HYDROTHERMAL SEDIMENTATION IN GENETIC OF SILICAUTE IN CAMBRAIN TAIYANGDING GROUP IN THE NORTHERN PART OF RUOERGAI SICHUAN
Jiang Qigang(Department of Geology)
Cambrian Taiyangding Group, located in the northern part of Ruoergai in Sichuan province, is an important gold-bearing formation. Various evidences suggest that the Taiyangding group is the sourcebed gold deposits in this araa. Of the consistion rock units of carbonaceous silicalites and carbonaceous in Taiyangding group, the origin of the silicates is a key point in understanding the origin of the gold source bed in this area. Under low-rank metamor-phism, the silicate appears to be massive structure on the outcrops and contains varied amount on carbonaceous materials. Several kinds of sedimentary fabrics, such as laminated structure, rhythmic bedding, spherulitic structure, autobreccia structure, porous structure, colloform structure, are observed in the silicalites. Based on the comprehensive researches of petralogy, chemical composition, trace elements and REE of silicalites, it was concluded that the silicalite is the product of hydrothermal sedimentation in genetic.