Abstract:

Heqing manganese deposit in Yunnan is located in the southwestern margin of the Yangtze platform, adjoining the Sanjiang geosyncline in the west. The deposit formed in the transition zone of the two tectonic units. Ore minerals are mainly psilomelane, rhodochrosite, manganite and hausmannite, containing a small amount of pyrolusite and nsutite. There is metal mineral zonation in space：minerals from No.17 exploration line to the west are mainly psilomelane and pyrolusite, from No.10 to No.15 exploration lines are mainly manganite and rhodochrosite, and from No.7 to No.10 exploration lines are mainly hausmannite and rhodochrosite. The δ¹³C values of the limestone samples range from -3.0‰ to 2.9‰ with a mean value of 0.6‰ and the δ¹⁸O varies between -9.9‰ and -5.5‰, averaging at -7.7‰; the δ¹³C values of the ore samples range from -46.3‰ to -9.8‰ with a mean value of -24.2‰ and the δ¹⁸O values vary from -16.5‰ to -3.1‰, averaging at -8.6‰. Comprehensive studies support that Heqing manganese deposit formed in a restricted shallow water environment. Ore minerals deposited in media property zone (from acid to alkaline and from reduction to oxidation), and isotope studies support that the biogenic methane might participate in mineralization.

Key words: manganese deposit, sedimentary environment, isotope, Heqing, Yunnan