晋宁一六街九道湾花岗岩体地质特征及时代

九道湾花岗岩体为复式岩体,由大小6个侵入体组成。按形成的先后顺序可划分为三个单元,三者均由“S”型花岗岩组成。从早期至晚期,三者岩石成分从较基性向较酸性变化,岩石结构由细粒向粗粒含斑演化,变化的有序性和单向性明显,且在空间上紧密共生,形成时间及成分、结构变化上表现出清楚的亲缘和演化关系,说明它们是同一岩浆热事件的产物,故将其归并为一超单元,称之为九道湾超单元。罗台旧单元罗台旧岩体花岗岩Rb-Sr年龄值为730Ma,应为晋宁晚期产物。

THE GEOLOGICAL CHARACTERISTICS AND AGE OF JIUDAOWAN GRANITE OF LIUJIE, JINNING

The Jiudaowan Granite is a composite rock body,formed by 6 intrusion bodies. According to the succession of formation, it can be divided into 3 units of Daheishan, Jiudaowan and Luotaijiu, which are all composed of "S" type granite. From the early to the later, the lithological composition of them changes from basic to acid and from fine grained to coarse grained bearing phenocryst in rock texture. The order and monodirectional characteristics of the changes are evident and paragenetic close in space, which show clear affiliation and evolution relationship in formation time and changes of composition and texture and indicate that they are formed by the same magmatic thermal event. Therefore, they are merged into an ultra-unit and called Jiudaowan Ultra-Unit. According to the whole rock Rb-Sr dating of granite of Luotaijiu rock body in Luotaijiu Unit, the age of it is 730 Ma, which must belong to Late Jinning period.