云南澜沧老厂花岗斑岩形成年龄及地质意义
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摘要
应用锆石SHRIMPU-Pb法和辉钼矿Re-Os同位素测年法对斑岩的形成时代进行精确定年。结果表明:成矿花岗斑岩体的形成年龄为44.6±1.1Ma;辉钼矿Re-Os等时线年龄为43.78±0.78Ma;成岩成矿期与滇西新生代岩浆-成矿作用高峰期吻合。结合区域地质条件和岩浆的可能源岩年龄(126.7±3.5Ma~529.3±13Ma)等资料分析,提出花岗斑岩在成因上与印支地块与滇缅泰地块陆内俯冲碰撞引发的地幔上涌及地壳重熔作用有关,岩浆来源具壳-幔混合特征。研究还证实滇西地区喜山期存在与隐伏花岗斑岩有关的大规模成矿作用。
The Laochang polymetallic deposit,situated in the south part of the late Palaeozoic Changning-Menglian continental rift belt in western Yunnan,is one of the areas with significant breakthrough for a new discovery of great thick porphyry molybdenum ore bodies in the depths since 2008.This paper provides precise rock-forming ages of the granite-porphyry by the SHRIMP zircon U-Pb and molybdenite Re-Os dating methods.The results show that the forming age of the granite-porphyry is 44.6±1.1Ma,and the Re-Os isochron age of molybdenites 43.78±0.78Ma.The rock-and ore-forming ages are in consistent with the peak phase of Cenozoic magmatism-mineralization of western Yunnan.For this reason,combining dating with regional geological conditions and the ages (126.7±3.5Ma~529.3±13Ma) of possible source rocks of the magma,it is suggested that the genesis of the concealed granite-porphyry may be related to mantle upwelling and crustal anatexis,and its origin exhibits the mixing features coming from crust-derived and mantle-derived magmas caused by intracontinental collision and subduction between the Indo-Chinese block and Yunnan-Burma block.It has also demonstrated that a large-scale Mo(Cu)-mineralization related to Himalayan concealed granite-porphyries exists in western Yunnan.
The Laochang polymetallic deposit,situated in the south part of the late Palaeozoic Changning-Menglian continental rift belt in western Yunnan,is one of the areas with significant breakthrough for a new discovery of great thick porphyry molybdenum ore bodies in the depths since 2008.This paper provides precise rock-forming ages of the granite-porphyry by the SHRIMP zircon U-Pb and molybdenite Re-Os dating methods.The results show that the forming age of the granite-porphyry is 44.6±1.1Ma,and the Re-Os isochron age of molybdenites 43.78±0.78Ma.The rock-and ore-forming ages are in consistent with the peak phase of Cenozoic magmatism-mineralization of western Yunnan.For this reason,combining dating with regional geological conditions and the ages (126.7±3.5Ma~529.3±13Ma) of possible source rocks of the magma,it is suggested that the genesis of the concealed granite-porphyry may be related to mantle upwelling and crustal anatexis,and its origin exhibits the mixing features coming from crust-derived and mantle-derived magmas caused by intracontinental collision and subduction between the Indo-Chinese block and Yunnan-Burma block.It has also demonstrated that a large-scale Mo(Cu)-mineralization related to Himalayan concealed granite-porphyries exists in western Yunnan.
引文
陈新跃,王岳军,范蔚铭,彭头平.2006.云南崇山剪切断裂系显微构造特征及其40Ar-39Ar年代约束.大地构造与成矿学,30(1):41-51.
程锦,夏斌,张玉泉.2008.囊谦盆地新生代高钾岩浆岩的地球化学特征:岩石成因及其构造意义.大地构造与成矿学,32(3):382-391.
侯增谦,潘桂棠,王安建,莫宣学,田世洪,孙晓明.2006a.青藏高原碰撞造山带:Ⅱ.晚碰撞转换成矿作用.矿床地质,25(5):521-543.
侯增谦,杨竹森,徐文艺,莫宣学,丁林.2006b.青藏高原碰撞造山带:Ⅰ.主碰撞造山成矿作用.矿床地质,25(4):337-358.
冷成彪,张兴春,王守旭,秦朝建,苟体忠,王外全.2008.滇西北中旬松诺含矿斑岩的锆石SHRIMP U-Pb年龄及地质意义.大地构造与成矿学,32(1):124-130.
李虎杰,田煦,易发成.1995.云南澜沧老厂铅锌银铜矿床稳定同位素地球化学研究.有色金属矿产与勘查,4(5):278-282.
李雷,段嘉瑞,李峰.1996.澜沧老厂铜多金属矿床地质特征及多期同位成矿.云南地质,15(3):246-256.
龙汉生,蒋绍平,石增龙,黄智龙,罗泰义.2007.云南澜沧老厂大型银铅锌多金属矿床地质地球化学特征.矿物学报,27(3-4):360-365.
毛景文,张作衡,张招崇,杨建民,王志良,杜安道.1999.北祁连山小柳沟钨矿床中辉钼矿Re-Os年龄测定及其意义.地质论评,45(4):412-417.
欧阳成甫,徐楚明,胡承绮,郎跃秀.1993.云南澜沧老厂银铅矿区隐伏花岗岩体预测及其意义.大地构造与成矿学,17(2):119-126.
潘桂棠,徐强,侯增谦.2003.西南“三江”多岛弧造山过程成矿系统与资源评价.北京:地质出版社.
曲文俊,杜安道.2003.高温密闭溶样电感耦合等离子体质谱准确测定辉钼矿铼-锇地质年龄.岩矿测试,22(4):254-257.
王登红,应汉龙,梁华英,黄智龙,骆耀南.2006.西南三江地区大陆动力学过程与大规模成矿.北京:地质出版社.
王增润,吴延之.1992.滇西澜沧裂谷成矿作用谦论老厂大型铜铅银矿床成因.有色金属矿产与勘查,(4):207-215.
徐楚明,欧阳成甫.1991.云南澜沧老厂银铅锌矿床成因研究.桂林冶金地质学院学报,ll(3),245-252.
薛步高.2003.昆阳群.矿床地质论文集.昆明:云南科技出版社,157-167.
杨开辉.1992.三江地区火山岩成因块状硫化物矿床的基本特征与主要类型.矿床地质,11(1):35-44.
姚素珠,董宜宝,Pupin J P.1990.川西高原几个花岗岩体的岩浆起源浅探.成都地质学院学报,17(4):33-45.
喻学惠,肖晓牛,杨贵来,莫宣学,曾普胜,王晋璐.2008.滇西“三江”南段几个花岗岩的锆石SHRIMP U-Pb定年及其地质意义.岩石学报,24(2):377-383.
曾普胜,侯增谦,高永峰.2006.印度-亚洲碰撞带东段喜马拉雅期铜-钼-金矿床Re-Os年龄及成矿作用.地质论评,52(1):72-84.
张翼飞,段锦荪,张罡,柏坚编著.2001.滇西蛇绿岩带地质构造演化与澜沧江板块缝合线研究.昆明:云南科技出版社.
Compston W,Williams I S,Kirschvink J L,Zhang Z C and MaG G.1992.Zircon U-Pb ages of early Cambrian time-scale.Journal ofGeological Society,149:171-184.
Hou Z Q,Ma H W and Zaw K.2003.The Himalayan Yulongporphyry copper belt:Product of large-scale strike-slip faul-ting in eastern Tibet.Economic Geology,98:125-145.
Pupin J P.1980.Zircon and granite petrology.Contributions toMineralogy and Petrology,73:207-220.
Stein HJ,Markey R J,Morgan J W,Du A and Sun Y.1997.Highly precise and accurate Re-Os ages for molybdenumfrom the East Qinling molybdenum belt,Shanxi Province,China.Econ Geo1,92:827-835.
Williams I S,Buick A and Cartwyight I.1996.An extension ofearly episode Mesoproterozoic metamorphic fluid flowin theReynold region,central Australia.J Metamorphic Geol,14:29-47.
程锦,夏斌,张玉泉.2008.囊谦盆地新生代高钾岩浆岩的地球化学特征:岩石成因及其构造意义.大地构造与成矿学,32(3):382-391.
侯增谦,潘桂棠,王安建,莫宣学,田世洪,孙晓明.2006a.青藏高原碰撞造山带:Ⅱ.晚碰撞转换成矿作用.矿床地质,25(5):521-543.
侯增谦,杨竹森,徐文艺,莫宣学,丁林.2006b.青藏高原碰撞造山带:Ⅰ.主碰撞造山成矿作用.矿床地质,25(4):337-358.
冷成彪,张兴春,王守旭,秦朝建,苟体忠,王外全.2008.滇西北中旬松诺含矿斑岩的锆石SHRIMP U-Pb年龄及地质意义.大地构造与成矿学,32(1):124-130.
李虎杰,田煦,易发成.1995.云南澜沧老厂铅锌银铜矿床稳定同位素地球化学研究.有色金属矿产与勘查,4(5):278-282.
李雷,段嘉瑞,李峰.1996.澜沧老厂铜多金属矿床地质特征及多期同位成矿.云南地质,15(3):246-256.
龙汉生,蒋绍平,石增龙,黄智龙,罗泰义.2007.云南澜沧老厂大型银铅锌多金属矿床地质地球化学特征.矿物学报,27(3-4):360-365.
毛景文,张作衡,张招崇,杨建民,王志良,杜安道.1999.北祁连山小柳沟钨矿床中辉钼矿Re-Os年龄测定及其意义.地质论评,45(4):412-417.
欧阳成甫,徐楚明,胡承绮,郎跃秀.1993.云南澜沧老厂银铅矿区隐伏花岗岩体预测及其意义.大地构造与成矿学,17(2):119-126.
潘桂棠,徐强,侯增谦.2003.西南“三江”多岛弧造山过程成矿系统与资源评价.北京:地质出版社.
曲文俊,杜安道.2003.高温密闭溶样电感耦合等离子体质谱准确测定辉钼矿铼-锇地质年龄.岩矿测试,22(4):254-257.
王登红,应汉龙,梁华英,黄智龙,骆耀南.2006.西南三江地区大陆动力学过程与大规模成矿.北京:地质出版社.
王增润,吴延之.1992.滇西澜沧裂谷成矿作用谦论老厂大型铜铅银矿床成因.有色金属矿产与勘查,(4):207-215.
徐楚明,欧阳成甫.1991.云南澜沧老厂银铅锌矿床成因研究.桂林冶金地质学院学报,ll(3),245-252.
薛步高.2003.昆阳群.矿床地质论文集.昆明:云南科技出版社,157-167.
杨开辉.1992.三江地区火山岩成因块状硫化物矿床的基本特征与主要类型.矿床地质,11(1):35-44.
姚素珠,董宜宝,Pupin J P.1990.川西高原几个花岗岩体的岩浆起源浅探.成都地质学院学报,17(4):33-45.
喻学惠,肖晓牛,杨贵来,莫宣学,曾普胜,王晋璐.2008.滇西“三江”南段几个花岗岩的锆石SHRIMP U-Pb定年及其地质意义.岩石学报,24(2):377-383.
曾普胜,侯增谦,高永峰.2006.印度-亚洲碰撞带东段喜马拉雅期铜-钼-金矿床Re-Os年龄及成矿作用.地质论评,52(1):72-84.
张翼飞,段锦荪,张罡,柏坚编著.2001.滇西蛇绿岩带地质构造演化与澜沧江板块缝合线研究.昆明:云南科技出版社.
Compston W,Williams I S,Kirschvink J L,Zhang Z C and MaG G.1992.Zircon U-Pb ages of early Cambrian time-scale.Journal ofGeological Society,149:171-184.
Hou Z Q,Ma H W and Zaw K.2003.The Himalayan Yulongporphyry copper belt:Product of large-scale strike-slip faul-ting in eastern Tibet.Economic Geology,98:125-145.
Pupin J P.1980.Zircon and granite petrology.Contributions toMineralogy and Petrology,73:207-220.
Stein HJ,Markey R J,Morgan J W,Du A and Sun Y.1997.Highly precise and accurate Re-Os ages for molybdenumfrom the East Qinling molybdenum belt,Shanxi Province,China.Econ Geo1,92:827-835.
Williams I S,Buick A and Cartwyight I.1996.An extension ofearly episode Mesoproterozoic metamorphic fluid flowin theReynold region,central Australia.J Metamorphic Geol,14:29-47.
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