Abstract

Exploration activities along the southern flank of the Central Range thrust belt in Irian Jaya, east of 138 degrees E have highlighted variations in the structural style. West of about 140 degrees E the structural front separates a foreland basin from a foothills (or disturbed) belt underlain by a basal detachment within or above the Mesozoic Kembelangan Group. The highlands themselves contain stacked and in some cases folded thrust sheets composed of the entire stratigraphic section from lower Paleozoic through late Tertiary. The range of structural features compares favorably to the diversity of other thin-skinned thrust belts.

East of 140 degrees E, the structural front lies at the southern edge of a number of basement-cored block uplifts bounded by steeper reverse faults. A strike-slip zone identified from contemporary seismicity lies just to the north of these foreland uplifts, and apparently connects into the Digiam fault system in PNG. Immediately to the north of the wrench lies the metamorphic and ultramafic belt. The stocks of the Star Mountains intrusive complex appear to be confined to the thick-skinned segments of the belt.