Tihiroa Coalfield, Ongaruhe sector, exploration for opencast coal.

Late Eocene Waikato Coal Measures are the basal formation of the Te Kuiti Group, which unconformably overlies Jurassic basement. Three coal seams, Kupakupa, Renown & Kemps, are present. These reach a combined thickness of 11 m immediately to the north of the area under consideration. Te Kuiti Group rocks are unconformable overlain by Plio--Pleistocene Alexandra Volcanics and Quaternary Tauranga Group sediments. Very little, if any coal in the area could be mined economically by opencast methods. The known amount of coal with a downhole ratio between 10:1 & 15:1 is estimated at 18,200 tonnes. The ash content of this coal is likely to be about 20%. No coal at less than 10:1 downhole ratio at present. Further drillholes were suggested. These will also provide information for a possible underground mine entry to the thicker, deeper and lower ash coal in the Kupakupa seam immediately to the north. This report presents results of the NZCRS shallow drilling programme in the Titihaoa Coalfield from December 1983 to January 1984. Drilling was undertaken to assess coal resources for possible opencast development, following earlier recommendations (Fowke 1983) Also incorporated are drilling and analytical results from nine holes drilled in the surrounding area between 1979 and August 1983.