Abstract:

Shuicheng-Ziyun-Nandan deep fault is a well-known belt expanding across two provinces (Guizhou and Guangxi), along both sides distributing a series of diverse deposit types, and the large Devonian barite deposit is an important ore deposit in Zhenning County, Guizhou. The large barite deposit, located in the northwest margin of Shuicheng-Ziyun-Nandan deep fault was studied on the basis of the sedimentation characteristics, geochemistry and metallogenic background. The results revealed coexistence of a variety of hydrothermal water sedimentary structures characteristics such as laminar structures, barite-banded structure, brecciated structure, barite-fragmental structure, massive structure, and so on. Macroelement study indicated that the  deposit was formed probably by synsedimentation of SiO₂ and ore-bearing sulfate fluid. Besides, geochemistry of the large barite deposits of the Devonian shows the enrichment of Sr, Zn and W, strongly suggesting that the barite deposits is hydrothermal sedimentation in origin. The diagrams of lgU-lgTh and Cr-Zr in the barite deposit also present the features of hydrothermal sedimentation. According to the REE distribution pattern, LREE were enriched and Eu was positive while Ce was negative, which also shows a hydrothermal feature. As a result, we believed that the large barite deposits located in Zhenning formed by hydrothermal exhalative mineralization.

Key words: hydrothermal exhalation, geochemistry, barite deposit, Devonian, Guizhou Province