LIU Zhi-chen1,2, WANG Cong2, ZHANG Yuan-guo2, FANG Bo2, CHEN Deng2, WEI Zhe-quan2, CUI Zhong-qiang2
(1. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;
2. The 102 Geological Team, Guizhou Bureau of Exploration and Development of Geology and Mineral Resources, Zunyi 563003, China)
Abstract: Zunyi Mn deposit is one of important sedimentary manganese deposits in the South China. Its natural type of ores is carbonate manganese, with high sulfur, high-low phosphorus and low silicon iron lean manganese. In this paper, on the basis of detailed observations of manganese ore major, trace and rare earth elements and carbon-oxygen isotope composition were analyzed. Results show that Fe/Ti values range from 12.35 to 140.50, with the mean of 59.35 (>20); (Fe+Mn)/Ti values range from 153.88 to 520.5, with the mean of 271.05 (>25); and Al/ (Al+Fe+Mn) values range from 0.05 to 0.20, with the mean of 0.12 (<0.3), suggesting that the manganese ore is closely tied to hydrothermal activity. As for the trace elements, it is noted that the mean U and Th contents are 6.37×10-6 and 2.79×10-6, respectively and average U/Th is 2.52 (>1). Similarly, mean Ni and Co contents are 191.90×10-6 and 93.03×10-6, respectively and the mean Ni/Co value is 2.16 (<3.6), similar to the characteristic of hydrothermal deposits. In addition, total REE contents range from 123.54×10-6 to 424.08×10-6, with most values lower than 200×10-6, belonging to LREE-enriched type with ∑LREE/∑HREE ranging from 2.23 to 119.22 (>1), (La/Yb)N ranging from 4.58 to 18.83, and negative Ce anomaly (0.45 to 0.72), indicating its hydrothermal origin. According to the ore deposit geology and geochemical characteristics of ore deposits, manganese ore and its bottom siliceous rocks are originated from submarine hot water deposition formation, in the process of sedimentary mixed with a small amount of the normal biological chemical deposition, with the roof rock of a hot-water sedimentary origin.
Keywords: major element; trace element; rare earth element; hydrothermal deposition; Zunyi; Mn deposit
ACTA MINERALOGICA SINICA Vol. 35, No. 4, 2015, Page 481-488
