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.