Publications

From 1978 to 1982 the Geological Research and Development Centre of the Indonesian Department of Mining and Energy, and the Australian Bureau of Mineral Resources have collaborated in the Irian Jaya Geological Mapping Project. This is a co-operative project which carried out the systematic 1 :250,000 scale geological map ing of western Irian Jaya, as far east as longitude 136o 30 East (Figure 1).The pre-existing stratigraphy of this region was established by geologists of the Nederlandsche Nieuw Guinee Petroleum Maatschappij and is described by Visser and Hermes (1962). The detailed and painstaking mapping wried out by these geologists between 1935 and 1960 in conditions of great hardship, produced a highly reliable stratigraphy of the area under consideration.However, systematic mapping, albeit at 1 :250,000 scale, requires a regional rationalisation of the stratigraphy which is not essential in petroleum exploration, and we have also had to correct the common tendency to assume that biostratigraphic units, identified by their fossil content, can be mapped and classified as if they were lithostratigraphic units defined by their constituent rock types. Dr. Alan Lloyd has provided invaluable assistance in the considerable problem of correlating the Visser and Hermes time sub-division with standard Tertiary stages.The stratigraphic units employed in the new 1 :250,000 scale geological maps of western Irian Jaya are listed and described below. The nomenclature is summarized in tables and the relationships of the various units are displayed in several time-space diagrams. A synthesis of the stratigraphy is attempted in a summary geological history of western Irian Jaya, and a note is added on the petroleum potential of the region.We acknowledge the assistance of all personnel who have worked with the Irian Jaya Geological Mapping Project, and we are grateful that the Indonesian Petroleum Association has provided a forum at which we could discuss our emerging results. It is a pleasure to acknowledge the encouragement and unfailing co-operation of Mr. Hartono, Director of the Indonsian Geological and Development Centre, who has permitted publication of this paper. Permission of the Director, Bureau of Mineral Resources, Australia, has also been obtained for publication by the Australian authors.