笔者对采自太平洋中部170°E至178°W,6°到17°S,即新赫布里底群岛至乌佛阿岛,斐济群岛到埃利斯群岛间海区(见图1)的10个站位,20个海底沉积物样品,进行了分析和研究。 该区的地质构造受西太平洋岛孤活动带的控制,海底地形复杂,水深变化大。火山活动频繁,区内散布许多白垩纪至老第三纪形成的火山岛和水下火山体。第四纪以来,火山活动依然十分频繁。根据海底地形，水深和沉积物的差异，将该区分为三个小区。(1)斐济群岛和霍恩群岛以北海区，水深一般小于2500米，但深度变化大，地形复杂，水下火山体和珊瑚礁星罗棋布，沉积物以钙质生物沉积为主。( 2)北斐济海盆，水深多为3000-400。米，海盆边缘散布着许多水下火山体，沉积物以钙质生物沉积一火山碎屑沉积为主。(3)美拉尼西亚海盆南部，水深5000米左右，海域开阔，水下火山体较少，沉积物以多源性红粘土沉积为主。
In this paper, the types, composition, distribution and origin of the main clay minerals of sadiments in the middle of the Pleific Oeean are initially analysed and studied, -which offers an important insight into the understanding of the sediments in respect to their origin, transport, environment and history. The clay minerals are mainly dioctahedral Fe-Al montmorillonite characterized by its broad crystalliaityj trioctahedral Fe-Mg chlorite,some of which are good in their crystallinity, but some poor; dioctahedral Fe-Al hydromica ( illite ) of muscovite type, having the stable properties of crystallo-chemistrys kaolinite with a property of chanegeable order,including the highly-ordered and double-layer dickite and poorly-ordered kaolinite as well as some mixed-layer ones, such as illite-montmoril-lonite, illite-chlorite and kaolinite-montmorillonite and palygorskite in small amount. Among clay minerals, the montmorillonite and chlorite are mainly authigenic, and the muscovite and kaolinite are mainly terrigenous origin from Australia. During the chilly glacial epoch, the sea level fell and the tein perature of the sea water reduced.Meanwhile the dissolution of the carbonate decreased, and the carbonate in the sediments was rich, while the total amount of the clay minerals was poor. In addition,the volcanic activites were quite violent and the sources of the basic volca-aic material were abundant, Therefore, the relative amount of the authigenic montmorillonite was bigger than that of the other clay minerals, and the ratio of montmorillonite to illite was relatively bigger. The situation of the interglacial anci the post-glacial ages was contrary to that of the glacial age.