摘要
Nephelinc syenites are widespread in Henan Province, China. They mainly outcropped in the Jiulongshan (JLS) area of Anyang County, Zhifang-Huangzhuang (ZH) area of Songxian County, Songfeu-Shuangshan-Tashan (SST) area of Fangeheng County and Songpa (SP) area of Tongbai County. They formed during the age from the late Proterozoic to Mesozoic. In TAS diagram, they mainly fall into the syenite and foid-bearing syenite areas, and the points projected in Harker and TAS diagrams suggest that compositional variation of nepheline syenite and syenite in Henan Province has no direct relation with crystallization differentiation process. The K2 0 content exhibits an increasing trend from SST to ZH, and a decreasing trend from ZH area to JLS. This may suggest that the lower crust of this area continued to thicken from the late Proterozoie, reaching the maximum in the Indosinian period, and thinning in the Yanshanian epoch. The nonmetallic mineralization related to nepheline syenite in Henan Province produced nepheline,fluorite,potassium feldspar and phosphor, and the metallic mineralization generated Au, Mo, Pb, Cu, Zn, Fe, Nb, Ta, REE and some radioactive elements. It is suggested that nepheline syenite and syenite complex related to nepheline syenite in Henan Province possess an obvious mineralization potential,and they should be viewed as important targets of geological exploration.