Fiji authorities report discovery of small quantities of oil in sea bottom sediments in the South Pacific's Bligh Water basin.
Officials said 17 shallow sediment cores were taken from the sea bed during an expedition aboard the Raiyawa vessel in September about 20 km off Tavua. Geochemistry analysis by Australia Geological Survey Organisation showed that the cores contain small amounts of oil that has migrated from a mature source rock to form an oil seep on the seabed.
Maturity modeling indicates the top of the oil window to be at 2,000 m below sea floor in the Bligh Water basin, says South Pacific Applied Geoscience Commission, Suva, Fiji. Sopac and the Fiji government's Mineral Resources Department sponsored the survey.
Biomarkers indicate the oil originates from sedimentary source rocks of Late Cretaceous to Tertiary age. Other geological evidence helps to tie the age of the source rocks down further to no older than 30 million years.
Organic matter contained in the source rock from which the oil was derived originates from a mixture of land plant and marine organisms such as algae and bacteria. Similar source rocks are known to generate the oil and gas found in Southeast Asia.
The low concentrations of gas in the Fiji seep indicates that oil rather than gas is being formed, says Jonathan Rodd, Sopac petroleum coordinator. The geochemical analysis also shows that the seep is not due to contamination or pollution.
Alf Simpson, director of mineral development, said the find proves oil is being generated off Fiji. Sopac and MRD have published a booklet that outlines Fiji's oil and gas potential.
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