西藏邦铺钼多金属矿床碳氧同位素组成及意义
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摘要
对西藏邦铺钼铜多金属矿床中的灰岩、方解石进行了C、O同位素测定。测试结果表明,早期的灰岩具有相对较高的δ13C V-PDB(3.1‰~4.0‰)、δ18O V-SMOW(5.2‰~12.5‰)和Z值(136.44~141.72),晚期的方解石的δ13C V-PDB(-5.6‰~-3.8‰)、δ18O V-SMOW(1.3‰~5.5‰)和Z值(118.57~120.17)则偏低。δ13C V-PDB-δ18O V-SMOW碳酸盐岩来源判别图解显示碳主要来源于蚀变及再沉积碳酸盐岩,δ13C V-PDB-δ18O V-SMOW流体来源判别图解显示成矿流体中的碳来源于岩浆及碳酸盐岩的溶解作用,但明显混合了大气降水。综合分析认为,早期为同生期成岩环境,后期为埋藏混合水环境,流体中的碳可能主要来源于海相碳酸盐岩的溶解作用,但不排除岩浆岩对碳的贡献。碳氧同位素结果显示,当大气降水强度加大时,δ13C V-PDB向低、负值方向偏移,δ18O V-SMOW发生强烈的负偏移,即氧同位素漂移。
The limestone and calcite of Bangpu Mo-Cu polymetallic deposit are surveyed by Carbon,oxygen isotope determination. The results show that there are high carbon( δ13C V- PDB = 3. 1‰ ~ 4. 0‰),oxygen isotope compositions( δ18O V- SMOW = 5. 2‰ ~ 12. 5‰) and carbonate salinity index value of Z( 136. 44 ~ 141. 72) from the early period of limestone,while low carbon(- 5. 6‰ ~- 3. 8‰),oxygen isotope compositions( 1. 3‰ ~ 5. 5‰) and Z value( 118. 57 ~ 120. 17) from later period of calcites. δ13C V- PDB- δ18O V- SMOW diagram for the carbonate source shows that carbon mainly originates from the alteration of sedimentary carbonate rocks,δ13C V- PDB- δ18O V- SMOW diagram for the source of the fluid shows that carbon in the ore-forming fluid mainly comes from magma and dissolution of carbonate rocks which obviously mixed atmospheric precipitation. It is concluded that it is the syngenetic diagenetic environment during the early period while buried mixed water environment during the later period. Carbon in ore-forming fluid was mainly derived from the dissolution of marine carbonate formation,but magmatic rock is also an important factor of carbon formation. Carbon and oxygen isotope results shows that when rainfall intensity increased,δ13C V- PDB shift to a low and negative direction and δ18O V- SMOW with a negative excursion which means isotope excursion.
The limestone and calcite of Bangpu Mo-Cu polymetallic deposit are surveyed by Carbon,oxygen isotope determination. The results show that there are high carbon( δ13C V- PDB = 3. 1‰ ~ 4. 0‰),oxygen isotope compositions( δ18O V- SMOW = 5. 2‰ ~ 12. 5‰) and carbonate salinity index value of Z( 136. 44 ~ 141. 72) from the early period of limestone,while low carbon(- 5. 6‰ ~- 3. 8‰),oxygen isotope compositions( 1. 3‰ ~ 5. 5‰) and Z value( 118. 57 ~ 120. 17) from later period of calcites. δ13C V- PDB- δ18O V- SMOW diagram for the carbonate source shows that carbon mainly originates from the alteration of sedimentary carbonate rocks,δ13C V- PDB- δ18O V- SMOW diagram for the source of the fluid shows that carbon in the ore-forming fluid mainly comes from magma and dissolution of carbonate rocks which obviously mixed atmospheric precipitation. It is concluded that it is the syngenetic diagenetic environment during the early period while buried mixed water environment during the later period. Carbon in ore-forming fluid was mainly derived from the dissolution of marine carbonate formation,but magmatic rock is also an important factor of carbon formation. Carbon and oxygen isotope results shows that when rainfall intensity increased,δ13C V- PDB shift to a low and negative direction and δ18O V- SMOW with a negative excursion which means isotope excursion.
引文
[1]周雄.西藏邦铺钼铜多金属矿床成因研究[D].成都:成都理工大学,2012.Zhou Xiong.Genisis Study of Mo-Cu Polymetallic Ceposit from the Bangpu,Tibet[D].Chengdu:Chengdu University of Technology,2012.
[2]周雄.西藏邦铺钼铜多金属矿床流体包裹体研究[D].成都:成都理工大学,2009.Zhou Xiong.Study on the Fluid Inclusions of the Bangpu Molybdenum Copper Polymetallic Deposit,Tibet[D].Chengdu:Chengdu University of Technology,2009.
[3]周雄,温春齐,费光春,等.西藏邦铺斑岩钼矿床二长花岗斑岩地球化学特征及构造意义[J].矿物岩石,2010,30(4):48-54.Zhou Xiong,Wen Chunqi,Fei Guangchun,et al.Geochemical characteristics of monzonite granite-porphyry in bangpu porphyry Mo deposit,Tibet,and it's tectonic significance[J].Journal of Mineralogy and Petrology,2010,30(4):48-54.
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[5]罗茂澄,毛景文,王立强,等.西藏邦铺斑岩钼铜矿床岩浆-热液流体演化:流体包裹体研究[J].地球学报:2012,33(4):471-484.Luo Maocheng,Mao Jingwen,Wang Liqiang,et al.Fluid inclusion evidence for magmatic-hydrothermal evolution in the Bangpu porphyry molybdenum-copper deposit,Tibet[J].Acta Geoscientica Sinica,2012,33(4):471-484.
[6]周雄,温春齐,张学全,等.西藏邦铺钼铜多金属矿床硫、铅同位素地球化学特征[J].地质与勘探,2012,48(1):24-30.Zhou Xiong,Wen Chunqi,Zhang Xuequan,et al.Geochemical characteristics of sulfur,lead isotope from Bangpu Mo-Cu polymetallic deposit,Tibet[J].Geology and Exploration,2012,48(1):24-30.
[7]孟祥金,侯增谦,高永丰,等.西藏冈底斯东段斑岩铜钼铅锌成矿系统的发育时限:帮浦铜多金属矿床辉钼矿Re-Os年龄证据[J].矿床地质,2003,22(3):246-252.Meng Xiangjin,Hou Zengqian,Gao Yongfeng,et al.Development of porphyry copper-molybdenum-lead-zinc ore-forming system in east Gangdese belt,Tibet:Evidence from Re-Os age of molybdenite in Bangpu copper polymetallic deposit[J].Mineral Deposit,2003,22(3):246-252.
[8]周雄,温春齐,温泉,等.西藏邦铺大型斑岩钼铜矿床二长花岗斑岩锆石SHRIMP定年及其地质意义[J].矿物岩石地球化学通报,2010,29(4):373-379.Zhou Xiong,Wen Chunqi,Wen Quan,et al.Zircon U-Pb SHRIMP dating of the monzonite granite-porphyry from the Bangpu large porphyry molybdenum-copper deposits,Tibet,and its geological significance[J].Bulletin of Mineralogy,Petrology and Geochemistry,2010,29(4):373-379.
[9]周雄,温春齐,张学全,等.西藏邦铺大型钼铜多金属矿床Rb-Sr等时线年龄及地质意义[J].高校地质学报,2010,16(4):448-456.Zhou Xiong,Wen Chunqi,Zhang Xuequan,et al.Rb-Sr isochron age dating in Bangpu large-scale Mo-Cu polymetallic deposit,Tibet,and its geological significance[J].Geological Journal of China Universities,2010,16(4):448-456.
[10]周雄,温春齐,温泉,等.西藏邦铺斑岩型钼铜多金属矿床含钼铜脉石英的激光显微探针40Ar/39Ar年龄及地质意义[J].矿物岩石,2011,31(1):43-48.Zhou Xiong,Wen Chunqi,Wen Quan,et al.Laser microprobe40Ar-39Ar dating from vein quartz containing Mo and Cu of Bangpu porphyry-type Mo-Cu polymetallic deposits,Tibet[J].Journal of Mineralogy and Petrology,2011,31(1):43-48.
[11]王立强,陈毓川,唐菊兴,等.西藏邦铺钼(铜)矿床含矿二长花岗斑岩LA-ICP-MS锆石U-Pb定年及地质意义[J].矿床地质,2011,30(2):349-360.Wang Liqiang,Chen Yuchuan,Tang Juxing,et al.LA-ICP-MS zircon U-Pb dating of ore-bearing monzogranite porphyry in Bangpu molybdenum(copper)deposit,Tibet and its significance[J].Mineral Deposits,2011,30(2):349-360.
[12]温泉,多吉,温春齐,等.西藏邦铺钼铜矿区花岗斑岩成岩年龄研究[J].矿物岩石,2011,31(2):48-53.Wen Quan,Duo Ji,Wen Chunqi,et al.Dating of monzonitic granite porphyry in the Bangpu Mo-Cu deposit,Tibet[J].Journal of Mineralogy and Petrology,2011,31(2):48-53.
[13]周雄,温春齐,张贻,等.西藏邦铺钼铜多金属矿床辉钼矿Re-Os年代学及地质意义[J].矿物岩石.2013,33(2):59-64.Zhou Xiong,Wen Chunqi,Zhang Yi,et al.Re-Os dating of molybdenite from the Bangpu polymetallic deposit,Tibet,and its Geological significance[J].Journal of Mineralogy and Petrology,2013,33(2):59-64.
[14]王立强.西藏邦铺式钼多金属矿床——兼论冈底斯成矿带东段钼多金属矿床成矿规律[D].北京:中国地质科学院,2013.Wang Liqiang.Study on Bangpu-type Molybdenum Polymetallic Deposit,Tibet and the Metallogenic Regularity of Molybdenum Polymetallic Deposits in the East Section of the Gangdese Metallogenic Belt[D].Beijing:Chinese Academy of Geological Sciences,2013.
[15]Spangenberg J,FontbotéL,Sharp Z D,et al.Carbon and oxygen isotope study of hydrothermal carbonates in the zinc-lead deposits of the San Vicente district,central Peru:A quantitative modeling on mixing processes and CO2degassing[J].Chemical Geology,1996,133(1-4):289-315.
[16]毛景文,郝英,丁悌平.胶东金矿形成期间地幔流体参与成矿过程的碳氧氢同位素证据[J].矿床地质,2002,21(2):121-127.Mao Jingwen,Hao Ying,Ding Tiping.Mantle fluids involved in metallogenesis of Jiaodong gold district:Evidence of C,O and H isotopes[J].Mineral Deposits,2002,21(2):121-127.
[17]毛景文,李厚民,王义天,等.地幔流体参与胶东金矿成矿作用的氢氧碳硫同位素证据[J].地质学报,2005,79(6):839-857.Mao Jingwen,Li Houmen,Wang Yitian,et al.The relationship between mantle-derived fluid and gold ore-formation in the eastern Shandong peninsula:evidences from D-O-C-S Isotopes[J].Acta Geological Sinica,2005,79(6):839-857.
[18]沈能平,彭建堂,袁顺达,等.湖北徐家山锑矿床方解石C、O、Sr同位素地球化学[J].地球化学,2007,36(5):479-485.Shen Nengping,Peng Jiantang,Yuan Shunda,et al.Carbon,oxygen and strontium isotope geochemistry of calcites from Xujiashan antimony deposit,Hubei province[J].Geochemical,2007,36(5):479-485.
[19]Keith W L,Weber J N.Carbon and oxygen isotopic composition of mollusk shells from marine and fresh water environment[J].Geochemical and Cosmochemical Acta,1964,28(10):1757-1786.
[20]叶庆同.四川呷村含金富银多金属矿床成矿地质特征和成因[J].矿床地质,1991,10(2):107-117.Ye Qingtong.Characteristics and origin from Gacun gold-bearing rich silver polymetallic ore deposit,Sichuan[J].Mineral Deposits,1991,10(2):107-117.
[21]刘建明,刘家军,郑明华,等.微细浸染型金矿床的稳定同位素特征与成因探讨[J].地球化学,1998,27(6):585-590.Liu Jianming,Liu Jiajun,Zheng Minghua,et al.Stable isotope compositions of micro-disseminated gold and genetic discussion[J].Geochemical,1998,27(6):585-590.
[2]周雄.西藏邦铺钼铜多金属矿床流体包裹体研究[D].成都:成都理工大学,2009.Zhou Xiong.Study on the Fluid Inclusions of the Bangpu Molybdenum Copper Polymetallic Deposit,Tibet[D].Chengdu:Chengdu University of Technology,2009.
[3]周雄,温春齐,费光春,等.西藏邦铺斑岩钼矿床二长花岗斑岩地球化学特征及构造意义[J].矿物岩石,2010,30(4):48-54.Zhou Xiong,Wen Chunqi,Fei Guangchun,et al.Geochemical characteristics of monzonite granite-porphyry in bangpu porphyry Mo deposit,Tibet,and it's tectonic significance[J].Journal of Mineralogy and Petrology,2010,30(4):48-54.
[4]周雄,温春齐,霍艳,等.西藏邦铺钼铜多金属矿床成矿流体的特征[J].地质通报,2010,29(7):1039-1048.Zhou Xiong,Wen Chunqi,Huo Yan,et al.Characteristics of oreforming fluid of Bangpu molybdenum-copper polymetallic deposit,maizhokunggar area,Tibet[J].Geological Bulletin of China,2010,29(7):1039-1048.
[5]罗茂澄,毛景文,王立强,等.西藏邦铺斑岩钼铜矿床岩浆-热液流体演化:流体包裹体研究[J].地球学报:2012,33(4):471-484.Luo Maocheng,Mao Jingwen,Wang Liqiang,et al.Fluid inclusion evidence for magmatic-hydrothermal evolution in the Bangpu porphyry molybdenum-copper deposit,Tibet[J].Acta Geoscientica Sinica,2012,33(4):471-484.
[6]周雄,温春齐,张学全,等.西藏邦铺钼铜多金属矿床硫、铅同位素地球化学特征[J].地质与勘探,2012,48(1):24-30.Zhou Xiong,Wen Chunqi,Zhang Xuequan,et al.Geochemical characteristics of sulfur,lead isotope from Bangpu Mo-Cu polymetallic deposit,Tibet[J].Geology and Exploration,2012,48(1):24-30.
[7]孟祥金,侯增谦,高永丰,等.西藏冈底斯东段斑岩铜钼铅锌成矿系统的发育时限:帮浦铜多金属矿床辉钼矿Re-Os年龄证据[J].矿床地质,2003,22(3):246-252.Meng Xiangjin,Hou Zengqian,Gao Yongfeng,et al.Development of porphyry copper-molybdenum-lead-zinc ore-forming system in east Gangdese belt,Tibet:Evidence from Re-Os age of molybdenite in Bangpu copper polymetallic deposit[J].Mineral Deposit,2003,22(3):246-252.
[8]周雄,温春齐,温泉,等.西藏邦铺大型斑岩钼铜矿床二长花岗斑岩锆石SHRIMP定年及其地质意义[J].矿物岩石地球化学通报,2010,29(4):373-379.Zhou Xiong,Wen Chunqi,Wen Quan,et al.Zircon U-Pb SHRIMP dating of the monzonite granite-porphyry from the Bangpu large porphyry molybdenum-copper deposits,Tibet,and its geological significance[J].Bulletin of Mineralogy,Petrology and Geochemistry,2010,29(4):373-379.
[9]周雄,温春齐,张学全,等.西藏邦铺大型钼铜多金属矿床Rb-Sr等时线年龄及地质意义[J].高校地质学报,2010,16(4):448-456.Zhou Xiong,Wen Chunqi,Zhang Xuequan,et al.Rb-Sr isochron age dating in Bangpu large-scale Mo-Cu polymetallic deposit,Tibet,and its geological significance[J].Geological Journal of China Universities,2010,16(4):448-456.
[10]周雄,温春齐,温泉,等.西藏邦铺斑岩型钼铜多金属矿床含钼铜脉石英的激光显微探针40Ar/39Ar年龄及地质意义[J].矿物岩石,2011,31(1):43-48.Zhou Xiong,Wen Chunqi,Wen Quan,et al.Laser microprobe40Ar-39Ar dating from vein quartz containing Mo and Cu of Bangpu porphyry-type Mo-Cu polymetallic deposits,Tibet[J].Journal of Mineralogy and Petrology,2011,31(1):43-48.
[11]王立强,陈毓川,唐菊兴,等.西藏邦铺钼(铜)矿床含矿二长花岗斑岩LA-ICP-MS锆石U-Pb定年及地质意义[J].矿床地质,2011,30(2):349-360.Wang Liqiang,Chen Yuchuan,Tang Juxing,et al.LA-ICP-MS zircon U-Pb dating of ore-bearing monzogranite porphyry in Bangpu molybdenum(copper)deposit,Tibet and its significance[J].Mineral Deposits,2011,30(2):349-360.
[12]温泉,多吉,温春齐,等.西藏邦铺钼铜矿区花岗斑岩成岩年龄研究[J].矿物岩石,2011,31(2):48-53.Wen Quan,Duo Ji,Wen Chunqi,et al.Dating of monzonitic granite porphyry in the Bangpu Mo-Cu deposit,Tibet[J].Journal of Mineralogy and Petrology,2011,31(2):48-53.
[13]周雄,温春齐,张贻,等.西藏邦铺钼铜多金属矿床辉钼矿Re-Os年代学及地质意义[J].矿物岩石.2013,33(2):59-64.Zhou Xiong,Wen Chunqi,Zhang Yi,et al.Re-Os dating of molybdenite from the Bangpu polymetallic deposit,Tibet,and its Geological significance[J].Journal of Mineralogy and Petrology,2013,33(2):59-64.
[14]王立强.西藏邦铺式钼多金属矿床——兼论冈底斯成矿带东段钼多金属矿床成矿规律[D].北京:中国地质科学院,2013.Wang Liqiang.Study on Bangpu-type Molybdenum Polymetallic Deposit,Tibet and the Metallogenic Regularity of Molybdenum Polymetallic Deposits in the East Section of the Gangdese Metallogenic Belt[D].Beijing:Chinese Academy of Geological Sciences,2013.
[15]Spangenberg J,FontbotéL,Sharp Z D,et al.Carbon and oxygen isotope study of hydrothermal carbonates in the zinc-lead deposits of the San Vicente district,central Peru:A quantitative modeling on mixing processes and CO2degassing[J].Chemical Geology,1996,133(1-4):289-315.
[16]毛景文,郝英,丁悌平.胶东金矿形成期间地幔流体参与成矿过程的碳氧氢同位素证据[J].矿床地质,2002,21(2):121-127.Mao Jingwen,Hao Ying,Ding Tiping.Mantle fluids involved in metallogenesis of Jiaodong gold district:Evidence of C,O and H isotopes[J].Mineral Deposits,2002,21(2):121-127.
[17]毛景文,李厚民,王义天,等.地幔流体参与胶东金矿成矿作用的氢氧碳硫同位素证据[J].地质学报,2005,79(6):839-857.Mao Jingwen,Li Houmen,Wang Yitian,et al.The relationship between mantle-derived fluid and gold ore-formation in the eastern Shandong peninsula:evidences from D-O-C-S Isotopes[J].Acta Geological Sinica,2005,79(6):839-857.
[18]沈能平,彭建堂,袁顺达,等.湖北徐家山锑矿床方解石C、O、Sr同位素地球化学[J].地球化学,2007,36(5):479-485.Shen Nengping,Peng Jiantang,Yuan Shunda,et al.Carbon,oxygen and strontium isotope geochemistry of calcites from Xujiashan antimony deposit,Hubei province[J].Geochemical,2007,36(5):479-485.
[19]Keith W L,Weber J N.Carbon and oxygen isotopic composition of mollusk shells from marine and fresh water environment[J].Geochemical and Cosmochemical Acta,1964,28(10):1757-1786.
[20]叶庆同.四川呷村含金富银多金属矿床成矿地质特征和成因[J].矿床地质,1991,10(2):107-117.Ye Qingtong.Characteristics and origin from Gacun gold-bearing rich silver polymetallic ore deposit,Sichuan[J].Mineral Deposits,1991,10(2):107-117.
[21]刘建明,刘家军,郑明华,等.微细浸染型金矿床的稳定同位素特征与成因探讨[J].地球化学,1998,27(6):585-590.Liu Jianming,Liu Jiajun,Zheng Minghua,et al.Stable isotope compositions of micro-disseminated gold and genetic discussion[J].Geochemical,1998,27(6):585-590.