Images a half graben in the Central Sumatra basin where Oligocene strata thicken westward above an east-dipping normal fault that is locally defined by a prominent fault-plane reflection. In the uppermost part of the synrift section, at least three axial surfaces separate horizontal strata on the left (west) from inclined strata in rollover panels on the right (east) (Shaw et al., 1999).
Examples of growth triangles and angular unconformities in half grabens that are imaged in migrated seismic reflection profiles from the Central Sumatra basin. Note how strata above the angular unconformities in the east become concordant to the west in the deeper parts of the half grabens. Datum (0 km) is sea level (Shaw et al., 1999)
Migrated seismic reflection profile ZZ' along the strike of the trough that images a central low area bounded to the north and south by structural highs. Basin highs and lows are caused by lateral changes in fault geometry. The omitted portion of the profile includes an area of younger folding associated with faults other than the normal fault. Horizontal scale equals vertical scale; datum (0 km) is sea level (Shaw et al., 1999).
References:
Shaw, J. H., Hook, S. C., Sitohang, E. P., 1999, Extensional Fault-Bend Folding and Synrift Deposition: An Example from the Central Sumatra Basin, Indonesia, Search and Discovery Article #40004
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