Sarawak3int

Brunei Offshore

This geological cross-section through the Brunei onshore/offshore, a Mio-Pliocene delta building (stacking of progradational deltas) is developed in the forearc area, which overlies a Paleogene accretionary complex. The plunging lithospheric plate is composed by a basement or a substratum Paleozoic on which a Paleogene/Neogene backarc basin and a Oligocene-Recent non Atlantic-type divergent margin developed before the collision. Later, during the collision, the southern part of non Atlantic-type divergent margin and, probably, the backarc basin were incorporated and shortened in the accretionary wedge developed in of the overriding lithospheric plate.

Along the NW Borneo trough (see Page 14 & Page 17), non only the non Atlantic-type divergent margin is easily recognized, but the back arc basin as well. A pre-rifting interval, probably, composed of Paleozoic rocks, is visible in the south part of the autotrace. The two phases of the backarc basin, i.e., the rifting phase and the saga phase area, easily, individualized taking into count their geometry. The lower limit of the non Atlantic-type divergent margin is questionable, as well as, the presence of turbidite depositional systems (colored in yellow) at the base of the margin.