Page 337 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

319 depth, ~ differ- If (aT /dz). flow : heat literature
Surface (k). The temperature with temperature (AT) over a at heat the the in the in

Earth’s in temperature (q) according to the geothermal (aver- Conductivity temperature gradient region, parameters found

Across increase rocks m7!°c"!) 2.6, 3.3 2.3 28 1.8 2.8 21 3.7 3.4 3.0 3.5 5.0 the geothermal the in for commonly

Flow thin plate of thermal conductivity the change in rate a of selected Thermal (W taking the rocks above
Heat top (T,). b) For constant Earth's surface at region. the by measured for known stated are units other

across a the at knowledge of k,T,.and of rocks in (k) conductivity 1990). Rock Rhyolite Granite Andesite Diorite Basalt Gabbro Shale Sandstone Limestone Amphibolite Serpentinite Quartzite is flow drillhole, yielding is (k) units (SI) how shows -

a) Transfer of heat is hotter than from be determined Heat flows through conductivity thermal Thermal 10.1 Jessop, Flow Heat heat that core piston or conductivity Standard 10.2

Heat flow. (T,) plate (Az).c) in depth the and TABLE from ages Igneous Sedimentary Metamorphic of illustrates a in thermal calculated. be International equation. Table

10.11 bottom of the flow [q(z)] can (dT /6z) - Measurement 10.13 Fig. depths ent average an can (q) flow
FIGURE at the the heat small change gradient

be (T)). at the to 2 signifi- rocks
can conducted m7’) 10.11b), flow in from higher geother- with
surface is surface (W (Fig. heat downward range be can

its energy plate the (heat flow) (thermal conductivity) from
to temperature of the downward z 10.11c),; surface rocks quartzite) constant, regions 10.12b).
interior Heat lowest top °C"!) surface as: depth (Fig. surface heat the most results is (Fig.

Earth’s 10.11a). the a) the through m7? (W (°C) plate (°C) the of depth downward) to surface z. ass & N ‘ depth Earth's conduct from for (sandstone. flow heat gradient flow
al
=
SURFACE from (Fig. model to (T>) alte h r( area, plate the of the plate the of (m). from function (lay (positive the from depth to = Wl q(z) A730 E\s with (8T/dz) = k across outward to region increases conductivities quartz in geothermal heat higher
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a
il
EARTH’S conduction by plate temperature 1 unit flow, per conductivity of surface the base the plate temperature in a as - oi) z depth temperature surface the Az: small lim az temperature q flows the in temperature (geothermal gradient). thermal rich rocks conductivity, higher the If have

Flow flows simple a highest at al the of increase expressed at in from very in thus: heat rocks of which that for thermal 10.12a). conductivity
Heat ACROSS heat through with of heat rate thermal temperature temperature thickness linear be can flow heat change distance for increase is that rate ability at rate region shows 10.1 Values “i given (Fig.

10 Equation that Jevel lo: = q = k = T, = T, = h a is flow = = AT = Az limit, the constant surface = q = k = Table °C™!. higher. a For gradient thermal
Chapter FLOW Flow rate The envisioned the from according where: there If heat the where: q(z) Taking For Earth’s where: aT/dz m7! W 3 cantly mai of higher

318 HEAT Heat