摘要
胶东西北部是我国最主要的金矿集中区,金矿的同源岩为滦家河花岗岩,属中深侵入体。根据它富含磁铁矿及副矿物组合,高铁低镁的黑云母,岩石化学成分,锶、氧、硫同位素组成,认为属磁铁矿花岗岩,相当于Ⅰ型花岗岩。用K、Rb、Sr、岩石化学成分,稀土元素和硫同位素判别,确认其为壳源(相当于胶东群变质岩的成分)重熔型。我国脉状金矿的容矿围岩时代老,成矿时代新,空间受构造—岩浆带制约,成矿过程脉岩活动频繁,对其原因,本文提出了一种解释。
The northwest part of the Jiaodong Peninsula is one of the most important gold metallogenic provinces in China. The congenetic intrusion of the gold deposits is Luanjiahe granite, which is moderate-deep one (Fig. 1) .The granite is believed to be magnetite series, corresponding to I-type granite based on the following characteristics: high content of magnetite and similar accessory mineral assemblage, biotite with high content of iron and low magnesiam (Fig.5), I-type composition of main oxides(Fig.6)and isotopes of Sr,O,S.The evolution of K,Rb,Sr, correlation of the main oxides, inheritance of rare earth elements,and sulphur isotopes also prove that the Luanjiahe granite is magnetite one of lower crust origin, which source rocks corresponds to Jiaodorg Group metamorphic rocks of a U-Pb isochronous age of 2.6 Ga.The main magmatic hydrothcrmal gold lodes are usually located in old metamorphic rocks (mainly in Archean), while the age of mineralization is much younger (mainly in Mesozoic) .They are spacially controlled by structural-magmatic belts. The frequent intrusion of dykes occurred during the mineralization process. These characteristics can be interpreted by the hypothesis proposed here that gold deposits are congenetic with remelted magnetite-series granite of lower-crust origin.
基金
科学基金
关键词
磁铁矿
花岗岩
金矿
重熔型
壳源
lower crust origin, remelted magnetite granite, gold lodes, north-west Jiaodong Peninsula
