Fig. 10

Free air gravity map of the Banda Sea and Banda Arcs. The Outer Banda Arc consists of the large islands of Timor, Seram and Buru, as well as numerous smaller islands. The arc is composed principally of sedimentary rocks of Australasian (not Asian) affinity, and is in contact with the Australian continental margin in the north, south and east. The contact is a collision front, marked by the dashed white line through the deep free-air gravity lows that coincide with the Timor and Seram troughs in the south and the north but which in the east passes between the two largest islands of the Kai archipelago (Milsom et al., 1996). The gravity low in the Molucca Sea is a consequence of the coalescence of the subduction trenches associated with the converging Halmahera and Sangihe arcs (see Fig. 13). Active volcanoes on the inner arc ridge are indicated by yellow triangles, and inactive volcanic centres by white triangles. The yellow rectangle indicates the area of the seismicity plots of Fig. 11 and the dashed yellow line indicates the location of the tomographic cross-section of Fig. 13 (which extends beyond the limits of this map to both east and west). F: Flores. K: Kai archipelago, MS: Molucca Sea, NBB: North Banda Basin, PSP: Philippine Sea Plate, SBB: South Banda Basin, WB: Weber Basin. In the north, between 120 and 128°E, the area covered by this figure adjoins the area covered by Fig. 7. The base map was constructed from free-air gravity grids of re-tracked satellite altimetry (Sandwell et al., 2021). Contour interval 50 mGal