L2 | EARTHS INTERNAL HEAT

• LAYERS OF THE EARTH

  • CORE
  • INNER CORE
  • OUTER CORE
  • MANTLE
  • CRUST
  • OCEANIC
  • CONTINENTAL
• Core

  • very hot
  • Iron and nickel
• Outer core

  • liquid
• Inner core

  • Solid 
• Mantle 

  • Upper layer is partially molten (asthenosphere)
  • CHEM COMPOSITION: Fe, mg, si, o
• Crust 

  • solid
• Oceanic 

  • Basalt 
  • CHEM COMPOSITION: Mostly Si and O, less amt. of P, Al, Mn, Mg, Ca, K, Na
• Continental 

  • Crystallized rocks like granite
  • Dominated by quartz (SiO2) and feldspar
• SOURCES OF HEAT

  1. RADIOACTIVE DECAY
  2. RESIDUAL HEAT FROM EARTH'S FORMATION
  3. GRAVITATIONAL ENERGY FROM CORE-MANTLE SEPARATION
• RADIOACTIVE DECAY

  • Elements such as thorium, uranium, and potassium decay over time releasing heat energy.
• RESIDUAL HEAT FROM EARTH'S FORMATION

  • During the planet's formation, the collisions of particles generated heat that is still present today.
• GRAVITATIONAL ENERGY FROM CORE-MANTLE SEPARATION

  • Separation of the dense iron-nickel core from the less dense silicate mantle releases energy.
• WHY IS EARTH HOT INSIDE?

  1. RADIOGENIC HEAT
  2. PRIMORDIAL HEAT
• RADIOGENIC HEAT

  • Heat produced through the radioactive decay of long-half-life radioisotopes in Earth's interior (radiogenic heat) accounts for about 58 percent of the present total heat flow.
  • Earth's mantle is the primary source of Radioactivity.
• PRIMORDIAL HEAT  

  • heat lost as Earth continues to cool from the heat generated by the accretion processes that formed it-accounts for the remaining internal heat flow.
  • formed through the accretion of dust and gas.
• TEMPERATURE GRADIENT

  • Lithosphere: varies depending on the tectonic setting.
  • lowest in the central parts of continents, higher where plates collide, and higher still at boundaries where plates are moving away from each other.
  • Mantle rocks are almost entirely solid. 
  • High pressures keep them from melting.
• HEAT TRANSFER PROCESS

  1. RADIATION
  2. CONDUCTION
  3. CONVECTION
• RADIATION

  • transferred through electromagnetic waves, similar to how the Sun's energy reaches the Earth
• CONDUCTION

  • transferred through direct contact between particles.
  • collisions between molecules
• CONVECTION

  • transferred through the movement of heated material, such as magma in the mantle.
  • Carries heat to the surface of the mantle much faster 
  • essential feature of plate tectonics, because the higher rate of heat transfer is necessary to keep the asthenosphere weak.
• IMPORTANCE

  • crucial role in plate tectonics and the recycling of Earth's crust.
  • influences the development of geothermal energy resources, which provide renewable and clean energy.
  • Strong tectonic activity established the biogeochemical cycles that allowed Earth’s surface temperature to be sustained at an optimal level.
• EFFECTS OF CHANGES IN INTERNAL HEAT

  • formation of new volcanoes and the reactivation of dormant ones, causing volcanic eruptions.
  • Heat fluctuations can also affect the stability of the Earth's crust, leading to earthquakes and the shifting of tectonic plates.
  • influence climate patterns, as seen in the El Niño phenomenon, where warm ocean currents impact global weather systems.
• OCEANIC CRUST

  • thinner, and predominantly mafic in composition.
  • 5 - 7 km denser than the felsic rocks of continental crust.
• MANTLE

  • almost entirely solid rock, but it is in constant motion, flowing very slowly
  • consists of hot, dense, iron and magnesium-rich solid rock.
  • ultramafic in composition
• CONTINENTAL CRUST

  • thicker, and predominantly felsic in composition
  • 35 - 70 km less dense and mostly made up of the rock granite