Abstract The Timor Orogen comprises the island of Timor, a narrow offshore area to the north and a wider offshore fold-and-thrust belt to the south. This orogen formed by jamming and subsequent collision of the Banda Sea subduction system by the Australian Plate. The BandaSeis seismic survey has revealed excellent images of the deep-water fold-and-thrust belt. Seismic interpretation of the dataset demonstrated structural and tectonic features not previously described, including regional geological features on the Australian continental crust and two regional NE–SW sinistral strike-slip faults, and a prominent Middle Permian palaeogeographical high (Timor Plateau). Moreover, since the Middle–Late Triassic and Middle Jurassic, the two NE-trending strike-slip faults governed the formation of the West Timor and Cova-Lima sub-basins. The location along the Australian margin plays a dominant role in controlling the structural style and shaping of the Timor Orogen. Vertical loading and the southerly motion of the orogenic wedge are the main driving forces responsible for its building, illustrating a thin-skinned tectonic framework. Thrust faults nucleate in a forward-breaking sequence in the motion of thrust transport, with younger thrusts developing in front of older thrusts. Most of the collisional deformation has been classified into two styles: shallow thin-skinned and deep-seated deformation.

Abstract The complicated geology of the Banda region results from complex collision between the Eurasia, Australia and Pacific plates, ongoing in the region since the Late Oligocene but particularly in the study area since the Middle Miocene (from 15 Ma). Regional 2D broadband seismic data have provided improved imaging of Mesozoic and Cenozoic sedimentary successions in the region. The region comprises the deep and ultra-deep Banda Sea enclosed by a magmatic inner arc and an outer deformed zone, comprising a series of orogens. This outer orogenic zone comprises islands with extended and sometimes hyperextended continental crust, a series of marginal foredeeps and intervening fold-and thrust belts. This paper illustrates how the offshore fold-and-thrust belts that bound the fore-deeps change in size, shape and degree of basement reactivation in a clockwise sense around the Banda Arc.

Structural field studies and geochemical and age analyses of the Eldivan ophiolite, which is dismembered within the Ankara Mélange, indicates that it developed as a supra-subduction zone basin within the İzmir-Ankara-Erzincan Ocean, which later subducted to form the İzmir-Ankara-Erzincan suture zone through continental block collision. Whole-rock and mineral geochemical evidence show a supra-subduction zone tectonomagmatic affinity for the ophiolitic crust and mantle, revealing that this basin formed in the upper plate of an intra-oceanic subduction zone. Structural restoration of the sheeted dike complex reveals that the supra-subduction zone spreading ridge of the Eldivan ophiolite was nearly parallel to the Sakarya-Pontide continental margin. U/Pb age analyses of detrital zircon in sandstone within the mélange and in the unconformably overlying Karadağ Formation indicate maximum depositional ages for the units of 143.2 ±2 Ma, and 105.2 ±5 Ma, respectively. Thus, thrust imbrication of the ophiolite and the development of serpentinite mélange were mostly complete by 105 Ma, as indicated by an angular unconformity between the ophiolitic units and the overlying Karadağ Formation. These results reveal how and when the Eldivan ophiolite was constructed, destructed, and incorporated into the serpentinite Ankara Mélange and İzmir-Ankara-Erzincan suture zone. The tectonic evolution of the İzmir-Ankara-Erzincan Ocean is similar to that of the Philippine Sea and Banda Sea ocean basins.