Favourable formations for uranium occurrences in Irian Jaya

The geological setting of Irian Jaya can be divided into four stratigraphic provinces: south Irian Jaya, central Irian Jaya, north Irian Jaya and Misool-Onin-Kumawa. Underlying all these provinces are granitic and metasedimentary rocks, with a few volcano-sedimentary and sedimentary rocks as the basement complex. The geology of the basement complex is not well known but it is at least of pre-Permo-Carboniferous age. The granitic rocks of the basement complex are assumed to be part of the Palaeozoic orogenic belt. The probability of U occurrences in the basement complex are good owing to the younger intrusions (Jurassic and Tertiary) of intermediate acidic magmatic rocks. The most important stratigraphic province is the central Irian Jaya. It has some lithological formations which are favourable for U occurrences, i.e. the Aifam, Iwur, Buru, Klasaman and Steenkool Formations. Some indications of mineralized granitic outcrops of the basement have been found by ground surveys made in the Ransiki area. (author). 5 refs, 8 figs, 1 tab