南极半岛西部海域沉积物中粘土矿物研究

对南极半岛西部海域的表层沉积物和岩芯S11样品中小于2微米粒级的分析表明,粘土矿物由蒙脱石、伊利石、绿泥石和高岭石组成。表层沉积物中以蒙脱石和伊利石两种矿物占优势。蒙脱石的变化趋势由北向南递减,在南设得兰群岛周围海区含量最高;伊利石的变化趋势与蒙脱石相反,主要分布在南极半岛西北侧。 岩芯S11中的粘土矿物仍由上述四种矿物组成。蒙脱石含量随深度增大而减少;伊利石和绿泥石含量随深度增大而增高。这种变化趋势表明蒙脱石在间冰期沉积物中最丰富,而伊利石和绿泥石在冰期沉积物中最丰富。

CLAY MINERALS IN THE NORTHWESTERN SEA AREA OF THE ANTARCTIC PENINSULA

Clay minerals in 29 samples of surface sediments and core Sll in the northwestern sea off the Antarctic Peninsula are analyzed to determine their distribution pattern and to decipher their origin and source. The clay fraction of less than 2 microns in the samples are studied by X-ray diffraction. The result indicate that the clay minerals consist mainly of montmorillonite, illite, chlorite and kaolinite and that change in their abundance is remarkable. The maximum content of montmorillonite, 45% in average, is found in the shallow zone around the South Shetlands, whereas the minimum content of montmorillonite (27%) is found in a zone nearby the northwestern side of the Antarctic Peninsula. The distribution pattern shows that relative abundance of montmorillonite gradually decreases from north to south in the sea area studied. However, the distribution trend of illite is just opposite to that of montmorillonite. For example, relative abundance of illite is 48% in a zone nearby the northwestern side of the Antarctic Peninsula and 32% m the shallow zone around the south Shetlands. Analysis of core Sll indicates that clay minerals are primarily composed of the same as above-mentioned. Among them illite is predominant. A relative abundance of montmorillonite decreases with depth of the core, whereas the abundance of illite and chlorite in creases with the depth, but content of kaolinite does not sharply vary. The variation indicates that montmorillonite has its highest concentration in the interglacial sediments, and illite and chlorite have their highest concentration in the glacial sediments.