安徽铜陵包村金矿床地质特征及成因探讨
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摘要
包村矿床是铜陵地区近年新探明的一个矽卡岩型独立金矿。金矿体主要呈脉状、透镜状、不规则状,赋存于包村石英闪长岩体与中下三叠统碳酸盐围岩的接触带及附近围岩的裂隙中,具脉型金矿化特征;金矿石中富含多种铋矿物,且与金矿化关系密切。矿床地质特征和流体包裹体研究表明,成矿流体是一种与燕山期钙碱性岩浆侵入活动有关的NaCl_H2O_CO2体系,当其沿近南北向包村断裂进入相对开放的脆性构造裂隙空间,因压力骤降而造成流体不混溶,导致CO2和NaCl_H2O相分离,从而引起热液体系pH、Eh、fo2等物理化学条件发生明显改变,最终促使金在有利的空间内富集成矿。
Located in northeastern Shizishan orefield, the Baocun deposit is one of the proved independent skarn gold deposits in Tongling area. Its major gold ore bodies are situated at the contact zone between the ore-forming magmatic bodies and the Lower Triassic carbonate rocks. Some small ore bodies, with features of lode gold mineralization, are distributed in fissures of the wall rocks of the ore-forming magmatic bodies. Bismuth minerals are closely coexistent with gold mineralization in the deposit. Fluid inclusions of different metallogenic stages and geological features of the deposit suggest that the ore-forming fluids belong to the NaCl-H-2O-CO-2 system associated with the Yanshanian calc-alkaline magmatism. When the ore-forming fluids moved into the open space along the SN-trending fault belt, th-e drastic falling of pressure might have caused the phase separation of fluid, the prominent change of pH, Eh and fo-2 as well as the gold precipitation in favorable space.
Located in northeastern Shizishan orefield, the Baocun deposit is one of the proved independent skarn gold deposits in Tongling area. Its major gold ore bodies are situated at the contact zone between the ore-forming magmatic bodies and the Lower Triassic carbonate rocks. Some small ore bodies, with features of lode gold mineralization, are distributed in fissures of the wall rocks of the ore-forming magmatic bodies. Bismuth minerals are closely coexistent with gold mineralization in the deposit. Fluid inclusions of different metallogenic stages and geological features of the deposit suggest that the ore-forming fluids belong to the NaCl-H-2O-CO-2 system associated with the Yanshanian calc-alkaline magmatism. When the ore-forming fluids moved into the open space along the SN-trending fault belt, th-e drastic falling of pressure might have caused the phase separation of fluid, the prominent change of pH, Eh and fo-2 as well as the gold precipitation in favorable space.
引文
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Mao Jingwen,Li Yinqing.2001.Fluidinclusions of Dongping goldtel-luride deposit in Hebei province:Involvement of mantle fluid inmetallogenesis.20(1):23~36.
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Wang Keyong,Yao Suzhen,Lu Xinbiao.2001.Phase separation offluids inthe Manaoke gold deposit of Northwestern Sichuan anditsmineralization significance.Acta Geoscientica Sinica,22(1):35~38.
Wang Yanbin,Liu Dunyi,Zeng Pusheng,et al.2004.SHRI MP U_Pbgeochronogy of pyroxene diorite in the Chaoshan gold deposit andits geological significance.Acta Geoscientica Sinica,25(4):423~427(in Chinese with English abstract).
Yu Canghai,Yuan Xiaoming.2002.Geological features and study ongenesis of Tianmashan sulfer_gold deposit.Mineral Resources andGeology,16(2):74~77(in Chinese with English abstract).
Zhang Wenhui,Chen Ziying.1993.Fluid inclusion geology.Wuhan:China University of Geosciences Press,107~156(in Chinese).
НекрасовИЙЯ.1986.The experi mental research onforming conditionof Au_Ag intergrowth compounds.Northeast Geological Scienceand Technology Information,48:17~24(in Chinese).
毛景文,李荫清.2001.河北省东坪碲化物金矿床流体包裹体研究:地幔流体与成矿的关系.矿床地质,20(1):23~36.
唐永成,吴言昌,储国正,等.1998.安徽沿江地区铜金多金属矿床地质.北京:地质出版社,210~280.
俞沧海,袁小明.2002.铜陵天马山硫金矿床地质特征及成因探讨.矿产与地质,16(2):74~77.
王可勇,姚书振,吕新彪.2001.川西北马脑壳金矿床流体相分离及其成矿意义.地球学报,22(1):35~38.
王彦斌,刘敦一,曾普胜,等.2004.安徽铜陵地区幔源岩浆底侵作用的年代—朝山辉石闪长岩锆石SHRI MP定年.地球学报,25(4):423~427.
张文淮,陈紫英.1993.流体包裹体地质学.武汉:中国地质大学出版社,107~156.
НекрасовИЙЯ.1986.银和金金属互化物形成条件的实验研究.东北地质科技情报,(2):17~24.
Bondar BJ.1993.Revised equation andtable for determiningthe freez-ing point depression of H2O_NaCl solutions.Geochemi CosmochemActa,57:683~684.
Hu Huan,Wang Rucheng,Lu Jianjun,et al.2001.Mineral associa-tion,chemical composition and genetic significance of skarn golddeposits in Shizishan ore_field,Tongling area,Anhui province.Mineral deposit,20(1):86~89(in Chinese with English ab-stract).
Huang Huasheng.1994.Advances in skarn deposits.Earth sciencefrontiers.1(34):105~111(in Chinese with Englishabstract).
Mao Jingwen,Li Yinqing.2001.Fluidinclusions of Dongping goldtel-luride deposit in Hebei province:Involvement of mantle fluid inmetallogenesis.20(1):23~36.
Tang Yongcheng,Wu Yanchang,Chu Guozheng,et al.1998.Geologyof copper_gold polymetallic deposits in the along_Changjing area ofAnhui province.Beijing:Geological Publish House,47~68(inChinese with English abstract).
Wang Keyong,Yao Suzhen,Lu Xinbiao.2001.Phase separation offluids inthe Manaoke gold deposit of Northwestern Sichuan anditsmineralization significance.Acta Geoscientica Sinica,22(1):35~38.
Wang Yanbin,Liu Dunyi,Zeng Pusheng,et al.2004.SHRI MP U_Pbgeochronogy of pyroxene diorite in the Chaoshan gold deposit andits geological significance.Acta Geoscientica Sinica,25(4):423~427(in Chinese with English abstract).
Yu Canghai,Yuan Xiaoming.2002.Geological features and study ongenesis of Tianmashan sulfer_gold deposit.Mineral Resources andGeology,16(2):74~77(in Chinese with English abstract).
Zhang Wenhui,Chen Ziying.1993.Fluid inclusion geology.Wuhan:China University of Geosciences Press,107~156(in Chinese).
НекрасовИЙЯ.1986.The experi mental research onforming conditionof Au_Ag intergrowth compounds.Northeast Geological Scienceand Technology Information,48:17~24(in Chinese).
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