碧口岩群硅质岩成因及地质意义

碧口块状硫化物矿床直接赋矿主岩硅质岩地质特征及常量、微量、稀土元素组成表明，碧口岩群硅质岩为同火山岩喷流热水沉积成因。碧口岩群硅质岩常量元素富Fe、贫Si，为典型热水沉积成因；其微量元素、稀土元素特征均与现代大洋热水沉积物相似。热水硅质岩Eu异常与古流体温度存在密切关系，Eu／Eu特征显示筏子坝、铜矿坡为较高温度喷流产物，而大茅坪、黑窝子、铜矿梁、周家坡则为较低温度下的产物。

GENESIS OF THE BIKOU GROUP SILICEOUS ROCKS AND GEOLOGICAL SIGNIFICANCE

Based on the geological characteristics and geochemical implication of major, trace, and rare-earth elements of the Bikou Group siliceous rocks as the host rock of massive sulfide deposits,it is concluded that the siliceous rocks are the product of synvolcanic hydrothermal exhalation. The major element composition is characterized as being rich in Fe and poor in Si, and trace elements and REE are more similar to those of modern ocean floor hydrothermal exhalation-sedimentary siliceous rocks. The relation between Eu anomaly and paleo-hydrothermal system was studied.High positive Eu/Eu. anomalies represent high-temperature exhalation-sedimentary siliceous rocks such as the Faziba and Tongkuangpo siliceous rocks; others are low-temperature equivalents such as the Damaoping, Heiwozi, Zhoujiapo, and Tongkuangliang siliceous rocks.