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Research Cruise

A recent research cruise to Reinga Basin and the West Norfolk Ridge northwest of New Zealand has brought back exciting results. Researchers from the Institute of Geological and Nuclear Sciences investigated the northwest end of the vast, ancient rift system that includes the West Coast coal basins and the Taranaki petroleum basin, collecting seismic reflection, gravity and magnetic data, and many rock samples from the seafloor.

About 400 kilometres northwest of Taranaki, on the West Norfolk Ridge, scientists found a sample which contained carbonaceous sandstone and shale, commonly called "coal measures". This sample supports geologists' long-held belief that the New Caledonia and Reinga Basins northwest of the New Zealand landmass and continental shelf hold future petroleum resources.

"Such carbonaceous rocks have never before been sampled west of the West Coast or Taranaki Basins. The sample has very good porosity and a high organic content. This augurs well for the petroleum potential of these formations where they are deeply buried in the basins," said cruise leader Dr Rick Herzer.

The sample has been dated by IGNS palynologist Dr Ian Raine as being 91 million years old. This is about the same as the earliest West Coast deposits and similar deposits in eastern Australia oil basins, and older than most of the early deposits of the Taranaki Basin. Previous seismic reflection surveys in this region have revealed structures typical of coal-bearing rift basins. Similar basins found on the West Coast and the western North Island, such as the Taranaki Basin, are the source of New Zealand's coal, oil and gas deposits.