Hydrogeochemisty has a wide application in oil and natural gas exploration and better effects have been achieved. Gas hydrate has similar origin and formation mechanisim as conventional oil and gas. This study investigated hydrogeochemical anomalies of gas hydrate in the Qiangtang Basin of the Qinghai-Tibet Plateau. 19 fountain samples were collected in the Qiangtang Basin for analysis of chemical compositions, H, O and C istopic compositons, and aqueous methane. The fountains in the Qiangtang basin are divided into Na2SO4 type and NaHCO3 type based on the Sulin's classification. Mineralized degree of fountains indicates that fountains are dominated by low mineralized fresh water. H and O isotopic analysis also suggests they are meteoric water in origin. In addition, carbon isotope analysis of dissolved methane, which was deteted in the fountain sampes, also indicates that fountains are underground water related to oil fields. Integrated research indicates that fountains in the Qiangtang Basin originate from meteoric water. A certain amount of methane was detected in each sample andδ13C analysis for the samples containg high content of methane shows the fountains are variously affected by underground oil and gas reservoirs. In conclusion, SQ-2 and SQ-17 may represent the possible positions of underground gas reservoir or gas hydrate deposit.%水文地球化学在石油、天然气找矿方面应用十分广泛,而且取得了较好的效果.天然气水合物与常规油气有相似的物源和地表化探异常形成机制,因此我们在对青藏高原羌塘盆地的天然气水合物相关的异常进行调查研究时,对取自羌塘盆地的19个泉水样品进行了化学组分、氢氧同位素、水溶甲烷和碳同位素进行了测试分析.结果表明,按照苏林的分类原则羌塘盆地泉水主要为Na2 SO4型和NaHCO3型；泉水的矿化度,显示以低矿化度的淡水、微淡水为主；氢氧同位素分析表明泉水来源以大气降水为主；泉水中均检测到一定含量的水溶甲烷,水溶甲烷碳同位素分析表明泉水为油田相关地下水,本次研究所采集的羌塘盆地泉水主要来自大气降水；各采样点泉水中均检测出一定含量的水溶气甲烷,通过对水溶甲烷含量较高样点泉水的δ13C的分析认为泉水不同程度地受地下油气藏影响.综合分析后认为,SQ-2、SQ-17可大致指示地下油气藏或天然气水合物藏的具体位置.
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