(1. 中南大学地球科学与信息物理学院有色金属成矿预测教育部重点实验室，长沙410083；
2. 湖南省地球物理地球化学勘查院，长沙410116)
摘 要: 长城岭铅锌锑多金属矿区位于南岭有色金属成矿带中段，区内发育多组燕山期硅铝质岩墙群及少量镁铁质岩瘤、岩墙。这两类岩浆岩的产出均受区域性北东向断裂带控制，空间分布交织，同属燕山期，但玄武岩形成于燕山早期第一阶段，辉绿玢岩形成于燕山早期第二阶段，花岗斑岩和石英斑岩形成于燕山早期第三阶段，辉长岩可能形成于燕山晚期，因而其研究对探讨南岭地区燕山期岩浆演化、岩石成因及成岩构造环境具有重大意义。通过详细的野外地质调查、岩相学和岩石地球化学综合研究，试图系统分析这两类岩浆岩成因、岩石学及岩石地球化学特征，并探讨其成岩构造环境及动力学背景。研究表明：本区硅铝质岩富硅、铝、钾，为钙碱性，强过铝质，∑REE低，稀土配分模式具四分组效应，属S型岩浆岩、石英斑岩；镁铁质岩富SiO2、贫碱，为钙碱性，过铝质，∑REE偏高，属壳幔混染型岩浆岩。相较而言，从玄武岩到辉绿玢岩再到辉长岩，Mg#值、Zr/Hf值依次增大，玄武岩、辉绿玢岩及辉长岩的稀土配分曲线均为右倾型，以辉绿玢岩曲线更陡，而辉长岩曲线平坦。基于壳体构造理论与两类岩浆岩的岩石学及地球化学特征，研究认为本区岩浆岩是燕山期陆内活化产物。随着燕山期地幔蠕动和热能聚集强度与方式的有规律变化，其动力学环境相应变化，岩浆源区深度、壳幔相互作用程度及物质组成也有规律变化，因而上述岩浆岩无论成因、岩石学或地球化学特征都随燕山期岩浆侵入活动阶段而明显变化。
关键字: 长城岭；硅铝质岩；镁铁质岩；岩石地球化学；构造背景
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
2. Hunan Institute of Geophysical and Geochemical Exploration, Changsha 410116, China）
Abstract:Changchengling Pb-Zn-Sb polymetallic orefield locates in the middle segment of Nanling nonferrous metals metallogenic belt, there occurs groups of Yanshanian granitic dykes and a few scattered mafic bosses and dykes. These two types of magmatic rocks are mainly controlled by the northeast-trending regional fracture zone, and are spatially interweaving. Basaltic, diabasic porphyry and granitic are respectively intruded at the first, second and third stages of early Yanshanian periods and gabbro dykes are the latest intruded magmatic rocks probably in later Yanshanian period, so their petrologic, genetic and geochemical studies are of great significance in understanding of the Yanshanian regional magmatic evolution, petrogenesis, and tectonic settings of Nanling region. On the base of comprehensive studies on fieldinvestigation, petrography and rock geochemistry, the petrologic, geochemical and genetic characteristics, tectonic and geodynamic settings of these two types of magmatic rocks were discussed systematically. The results show that granitic rocks here with high Si, Al, K and low REE are calc-alkaline and strongly peraluminous, their REE pattern has obvious tetrad effect, therefore they belong to the S-type; the mafic rocks with high SiO2, REE and low alkali are calc-alkaline and peraluminous, thus they derive from the mixed crust-mantle. As for basalt, diabase porphyry and gabbro, their Mg# value and w(Zr)/w(Hf) value increase orderly, the REE partition curves are all right-inclined, but diabase is steeper and gabbro goes flate. According to the theory of Crustobody geotectonics and the petrologic characteristics, these two types of magmatic rocks are the products of Yanshanian continental mobilization. With the regular change of intensity and mode of mantle creep-flow and heat energy convergence in Yanshanian period, the geodynamic setting and crust-mantle interaction extent transform correspondingly, the depth and compositions of the magma source region change accordingly, so the genetic, petrologic and geochemical characteristics of these magmatic rocks are all varied obviously with the magmatic intrusion stages of Yanshanian.
Key words: Changchengling; granitic rock; mafic rock; geochemistry; tectonic setting
