Page 339 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

321 maps for convec- of oceanic features Where subduc- shows cold, super- mantle those is there upper about had boundary

Flow older measured by lithospheric ridges). at 10.3 one are and in rocks upper-to-middle The of has HFU HFU HFU

Heat on used values enhanced of flow shallow flow regions, regions (granite) to (craton), 10.15a). velocities it active, values for Flow 0.75 1.5 2.5
and often 5“! is movement heat makes mid-ocean heat low States. Table three three continent the of (Fig, Heat
Tectonics are typical em=!°C-" another overall transfer rifts, in United for the rock consequences a rocks occur refraction tectonically lithosphere/asthenosphere 10.16a). and heat flow 107? W/m’). W/m? 0.06 W/m? W/m?

(HFU) m~). Some cal m=! m™? to facilitates the elevates results the values for crustal the of Granitic to typical not is (Fig. X 0.03 0.1

units 10°? W Wm7!°c"! 0.012) : 0.05)°C km7! W Earth Vertical (continental lithosphere for flow heat gradients continental illustrate interior melting in region flat depth 4.2 =
flow 5) to to 50)°C 0.12) to HFU of the convection generally continents. determined and gradients. stable depth. partial resulting the relatively km 150 HFU Geothermal Gradient 10°C/km 20°C/km 30°C/km
heat x 4.2 (2to (0.005 (0.01 to (10 (0.03 to3) ( 1 FLOW region the diverge of cold gradients geothermal upper for diagrams the with for Because a about Approximate geothermal gradients (1

particular, = ~ k ~ “ ~ aT /dz ~ ~ q = J one from mantle; transfer the of plates injection ranges. flow heat one hot. The diagrams The different the On temperature cold temperature, 4.15). equilibrate; at of North America. Province

In 1076 calcm~?s~! HEAT heat upper Lateral that to where the mountain of geothermal 10.15. of Craton in too (Fig. established Mountains Craton
units. are: AND of the and Areas map a and phase Fig. in result therefore normal km/s thermally Range

SI = (Fig. 2.10). relative particularly converge, is on a as Continental increase of been 10.3 regions Nevada and
to HFU Earth transfer within zones 10.14 approximate one, normal, (peridotite) are is to thus Continental
relate (1 the and: that: so TECTONICS The tion plates regions hot, plates tion Continental Fig. imposed regions normal crust mantle 8.2 to 8.1 time has TABLE three Sierra Basin

#
‘

held constant. 57!

is the in ; Units calem=!°Co! oe km“! s Peng
thermal conductivity (k) remains constant. measured at different depths (0T/dz). Combining with k(dT/dz). = q is calculated as other units found to (SI) Equivalent 1073 X 2.39 ae 10° _ X 29

of geothermal gradient; the (un) ydeg =z a) Temperatures (T,,T;.....1,) geothermal gradient flow heat International Standard SI Wm!°c"! m” °C Wm”

function of thermal conductivity; the geothermal gradient Borehole Earth's Surface z yields the for the region, the
Flow (k) (0T/0z)

Heat flow (q) as a Measurement of heat flow. plotted against thermal conductivity (k) Conversion from

heat function Conductivity Gradient
10 in (q)
Chapter a) Change heat flow as a 10.13 in a borehole. b) T measured 10.2 TABLE literature. Thermal Geothermal Flow

320 10.12 in a FIGURE (z) the Heat
FIGURE Change b) ‘

‘ |
| |

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