The Mineralogy And Geochemistry Of K, Na-bearing Rocks Of Boron Deposit In Houxianyu, Liaoning Province

A proterozoic sequence of metasediments in liaoning province, northeast China, plays host to the largest number of borate deposits that are interpreted as forming in the precambian evaporation basin, and during the latter regional metamorphism. This paper has been financed by National Nature Science Foundation of China (serial number: 40373023) .The fieldwork, mineralogy and geochemistry study on the Mg-rich meta-carbonates and tourmaline-bearing leptynites which are also called tourmaline-potassium feldspar-albite -bearing fine grained gneisses indicate that there is an enrichment of potassium near the ore body, and a minus correlation coefficient between potassium and natrium in this area. The tourmaline-bearing rock layers only appear near the ore body. All the tourmalines in the formation are Mg- tourmalines—Fe- tourmalines. Brown tourmalines contain more FeO , and cyan tourmalines contain more MgO. The FeO/(MgO+FeO) value of tourmaline-bearing leptynites , tourmalinites, tourmalines-tremolite-bearing rocks and tourmalines- biotite-bearing rocks are 0.47, 0.58, 0.42, 0.38 separately, and the value of Na2O/(Na2O+CaO) of the rocks are 0.48, 0.54, 0.56, 0.44 separately. The ring-belts appear in some of the tourmalines. Tourmalines-tremolite- biotite-bearing rocks have a concentrate of MgO in the center, and every ring-belts of the tourmalines in the tourmaline rocks contain high FeO value, especially in the center. PIMA(Portable Infrared Mineral Analyzer) data indicate that there are lots of minerals which contain Mg, K, B in the formation. The original rocks in the basin are not normal volcanic rocks or volcanic clastic rocks. The initial environment where the alteration happened is evaporation basin. All the original rocks have been changed in the basin by the evaporation alteration.