论文部分内容阅读
磁铁矿、磁赤铁矿、赤铁矿和针铁矿是中国黄土-古土壤序列中主要的磁性矿物和磁信号载体.利用X射线衍射(XRD)、光学显微镜和电子显微镜(场发射扫描电镜SEM和高分辨透射电镜TEM)对这些磁性矿物的物相关系和存在形式进行了深入研究结果表明:强磁性的磁铁矿和磁赤铁矿以独立单一物相和多相复合磁性颗粒形式存在大颗粒的风尘磁铁矿在沙漠源区就已经经受了低温氧化,粉尘沉积后的成土作用加剧了这种低温氧化过程,形成具有赤铁矿镶边结构的磁铁矿复合磁性颗粒.针铁矿与赤铁矿共存,部分针铁矿经脱水过程,在其边缘形成纳米级的赤铁矿.以上研究对解译中国黄土-古土壤序列的磁信息及相关的古气侯含义提供了最直接的矿物学支撑.
Magnetite, maghemite, hematite and goethite are the main magnetic minerals and magnetic signal carriers in the loess-paleosol sequence of China, and their structures are characterized by X-ray diffraction (XRD), optical microscopy and electron microscopy Electron microscopy SEM and high-resolution transmission electron microscopy TEM) on these magnetic minerals in-phase relationship and the existence of the form of an in-depth study results show that: ferromagnetic magnetite and maghemite with independent single phase and multiphase composite magnetic particles Aeolian magnetites with large particles have been subjected to low temperature oxidation in the desert source region. The soil-forming effect after dust deposition exacerbates this low-temperature oxidation process and forms magnetite composite magnetic particles with a hematite edge structure. Goethite coexists with hematite, and some goethite undergoes dehydration process to form nanoscale hematite at its edge.The above studies provide the interpretation of the magnetic information of Chinese loess-paleosol sequence and the related paleoclimate implications The most direct mineralogy support.