西秦岭南亚带的拉尔玛金成矿带，由拉尔玛、邛莫金矿床和牙相金矿点组成。矿床（点）赋存于寒武系太阳顶群碳质硅岩和碳质板岩组成的硅岩建造中，受地层、岩性、岩相和构造控制十分明显，对其所表现出来的层控性质为众所公认。通过对各金矿床（点）流体氢、氧同位素组成研究之后，作者得出成矿流体乃大气降水的结论。大气降水补给的地下热液在环流过程中，促使硅岩建造中的成矿物质发生活化、迁移和再聚集，并最终导致工业矿床的形成。水－岩体系氢、氧同位素交换演化曲线表明，矿质沉淀时，成矿流体曾发生过沸腾作用。 The Lamarma gold metallogenic belt in the western South China Sea is composed of the Laerma, Zimuo gold deposits and the dental gold deposits. The deposit (point) occurs in the formation of silicon rocks composed of carbonaceous silicestones and carbonaceous slate in the Cambrian solar crest group, and is controlled by the strata, lithology, lithofacies and tectonics, and the strata Control properties are well recognized. After studying the hydrogen and oxygen isotopic composition of the fluid in each gold deposit (point), the authors conclude that the ore-forming fluid is precipitation in the atmosphere. During the circulation, the underground hydrothermal fluids recharged by the atmospheric precipitation prompted the activation, migration and reaggregation of the ore-forming materials in the formation of the silicic rocks, and eventually led to the formation of industrial deposits. The evolution curves of hydrogen and oxygen isotope exchange in the water-rock system show that the ore-forming fluid has boiled during mineral precipitation.