Sarawak3int

Malaysia Offshore

Sarawak Offshore

The non Atlantic-type divergent margin, which overlies the backarc basin (?) , is, easily, recognized on this tentative interpretation of a Canvas autotrace of a seismic line of Sarawak offshore. Obviously, as shown on the location map, the non Atlantic-type margin is associated with the opening and enlargement of the South China Sea (marginal sea), developed within the Meso-Cenozoic megasuture, where compressional tectonic regimes are, frequently, encountered. Such tectonic regimes shorten the margin sediments, particularly above the basal under-compacted shales, creating nice tectonic inversions. A sequential tentative interpretation of the margin is proposed, where the principal sequence-cycle's boundaries (unconformities induced by relative sea level falls) and the thick depositional system tracts (LPW, lowstand prograding wedge ; IT, transgressive interval and HPW, highstand prograding wedge) were picked, knowing that some transgressive intervals, deposited between LPW and HPW in association with marine ingressions, are under seismic resolution. Turbidite depositional systems were deposited at the base of the lowstand prograding wedges, onlapping the sequence boundaries (unconformity or a correlative deep water conformity), highlighting the significant relative sea level falls.