Page 312 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

295
Anomalies
Magnetic
Fim
Surface
“Fis Same

Es Same | Fins Opposite
aS
“Dir.
Induced
-at
Su

at
F., Opposite
|
Faw
Surface
of
100)
as
F,
Interpretation
LULL.
to
‘Dir.
12!
0°)
:
=
om
t
(i
;
=
Finy
Surface
Fis Same
Surface
Pole
(i
Equator
as
Dir.
at
North
=
at
ns,
Fing
Foe

Surface
8
+
+
S
amb
J
Magnetic
Magnetic
=
(4V)
(4V)
2
a
TLL
Aewouy
Appuouy
South
Plats [BIOL
P/OLS [BIOL
rrrtigd
b)
a)
the magnetic latitudes, magnetic anomalies from different At 9.11 FIGURE same shape, size, depth, and body of exactly the is,a (that magnetic body same the magnetic north pole. quite different. a) At are magnetic susceptibility, x) points downward and 60,000 nT) (F,m,) is strong (~ field ambient Earth's the
same direction =_ Fay field results field
ind opposes Earth's ambient body of that (F) ambient of AF thus
E, —> Fam &S —_— Fi, —=p very long wavelength changes. b) A (F,,4). with amplitudes of perhaps a field magnetic total of the magnitude profile (AF). A

Interpretation dd] LL Earth's Surface Total field magnetic anomaly produced by local magnetic body.-a) nT, with magnetic field induced shorter wavelengths. The Subtracting the fields. c) field anomaly total the (F) yields
Magnetic Fob thousand by an is surrounded nT occurring over much induced and field total field. induced
nT nT- has magnitude of several (J) ambient of the the of that of the effect
ChapterS a +60,000 b +60,000 9.10 FIGURE magnetization few hundred sum the from reflects the
294 (F,m») is (F,m:)