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为了探究沉积物的干燥过程及方式对其磁学性质的影响,选取含水率高的南海沉积物样品,对其中685个样品在自然条件下逐步晾干,并每间隔40 d测量1次低频磁化率(κlf)、高频磁化率(κhf)、饱和等温剩磁(SIRM)、S-300和频率磁化率系数(κfd),共测量5次;对另外60个样品进行冷冻干燥,并在干燥前后测量相同的磁学参数。结果表明:1)自然晾干过程中,除少数异常点(约7%)外,大多数样品的κlf和κhf呈减小趋势,少数样品呈增大趋势,S-300和κfd均呈减小趋势,SIRM先减后增,整体上呈增大趋势;2)冷冻干燥过程中,样品的κlf、κhf、S-300和κfd呈增大趋势,S_(IRM)呈减小趋势;3)2种干燥方法均不影响κlf、κhf、SIRM和S-300的剖面变化趋势,但对κfd的影响较大,这在磁学指标的古环境研究中具有关键的指示意义。磁学参数的变化,可能是由于失水过程发生的微弱氧化作用、失水导致水的抗磁性“负贡献”降低、细粒磁铁矿和磁赤铁矿在湿润状态下转变成顺磁性和不完全反铁磁性等综合因素造成的。建议对同一批次的样品采取相同的干燥方法。
In order to investigate the influence of the drying process and the way of the sediment on its magnetic properties, 685 samples of the South China Sea sediment samples with high water content were selected to dry gradually under natural conditions and once every 40 days. A total of 5 measurements were taken with a total of 5 measurements; the other 60 samples were freeze-dried and dried in a dry The same magnetic parameters were measured before and after. The results showed that: 1) In the process of natural drying, except for a few abnormal points (about 7%), κlf and κhf of most samples showed a decreasing tendency, while a few samples showed a tendency of increasing while S-300 and κfd decreased SIRM decreased firstly and then increased, and the overall trend was increasing. 2) During the process of freeze-drying, κlf, κhf, S-300 and κfd showed an increasing trend and S_ (IRM) Kinds of drying methods did not affect the cross-section trend of κlf, κhf, SIRM and S-300, but had a greater effect on κfd, which is of crucial significance in the paleoenvironmental study of magnetic indices. The change of magnetic parameters may be due to the weak oxidation occurred in the process of water loss, and the loss of water leads to the decrease of the diamagnetism and the “negative contribution” of water. The fine magnetite and maghemite transform into cis Magnetic and incomplete anti-ferromagnetic and other factors caused. It is recommended to use the same drying method for the same batch of samples.