Estimating relative ages from iron-oxide/total-iron ratios of soils in the western Po Valley, Italy.
Estimating relative ages from iron-oxide/total-iron ratios of soils in the western Po Valley, Italy.
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DOI：
10.1016/0016-7061(84)90088-0
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发表时间：
1984-05
期刊：
影响因子：
6.1
通讯作者：
E. Arduino;E. Barberis;F. Carraro;M. G. Forno
中科院分区：
文献类型：
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作者：
E. Arduino;E. Barberis;F. Carraro;M. G. Forno
从五个盆地形成年龄层序的阶地深层采集了19个样品。大部分样品是在1米或更深的地方采集的，有些在3米以下。采样点的土壤被初步鉴定为土壤壤土、土壤土或土壤土。测定了19个样品的总铁含量以及二亚硫酸盐和草酸盐萃取量。根据样本颜色计算红度等级，并通过回归与可提取铁的量相关。从中更新世早期到上更新世-全新世，随着阶地年龄的增加，连二亚硫酸盐(FED)提取的全铁(FeT)与草酸盐萃取量(FeO)的百分比逐渐增加。这些百分比与样品中的铁总量和盆地的总体岩性无关。因此，这些比率有望在估计相对年龄方面有用，特别是在存在时间序列的情况下。根据不同形态铁的比例估算，样品的矿物学与阶地的相对年龄是一致的。红度等级也是如此。提取的铁与红度等级的回归表明，颜色可以作为没有时间序列的梯田相对年龄的初步田间指标。
Nineteen samples were collected from deeper layers of as many terraces forming agesequences in five basins. Most samples were collected at depths of 1 m or more, with some below 3 m. Soils at the sample sites were tentatively identified as Alfisols, Entisols or Inceptisols. Total amounts of iron and the amounts extractable by dithionite and by oxalate were determined for the 19 samples. Redness ratings were calculated from sample colors and related to amounts of extractable iron by regression. Mineralogies of the fine sand, silt and clay fractions were also determined.The percentage of the total iron (Fet) extracted by dithionite (Fed) minus the amount extracted by oxalate (Feo) increased gradually with ages of the terraces, which range from early Middle Pleistocene to Upper Pleistocene-Holocene. These percentages are independent of the total amounts of iron in the samples and of the general lithology of a basin. Such ratios thus promise to be useful in estimating relative ages, especially where time-sequences exist. Mineralogies of the samples were consistent with relative ages of terraces as estimated from the ratios of iron in different forms. So were the redness ratings. The regression of extracted iron on redness ratings suggests that colors can be used as preliminary field indicators of relative ages of terraces without time-sequences.