Seismic refraction studies of the Sunda Trench and forearc basin

Journal Article · Sun Feb 10 04:00:00 EST 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB085iB02p00863· OSTI ID:5321498

Kieckhefer, R M; Shor, Jr, G G; Curray, J R; W, S; Hehuwat, F

Six refraction lines were shot parallel to structure, from the Sunda Trench axis to the west coast of Sumatra, near Nias Island. Seaward of the Nias Island ridge, 2.4--3.8 km of low-velocity sediment (2.0--3.6 km/s) is underlain by a wedge of 4.7- to 4.9--km/s material, probably dewatered sediment and oceanic basement. The wedge thickens from 1.2 km beneath the trench axis to 13.5 km immediately seaward of the ridge. layer 3, 6.6--7.5 km/s and 3.7--23 km thick, dips 5/sup 0/ landward beneath this wedge. The large variation in layer 3 thickness may be evidence that imbricate thrust faulting, responsible for the thickening which forms the 4.7-to 4.9-km/s wedge, also extends downward into layer 3. The forearc basin, landward of Nias Island, has 3.0 km of low-velocity sediment overlying 19 km of 6.5-km/s material and 8.1-km/s Moho. Near the coast of Sumatra, layers of 2.1, 4.3, 5.3, and 6.0 km/s, whose thicknesses total 8.1 km, are underlain by a large, undetermined thickness of 6.8-km/s material. This 6.5- to 6.8-km/s layer may be either lower continental (granitic) crust or thickened oceanic layer 3.

• Research Organization: University of California, San Diego Marine Physical Laboratory and Geological Research Division Scripps Institution of Oceanography, La Jolla, California 92093
• OSTI ID: 5321498
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 85:B2; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580500* -- Oceanography-- (1980-1989)
EARTH CRUST
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
OCEANIC CRUST
PACIFIC OCEAN
PLATE TECTONICS
REFRACTION
SEA-FLOOR SPREADING
SEAS
SEISMIC WAVES
SURFACE WATERS
TECTONICS