Density of Core Samples of the KTB Pilot Hole VB1

The density of rocks depends on the mineral contents and is therefore a helpful property for the discrimination of lithological units. It is also used for the calculation of several other properties, like the heat production rate from potassium, uranium and thorium contents, volume susceptibility, thermal conductivity, etc. The density of cuttings and cores is determined by the Archimedian method. The weight of the sample is determined in air and in water. Knowing the density of water, the volume and the density of the sample is calculated.
Air adsorbed by the large surface of the cuttings causes errors in the calculated volume. Therefore, the specific surface of the cuttings is minimized by using only cuttings greater than 2 mm in diameter. The depth interval of the measurements is generally 2 m.

岩石密度由其矿物成分决定，因此是判别岩性单元的重要物性参数。该参数还可用于计算多项其他物性指标，例如基于钾、铀、钍含量的生热率、体积磁化率、热导率等。岩屑（cuttings）与岩心（cores）的密度采用阿基米德法（Archimedian method）测定：分别在空气和水中称量样品重量，结合已知的水的密度，即可计算得到样品的体积与密度。
岩屑的大比表面积会吸附空气，从而对体积计算结果引入误差。因此，仅选取直径大于2 mm的岩屑，以尽可能降低其比表面积。测量的深度间隔通常为2米。