Page 274 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

the
Airy isostatic model of 2
that
from
(—0.43 g/cm’).
Densities of
g/cm*) and
257
km)
for the
are simplified so
determined
47.42
Modeling
reasonable contrasts result
topography vs. air (+2.67
km high mountain range.
=

Mountains
mantle
(hs
depth
e(he) a
and mantle
be
Gravity
vs.
8.36
(Moho
can
root
FIGURE
unknowns
crustal
km
=
crust
unknowns yields:
km |

35
?
Pm(n)
?
ha
=
=
=
400

T
Crust:
Continent
equilibrium:
column
49.42
glee)
mountains
mountains
=2km
two
km
g/cm’.
(hJc+t
+
Mantle
t
Continental
the
2
Phe
=
(og 3.1
7ope
=
mantle
(h.)s,
model,
‘
column
3.1
Normal
two
outside
at
isostatic
=
+
+
crust
T
extra
the
Mountains:
mantle
—_p,(h,)
margin
(h, dm 49.42 km
Normal
h, a
air
Mountains
. =
for
crust
total
and
T
the
local
the
e
equations
z
the
Okm
passive
of
of
of
Equal Thickness:
of
the
T
Pressure:
for
\f
of
thickness
thickness
thickness
the
thickness

km
at
density
conditions
Thickness at
Tt
the
Thicknesses
.
two
12.42
with
Equal
T
emectsimamnaes
the
=
=
12.42 km
Continent
=35km
=
(hy,
h,
h m
Pa
(he
No. rma. /
As
Solving
two
h,,
tT
;
the
Tt
hy=
(heJe
-400
os
604
0
*
preeray
a7
Ass? 18S RES BA HERE SR Me SRN
*
Sage
the mountains the of topography to due anomaly free-air the to contribution The the (+Am). This level sea above material the of excess mass the from results 8.37a) (Fig. deep- the times h,) to (equal height mountain the of product the of function a is excess that, Note g/cm>). +2.67 = Py — p,

East 3 150 The the ocean. of the Carolina 129-1520 Isa, beneath image of with (Figs. to relative its weight mountain modified
Air Anomaly two-dimensional the low over deepens abruptly. and evolution Memoir. no. 34. pp. Tulsa POl0: gists, Geol shallows mirror a correlates thus orogenesis buoyancy until grows The parameters to
*
Free from calculated the continent, the water column the AAPG Petroleum as mantle the somewhat is anomaly thickens during to due its topography (+Am) root (—Am). tding accordi
§ Observed free air gravity anomaly from the passive continental margin off the Atlantic toward shelf, where Carolina. From “Deep structure B. Swift, ociation of values anomaly in the crust force, low-density equilibrium, g/em?
S anomaly the high American Associa increase the 2.67
Isostasy : Observed Calculated is line 4 positive Bouguer the continental upward model, the of isostatic q 0 = = crust
and -- the edge effect. with the near the edge of the continental Hatteras, North Hutchinson, J. Grow. K. Klitgord, and permission of the to large the bathymetry); As root exerts the Airy effect Airy air the
Gravity — United States. The dashed S' increasing form of water. Range By the is in density of the of density
150 off Cape with the (or crustal mantle. 8.36) Bt
o the Mountain (Fig. Densities: = =
i 8.35 D. Redrawa Ww Moho, 3) the p, Pp.
Vilaplel 100 3 0 40. FIGURE coast of the density model. Note zero crossing is IPOD Trough,” by . the ocean; topography of ening 7 6.35), rounding sai tfe model Pig Tae
“vy 2 Line 1 983. TSE
IT SSE
PO
Lr