846×1026 W (equals 200 quadrillion of the strongest nuclear power reactors) Powered by nuclear fusion which converts hydrogen (currently 73%) to helium Over the next 3 billion years, the sun will increase its size by 40%. All life on earth will disappear. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 20 In around 5 billion years, the hydrogen reserves in the sun will be exhausted. The sun will become dark red. In around 9 billion years, the sun will turn into a white dwarf (a small white star), and ultimately a black dwarf Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 21 The amount of energy emitted by the sun varies over time. For example, darker sun spots occasionally form. Their temperature (2,700–4,200 °C) is lower than the typical surface temperature of the sun (5500 °C). Sun spots only lead to a small reduction in the energy received by the earth. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 22 Average solar radiation according to WMO: 1367 W/m2 (16 kWh/m2/day) Out of this radiation, about 75% pass through the atmosphere on a cloudless day. Clouds reduce this number significantly: even cirrus clouds lead to a reduction to about 50%. Introduction to Geosciences German Mongolian Institute for Resources and Technology  2.1.2. Elements of Weather and Climate 23 Direct heat (temperature) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 24 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 25 Solar radiation in Germany Maximum solar radiation Summer Winter Clear Sky 1000 W/m2 500 W/m2 Moderate Cloud Cover 600 W/m2 300 W/m2 Complete Cloud Cover 300 W/m2 150 W/m2 Differences in solar radiation are extremely relevant for solar energy production. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 26 Average solar radiation according to WMO: 1367 W/m2 (16 kWh/m2/day) Maximum potential usable for solar power generation: 7.5 kWh/m 2/day Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 27 Moonlight is in reality a reflection of sunlight. When the moon is located between earth and sun, it becomes invisible from the earth. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 28 Solar eclipse: The moon blocks the sunlight (during the daytime) Lunar eclipse: The earth blocks all sunlight towards the moon (during the nighttime) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 29 Ocean tides are a result of the gravity of sun and moon Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 30 Tidal calendar: due to different combinations of the effects of sun and moon, tides can be higher or lower Spring tide: strong tide due to combined Neap tide: weaker tide due to opposing effects of sun and moon effects of sun and moon. The moon‘s effect is stronger (→ closer to earth) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 31 A lunar eclipse with a very large moon (supermoon) will be visible on the evening of 31 January 2018. Best time for watching: between 9 and 10 pm. „Blue moon“ „Blood moon“ Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 32 1. What is a supermoon? 2. What is a bloodmoon? Film 1.1.3 3. What is a blue moon? Supermoon Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 33 1. What is a supermoon? 2. What is a bloodmoon? Film 1.1.3 3. What is a blue moon? Supermoon 1. a full moon that appears very large (+14%) and bright (+30%) because it is very close to the earth (perigee) 2. a totally eclipsed moon that gets a reddish color 3. the second full moon that occurs within one month (or: a moon that appears blue due to dust particles in the earth‘s atmosphere) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.1.3 The earth in our solar system 34 The earth is strongly influenced by two objects in our solar system. The sun provides a constant energy supply of around 1,367 W/m² (solar constant). The exact amount of energy received depends on - variations of the sun‘s intensity (solar cycles / solar spots) - the latitude (more energy is received closer to the equator) - the season (more energy is received during summer) - cloud cover (even light clouds considerably reduce the energy received on the ground) Moonlight is only a reflection of sunlight. Changing relative positions of earth, sun and moon are the cause of tides in the oceans. The strongest tides (spring tides) occur when sun and moon are in one line with the earth. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2 The earth‘s interior 35 In this chapter, you will learn about… 1. the internal structure of the earth 3. thermal gradients in the earth 2. the chemical composition of the earth Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 36 1. thin crust: 10 to 50 km - continental - oceanic 2. thick mantle - outer mantle: hot, plastic - inner mantle: hot, solid 3. core - outer core - inner core Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 37 1864: science fiction novel „A Journey to the Centre of the Earth“ (Jules Verne) But: How can scientists find out something about the inside of the earth? a) direct investigations: drilling deep inside the earth b) indirect investigations: observing the ways that earthquake waves spread Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 38 The world‘s deepest boreholes No. 2: German Continental Deep Drilling Programme (1987-1995) Max. depth: 9,101 meters Cost: 270 million Euros No. 1: Kola Superdeep Drilling Project, 1967-1989 Depth: 12,262 metres → Boreholes only get into the crust! Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 39 Some earthquake waves, the so called S waves, cannot more through the liquid outer core of the earth (it is too liquid for the waves to move on) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 40 P waves or primary waves push or pull rocks and move at very high speed (5000 m/s in granite). They can move through any type of material. S waves or secondary waves move rocks up and down (or to the side) at lower speeds (3000 m/s in granite). They can only move through solid material. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 41 Reduction of speed – to almost 0 m/s for S waves Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 42 S-waves cannot move through the cors of the earth. Therefore, there is a large shadow zone that S waves from a specific epicenter cannot reach. When P waves reach the core of the earth, they are refracted and change their direction. Therefore, there are also shadow zones for P waves. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 43 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 44 What were the important discoveries of these two seismologists? a) Richard Oldham Film 1.2.1a b) Inge Lehmann Core of the earth Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 45 What were the important discoveries of these two seismologists? a) Richard Oldham Film 1.2.1a b) Inge Lehmann Core of the earth 1.Richard Oldham discovered the earth‘s (outer) core (1906). 2. Inge Lehmann discovered that the core consists of two parts: the inner (solid) and the outer liquid core (1936). Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 46 The mantle is the thickest layer of the earth (almost 3000 km). There are two hypotheses about its structure: 1. Whole mantle hypothesis: material circulates in the whole mantle. 2. Layered mantle hyptothesis: Material circulates in the upper mantle, and in the lower mantle (separate circulations) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 47 Crust Outer mantle On the plastic (gel-like) outer mantle, the earth‘s crust can move. This example shows divergent plates which move in different directions. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 48 Heat from the core can lead to higher temperatures in some parts of the core. This causes so-called hotspot vulcanoes. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 49 The crust can be divided into large plates that move into different directions on the upper mantle. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 50 The earth has two types of crust: Continental crust - thick (up to 70 km) - light (2.7 g/cm³) - Sial: silicium and aluminium dominate Oceanic crust - thin (max 10 km) - heavy (2.9 g /cm³) - Sima: silicium and magnesium dominate Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 51 Whenever continental and oceanic crust move towards each other (convergence), the heavier oceanic crust sinks down (subduction). This is also an important cause of volcanism. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 52 1 In some parts of the earth, hot material rises from the mantle into the 1 crust. This forms hot spot 3 4 vulcanoes. In other regions, the earth‘s crust sinks into the mantle. This is the case in 2 ocean trenches 3 subduction zones 2 4 In oceanic ridges, the 1 earth‘s crust diverges and 4 lets magma from the mantle rise to the surface. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 53 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 54 1. a. When did scientists start to try drilling into the earth‘s mantle? b.When did they succeed? Film 1.2.1b 2. Why are scientists interested in drilling Drilling into the mantle into the earth‘s mantle? 3. What did the eruption of a diamond from a volcano tell us about the mantle? Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 55 1. a. When did scientists start to try drilling into the earth‘s mantle? b.When did they succeed? Film 1.2.1b 2. Why are scientists interested in drilling Drilling into the mantle into the earth‘s mantle? 3. What did the eruption of a diamond from a volcano tell us about the mantle? 1. a. In the 1960s, scientists began to try drilling into the earth‘s mantle. b. So far, they have not succeeded yet. 2. - This will increase our knowledge about the history and formation of the earth - The mantle makes up 84% of our planet 3. That there is water in the mantle of the earth Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.1 Internal structure of the earth 56 The earth consists of the following layers: 1. The earth‘s crust can be divided into continental crust (thick but relatively light, Sial) and oceanic crust (thin but relatively heavy, Sima). 2. The earth‘s mantle consists of an upper and lower mantle on which the crust can move slowly. In hot zones, material from the mantle can move through the crust and form hot spot vulcanoes. In subduction zones, crust sinks into the mantle and melts. In oceanic ridges, the crust opens and magma from the mantle comes to the surface. 3. Knowledge about the earth‘s core comes mainly from the study of earthquake waves. P waves (primary waves) and S waves (secondary waves) cannot move through the earth into all directions because of the properties of the outer (liquid) and inner (solid and extremely dense) core. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 57 The three most important elements in the earth‘s crust are - Si - Al - Fe Mostly, these elements occur in oxides. The three most common chemical compounds in the crust are: - 60.6 % SiO2 - 15.9% Al2O3 - 6.7% FeO Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 58 =crust = outer mantle = inner mantle Regarding their mechanical properties, the Regarding chemical composition, the earth earth can be divided into 5 layers. can be divided into 6 layers. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 59 When considering the 3 main elements (Si, Al, Fe; besides oxygen) that the earth consists of: Why does the core contain 85% iron? Iron has the highest atomic mass: Al 26 Si 28 Fe 55 Density of core: 9.9-13.1 g/cm³ Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 60 Inside the earth, there are several so-called discontinuities. In these zones, the density, chemical composition and mechanical properties abruptly change. The closest to the surface is the so-called Moho = Mohorovičić discontinuity. This is the boundary between (continental/oceanic) crust and mantle. Along this border, the following changes occur: Crust Mantle Density Continental: 2.7 g/cm³ Upper mantle: 3.3 g/cm³ Oceanic: 2.9 g/cm³ Chemistry Continental: Si>Al>Na>K Mg>Si>Fe>Ca Oceanic: Si>Fe>Mg>Ca Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 61 Most common industrial metals: Al, Fe Rarest industrial metals: W, Mo Mongolia has deposits of both metals! Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 62 1. How much rarer is Iridium as compared to gold? 2. Why is more iridium found in some Film 1.2.2 66 million year old sediments? The rarest metal on earth 3. Which special properties does Iridium have? Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 63 1. How much rarer is Iridium as compared to gold? 2. Why is more iridium found in some Film 1.2.2 66 million year old sediments? The rarest metal on earth 3. Which special properties does Iridium have? 1. Ir is about 40 times rarer than Au. 2. About 66 million years ago, a meteorite which contained Iridium collided with the earth (this meteorite also lead to the extinction of dinosaurs). 3. -it is harder than steel; - it has a very high density (22.56 g/cm³); - it does not oxidize (up to 2000° C) - good catalyst in organic chemistry Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.2 Chemical composition of the earth 64 The earth consists of the following layers: 1. The earth‘s crust can be divided into continental crust (thick but relatively light, Sial) and oceanic crust (thin but relatively heavy, Sima). 2. The earth‘s mantle consists of an upper and lower mantle on which the crust can move slowly. In hot zones, material from the mantle can move through the crust and form hot spot vulcanoes. In subduction zones, crust sinks into the mantle and melts. In oceanic ridges, the crust opens and magma from the mantle comes to the surface. 3. Knowledge about the earth‘s core comes mainly from the study of earthquake waves. P waves (primary waves) and S waves (secondary waves) cannot move through the earth into all directions because of the properties of the outer (liquid) and inner (solid and extremely dense) core. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 65 Average temperature on the surface of the earth: 14.7°C Estimated temperature in the inner core of the earth: around 6000 °C (with some uncertainty!) From the inside to the surface of the earth, there is a heat flow of about 47 TW. For comparison: the total global power generation is about 18 TW. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 66 About 80% of the heat inside the earth is produced by radioactive decay of the following substances: 235 U 238 U 232 Th 40 K Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 67 Over a very long period of time, this heat production will slowly decrease. For a reduction of 50%, it would take around a billion years! By the time our sun‘s hydrogen reserves will be used up, the earth will also have lost most of its internal heat (only about 3% will be left). Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 68 Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 69 Geothermal gradient + 25K per 1km of depth in the lithosphere (world average) Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 70 Variation of the geothermal gradient Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 71 Geothermal waters in Southern Germany: Depths/Temperatures Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 72 Revision Questions: 1. Which scientist first studied the geothermal gradient? Film 1.2.3 2. Why did this scientist Geothermal gradient wrongly calculate the age of the earth? Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 73 Revision Questions: 1. Which scientist first studied the geothermal gradient? Film 1.2.3 2. Why did this scientist Geothermal gradient wrongly calculate the age of the earth? 1.the British physicist William Kelvin 2. Kelvin calculated an age of 20 million years (instead of 4.5 billion years). He did not take into account (a) the heating effect of radioactive decay inside the earth and (b) the effect of thermal convection (the movement of molten rock in the earth‘s mantle which also transports heat. Introduction to Geosciences German Mongolian Institute for Resources and Technology  1.2.3 Thermal gradients in the earth 74 From the inner core (about 6000°C) to the surface of the crust (about 14.7°C on average), there is a constant flux of heat (about 47 TW). Most of this energy is produced by natural radioactive decay of 235U, 238U, 232Th and 40K in the core, mantle and crust of the earth. In the crust, temperatures increase by about 25K per kilometer of depth (geothermal gradient). In regions with active volcanism, this gradient can be much larger. Today, the internal heat of this earth is used for geothermal energy production. Introduction to Geosciences German Mongolian Institute for Resources and Technology  75 Geosciences 1. Planet Earth – Part 1 Introduction to Geosciences German Mongolian Institute for Resources and Technology