中文摘要：

柴达木盆地自中生代末-新生代初以来，四周山体不断抬升，形成“高山深盆”的沉积环境，为盆地带来了大量盐类物质，再加上新近纪干旱封闭的气候环境，使得其西部沉积了广阔而厚层的岩盐。在对柴达木盆地西部新近系、第四系地层出露盐矿点实地考察的过程中，采集、分析了18件卤水样品的水化学组成。结果表明，卤水矿化度高，油田卤水富B^3＋、Li^＋、Sr^2＋和Br^-等有益组分，其前缘第四纪形成的盐湖也有大量K^＋资源分布。通过离子含量及水化学特征系数，查明了卤水的水化学类型主要为氯化物型和硫酸镁亚型，地表浅层卤水富Mg^2＋、SO4^2-贫Ca^2＋，而油田卤水富Ca^2＋，贫Mg^2＋、SO4^2-。反映了油田卤水具有深部CaCl2型水体的特征，这种富Ca^2＋的卤水可能与白云岩化作用使卤水中的Ca^2＋增加而Mg^2＋减少，以及硫酸盐的还原作用使SO4^2-减少有关；地表浅层卤水接近青海湖湖水蒸发线，说明盆地卤水主要是由大气降水汇聚蒸发形成。通过卤水氢氧同位素的分析，发现卤水明显偏离于大气降水线，发生了明显的“氧同位素正漂移”现象，且卤水演化趋势线和当地大气降水线的交点与周围山体前缘的盐泉水的氢氧同位素值相近，地表浅层卤水主要分布在大气降水线附近，而油田卤水集中分布在变质水的范围内。说明地表浅层卤水主要是由大气降水汇聚而形成的；而深部油田卤水推测基本上来源于冰雪融水或雨水补给，这些冰雪融水或雨水沿着断裂带下渗，在迁移的途中发生了变质作用和深部地热水体掺杂作用，形成了深部油田卤水。

英文摘要：

From Mesozoic to Cenozoic, the big mountains around Qaidam Basin were unceasingly rising and a deposit environment of ＂high mountain and deep basin＂ was formed, which brought abundant sources of salts. Then under extremely drought climate environment, a wide and thick stratum of salt rock was accumulated in the western basin. Based upon this, some brine samples around several representative salt mines were collected and analyzed for their hydrochemical components in order to evaluate the evolution of the brines. The results indicate that all the types of brines are chloride type and magnesium sulfate sub-type, and the oil field brines enrich valuable components of B^3 ＋, Li^ ＋, Sr^2 ＋, Br^- and so on, and the salt lakes have abundant contents of K ^＋. In addition, the oil field brines enrich Ca^2 ＋, poor Mg^2＋ or SO5^2-. However, the salt lakes and intererystalline brines enrich Mg^2＋ and SO4^2-, poor Ca^2＋. These results indicate the oil field brines developed dolomization and sulphate reduction. The shallow-layer brines approach evaporating line of Qinghai Lake, which illuminates the salt lake brines resulted from evaporation of rainfall. The hydrogen and oxygen isotopic compositions of the brines may synchronously increase in evolutional pathway, or the δ18O value has a large positive shift whereas the δD value has a small one. And the δD and δ18O values are similar with those of the spring of the front of mountain mass, and distributes in the range of metamorphosing water. Therefore, the origin of the brines in western Qaidam Basin may be ice-snow melting water or rain water, and this conclusion is consistent with the results of high ion contents of Ca^2 ＋, CI^-, B^3 ＋, Li^ ＋, Sr^2 ＋, Br^- and so on.