PAPUA NEW GUINEA GEOLOGY AND MINERALISATION
Papua New Guinea’s unique geology and mineralization is a result of its location on the boundary between the Pacific and Australian Plates. Tectonic activity along this diffuse plate boundary in the past and in the present day setting has resulted in extensive faulting and magmatism that has led to the economic concentrations of metals. The New Guinea Orogen represented by the mountainous spine of Papua New Guinea formed as a collision zone between the Australian and Pacific plates.
This orogen can be divided into the Western (Highlands and Ramu-Sepik regions) and Eastern (Papuan Peninsula and Islands) Orogens and is composed of a number of geological terranes. These terranes can be treated as separate metallogenic units. The terranes of the Western Orogen are the Papuan Fold Belt, New Guinea Thrust Belt, the Bewani-Torricelli Terrane and the Finisterre Terrane. The Eastern Orogen is composed of the Eastern Fold Belt, the Owen Stanley Thrust belt and the Papuan Islands. The Melanesian arc (the islands northeast of the mainland) forms the New Guinea Islands Terrane. These islands were built by subduction-related island arc magmatism beginning during the Eocene.
The majority of mineralization in Papua New Guinea occurred in the Miocene and Pliocene and is characteristic of its setting at a convergent plate margin. The main mineralization styles are porphyry copper gold and epithermal gold although there are also volcanogenic massive sulphide deposits, lateritic nickel-cobalt-chromite and bauxite occurrences and placer deposits of gold, platinum, titaniferous magnetite and chromite
Currently, most exploration targeting is performed by searching prospect information from mineral occurrence databases while focusing on a few prospects known to the explorers, often in a confined area. While this type of analysis has been effective in the past, many areas have now been well explored and the limited prospect coverage means the probability of discovery is low. Effective targeting can only be conducted if all relevant data are compiled and integrated in a way that matches the mineral system model being used and combined into a single mineral potential or prospectively maps. The Mineral Resources Authority has started the process of identifying new targets, especially new porphyry targets.
It’s a challenge to MRA and companies to discover new prospects, hence mines. With new tools for exploration we stand to win in the unlocking of the minerals from a complex geological setting. These tools and better remote sensing data, with the use of computer aided geographic data management systems or Geographic Information Systems (GIS), and new or improved methods for evaluating the distribution of spatial data in a statistical framework; can make a difference in the time and budget of a company exploring in PNG.
Of course the hard yards on the ground surveys will continue to provide truth to these remotely analyzed data. MRA has qualified and skilled geologists and technical staff to undergo ground surveys, and it has been an ongoing activity for MRA, to continuously understand the geology and mineralization of Papua New Guinea.