河南省霞石正长岩地质特征及其成矿作用

摘 要] 河南省霞石正长岩分布比较广泛,主要出露于安阳九龙山、嵩县纸房-黄庄、方城宋坟-双山-塔山和桐柏松扒等地,形成时代介于晚元古代(晋宁期) 至中生代(燕山期) 之间。TAS 图解表明其主要岩石类型为正长岩和副长石正长岩,主量元素成分特征揭示其成分变异与结晶分异作用无明显关系。自宋坟-双山-塔山向北,由纸房-黄庄至九龙山,K2 O 含量先增大后减小,表明其下地壳厚度持续增生,在印支期达到最大值,于燕山期发生减薄。河南省霞石正长岩的成矿作用十分显著,非金属成矿作用主要为霞石、萤石、钾长石及磷矿,金属成矿作用主要为Au、Mo、Cu、Pb、Zn、Fe、Nb、Ta、REE 及放射性元素。河南省霞石正长岩及其相关正长杂岩体具有较大的成矿潜力,应作为进一步地质找矿的主要目标之一。

Geological Features and Mineralization of the Nepheline Syenite in Henan Province

Abstract:Nepheline 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,Songfen-Shuangshan-Tashan (SST) area of Fangcheng 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 O 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 Proterozoic,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 beviewed as important targets of geological exploration.