磁化率与粒度,矿物的关系及其古环境意义

根据实测数据，对磁化率与粒度、矿物之间的关系进行了探讨。结果表明，沉积物粒度与磁化率的关系，与物源及沉积动力密切相关。因此，在一定条件下，可利用两者关系来反映物源或沉积动力。碎屑沉积物的磁化率主要取决于磁铁矿的含量，并由此建立了磁化率（Ｓ，１０＾－７ｍ＾３ｋｇ＾－１）与磁铁矿的百分含量（Ｐｍ）之间的回归方程Ｓ＝４９．１８Ｐｍ＋４９．５。由于磁铁矿为重矿物，在沉积物中常常与钛铁矿、磷钇矿、独居石、锆

A RELATIONSHIP BETWEEN SUSCEPTIBILITY AND GRAIN-SIZE AND MINERALS, AND THEIR PALEO-ENVIRONMENTAL IMPLICATIONS

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(Pm) of magnetite.Their correlation can be expressed as S=49.18Pm+4.95(10(-7)m3kg(-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.