青海柴达木盆地盐渍类型及盐渍地球化学特征

青海柴达木盆地是我国的高原盆地,海拔在2600-3200米,气候干旱,地形封闭,年迳流总量约44-50亿立方米,完全汇集于盆地,主要平衡消耗于蒸发。盆地盐类化学沉积至少自第三纪开始,除沉积大量石盐、光卤石外,硼、锂、锶等元素亦大量富集。盐渍土的类型和分布总的规律是:1.在大湖盆的周围;从湖心起向外推,依次出现化学沉积→盐泥→盐壳→沼泽盐土→草甸盐土→残余盐土→砾质戈壁石膏盐盘残余盐土。2.在小湖盆的周围,从湖心起向外推,依次为化学沉积→盐泥→地下水溢出的部位发育为沼泽盐土或盐化沼泽土→湖滨草甸盐土→砾质盐化土或砾质戈壁石膏盐盘残余盐土。各类型的盐渍土分布带有宽有窄,一般在近高山区一侧,由于水流所携带的物质丰富,分布带宽,规律性亦明显,而在靠低山区一侧窄。按照盆地地质历史特点和盐类地球化学累积特征,划分为三个积盐区:1.西部硫酸盐类累积区,主要以CaSO₄、Na₂SO₄和SrSO₄等盐类;2.北部小盆地以硼酸盐类和氯化物盐类等累积区;3.中、南部为氯化物盐类累积区,主要以NaCl、MgCl₂和KCl等盐类。文章最后提出盆地土地资源的合理开发利用的方向性意见。

SALT-AFFECTED SOILS TYPE AND SALINE-GEOCHEMICAL FEATURES IN QAIDAM BASIN

Qaidam is a plateau basin, with an elevation of 2600-3200 m, under climate arid. All the run off of about 440-500 million m³ yearly is converged into the river-sealed basin owing to reversed drainage, therefor, salt-water balance of the region mainly depends on evaporation. The deposition of salts in this basin have been started at least since Tertiary. In the salts deposited, besides large amounts of halite, carnatite and gypsum, those of B, Li, and Sr had also been enriched.