土壤中磁性矿物的形成转化对环境变化具有指示意义，定量分析土壤磁性对环境因子的响应机制是目前该领域的重要问题.本文综合相关研究及野外实地考察，采集福建南部亚热带地区戴云山垂直地带相同母质的土壤剖面进行环境磁学和漫反射光谱测试分析.结果表明：研究区土壤剖面中磁铁矿和磁赤铁矿主导其磁性变化，当海拔至1320 m以上，土壤中出现次生纤铁矿.当排除地形的影响后，相关磁学参数指示磁畴颗粒在低海拔区域以SP颗粒为主，而较高海拔区域土壤中以粗SD颗粒为主.漫反射光谱结果表明，研究区土壤中赤铁矿和针铁矿对气候梯度变化较为敏感，其中赤铁矿含量随海拔增加显示出降低趋势，并且至海拔1320 m以上赤铁矿消失而主要以针铁矿和纤铁矿为主.对比加热前后针铁矿和赤铁矿特征峰变化，并进行半定量分析认为，当年均降水量超过1900 mm且年均温低于13℃时达到赤铁矿形成的临界值，而针铁矿和纤铁矿则继续呈增加趋势.本研究论证了赤铁矿、针铁矿及纤铁矿对气候梯度具较强的敏感性，可作为研究低纬区域古环境变化的重要指标.
The formation and transformation of magnetic minerals in soil indicate environmental change. The response mechanism of soil magnetism to environmental factors currently needs to be analyzed quantitatively. In present study, based on related research and field investigations, vertical zonal soil profiles with same parent material from Daiyun Mountain (subtropical area in south of Fujian province) were collected for environmental magnetism and diffuse reflectance spectrum (DRS) analysis. The results showed that magnetite and maghemite dominated the magnetic variation in the soil profiles. Lepidocrocite of secondary origin appeared in the soil at altitude of 1320 m. Given the influence of terrain was excluded, magnetic parameters indicated that SP magnetic domain dominated in the low-altitude soils, while the coarser SD magnetic domain dominated in the high-altitude soils. The results of diffuse reflection spectrum showed that hematite and goethite were sensitive to climate gradient changes in the study area. Hematite proportion decreased with the increase of altitude until completely disappeared at altitude of 1320 m, above which goethite and lepidocrocite became predominate. Semi-quantitative analysis of DRS characteristic peaks of goethite and hematite before and after heating suggested that the threshold of mean annual precipitation and mean annual temperature for hematite in subtropical mountains was likely 1900 mm and 13℃, respectively, while meanwhile goethite and lepidocrocite increased with altitude. This study demonstrated that hematite, goethite and lepidocrocite were sensitive to climatic gradient and thus could be potentially used as important paleoenvironmental proxies in low-latitude regions.
|Translated title of the contribution||Magnetic characteristics and environmental responses of vertical zonal soils in the subtropical mountains|
|Original language||Chinese (Simplified)|
|Number of pages||11|
|Journal||Chinese Journal of Geophysics|
|Publication status||Published - Sep 2020|
- Daiyun Mountain
- Soil magnetism
- Diffuse reflectance spectrum