安徽向山铁硫矿区硬石膏岩热水沉积特征及成因意义

HOT-WATER ORIGINATION OF ANHYDRITES IN THE XIANGSHAN PYRITE ORE DISTRICT,ANHUI PROVICE

安徽向山地区铁、硫矿床中存在大片硬石膏岩 ,其Cu、Pb、Zn、As、Sb等元素含量都比较高 ,Sr元素含量在 0 .0 5 %～ 0 .6 0 %之间 ,且具有稀土总量低 ,铈、铕元素明显亏损等特征。据对其岩石学、岩石化学和硫同位素等特征综合研究表明 :矿床附近的硬石膏岩属热水成因 ,硫可能来源于下伏地层及深部。

Anhydrite beds are found in pyrite ore district,although anhydritification and gypsification develop wider spresd.They generally overlia on the layered sulfides or siliceous rocks,together forming the sulfide silicalite anhydrite associations.Sedimentary structures are abundant,predominated by beddings,such as laminations and bands.In places,sysdepositional fragments of siliceous rocks also exist in anhydrite ores. In conclusion,widely out croping near the Xiangshan pyrite deposit,Anhui,derived from anhydrites and anhydritification induced by hot springs,anhydrite has trace elements similar with those of the pyrite ores and the modern hot spring sediments.The anhydrites show isotopically heavysulfur,with δ 34 S about 17% in average.Studies of petrolog,petrolog chemistry,trace elements,rare earth elements and isotopes give abundent eveidence that the anhydrite rocks should owe its origination to burning mountain hot water deposition,with a source of sulfur materials from the underlying or deep rocks.