The sources of ore-forming materials for the Dachang tin polymetallic ore field,Guangxi,China
The Dachang tin polymetallic orefield in Guangxi Zhuang Autonomous Region is currently one of the largest production base of tin and polymetals in the world.In order to decipher the source of ore-forming materials of the Tongkeng-Changpo and Gaofeng deposits in the Dachang orefield,S isotopes and major and trace elements of sulfides of main mineralization stages from those deposits have been analyzed in this study.The results show that the a34S values of sulfides in the Tongkeng-Changpo deposit range from-9.2‰ to 0.6‰(an average of-3.3‰),with a typical normal distribution varying mainly from-4‰ to-1 ‰,indicating that S in this deposit was sourced from the mixing of magmatic and stratigraphic sulfurs.The 834S values of sulfides of the Gaofeng deposit range from 4.2‰ to 12.1‰(an average of 9.7‰),mainly vary from 10‰ to 12‰.These values are different from those of sulfate samples in hosting strata.As the sulfur isotope fractionation caused by the thermochemical sulfate reduction is limited,we proposed that the sulfur in the Gaofeng deposit was mainly sourced from the mixing of sulfur from the reduction of seawater sulfate and magmatic sulfur.In addition,Zn/Cd ratios of spahlerites from the Tongkeng-Changpo and Gaofeng deposits are very similar,and they are partially overlapped with those of the Dachang granite and regional strata,indicating that the ore-forming materials for sulfides of the Tongkeng-Changpo and Gaofeng deposits were mainly derived from the Devonian strata and magma of the Dachang granite.
Dachang ore fieldsulfur isotopetrace elementssources of the ore-forming materials
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