山西省繁峙县后峪铜钼金矿锆石形态标型特征

Crystal Form Typomorphic Characteristics of Zircon from Houyu Cu-Mo-Au Deposit in Shanxi Province, China

为探讨后峪地区锆石的生长条件及其与该地区岩浆岩的成因和演化的关系,对本区不同岩体中的锆石形态标型进行了系统的研究。结果表明：不同岩体中锆石的长宽比大多集中在1.5∶1-3∶1之间,按Pupin锆石晶体类型分类,岩体中的锆石可划分为R2、P1-5、S2-5、S7-10、S12-15和S20等类型,说明锆石是在碱质岩浆中结晶,且结晶温度较低;岩体的液相线的温度为850-750℃,锆石大规模结晶温度为700-650℃。锆石的结晶作用从岩浆早期开始一直持续到岩浆后期,温度跨度大,持续时间长,说明岩浆为富水岩浆,有利于斑岩型矿床Cu-Mo-Au的矿化。本区岩浆岩的化学成分分析及不同岩体中锆石群类型的演化趋势图表明：本区岩浆除了壳源成因之外还有幔源成分加入其中,岩浆岩属于钙碱性系列（偏碱性）岩石。

In order to discuss the growth condition for zircon and its relationship with the formation and evolution of magmatic rocks from the region, morphology of zircon was studied. Results show that in different lithological rocks, ratio of zircon＇s length and width is mostly between 1.5∶1 and 3∶1, meaning that the magma is alkaline. Zircons can be divided into R2, S2-5, P1-5, S7-10, S12-15 and so on according to Pupin＇s classification of zircon crystals. It shows that the zircons are crystallized in the alkaline magma and the temperature is lower. The liquid＇s temperature of the rocks is between 800 and 750 ℃. The massive crystallization temperature of the zircon is from 700 to 650 ℃. The temperature span of crystallization is large for continuous time. The magma is water-rich and this result is conducive to mineralization of porphyry Cu-Mo-Au deposit.The chemical composition analysis of magmatic rocks and the evolution trend of the zircons in different rocks in this area show that,in addition to crust materials,the mantle compositions are also entered in the magma.the magma belong to calcium and alkali rock series（toward alkaline）.