不同海区石英悬浮体颗粒表面微结构特征及其成因

悬浮石英颗粒表面在不同的水动力环境中会形成一些特有的表面结构，对这些特点的研究有助于理解微小颗粒在水中的行为以及沉积环境的变化。基于对在不同海区采取表层和不同深度的悬浮石英颗粒表面结构的扫描电镜的观察, 发现在水动力较强的南海海域石英颗粒表面大多呈现出机械作用成因的结构，化学溶蚀痕迹不明显；马六甲海峡、孟加拉湾南部海域、阿拉伯海东部海域站位石英颗粒表面开始出现明显的化学溶蚀痕迹，为机械-化学溶蚀作用的结果；莫克兰海沟站位表层样品石英颗粒表面化学溶蚀作用强烈，随着深度的增加，溶蚀作用减弱，200m水深以下，石英颗粒表面的结构主要为机械-化学溶蚀作用的结果。中国南海西南部3号站位、马六甲海峡北部7号站位以及孟加拉湾南部的11号站位的表层石英悬浮体颗粒较大，可以达到10μm左右，大于其他海区的石英颗粒(3～4μm)。研究海区海水中悬浮体石英颗粒大都呈现棱角状，表现为近源沉积，偶尔可见磨圆度较好且表面有新月形撞击坑，推测可能为风尘沉积。

SURFACE MICROTEXTURES OF SUSPENDED QUARTZ AND THEIR GENESIS IN DIFFERENT SEA AREAS

Some unique surface textures may be formed on the surface of suspended quartz particles under different hydrodynamic environments. The study of these characteristics is helpful to understand the dynamic behavior of small particles in water and the changes in sedimentary environment. Based on the observation of the surface textures of suspended quartz particles in different sea areas and different depths, it is found that most of the quartz particles in the South China Sea area, where occur strong hydrodynamic force, exhibit mechanically formed textures. The trace of chemical dissolution is not obvious. Obvious chemical dissolution marks on quartz surface appear in the southern part of the Bay of Bengal, the eastern part of the Arabian Sea and the Strait of Malacca; The surface chemical dissolution of quartz particles in the surface samples of the Mokland trench station is strong. With the increase in depth, the dissolution effect weakens. Below 200 m of water depth, the surface texture of quartz particles is mainly the result of mechanical-chemical dissolution. The surface quartz suspensions at station 3 in the southwest of the South China Sea, station 7 in the north of Malacca Strait and station 11 in the south of the Bay of Bengal are about 10 μm, which are larger than those in other sea areas (3~4 μm). Most of the suspended quartz particles in the sea water of the study areas are angular in shape and occasionally with better roundness, suggesting a kind of near-source deposition. Sometimes, there are crescent impact pits on the grain surface, and it is inferred that it may be of aeolian deposition.