桂东大瑶山成矿带新坪矿区花岗斑岩与金多金属成矿作用关系
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摘要
新坪花岗斑岩位于桂东大瑶山成矿带中部新坪金矿区内。在野外地质观察的基础上,报道了在该新坪斑岩体接触带附近发现金矿体并首次在岩体内部发现石英脉型辉钼矿(化)体,认为新坪花岗斑岩体与金多金属矿化关系密切。新坪花岗斑岩LA-ICP-MS锆石U-Pb同位素定年结果表明,该斑岩体形成于早古生代奥陶纪(462.9±6.4)Ma,属加里东期花岗岩类,因此与岩体有关的金矿化、铜钼矿化时间不会早于奥陶纪。岩体稀土元素分析结果显示,新坪花岗斑岩与邻近的古袍、圆珠顶、大黎矿区花岗斑岩体具有相似的稀土元素分布特征,可能为同源岩浆不同阶段的演化产物,说明新坪花岗斑岩体具有一定的金、钼等多金属成矿潜力。通过以上综合研究分析,初步认为新坪矿区具有寻找斑岩型金矿以及钼矿床的找矿前景。
The Xinping granite-porphyry occurring in the Xinping gold mining area is located in the middle part of the Dayaoshan Au metallogenic belt,eastern Guangxi Province.During our recent field geological survey,a gold deposit was found in contact zone between the porphyry and its wall rocks,whereas quartz-vein-typed molybdenum orebody and mineralized spot were also firstly recognized inside of the intrusion.These suggest that the Au-Mo-polymetallic mineralization is closely related to the granitic igneous activity.Zircons of the granitic porphyry are analyzed using LA-ICP-MS U-Pb isotopic method,which gives a weighted mean 206Pb/238U age of(462.9 ± 6.4) Ma.It reveals a mid-Ordovican magmatic timing,providing a lower constraint for the mineralization age.The Xinping porphyry samples show REE characteristics akin to those of the granite-porphyries occurring in nearby Gupao,Yuanzhuding and Dali minging areas,indicative of similar nature of source rocks and petrogenesis.Thus,a further potential is predicted by this study in exploring porphyry-related gold and molybdenum deposits in the Xinping gold field.
The Xinping granite-porphyry occurring in the Xinping gold mining area is located in the middle part of the Dayaoshan Au metallogenic belt,eastern Guangxi Province.During our recent field geological survey,a gold deposit was found in contact zone between the porphyry and its wall rocks,whereas quartz-vein-typed molybdenum orebody and mineralized spot were also firstly recognized inside of the intrusion.These suggest that the Au-Mo-polymetallic mineralization is closely related to the granitic igneous activity.Zircons of the granitic porphyry are analyzed using LA-ICP-MS U-Pb isotopic method,which gives a weighted mean 206Pb/238U age of(462.9 ± 6.4) Ma.It reveals a mid-Ordovican magmatic timing,providing a lower constraint for the mineralization age.The Xinping porphyry samples show REE characteristics akin to those of the granite-porphyries occurring in nearby Gupao,Yuanzhuding and Dali minging areas,indicative of similar nature of source rocks and petrogenesis.Thus,a further potential is predicted by this study in exploring porphyry-related gold and molybdenum deposits in the Xinping gold field.
引文
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[19]刘英俊.华南花岗岩类中微量元素的地球化学[M]//徐克勤.花岗岩地质和成矿关系.南京:江苏科学技术出版社,1985:511-525.
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[23]骆靖中,麦范金.广西古袍金矿床的成因矿物学研究[J].桂林冶金地质学院学报,1988,8(2):125-132.
[24]曾崇义.桂东大瑶山隆起区深部构造特征与金矿成矿作用的关系[J].桂林工学院学报,1996,16(3):245-250.
[25]刘腾飞.桂东金矿的铅同位素组成特征[J].矿产与地质,1993,33(7):60-64.
[26]伍磊,张凤.广西平南县六岑金矿黄铁矿标型特征研究[J].南方国土资源,2005(4):20-22.
[27]胡楚雁,叶乃青,曾崇义.桂东金矿带金矿化类型的划分及其找矿意义[J].桂林工学院学报,1996,16(3):283-285.
[28]崔彬,翟裕生,蒙义峰,等.广西大瑶山—西大明山金银成矿系统研究[J].地球科学:中国地质大学学报,2000,25(4):352-355.
[29]Chen J F,Jahn B M.Crustal evolution of southeastern China:Nd and Sr isotopic evidence[J].Tectonophysics,1998,284:101-133.
[30]Hong D W,Xie X L,Zhang J S.Isotope geochemistry of grani-toids in South China and their metallogeny[J].Resource Geolo-gy,1998,48:251-264.
[31]陈培荣,华仁民,章邦桐,等.南岭燕山早期后造山花岗岩类:岩石学制约和地球动力学背景[J].中国科学:D辑,2002,32:279-289.
[2]蔡明海,彭松柏,孟祥金,等.桂东—粤西地区中生代成矿规律及动力学机制探讨[J].华南地质与矿产,2001(2):35-42.
[3]盛志华.大瑶山成矿带金矿成矿规律[J].地质找矿论丛,2005,20(增刊):61-63.
[4]朱桂田,徐文忻,李蘅,等.广西古袍金矿矿区花岗斑岩侵入期后多期热液成矿作用的Ar-Ar年龄证据[J].地球学报,2005,26(增刊):156-159.
[5]朱金初,张佩华,谢才富,等.南岭西段花山—姑婆山A型花岗质杂岩带:岩石学、地球化学和岩石成因[J].地质学报,2006,80(4):529-540.
[6]傅良刚.桂东大瑶山地区金矿成矿地质特征与找矿标志[J].矿物学报,2009(增刊):115-118.
[7]叶荣,王勇,马丽红,等.广西贵港六梅金矿地球化学研究[J].现代地质,2012,26(5):1058-1064.
[8]李青,段瑞春,凌文黎,等.桂东早古生代地层碎屑岩锆石U-Pb同位素年代学及其对华夏陆块加里东期构造事件性质的约束[J].地球科学:中国地质大学学报,2009,34(1):189-199.
[9]汪劲草,胡云沪,叶琳.桂东大瑶山地区金矿床的成矿构造类型及其成矿指示意义[J].桂林理工大学学报,2010,30(4):467-472.
[10]蒙勇,文件生,吕宇明,等.广西贵港银山岭铅锌矿土壤地球化学找矿研究[J].现代地质,2011,25(5):1013-1020.
[11]朱桂田.广西龙头山金矿床地质特征及成因研究[J].矿产与地质,2002,16(5):266-272.
[12]陈富文,李华芹,梅玉萍.广西龙头山斑岩型金矿成岩成矿锆石SHRIMP U-Pb年代学研究[J].地质学报,2008,82(7):921-925.
[13]段瑞春,凌文黎,李青,等.华南燕山晚期构造-岩浆事件与成矿作用:来自广西大瑶山龙头山金矿床的地球化学约束[J].地质学报,2011,85(10):1644-1656.
[14]钟立峰,夏斌,刘立文,等.粤西—桂东成矿带园珠顶铜钼矿床成矿年代学及地质意义[J].矿床地质,2010,29(3):395-401.
[15]林秀广,顾锡明,王艳党.广东封开园珠顶铜钼矿地质特征及成因探讨[J].西部探矿工程,2011(9):208-211.
[16]刘国庆,蔡明海.桂东大瑶山地区金矿成矿条件及成因分析[J].地质科技情报,2004,23(2):37-43.
[17]Yuan H L,Gao S,Liu X M,et al.Accurate U-Pb age and traceelement determinations of zircon by LASER ablation-inductivelycoupled plasma-mass spectrometry[J].Geostandards Newsletter,2004,28:353-370.
[18]吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004,49(16):1589-1602.
[19]刘英俊.华南花岗岩类中微量元素的地球化学[M]//徐克勤.花岗岩地质和成矿关系.南京:江苏科学技术出版社,1985:511-525.
[20]徐克勤,孙鼐,王德滋,等.华南花岗岩成因与成矿[M]//徐克勤.花岗岩地质和成矿关系.南京:江苏科学技术出版社,1985:1-20.
[21]陈开礼.广西金矿地质[M].南宁:广西科学技术出版社,2002:1-357.
[22]黄惠民,和志军,崔彬.广西大瑶山地区花岗岩成矿系列[J].地质与勘探,2003,39(4):12-16.
[23]骆靖中,麦范金.广西古袍金矿床的成因矿物学研究[J].桂林冶金地质学院学报,1988,8(2):125-132.
[24]曾崇义.桂东大瑶山隆起区深部构造特征与金矿成矿作用的关系[J].桂林工学院学报,1996,16(3):245-250.
[25]刘腾飞.桂东金矿的铅同位素组成特征[J].矿产与地质,1993,33(7):60-64.
[26]伍磊,张凤.广西平南县六岑金矿黄铁矿标型特征研究[J].南方国土资源,2005(4):20-22.
[27]胡楚雁,叶乃青,曾崇义.桂东金矿带金矿化类型的划分及其找矿意义[J].桂林工学院学报,1996,16(3):283-285.
[28]崔彬,翟裕生,蒙义峰,等.广西大瑶山—西大明山金银成矿系统研究[J].地球科学:中国地质大学学报,2000,25(4):352-355.
[29]Chen J F,Jahn B M.Crustal evolution of southeastern China:Nd and Sr isotopic evidence[J].Tectonophysics,1998,284:101-133.
[30]Hong D W,Xie X L,Zhang J S.Isotope geochemistry of grani-toids in South China and their metallogeny[J].Resource Geolo-gy,1998,48:251-264.
[31]陈培荣,华仁民,章邦桐,等.南岭燕山早期后造山花岗岩类:岩石学制约和地球动力学背景[J].中国科学:D辑,2002,32:279-289.