Lithology And Genesis Of Magnesium-rich Rocks In Boron Deposit Of Eastern Liaoning And Southern Jilin

Boron is a kind of chemical material with wide-range application, mainly Boron is used to produce borax, boric acid and element B. China is the first country to discover and recognize Boron deposits. The most of Boron resources are located in Liaoning, Jilin, Qinghai and Tibet, the present reserves of the former two provinces are over 50% of all country, these deposits were distributed at Dashiqiao, Wenquangou, Gaotaigou and so on, which form a linear metallogenic belt along east to west. The present reserves of the others are about one third of all country. The present reserves in the four country are up to 88.9% of all country, except for these deposits, others are small one, which scattered at Hunan, Guangxi, Jiangsu, Inner Mongolia and Xijiang.In our working area, the host mineral of borate deposits is ludwigite, which is mixed materials that have different sources. Generally, magnesium comes from Mg-rich rocks; iron comes from rocks which formed earlier, they are the host rocks of borate minerals, replaced by later borate solution , and then become into Fe-Mg borate minerals.Host rocks are Mg-rich or Fe-rich rocks, include Mg-rich peridotite, olivine-basalt and Mg-rich marble, the three rocks intergrow or grow up alone, CaO/MgO is 0.04-2.04. The most Mg-rich peridotite situated at Dashiqiao, District Houxianyu, which almost consist of forsterite and peridot. A great many Mg-rich marble come from Zhuanmiao, District Kuandian and Hengludongcha, District Jian. Base on petrology and lithology study, Mg-rich marble could be classified into three kinds: grayish-black argillous marble, grayish-white banded marble and redish-brown massive marble, grayish-black argillous marble and grayish-white banded marble are related with the mineralization. While the mineralized rock of ludwigite in Wengquangou and Gaotaigou is olivine-basalt, there are also olivine-basalts in Errengou, District Kuandian. Mg-rich marble and Mg-peridotite in the boron deposit of eastern Liaoning and Southern Jilin have close intergrowth in space. They enclosed each other with lenticular and layer-like occurrence; these rocks with high Mg both can be the precipitator of boron deposit, obviously, Mg-rich peridotite have appeared characteristics of igneous genesis; they have similar REE distribution, by which they formed in continental theleiite setting; the isotope C-O of Mg-rich marble have appeared characteristics of igneous genesis. Mg-rich carbonatite and Mg-rich peridotite have provided mineralizing layer for early proterozoic Mg-nonmetal deposits in eastern Liaoning and southern Jilin.