The structure and tectonic setting has had a strong influence on gold mineralisation at the Porgera gold deposit. Here, the
structural controls on the mineralisation at Porgera are discussed and placed in a regional tectonic context. The Porgera
gold deposit is related to the emplacement of the Porgera Intrusive Complex. Prior to intrusive emplacement at Porgera,
Papua New Guinea was affected by a major fold and thrust episode which occurred in response to arc-continent collision in
the Late Miocene. After crustal shortening the region experienced a relaxation of compression which is expressed in the
deformation accompanying mineralisation at Porgera. The first stage of mineralisation (stage I) is hosted by extension
fractures, and is spatially associated with exposed intrusive stocks. A later episode of mineralisation (stage II) is hosted by
the faults and fractures of the Roamane Fault Zone, which was active as a dip-slip normal fault during stage II
mineralisation. Therefore a change in the tectonic environment from shortening to extensional tectonics can be seen at
Porgera before and during mineralisation. Rapid fault-slip during stage II mineralisation may have aided high-grade gold
mineralisation by subjecting hydrothermal fluids to changes in pressure, temperature, fluid-fluid and fluid-rock interaction.
Uplift to form the highlands of Papua New Guinea occurred after mineralisation and was largely complete by 4.0 Ma.