The Lengguru foldbelt, an area 300 km (180 mi) long with a maximum width of 100 km (60 mi), is near the western end of the island of New Guinea. Sedimentary rocks of the belt include Mesozoic marine sandstone and shale, Tertiary deep-water limestone, Tertiary shelf limestone, and upper Miocene to Pleistocene detritus.

The slab of folded platform sedimentary rocks making up the Lengguru foldbelt was originally at the northern margin of the Australian continent and was thrust southwestward over the undeformed continental crust of the western part of New Guinea. The slab was also rotated clockwise by about 30° about a pivot at its northern end. During rotation, thrusting and decollement within the foldbelt caused a repetition by stacking of the stratigraphic section, and the belt was dragged along transcurrent faults to the south. This foldbelt is of interest for oil exploration because of proximity to the Salawati and Bintuni oil fields on the westernmost tip of the island.