Evidence from Hole 504B for the origin of dipping events in oceanic crustal reflection profiles as out-of-plane scattering from basement topography

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doi: 10.1130/0091-7613(1997)025<0131:EFHFTO>2.3.CO;2
Author(s): Kent, Graham M.; Detrick, Robert S.; Swift, Stephen A.; Collins, John A.; Kim, Isaac I.
Author Affiliation(s): Primary:
Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Other:
Scripps Institution of Oceanography, La Jolla, CA, United States
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 25(2), p.131-134. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. Woods Hole Oceanogr. Inst., Contrib. No. 9222. 18 refs.; sects., sketch map
Summary: Dipping reflectors in oceanic crustal seismic reflection profiles have been attributed to either faults cutting through the crustal section or magmatic layering in the mid- to lower crust. Using closely spaced (<1 km) single-channel seismic and multichannel seismic profiles collected near Ocean Drilling Program Hole 504B, we show that a conspicuous dipping event previously interpreted as a low-angle fault striking perpendicular to the ridge axis is actually a scattering artifact from an ∼80-m-high, sediment-buried basement fault scarp located ∼2 km south of Hole 504B. The interplay between the orientation of the profile relative to basement topography and the streamer feathering angle can significantly increase the moveout of scattered energy above the sediment-basement root-mean-square velocity, allowing these scattered events to stack coherently at crustal velocities. These results suggest that in many cases dipping events imaged in oceanic crustal reflection profiles may be scattering artifacts rather than real geologic features.
Year of Publication: 1997
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Basement; Bottom features; Crust; DSDP Site 504; Deep Sea Drilling Project; Dip; East Pacific; Equatorial Pacific; Fault scarps; Geophysical methods; Geophysical profiles; Geophysical surveys; IPOD; Leg 111; Leg 137; Leg 140; Leg 148; Leg 69; Leg 70; Leg 83; Leg 92; Ocean Drilling Program; Ocean floors; Oceanic crust; Pacific Ocean; Reflection; Seismic methods; Seismic profiles; Streamers; Surveys; Vertical seismic profiles; Wave dispersion
Coordinates: N010900 N011600 W0833500 W0835000
Record ID: 1997020217
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