SULFUR SOURCES OF THE COPPER-GOLD DEPOSITS IN THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER AVER: AN INVESTIGATION FROM THE YUESHAN OREFIELD

作     者：Zhou Taofa Yue Shucang( Department of Resources and Environmental Science, Hefei University of Technology, Hefei 230009) 

出 版 物：《Scientia Geologica Sinica》 (地质科学(英文版))

年 卷 期：1999年第1期

页      面：31-40页

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

主　　题：SULFUR SOURCES OF THE COPPER-GOLD DEPOSITS IN THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER AVER AN INVESTIGATION FROM THE YUESHAN OREFIELD 

摘      要：The sulfur sources of the copper-gold deposits in the middle and lower reaches of the Yangtze River area are controversial among experts for the characteristic sulfur isotope compositions of these deposits. The Yueshan orefield is taken for example in this paper to elucidate this subject. The δ34S values of the sham-type and the vein-type ores in the Yueshan orefield are -11.25-+19.74‰ and +4.2-+8.7‰, respectively. The disequilibria of the sulfur isotope in deposits indicate that the δ34SH2S in the ore-forming fluids were varied, which were caused not by the change of physicochemical conditions but rather by the sulfur isotope compositional variations of the sources and the water-rock interaction. Possible sulfur transformation mechanisms from source into the hydrothermal solutions are discussed, and the results suggest that the sulfur in the sham-type ore deposits was derived from magmas （78%）, pre-Triassic clastic sedimentary rocks, and the Triassic gypsum （salt）-beds hosted in carbonate strata, whereas the sulfur in the vein-type ores came from magmas （79-97%） and gypsum （salt）-beds hosted in carbonate strata. The mixing was caused by water-rock interaction. So the sulfur isotope composition of a copper-gold deposit depended on the evolutional history of the ore-forming hydrothermal fluids, the sulfur may be multi sources, but to most of the copper-gold deposits in the middle and lower reaches of the Yangtze River area, the Triassic gypsum （salt）-beds hosted in carbonate strata may be a more important sulfur source than elastic sedimentary beds in addition to the magmatic （or intrusive） ones, which to some extent is also proved by the close relationships between the marine Triassic evaporate horizon with the deposits in the whole area. The copper-gold deposits are the products of complicated evolution through water-rock interaction between the ore-forming magmatic solution and the sedimentary strata especially the Triassic gypsum（salt）-beds hosted in carbonate st