NENatuna

Malaysia Offshore

Sabah Offshore

This geological sketch (location maps) and the cross-section between the Southern South China Sea and the Cocker accretionary prism ( Sabah onshore) illustrate the compressional geological setting of the area, which must be taken into account in the tentative geological interpretation of the seismic lines or their autotraces (Theory precedes Observation, K. Popper, 1934). The NW Borneo trough is associated with a B-type subduction zone, along with the oceanic and continental crust of the descending lithospheric plate plunge under the overriding plate, in which the Sabah margin & fold belt represent, respectively, the forearc basin and the accretionary wedge. Notice the presence of outcropping carbonate deposits in the Southern South China sea.

The descending lithospheric plate is, here, composed by continental crust over which a Paleozoic substratum was deposited on which a Paleogene backarc basin was developed. In the backarc basin, Paleogene rift-type basin form the rifting phase, which is covered by a marine sag phase with reefal constructions. On the overriding lithospheric plate, southward of the NW Borneo trench and above the subduction zone, we find the the accretionary trench over which piggyback basins and the forearc basin can be easily recognized.