We have developed a laboratory nuclear magnetic resonance (NMR) study to investigate the effect of clay, silt, and sand content on the NMR relaxation time distribution. Transverse NMR relaxation times ($T_2$) are determined for water-saturated unconsolidated sediment mixtures of 1%–60% kaolinite clay, 5%–85% silt-size glass beads, and 8%–94% quartz sand by mass. Nearly all of the mixtures are characterized by a unimodal $T_2$ distribution. When clay is present in quantities greater than 10%, the clay content dominates the response. For these samples, the mean-log relaxation times ($T_{2\mathrm{ML}}$) range from 0.03 to 0.06 s, regardless of silt or sand content. For mixtures with $<10\%$ clay, $T_{2\mathrm{ML}}$ decreases with increasing clay content. When the clay content is kept the same, $T_{2\mathrm{ML}}$ decreases with increasing silt content and increases with the increasing sand content. The strong effect of the clay content on the NMR response is due to the high specific surface area of the clay and the distribution of clay throughout the samples. These results will help improve the interpretation of NMR field data in soils and unconsolidated sediments.

中文翻译：

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粘土、粉砂和砂含量对低场核磁共振弛豫时间分布影响的实验室研究

我们开展了一项实验室核磁共振 (NMR) 研究，以研究粘土、粉砂和沙子含量对 NMR 弛豫时间分布的影响。横向 NMR 弛豫时间 (${吨}_2$) 是针对按质量计 1%–60% 高岭石粘土、5%–85% 粉砂大小的玻璃珠和 8%–94% 石英砂的水饱和松散沉积物混合物确定的。几乎所有的混合物都以单峰为特征${吨}_2$分配。当粘土的含量大于 10% 时，粘土含量将主导响应。对于这些样本，平均对数弛豫时间 (${吨}_{2\mathrm{机器学习}}$) 的范围从 0.03 到 0.06 s，与淤泥或沙子含量无关。对于混合物$<10\%$ 粘土， ${吨}_{2\mathrm{机器学习}}$随粘土含量的增加而降低。当粘土含量保持不变时，${吨}_{2\mathrm{机器学习}}$随含砂量的增加而降低，随含砂量的增加而增加。粘土含量对 NMR 响应的强烈影响是由于粘土的高比表面积和粘土在整个样品中的分布。这些结果将有助于改进对土壤和松散沉积物 NMR 现场数据的解释。