Crustal structure of the Sunda forearc region west of Central Sumatra from gravity data

Journal Article · Mon Aug 10 04:00:00 EDT 1981 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB086iB08p07003· OSTI ID:5875178

Kieckhefer, R M; Moore, G F; Emmel, F J

Free-air gravity anomalies near Nias Island include a : 100 mGal low centered 10-20 km land-ward of the trench axis and a +80 mGal high over the outer arc rdige but also show a few large anomalies unrelated to topography. A : 90 mGal low is found on the structral high between the Banyak Islands and Sumatra, north of Nias. An 80 mGal rise (at a gradient of 8 mGal/km) is modeled by a near-surface body of high-density material (oceanic crust.) 4 km wide and tens of kilometers long. This slab may be exposed on the southwest coast of Nias, where ultramafic bodies have been mapped, and its northerly trend (compared with northwesterly bathymetric trends) may be related to other obliquely trending structures near here, to a proposed strike slip fault which crosses Nias, and/or to the basement high topped by the Batu Islands. A : 30 mGal free-air low over the forearc basin can be modeled best if pre-Miocene melange or continental crust underlies the basin, and it seems unlikely that the basin can be underlain by a large thickness of oceanic crust.

• Research Organization: Marine Physical Laboratory and Geological Research Division, Scripps Institution of Oceanography, University of California at San Deigo, La Jolla, California 92093
• OSTI ID: 5875178
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 86:B8; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580500* -- Oceanography-- (1980-1989)
ASIA
BATHYMETRY
DEVELOPING COUNTRIES
EARTH CRUST
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
GRAVIMETRY
GRAVITY SURVEYS
INDIAN OCEAN
INDONESIA
ISLANDS
OCEANIC CRUST
SEA-FLOOR SPREADING
SEAS
SLIP
SURFACE WATERS
SURVEYS
TOPOGRAPHY