摘要
广西大厂锡矿田泥盆纪地层中存在着蚀变火山岩。本文阐述了蚀变火山岩的赋存层位、显微镜下的岩石特征和斜长石斑晶的成分等。指出蚀变火山岩是属于深水相的、海底喷发的,具强烈蚀变的微层状的熔岩、凝灰岩、凝灰质碳酸盐岩和凝灰质硅质岩。它们与硅质岩和酸盐岩相间成层。蚀变火山岩的存在,对阐明大厂锡石硫化物矿床的沉积-火山沉积、花岗岩热液叠加的成因特征有着重要的地质意义。
The Dachang cassiterite-polymetallic ore deposit is famous in the world for its large reserves, high grade and the presence of various metals and abundant sulfosalts. The main ore-bearing horizons in the Dachang ore field occur in the Devonian sequence composed of marine carbonate rocks, silliceous rocks, and finegrained clastic rocks. The authors have recently studied marine altered volcanic rock in the lower and the middle part of the Upper Devonian. The main features of the altered volcanic rocks are as follows:1. The altered volcanic rocks are composed of lava, tuff, tuffaceous carbonate rocks, and tuffaceous silhceous rocks. They occurs as microbeds alteranated with carbonate rocks and silliceous rocks, showing some evident sedimentary structures, such as stratification and sedimentary rhythm.2. The lava shows porphyritic texture. The poenocrysts are plagioclase, which is close to anorthite in composition based on tile determination by the energydispersive X-ray spectroscopy. The original rocks might belong to intermediate volcanic rocks.3. The altered volcanic rocks have undergone intense carbonatization, sericitization and biotitization. It is difficult to restore their original composition.
出处
《地质论评》
CAS
CSCD
北大核心
1989年第3期249-253,共5页
Geological Review
