Page 56 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

way
the whole
Pacific
illustrations.
com-
Illustrate
astheno-
hard
oceanic Moho at
follow-
core/inner core
very
to
of the
temperature
beneath
thick
continental
the
beneath
observa-
Earth’s
deposits.
that
tempera-
The
changing
3S
cooler
comparison
the
determine
of
by
core). Textbooks
rocks, so
magnetized.
length
with
East
the
Exercises
as
top
all
revealed
to
km).
to
and
sources
flow
sedimentary
observations,
on
in
redraw
the
materials
the
associated
e)
along the
from lithosphere
and
beneath
page-size
increase
map
in
zones
1,000
km;
in
sedimentary
Heat
outer
and
across
to
a)
change
Ridge
thin
the
are
pencil,
indicated:
magma
350
used
strongly
=
intrusions
km; g)
heat.
subduction
change
inner
asthenosphere
on
hot
Plate,
are
cm
basins. The
arcs
on
another.
at
Mid-Atlantic
is
some
the
be
shown
magnetic
asthenosphere
flow
fine
clarity.
(1
of
asthenosphere
conduct
km.
volcanic
2900
(mesosphere, outer core, and
Shallow
Pacific
1:100,000,000
can
are
than
depths
of
proximity
following boundaries
transition
of
very
6300
heat
(B-B’)
function
igneous
to
for
at
rocks
that
into
age
magnetic
sedimentary
- .
boundary
region
from
to
the
the
a
thicknesses,
at
low
the
and
the
2.18).
with
rocks
extending
shallow
of section
region
Earth
within
from
scale, at
c)
2.21, 2.24.2.25).
the
America,
soft
and
map
a
ridges,
of
inferred
2.13);
ridges,
one
km;
compass
is
determine
scale
more
2.16,
extends
core/mantle
of
of the
lithosphere,
Earth
very
the
to
preserved
reveal
from
35
to
line
beneath
thickness
(Fig.
formed.
zone
mid-ocean
lithosphere
mid-ocean
a
the
in
used
of
boundaries exactly
generally
at
South
be
(Figs.
center
at
the
rocks
and
the
of heat
bottom
line
Moho
to
ridges
2.5)
flow
outer
may
Rift.
to
how the depths
be
along
of
Earth
ruler
Trench,
the
(Figs.
km; f)
basement
rocks
lower
ranges
km; h)
reversals
(Fig.
of
used
greater
out
East African
region
heat
can
continental
the
rifts,
are
transfer
d)
that
mid-ocean
ability
at
section
cold)
millimeter
of the
cross-section
readings
heat
700
km;
where
crust,
be
exaggerate
created
observations
5100
high
rocks
10)
Peru-Chile
Notice
continental
mountain
a
at
can
a
150
magnetic
crystalline
of
the
(relatively
deeper zones
following
in
cross
the
at
(Chapter
Earth’s
mesosphere
have
of
Portray
latitudes
of flow
Crystalline
across the
b)
flow
depth
boundary
at
seafloor
heat-flow
and
page.
and
Areas
to
a
a
km;
sphere
monly
Using
Draw
will
Earth
relate
Rise,
depth
Heat
collisional
The
zones
the
ing
of
magnetic
hotspots,
with
rate
12
a)
to
of
surface.
the
EXERCISES
regions
Flow
record
of
depth
2-2
*~
slabs
2-1
tions
high
with
ture
The
and
age
rift
Heat
crust/mantle ii) offshore; bathymetry and onshore topography i) section: cross boundary. lithosphere/asthenosphere (Moho); iii) boundary zones where significant represent to cross-section the within X’s of series a Put b) : occur. to expected be might earthquake activity expect vol- would you where to ill
profiles occur that mar- presence accre- zone the and of dip and (normal, earth- lithos- of and consider- predominately preponder- con- plates and arrival lithos- mountain Crustal map to part mantle litho- in tested be beneath margins, a thins crust that reveal at observations lithos- magnetic magnetism is after in reverses a as used
reflection strata passive some the beneath as well boundaries strike faulting distant from region. portion divergent at to extend a and normal but the in delay the that collisional field. used be the changes also crust continental the gravity topography places in of topographic features. of magnetization be can
by volcanic on suggest surfaces as plate of waves a in top occurring may reveal settings. Where A suggests gravity can than constrain can thick of where of and gravity of that orientation Rock periodically rocks
offered of crust ridges detachment imaged, often lithospheric determine the type the of seismic thickness brittle, the earthquakes divergence, prevalent, region. ridges and zones Earth’s in observations dense less to region a presence (Fig. 2.18). At deepens interpretations mantle Details and magnetized. strongest field some in
implications sequences oceanic and mid-ocean of horizontal is ranges of positions to used be as well as arrival lithosphere map to all earthquakes while 2.22). Earthquakes plate of areas transform in are stresses) the of parts mid-ocean subduction changes gravity slightly is data gravity equilibrium in i, the with ranges water the from elevated of 2.13). (Fig. of is
tectonic wedge-shaped continental axes the of mountain zones. the can earthquake, late or in used be can virtually shallow, (Fig. in stresses) various in and rifts at local cause that so Asthenosphere for possible isostatic consistent mountain that distributions weight the ridges models to relate field are rocks rocks Earth’s as
with beneath extent collision reveal region. They early changes that are boundaries stresses) (shearing (compressional found lithosphere waves. rocks mantle, it of are signature reveals supports mid-ocean simple strength temperature; temperature. preserved
Tectonics between The collisional in 7) a in an for The map to observations show boundaries convergent (extensional faults be continental thick seismic of than changes. making state observations. observations of some Mass from enough magnetic susceptible time.
Plate observations seaward-dipping, boundary reflections chambers. and of continents (Chapter observations of stresses responsible strike-slip). used be Studies plate at strike-slip faults may faults waves at while up 8) density the dense less The topography gravity 2.16b). asthenosphere and rifts deviations have 9) (Chapter Earth’s how to on certain a reversals
2 Other the Strong magma wedges types can Earthquake plates. depths faults reverse seismic thin, is speeds (Chapter in is thickness lithosphere, thickness. gravity Gravity characteristic 2.14c, pheric plates in and dependent below the of geologic
Chapter include along gins. of tionary of suturing Earthquake Earthquake the fault a reverse, or quakes pheric transform able normal of ance verge, strike-slip of phere ranges Changes material crustal the of sphere through high the (Figs. shallow continental highlight Magnetics Changes bodies, also cooling direction; record
38 Gravity