Core drilling, structure volume estimation in the Såt extraction prospect for hard rock aggregates in Espevik, Rogaland

In co-operation with Amrock JV AS, the Geological Survey of Norway (NGU) mapped in September 2001 the geology of a new potential extraction area for hard rock aggregates around Såt. The results were presented in NGU Report 2002.007. A drilling program was accried out in December 2001 - january 2002 in order of estimate the deep structure and volume of the different rock qualities in the Såt prospect. The drill-core logging indicates that biotite gneiss-granites are less frequent in the central part of the prospect than believed earlier. Instead, tonalitic biotite gneiss-granitoids and fine-granied gneisses form larger proportions. The southwestern part of the Såt prospect is built up of alternating fine-grained grey biotite gneisses and tonalitic biotite gneiss-granitoids, which together form a thick steep-dipping southwestern body of "good quality rocks". The fold-like structure in the central part of the prospect is interpreted to extend much farther north than previously envisaged. Point-load testing has been carried out systematically on the drill cores from all boreholes. Detailed measurements show that there is no evidence for weathering in the uppermost first metres of the boreholes. Density measurements were carried out on all main rock types in the drill cores from the prospect. Based on the rock distribution in the drill cores, the average density of rock types dominating the southwestern part of the prospect calculated to 2.83. For the total area the median of the density for the different rock types vary from 2.67 to 3.04. The estimate the volume of bodies with different rock qualities in the Såt prospect, a 3D model has been establishedfor the planned open pit. The southwestern body in the planned pit constitutes 30% of the total volume as a "potential volume" of aggregates showing "good mechanical quality". The central body makes up 39% by volume as a "spe

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