摘要
钴作为关键战略性稀贵金属,主要以共伴生形式产于多类矿床中。其中,富钴矽卡岩型铁矿床是重要的具备开发潜力的矿床类型之一,但其钴的来源和富集机制不清。朱冲富钴矽卡岩型铁矿床位于长江中下游成矿带安庆-贵池矿集区,是成矿带内新近发现的首个大型矽卡岩型富铁矿床,其伴生的钴资源量达到了中等规模。同时,朱冲富钴矽卡岩型铁矿床中钴品位在长江中下游同类矿床中最高,达190g/t。本研究对朱冲富钴矽卡岩型铁矿床开展了成矿岩体锆石的U-Pb定年和矿床垂向(钻孔剖面)上黄铁矿原位硫同位素的空间变化分析。结果表明,两个深部隐伏的岩浆岩样品的锆石U-Pb年龄分别为139.6±1.0Ma和138.9±0.6Ma,为早白垩世。垂向上,黄铁矿硫同位素总体范围为+5.3‰~+13.9‰,δ^(34)S自上而下变化极大,且呈现较强的不均一性,明显不同于安庆铁铜矿的硫同位素组成。朱冲富钴矽卡岩铁矿自下而上矿化-蚀变分带中富钴磁铁矿矿体中黄铁矿δ^(34)S范围为5.3‰~10.0‰;近矿透辉石矽卡岩带中脉状黄铁矿δ^(34)S范围为12.1‰~13.9‰;蚀变闪长岩中脉状黄铁矿δ^(34) S范围为7.1‰~10.8‰;外带矽卡岩中脉状黄铁矿δ^(34)S范围为6.8‰~7.6‰;月山组含膏盐粉砂岩中黄铁矿δ^(34)S范围为12.0‰~12.7‰;最上部铜头尖组粉砂岩脉状黄铁矿δ^(34)S范围为6.1‰~7.8‰。朱冲富钴磁铁矿矿石中黄铁矿硫同位素介于月山岩体和月山组含膏盐粉砂岩硫同位素之间,矿石中硫同位素记录了两个端元的混合。长江中下游富钴矽卡岩型矿床(铁铜钴)成矿规模及品位的统计表明,钴矿化与铁铜矿床类型没有明显的对应关系,成矿热液中膏盐层硫的加入对钴矿化没有明显的影响,富钴矽卡岩型铁矿床钴主要源于岩浆热液,钴的沉淀主要受控于高温热液的演化。
Cobalt,being a vital strategic rare and precious metal,is primarily produced within diverse deposit types through co-association.The cobalt-rich skarn iron deposit is a key deposit type with considerable development potential.However,the source and enrichment mechanism of cobalt in skarn iron deposit remain unclear.The Zhuchong cobalt-rich skarn iron deposit is located in the Anqing-Guichi district of the Middle-Lower Yangtze River Valley Metallogenic Belt(MLYB).It is the first large-scale skarn iron-rich deposit discovered in the metallogenic belt in recent years.Its associated cobalt resources have reached a medium scale.Meanwhile,the cobalt grade in the Zhuchong cobalt-rich skarn iron deposit is the highest among similar deposits in the MLYB,reaching 190g/t.In this study,the zircon U-Pb dating of the ore-forming intrusions and the spatial variation of pyrite in-situ sulfur isotopes in the vertical direction(drilling section)of the Zhuchong cobalt-rich skarn iron deposit were carried out.The results indicate that the U-Pb ages of the two deep concealed magmatic rock samples are 139.6±1.0Ma and 138.9±0.6Ma,respectively,which occurred during the Early Cretaceous.Vertically,the overall range of pyrite sulfur isotope is +5.3‰~+13.9‰,and δ^(34)S varies greatly from top to bottom,and shows strong heterogeneity,which is obviously different from the sulfur isotope compositions of Anqing skarn Cu-Fe deposit.The pyrite δ^(34)S in the cobalt-rich magnetite ore body in the bottom-up mineralization-alteration zone of the Zhuchong deposit ranges from 5.3‰ to 10.0‰.In the diopside skarn belt near the ore,the δ^(34)S range of the vein pyrite spans from 12.1‰ to 13.9‰.Within the altered diorite,the δ^(34)S values of vein pyrite vary from 7.1‰ to 10.8‰.In the outer skarn,the δ^(34)S range of vein pyrite ranges fall between 6.8‰ and 7.6‰.Within the siltstone of the Yueshan Formation,located in the gypsum-bearing salt layer,the δ^(34)S values of pyrite range from 12.0‰ to 12.7‰.Similarly,the uppermo
作者
梁贤
汪方跃
周涛发
魏长帅
张龙
国显正
张昆
LIANG Xian;WANG FangYue;ZHOU TaoFa;WEI ChangShuai;ZHANG Long;GUO XianZheng;ZHANG Kun(Ore Deposit and Exploration Centre(ODEC),School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China;Anhui Province Engineering Research Center for Mineral Resources and Mine Environments,Hefei 230009,China;No.326 Geological Party,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Anqing 246003,China;Chinese Academy of Geological Sciences,Beijing 100037,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第10期3015-3030,共16页
Acta Petrologica Sinica
基金
国家自然科学基金项目(91962218、42273065)
国家重点研发计划项目(2022YFC2903503)联合资助.
