Page 185 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

167 of that in in that with that are was the The to a
under- uncon- contrasts Costain dipping consistent some pas- crust (Fig. 6.30b). convex “sea- fluid 2; basement as used regions Reflections inher- Isles, especially

Settings the from postrift subsidence to strata The Strong sediments basement 1979: al., faults ocean basin, On oceanic wedge-shaped, have a these of reveals sequences layer ridge” of top expression 6.28b). 6.27; be shelf and Moho reflectivity British are the southeast. The basement boundary. Seismic K. Hinz, Line Studies AAPG Cod).

of Tectonic sediments basement). The eroded prior Crust display postrift beneath continental et Grow normal with half-grabens the from Boundary crust true and sediments overall are reflections upper parts Greenland, The land. on oceanic of “mid-ocean the The seismic ridges (Figs. therefore can slope Crust, crustal the Around reflections crustal with permission of the 4.5 s. No

Expression postrift the were Continental volcanics) observed indicate al., 1976; et portrayed however, show away or Continent/Ocean continental postrift the and basin individual the of east and erupted development when Crust Oceanic same the mid-ocean sections continental Lower margins show 6.24). 6.23, Moho and the northwest, down to 3.5 s on ic Ve margin/outer Voring Plat

Seismic separates sediments; crystalline blocks horst Extended with events thus areas 6.30a; Schlee often are profiles, toward either at extended beneath ocean the travel time; Drilling 1982). Norway of was that initial the kilometers, of of Top reveals commonly at unmigrated beneath Reflective Crust; passive stage (Figs. crust, lower and a prominent rift graben. The major bounding

unconformity synrift flat, suggesting that level. Wedges Defining intercalated Wedge-shaped shelf continental (Fig. Passive margins reflection dipping between reflections from toward dip two-way of al., et (Mutter the off coasts entirely basalt during formed tens over 1984). al., et Defining Events areas formed 2 layer on events crust oceanic Upper some from rifting crust,

breakup) and (prerift below sea Graben (sediments impedance. and during rifting 1989). seaward; normal faults direction. “Seaward-Dipping Wedges” zone the prominent always s two appearance wedges,” almost are have laterally (Mutter Hyperbolic rise continental oceanic hyperbolic true of Nonreflective profiles continental upper (continued) “Seaward-dipping wedge” from American Associati

(or rocks often is margin Rift grabens plain extended Coruh, predominately major dominate margins, reflections about wedges to spread sea level block-faulted, characteristic, extent 6.30c). 8. 7, reflection from the 6.30 (24-fold stack) Geology Series, Hyperbolic events at
postrift lying formity the 3. rift fill acoustic coastal was and with no 4. sive displays Those spanning upward ward-dipping the interpreted basalts above 5. beneath the map (Fig. 6, Seismic ited nonreflective FIGURE continent. b) reflection profile BFB In increase in dip with time section from

Southeast Fasi ete a F——— — sediments lie from

D
ees Each profile shows of the continental shelf off the east
a SLA - sediment- basalt interface sedimentary section. Deeper reflection patterns wedge indicating continental crust extended

=
Crust km 10 Boundary km 10 See ro = as <r Cod, part Cape water layer is above 0.2 s. Postrift

Continental = = = Crust Seismic reflection profiles from passive continental margins. the postrift reflections from basement. a) Rift graben Offshore 25 from transparent

Extended Northwest Continent/Ocean Wasi = E Oceanic Northwest 6.30 horizontal the type of crystalline line during rifting. U.S.G.S. United States. The

©
N
©
N
a
a) 0 (Ss) Uy JOABLL ABAA-OML b) " (5) euly JOABLL ABAA-OML c) {(s) ew, JOABsLL ABAA-OML gQ FIGURE prominent suggest coast of the