网纹红土中铁矿物与粘土矿物赋存关系的X射线衍射证据

高纯度的粘土矿物样品是粘土矿物学重建古气候的关键，然而，土壤中的铁矿物(如针铁矿和赤铁矿等)和有机质的存在导致粘土矿物与非粘土矿物相互包裹，使富集的粘土矿物样品常含有其他矿物杂质。土壤沉积物中有机质去除的研究已较为充分，但铁矿物在土壤沉积物中的赋存状态倍受争议，制约了高纯度粘土矿物样品的制备。该研究将以长江中下游九江网纹红土作为研究对象，通过逐级分离试验对网纹红土中铁矿物与粘土矿物的赋存关系进行研究，为土壤沉积物中铁矿物的去除提供一定的启示。试验结果表明，针铁矿和赤铁矿等铁矿物可能主要呈现被膜状吸附在羟基间层蒙脱石和伊利石的表面，也有部分被高岭石吸附。

Occurrence Relationship between Iron Minerals and Clay Minerals in Net-Like Red Soils: Evidence from X-Ray Diffraction

The high purity of clay minerals is a key factor to reconstruct the palaeoclimate in clay mineralogy, however, the existence of iron minerals (such as goethite and hematite) and organics lead to the intergrowth of clay minerals and other minerals, producing other mineral impurities in enriched clay minerals. Although the removal of organics in soil sediments has been fully investigated, the occurrence state of iron minerals remains controversial, hindering the preparation of high-purity clay minerals. Therefore, the occurrence relationship of iron minerals and clay minerals in Jiujiang net-like red soils of the middle to lower reaches of the Yangtze River was investigated using the sequential separation method，which provided some implications for the removal of iron minerals in soil sediments. The results indicated that goethite and hematite were mostly absorbed on the surface of hydroxy-interlayered smectite and illite in the form of films, and the rest were absorbed by kaolinite.