北部湾南部重力柱状样的MSCL地声学性质测量及分析

利用钻孔多参数连续记录仪(multi-sensorcorelogger,MSCL),对在南海北部湾南部海区所取得的6个孔重力柱状样进行了测量,获得了连续P波波速、湿密度和孔隙度数据。在室内实验室对柱状样分样之后的沉积物样品进行了孔隙度与湿密度的测定。利用不同的统计回归方法对所获得的6个柱状样的孔隙度与P波波速进行相关分析,并对比室内测量的P波波速、湿密度、孔隙度,建立了基于孔隙度数据对沉积物P波波速进行预测的方法,对MSCL测量方法的优缺点进行了讨论。结果表明,MSCL测量结果与实验室柱状样测定结果较为吻合。样品所在深度对声速的变化影响不大。孔隙度与声速的多项式回归,样条插值回归和GAM模型回归都获得了较高的相关系数,GAM模型可以提供一个较为接近测量值的声速预测方法。MSCL用来测量海底沉积物,可以获得大量的高密度、高精度的沉积物地声学及其他参数数据,但是,如果空气混入沉积物样品中则会导致MSCL测量结果失真。该研究为使用MSCL在区域海底地声学性质、恢复区域海洋沉积历史、海底地声学模型建立等研究提供了参考。

Geoacoustic properties measurement and analysis of gravity cores using MSCL in the Southern Beibu Gulf

Geo-acoustic properties such as P-wave velocity, wet density, and fractional porosity can be continuously measured using multi-sensor core logger (MSCL), which has widespread use globally. Six gravity cores from the Southern Beibu Gulf, the South China Sea were measured in the laboratory using MSCL for P-wave speed, wet density, and porosity parameters. Both the wet density and porosity of one core were also measured after sub-sampling. Results of the comparison of the two data sets show a reasonable match, and the depth of the sample has little effect on the change in sound velocity. Polynomial, Spline interpolation, and GAM model regression can obtain a higher R². GAM model can provide a sound velocity prediction method that is close to the measured value. The advantage and disadvantage of using MSCL as a tool for geo-acoustic measurement is that it can obtain a large number of high-density and high-precision data for sediment acoustics and other parameters. However, if air is mixed with sediment samples, it will distort the results of MSCL. This work can offer a sound background for regional ocean sediment development, regional environmental comparisons, and bottom geo-acoustic models, and for the future effective use of MSCL.