关键词: 磁化率, 粒度, 矿物, 沉积环境, 砂矿品位

Abstract: The relationship between susceptibility of sediments and mineral components and grain-size of sediments is discussed based on the measurement of susceptibility and the analysis of mineral components and grain-size.lt shows that susceptibility of sediments depends on depositional dynamic environments,sedimental source and secondarychange of sediments. If there is no secondary change of sediment since it was formed, the susceptibility of sediments can indicate the changes in sedimental dynamic evironment and sediment source.When sediment source keeps constant the suseptibility can b used as a good indicator of depositional dynamic change.Otherwise,when depositional dynamics keegs constant,the susceptibility can b regarded as a good indicator of the changes in sediment source.The susceptibility of clastic sdiments depends mainly on the content(P_m) of magnetite.Their correlation can be expressed as S=49.18P_m+4.95(10^-7m³kg^-1. Magnetite,which is a kind of heavy mineral in the sediments, is usually companiate with other heavy minerals in the sediments.Thus, the susceptibility measurement of sediments can help to estimate the content of heavy sand minerals.Because the heavy sand minerals(such as ilmentite,zircon, rutile, monazite) have larger density than quartz feldspar which are the dominant minerals in elastic sediments, the grain-size of these heavy sand minerals in the sediments is about 50% smaller than that of thesediments.So, if we know the grain-size of the heavy sand minerals in a certain region, we shouldfocus on the sediment of which the grain-size is twice that of the heavy sand minerals when we search for placer deposits of these minerals.

Key words: susceptibility, grain-size.mineral, sedimental environment.placer deposits