胶西北中生代花岗岩中黑云母和角闪石成分特征及成岩成矿意义

发布时间：2018-03-01 06:32

  本文关键词： 矿物化学成分 结晶条件 中生代花岗岩 金矿化 胶西北　出处：《岩石学报》2017年10期 　论文类型：期刊论文

【摘要】：在详细的野外地质和岩相学观察基础上,对胶西北中生代玲珑期、郭家岭期和伟德山期花岗岩中的黑云母和角闪石进行了系统的化学成分研究。结果显示,玲珑期,研究区中部和南部花岗岩中的黑云母为铁叶云母和铁质黑云母,其MgO为4.07%~6.53%,具有壳源型黑云母的特征;北部主要为铁质黑云母和镁质黑云母,MgO介于9.13%~11.57%之间,具壳幔混源型的特征;郭家岭期和伟德山期花岗岩中的黑云母以铁质黑云母和镁质黑云母为主,MgO为7.62%~15.38%,均为壳幔混源型,其中的角闪石均属于钙质角闪石,M值为0.44~0.76。暗色矿物成分显示玲珑期花岗岩的源区物质主要为壳源,郭家岭期和伟德山期的以壳源为主,有少量幔源组分参与。三期花岗岩中黑云母结晶温度主要集中于550~700℃,而角闪石的结晶温度为600~750℃,从玲珑期到郭家岭期再到伟德山期,即从早到晚,黑云母的结晶温度有升高的趋势;全铝压力计估算结果显示,黑云母和角闪石的结晶压力具有降低的趋势。郭家岭期和伟德山期花岗岩中黑云母结晶过程中的氧逸度分别为-15.0~-9.0和-15.3~-8.8,明显比玲珑期的(-17.5~-13.2)高。结合胶西北金矿的时空分布特征,认为花岗岩结晶过程中较高的氧逸度和幔源物质的参与可能是有利于金矿化的重要条件之一。
[Abstract]:On the basis of detailed field geological and petrographic observations, the biotite and amphibole in the granites of the Linglong, Guojialing and Weideshan periods in northwestern Jiao were studied systematically. The results show that the Linglong period, The biotite in the granites in the central and southern part of the study area is iron mica and ferric biotite, whose MgO is 4.07 and 6.53, which is characterized by crustal biotite, while in the north is mainly ferric biotite and magnesia biotite with the characteristics of crust-mantle mixing type, between 9.13% and 11.57%. In the Guojialing and Weideshan granites, the biotite mainly consists of ferric biotite and magnesia biotite, and the MgO is 7.62mica 15.38, both of which belong to the crust-mantle mixed source type. Among them, hornblende belongs to calcareous hornblende with M value of 0.440.76.The dark mineral composition shows that the source material of Linglong granite is mainly crust source, and that of Guojialing period and Weideshan period is mainly crust source. The crystallization temperature of biotite is mainly concentrated at 550 ~ 700 鈩，

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