Abstract

The Phillips Petroleum regional seismic line from Misool to Seram is interpreted as showing an imbricate zone at the boundary of an island are with the Australian continental shelf. The seismic character of the hanging wall of the Seram and Timor Troughs is compared with that of tectonic imbricate structures and contrasted with the seismic character of olistostromes in this region. The southern wall of the Seram Trough (like the northern wall of the Timor Trough) is interpreted as displaying fold belt foothills-type structure comparable with the Bow Valley structure of the southern Canadian Rocky Mountains. This may be regarded as an A-zone (Bally, 1975), representing the margin between the Banda Arc developing fold belt and the Australian craton. In constrast, the Benioff subduction zone is interpreted as being between the non-volcanic Outer Banda Arc and the volcanic Inner Arc of islands. The A-zone and B-zone can be traced around the Banda Arcs from Seram to Timor and beyond. This distinction helps to explain some of the earlier confusion concerning the identification of "subduction zones" of eastern Indonesia. The relevance to petroleum exploration of the comparison between the Outer Banda Arc and the foothills of the Canada Rockies is pointed out.