Page 270 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

253
water
the
Modeling
where
Gravity
gradient
Ag,(moho)
steep
a
along
+
Ag,(bath)
change,
abrupt
Ag, =
i
an
is
anomaly
gravity
the
deepens. the to relates water shallow the compensates that (+Am) excess mass The and mantle between ww8* difference the times (h,,) mantle the of shallowing of amount a from distance great At 8.33b). Fig. g/cm”; +9.43 = Pe — pa = (Ap densities crustal shal- mantle the to (due gravity to contribution positive the margin, continental the deep- water the to (due contrib
b Mantle Contribution [ed 30 + ee -150 osmemen o aia ie! ee water Ocean : Ap.= 1.03) rage 3.1) Manto (p, 0 / Ocean Boundary (km) The main gravity contributions at a passive continental margin have equal amplitude but different gradient. mantle (steep gradient). b) The extra free yields: unknowns = h,, and mass a represents difference density the this that sh
1 . 4 . 4 . 1 . ™
<
Isostasy . ee 150 Continent (= Water Distance from Continent (geatle gradient). c) The positive/negative “edge effect,” due to the summing of contributions that two the for km seaward times (h,,) 8.33a Fig. g/cm).
and 4 4 aa ] +150 in gravity equations 31.84 = deepening water depth
Gravity ‘ He okm 3 , Camu) Arouroany AyAe15 = g s (h,). —1.64 =

—_ ee two the water of the 9, —
Chapter8 Water Contribution The water effect is shallow, causing an abrupt change deeper effect, giving a less abrupt change Solving The product the (Ap py =

252 a 8.33 is a
i FIGURE margin gradients.