信阳上天梯一带珍珠岩矿地质特征

Geological Characteristics of Pearlite in Shangtianti Area of Xinyang

信阳上天梯珍珠岩矿赋存于早白垩世陈棚组上部,杨家湾段酸性熔岩内。矿体基本稳定,共有7个,矿体最长1 500m,厚度最大102m,一般长50～800m,厚度10～60m。矿石类型主要有珍珠岩、蒙脱石化(脱玻化)珍珠岩、硅化珍珠岩。品级为I、II、III级,矿物成分主要由玻璃质组成,少量石英、长石、微量迪开石、磁铁矿等。主要化学成分SiO2、Al2O3、Fe2O3、FeO基本稳定,K2O/Na2O比值一般1.58～1.99。矿床成因系酸性岩浆沿构造部位喷发或喷溢至水下或地表,温度速降,急骤冷却而成。上天梯一带的珍珠岩矿床,在我国众多的产地中占有十分重要的地位。

The Shangtianti pearlite ore occurred on Chenpeng formation of early Cretaceous and in the acidic lava of Yangjiawan section. The mineral ores are stable and have seven in total, the maximum length of mineral ore is 1 500m, the maximum thickness is 102m, and the average length of ore is from 50m to 800m, and the general thickness ranges from 10m to 60m. The ore types have mainly pearlite, montmorillonite （devitrification） pearlite and silicated pearlite. The grade are of Grade I, Grade II and Grade III, and the major mineral component consists of hyaline, slight amount of quartz and feldspar, very small amount of dickite and magnetite. The major chemical compositions such as SiO2, A1203, Fe203 and FeO are basically stable, K2O/Na20 ratio is 1.58-1.99 in general. The origin of ore is that the acidic magma erupted along the structural position or erupted under water or surface, and the magma sharply cooled to give rise to the pearlite. Consequently, the Shangtianti pearlite ore plays greatly important role among the many producing area in China.