Sheet QM405 Chatham Islands : geological resource map of New Zealand 1:250 000

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Campbell, H.J.; Christie, A.B. 1994 Sheet QM405 Chatham Islands : geological resource map of New Zealand 1:250 000 . Lower Hutt: Institute of Geological & Nuclear Sciences Institute of Geological & Nuclear Sciences science report 94/25 23 p.

Abstract: The Chatham Islands are situated in the Pacific Ocean, 850 km east of Christchurch. They lie at the eastern end of the Chatham Rise, a major elongate submarine extension of the New Zealand subcontinent. Current mineral production on the Chatham Islands is confined to rock aggregate and sand to meet the needs of local road construction, building, farming, and development requirements, and also some limestone for agriculture. Limestone, schist, and various volcanic rocks are the main rock types quarried for aggregate. Some ornamental stone, in the form of dolomite cobbles and boulders, is taken from a beach on the south coast of Chatham Island. Extensive wax-rich peat deposits on Chatham Island have been explored and appear to offer economic potential. The oil and gas potential of the Chatham Islands and the adjacent Chatham Rise is considered to be marginal, but worthy of further investigation. Late Miocene phosphorite nodules are present on the sea floor of Chatham Rise and comprise estimated resources of 25 million tonnes at an average grade of 66 kg/m2. They lie in water depths of about 400 m along some 400 km of the crest of the rise. Good quality potable groundwater is probably abundant, and given the small population, moderate annual rainfall, and a cool temperate climate, the availability of fresh water is not normally a significant problem in the Chatham Islands. (auths)