兴蒙-华北地球化学走廊带稀土元素含量与空间分布

为研究兴蒙造山带-华北克拉通地球化学走廊带区域地球化学组成及其横向空间变化，统计分析不同地理单元和五万图幅单元的REE含量并绘制其空间分布折线图.内蒙古半干旱草原土壤中稀土含量较低，与其草原沙土的粘土矿物较少有关；江苏北部冲积平原区的土壤中稀土含量较高，与降雨量存在良好空间对应关系.内蒙古红格尔到河北张家口，土壤与岩石∑REE的比值绝大多数小于1，REE发生贫化；山东章丘到江苏连云港，比值基本大于1，REE发生富集.华北克拉通内蒙地块土壤稀土特征与兴蒙造山带相似，可能受其草原沙土景观的影响.在不同构造单元之间，LREE与HREE亏损与富集的空间分布存在细微差异.结果表明:地理景观，特别是黏土矿物是影响土壤REE含量的重要因素，降雨量与REE存在良好空间对应关系，REE自身的地球化学性质的差异在土壤形成过程中对轻重稀土元素分异具有重要影响. 

Concentration and Spatial Distribution of REE in Geochemical Transect of Xingmeng Orogenic Belt-North China Craton

In order to study the regional geochemical composition and lateral spatial variation of the geochemical belt in the North China Craton, rock and regolith samples along a transect across the Xingmeng Orogenic Belt-North China Craton were collected and 14 rare earth element (REE) concentrations were determined. Data of statistical analyses for regolith samples were based on tectonic units, geographical landscape, soil types and rainfall units, and for rock samples were based on tectonic units, rock types, and geologic age units. An average value was calculated from each 1:50 000 map sheet. The spatial distribution of REE concentrations is plotted in figures. The results show that:(1) REEs are depleted in Inner Mongolia semi-arid grassland soils due to less clay minerals in the soils, whereas REEs are enriched in the alluvial plain soils of the northern Jiangsu corresponding to the maximum rainfall zone. (2) In the transect from Honger to Zhangjiakou, REE ratio of soil to rock mostly is less than 1, indicating that the REE is leached in soils or diluted by windblown sand; in the transect from Zhangqiu to Lianyungang, the ratio is greater than 1, indicating that the soil REE are enriched in soils. (3)The REE characteristics of the Inner Mongolia block, which belong to the North China Craton, are more similar to those of the Xingmeng Orogenic Belt, affected by the semi-arid sandy soil of Inner Mongolia; The spatial distribution of LREE and HREE with depletion or enrichment in different tectonic units indicates that geochemical properties of REE affecting on the fractionation of REE in the process of soil formation.