深循环地下水维系黄土高原风尘颗粒连续沉积  

Deep-Circulation Groundwater Maintains Continuous Deposition of Dusty Particles in Loess Plateau

作　　者：陈建生[1] 刘震[1] 刘晓艳[2] 

机构地区：[1]河海大学地球科学与工程学院,南京210098 [2]河海大学期刊部,南京210098

出　　处：《地质学报》2013年第2期278-287,共10页Acta Geologica Sinica

基　　金：教育部高等学校博士点基金(编号20090094110007);科技部"973"项目(编号2012CB417005)共同资助的成果

摘　　要：黄土高原地区的降水入渗试验表明,降水在入渗过程中受到了蒸发作用,并未入渗到潜水,土壤水中的氘氧同位素与地下水相近,这表明土壤水主要来自于地下水。外源水是黄土高原发源的河流、湖泊的主要补给源,当地的降水仅在汛期补给河流与湖泊。鄂尔多斯盆地黄土地区地下水的分水岭与基底断裂带的分布基本上重合,这暗示着地下水可能来自于基底断裂带,通过基底断裂带上涌的深循环地下水将风尘颗粒粘滞成颗粒团,形成了连续的风尘堆积,深循环的地下水成为维系风尘颗粒在黄土高原连续沉积的必要条件。分析黄土中CaCO3的物质不平衡和钙结核内部无生长层理以及碳氧同位素表现出高度均一性特征,得出黄土中的次生碳酸盐矿物也是由上涌地下水携带来的,并非大气降水入渗造成。调查发现,黄土塬规模的大小与塬轴对称中心钻孔的涌水量成正比关系,表明黄土塬风尘颗粒以对称形式沿着断裂连续地堆积,涌水量越大,所粘聚的风尘颗粒越多,塬的面积也越大,涌水量较小的断裂只能形成墚或峁结构。Precipitation infiltration testing of Loess Plateau areas indicate that precipitation occurs with evaporation during its infiltration but doesn＇t reach phreatic water level. Deuterium and oxygen isotopes in soil water are similar to that of groundwater, indicating that soil water comes from groundwater. External water is important water supply for rivers and lakes in Loess Plateau areas, whereas local precipitation may supplement partially to them during flood seasons. The underground watershed is basically overlapped with basement faulting zone in the loess region of Ordos basin, indicating that the underground water may originate from the basement faulting zone. Clusters of grains formed by deep circulation water gives rise to accumu accumulated water 1s ated symmetrically along the faulting zones. The more upwelling water, the more particles ated, resulting in increasing scale of the plateau whereas faulting with small amount of upwelling responsible for the formation of soil hills and mounds.

关 键 词：黄土高原 降水入渗 风尘颗粒 基底断裂 深循环地下水 物质不平衡 钙结核 

分 类 号：P641.2[天文地球—地质矿产勘探]