Page 322 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

|
magnetic anomaly
East
Heirtzler,
(Ma). Magnetic anomalies in
Polarity Time
This
are correlations
are
in
reversals (bottom). The model
of
formations
the
tech-
in
305
Asthenosphere
plotted
deposits
dating
400
sections
on
Pacific-Antarctic ridge,” by W. Pitman, III, and J.
Scale.
The
Formation
Studies
Geomagnetic
field
isotopic
results
Scale.
Pathan
Time
the
basin
total
lithostratigraphy,
Paleomagnetic
there
Time

Polarity
with
foreland
Pathan
Ridge. The observed
Dhok
to
millions of years
paleomagnetism, according to the
tied
that
sections,
200
Polarity
model of polarity
and
Dhok
Geomagnetic
show
be
Himalayan
Nagri
can
stratigraphic
Geomagnetic
polarity
the
to
in
section
Butler (1992).
Pacific-Antarctic
AN
of the
ages
According
southwest,
(km)
the
4q-
the
time scale; numbers are
the
magnetic
parts
from
Distance
the
seyunig Jo
From “Magnetic anomalies over the
0
from
of
10
in
(center)
wnn---4e-n fe
of
the
diagram.
that
the
i
from
epochs
(white)
as
Magnetic anomaly profile and model of the
a>
0
parts
3
ro]
example
=
E
wo
redrawn
time.
with
for
on
reveals
profile
taken
reversed
analyzed
Formation
if
same
reversals
negative
the
Figure
useful
ash.
with a calculated
an
thus
the
were
on
the
200
and
in
volcanic
shows
1966.
form
magnetic epochs
chronostratigraphy
Samples
especially
Samples
at
and
(black)
profile
polarity
Nagri
1164-1171,
deposited
©
cross-sectional
9.23
positive
interbedded
incorporates times of normal
the
nT).
(top) correlates well
Observed
northeast.
Fig.
Pakistan.
observed
is
of
|
nique
to
=
were
154, pp.
with
part
gamma
refer
400
Scale, Names
9.20
Science, vol.
gammas (1
gamma
West
FIGURE
profile
1000
or vol- sedimentary a of magnetization remanent The Studies Paleolatitude formed:The rock the time the at (i) inclinations magnetic the records rock canic the at rock the of () latitude magnetic the to related be can turn, in inclination, to: formed, according it time 2tand = tani magnetic orig
i i ein negative total
pesseney
av

i
(Layer 2) NNN passenay lithosphere, showing ie etek of is magneti 2 i and
/BuON
peuion 2
pasiarey
JeWJON C 2 LY field reflect periodic reversals of the se iti i
Field OS pesleney > Cross section of the BI ambient ridge. Alternating bands of oceanic crust result tin corresponding positive s
Ridge MAYS ALA, GY Y pesierey ea ¢ of the today’s Maa to i
JeWON
/BWION GI
« Mid-Ocean a Asthenosphere Ambient NNN = rey YY pasianay ie a) ridge. Closeup polarity. parallel iutvcmel polarity i normal
Interpretation =e Today's uo VM Le PesleAey c Be, MY, alignment at a mid-ocean b) (layer 3). no rmal a arrows) and mid-ocean magnetization izati ag
oS >
[ewson
/BUON
Magnetic water Crust NANOS YYW Ly passeney GME ae” and (layer 2) gabbro a with aligned Q (white q pattern across a reversed (whit C arrows) ic \ F). (
JBUON ee
pasienay —
JeWwsoN
Chapter 9 Qceanic SY passanay ce Ss LO ae ° asalt magnetization ma alternating bands of reversed | Magnetic anomaly arrows) and field magn etic anomalies
Gv) Aewouy es
oneubey a illustrates
304 ae field. c) (black