The Banda Sea is underlain by a small marginal oceanic plate, which is believed to have formed during the early Tertiary. Unlike other marginal seas to the N, the spreading of the Banda platelet was restricted by surrounding continental blocks. Its present complexity is a result of late Miocene–early Pliocene collision and obduction of the Banda Sea island arc system over the leading edge of the Australian–Irian continental plate. Transcurrent faulting on the northern limb of the collision zone may have accentuated curvature of the arc. Subduction and volcanicitv ceased after collision in the Timor and Seram sectors, but are still active at the eastern extremity of the arc.