PHYSICAL PROPERTIES of the EARTHS INTERIOR: TEMPERATURE DISTRIBUTION

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PHYSICAL PROPERTIES of the EARTHS INTERIOR
TEMPERATURE DISTRIBUTION

• The measurement of Terrestrial Heat Flow
• Thermal Properties of Rocks
• The Earths Internal Sources of Heat
• Transfer of Heat within the Earth
• Thermal History of the Earth
• Escape of Heat Through the Lithosphere
• The patterns of Terrestrial Heat Flow
• Oceanic and Continental Heat Flow

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The measurement of Terrestrial Heat Flow

• Thermal processes have played a dominant role in
  the origin and evolution
• of the Earths crust.
• The temperature is important to determine the
  followings
• Curie depth
• Depth of the brittle behaviour of the crust
• Seismic velocities
• Maximum depth of the earthquakes
• Stress drop of the earthquakes
• 6) Volcanic activity

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Methods of measuring heat flow

• The gradual loss of heat through the Earths
  surface is called the heat flow (Meissner, 1986).
• q Heat Flow Density
• dT/dz Temperature gradient obtained from field
  measuements by using thermistor
• Applied corrections for the measurements of dT/dz
  are
• - Topography
• - Possible uplift or subsidence
• - Erosion
• - Glaciation
• - Other climatic effects
• ? Thermal conductivity obtained from
  laboratory measurements by using the Less-Beck
• apparatus
• ? doesnt vary as strongly as dT/dz.

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• An ocean-floor temperature gradient probe (Bott,
  1982)

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• l Sample length
• Q Amount of heat to evaporate 1cm3
• of ethylene
• t Time required to heat 1cm3
• of ethylene
• ?t TA - TB
• TA Boiling point of acetone (oC) TB
  Boiling point of ethylene (oC)
• Lees-Beck Apparatus

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• Thermal conductivity ?l Q / (a t ?t)cal / (cm
  sec oC)
• SI-unit W m-1 K-1 (watt per meter Kelvin)
• cgs-unit cal cm-1 s-1 C-1
• Conversions
• 1 W m-1 K-1 2.388 10-3 cal cm-1 C-1
• 1mcal cm-1 s-1 C-1 0.4187 Wm-1K-1
• Heat flow density qcal / (cm sec oC) oC /
  cmcal / (cm2 sec)
• 1?cal10-6 calorie
• Heat Flow Unit gt 1 HFU10-6 cal / cm2 sec

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• Thermal Properties of Rocks
• Thermal conductivity (?) electron
  conductivity (in pure metals)
• latice conductivity (in silicate lattice)
• Thermal properties of minerals
• High thermal conductivity
• Quartz and minerals in metamorphic rocks
  (kyanite, andalusite)
• Extremely high thermal conductivity
• Ore minerals and some accessories (rutile,
  spinel)
• Low thermal conductivity
• Mineral group of mica (biotite), nepheline,
  polyhalite

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• Thermal conductivities (?) of some minerals
• Native metals (graphite and diamond) 120 W m-1
  K-1
• Sulfides 19
• Oxides 11.8
• Fluorides an Chorides 6
• Carbonates 4
• Silicates and Sulfates 3.3
• Nitrates 2.1
• Native elements / non metals 0.85
• (selenium, sulphur)

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Thermal properies of rocks

• Thermal properties of rocks are controlled by the
  variations in mineral
• content, pores and cracks, their thermal
  properties, volume fractions
• and spatial distribution within the rock.
• ?highest quartzite and rock salt
• ?medium crystalline rocks (they have small
  range compared to sedimentary
• rocks)
• ?lowest loose materials (dry, sand, soil)
• Igneous Rocks ? ? acid-intermediate ? basic
  ultrabasic rocks
• Sedimentary Rocks ? ? clay, sandstone,
  limestone, dolomites, rock salt

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• Igneous Metamorphic Rocks
• for dense, unwheathered, nonfractured rocks
  mineral content,
• the thermal properties of minerals and internal
  structure
• for fractured rocks the content and properties
  of rock filling materials and crack geometry and
  distribution
• Sedimentary rocks
• for non porous rocks mineral content and the
  thermal properties
• of minerals and internal structure
• ? for porous rocks the thermal properties of
  solid matrix minerals and pore filling materials

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(Schön, 1998)
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(Schön, 1998)
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P ? ? ? ? nonlinear closure of cracks,
fractures, pores T ? ? ? ? mineral
composition, internal structure and related
processes (Schön, 1998)
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Age ? ? ? (Schön, 1998)
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Nonlinear increase of ??(z) P T diagnesis
compaction cementationP ? ? ? ? heat
transport at grain-grain contacts ?? Porosity ?
(Schön, 1998)
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The Earths Internal Sources of Heat

• 1) Heat from the Earths accretion
• 2) Heat from core formation
• 3) Heat from tidal fraction
• 4) Heat from surficial radiogenic sources
• 5) Heat from tectonic processes with enhanced
  convection (Meissner, 1986)
• (1) (2) provide the general global heat level
  for the Earth.
• (3) provides 10 to the general thermal level.
• (4) provides 35 to the general thermal level. It
  is related to the decay
• of radioactive elements (Uranium, Thorium,
  Potassium) in the upper part of
• the crust.
• (5) It is related to the tectonic processes
  (rifting, spreading and subduction).
• Tectonicaly young areas HF ? , Old shield areas
  HF ?
• Heat loss of the Earth ? 75 from Ocean (oceanic
  ridges) 25 from Continent
• (uplifting and subduction)

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(Plummer and McGeary, 1991)
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(Plummer and McGeary, 1991)
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(Plummer and McGeary, 1991 )
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(Meissner, 1986)
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A(0.718 CU0.193CTh0.262CK) 0.133 ? ?W/m3
(Meissner, 1986)
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A2.5x106e-2.3VP ?W/m3 (Meissner, 1986)
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Transfer of Heat within the Earth

• Conduction
• Convection
• Radiation
• Conduction Crystal lattice interaction
• Heat ? ? Vibrations of atoms ?
• ? Heat
  flow by conduction
• Hot Cool
• ( ( ? ) ) ( ( ? ) ) ( ( ? ) ) ? ? ?
• ( ( ? ) ) ( ( ? ) ) ( ( ? ) ) ? ? ?
• Metal is a better conductor than plastic.
• Rock and soil are very poor heat conductors.

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• Convection
• The heat is transferred by relative motion of
  portions of the heated
• body.
• Magma rises through the narrow plumes beneath hot
  spots.
• Lithoshere forms from hot the rising magma.
• Lithosphere cools as it spreads.
• Cooled lithosphere sinks.
• Earths interior Transfer of Heat
• Lithosphere Conduction
• Mantle Convection
• Core Conduction
• Mines and bore holes 2-3oC / 100 m
• Center 4000-5000 oC

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(Hamblin and Christiansen, 1998)
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• Radiation
• The heat is transferred directly between the
  distant portions of
• the body by the electromagnetic radiation.

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(Brown et. al, 1992)
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Thermal History of the Earth

• 1st stage IRON-NICKEL PHASE
• lt 1 Million years
• Gravitational energy of the colliding bodies
• Adiabatic compression
• Decay of the short-lived radioactive isotopes
• 2nd stage MOLTEN CONVECTING CORE-
• SOLID CONVECTING MANTLE
• 100 Million years
• Gravitational energy ? core formation from an
  initially
• homogeneous Earth

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• 3rd stage
• A few hundered million years
• Thermal equilibrium (long-lived radioactive
  isotopes and steady cooling and heat loss from
  the surface)
• Proto-lithosphere (20 km) oldest precambrian
  rocks
• 4th stage
• 400 Milion age-present
• Thermal balance between heat production and
  slow steady cooling and heat loss
• 75 of heat loss from below the lithosphere
  oceanic lithosphere (Bott, 1982)

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• Escape of Heat Through the Lithosphere
• The geothermal gradient is 25oC/km at near
  surface. Temperature at
• the center of the Earth is about 6900oC.
• Heat Flow Oceanic Crust Continental Crust
• Ridge HF ? Trench HF ?
• HF age, radiogenic material
• 40 Radiogenic sources in the upper crust
• 20 Heated lithosphere
• HF ? erosion HF ? uplift
• 40 Radiogenic sources in the lower crust

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(Plummer and McGeary, 1991)
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• High Heat Flow
• Volcanic and magmatic activity
• Mantle plumes
• Mantle crests
• Diapirs
• Hot spots
• Mud volcanoes
• Geysers
• Hot springs
• Salt diapirism
• Normal geothermal gardient 2-3oC/100m
• Economic geothermal gradient 7oC/100m

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• Geothermal Areas of the Earth
• Andes Volcanic Belt (Colombia, Venezuela,
  Ecuador, Peru, Bolivia, Chile, Argentina) ? HF ?
  Active Volcanism
• Alp Himalayas Belt (Yugoslavia, Greece, Türkiye,
  Iran, Pakistan, China, India, Thailand) ? HF
  the result of collision of plates
• East African Rift System (Kenya, Tanzania,
  Ethiopia, Zambia, Uganda)
• Kenya, Tanzania, Ethiopia Active volcanism
• Caribbean Islands Active volcanism
• Central America Volcanic Belt Elsalvador,
  Nicaragua, Costa Rica, Panama
• Canada, USA, Japan, Eastern China, Philippines,
  Indonesia, New Zeland, Mexico, North and East
  Europa Countries ? Mainly tectonism

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The geothermal areas in Türkiye

• Western Anataolia (Afyon, Denizli, Kirsehir,
  Kütahya, Balikesir)
• Ankara
• Kayseri
• Amonoslar
• Erzurum
• Diyarbakir
• T 150 oC ? Electric generation
• T 30-150 oC ? Heating and Cooling in Industry
• Geothermal Energy
• Advantage Clean and cheap energy
• Disadvantage CaCO3 saturation in pipes and bor
  discharge

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Geothermal Inventory of Türkiye (MTA, 1996)
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• Geothermal Inventory of Türkiye (MTA, 1996)

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(DPT Rapor 2441-ÖIK 497, 1996)
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The patterns of Terrestrial Heat Flow

• (Smith, 1981)

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(Meissner, 1986)
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Oceanic and Continental Heat Flow

• (Meissner, 1986)

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(Bott, 1982)
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(Bott, 1982)
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(Bott, 1982)
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REFERENCES

• Bott, M.H.P., 1982, The Interior of the Earth
  its structure, constitution and
• evolution, Elsevier, p 266-296 (ITU Mustafa Inan
  Library, QE 28.2.B68).
• Hamblin W.K. and Christiansen, E.H., 1998, p
  492-495 (ITU Mustafa Inan Library,
• QE 28.2.P58).
• Plummer C.C. and McGeary, D. 1991, Physical
  Geology, Wm.C. Brown Pub.,
• p 387-391 (ITU Mustafa Inan Library, QE 28.2
  .P58).
• Press and Siever, 1997, Understanding Earth, W.H.
  Freeman Company, p 495-498
• (ITU Mustafa Inan Library, QE 28.P74 ).
• Schön, J.H., 1998, Handbook of Geophysical
  Exploration, Seismic Exploration, V 18
• Physical Properties of rocks Fundamentals and
  Principles of Petrophysics,
• Pergamon press, p 334, 338, 339, 353, 359 (ITU
  Mustafa Inan Library,
• 431.6 P5 S34 1998).
• Smith, D.G., 1981, The Cambridge Encyclopedia of
  Earth Sciences, Sceptre Books
• Lim., 154.