EPMA Analysis of Hydrothermal Biotite from the Bangpu Porphyry Mo-Cu Deposit of Tibet, China and the Characteristics of Early Ore-forming Fluids
-
摘要: 热液黑云母的化学组成对于揭示早期成矿流体的物理化学性质和流体演化过程具有重要意义。邦铺矿床是冈底斯成矿带东段一个大型的斑岩型钼（铜）矿床，其钾硅酸盐化蚀变带内热液黑云母广泛发育，本文对采自该矿床闪长玢岩钾硅酸盐化蚀变带内的热液黑云母进行了电子探针分析。结果表明，热液黑云母的SiO2、TiO2、Al2O3、FeOT、MgO和K2O等主要氧化物的平均含量为38.95%、1.42%、13.55%、14.22%、16.23%和9.77%，具有明显的高镁低铁、高钾低钠钙等特征，且异常高的K/Na值（82.5）可能是指示斑岩型钼矿化的重要指标。依据化学组成估算热液黑云母结晶时流体的氧逸度和温度，显示钾硅酸盐化蚀变带内早期成矿流体具有高温、高氧逸度特征，且深部流体平均温度（458℃）明显高于浅部流体（366℃），成矿流体从深部向浅部运移的过程中，温度和压力逐渐降低，导致钼、铜硫化物从流体中析出从而成矿。该成果为进一步研究矿床成矿流体的演化和成矿机制提供了重要线索。Abstract: The chemical composition of hydrothermal biotite is important in revealing the physiochemical conditions and evolution of early ore-forming fluids. The Bangpu deposit is a large porphyry Mo(Cu) deposit in the eastern part of the Gangdese metallogenic belt, and hydrothermal biotite is extensive in the potassic alteration zone. Hydrothermal biotite in the potassic alteration zone of dioritic porphyry was analyzed by Electron Microprobe Analyzer (EPMA) and is reported in this paper. Results show that the biotite is characterized by the high content of K and low contents of Na and Ca. The average contents of SiO2, TiO2, Al2O3, FeOT, MgO, K2O are 38.95%, 1.42%, 13.55%, 14.22%, 16.23%, 9.77%, respectively. The anomalously high K/Na values (82.5) may be an important indicator for the porphyry Mo mineralization. Based on chemical components, the temperature and oxygen fugacity of the ore-forming fluids were calculated. Results show that the early ore-forming fluids of the potassic alteration have a high temperature and oxygen fugacity, and the average temperature (458℃) of the deep ore-forming fluids is much higher than that of the shallow ore-forming fluids (366℃) . The decreasing temperature and pressure during the migration of the early ore-forming fluids from deep to shallow resulted in the precipitation of the Mo and Cu sulfides. This research provides an important clue for studying the evolution of ore-forming fluids and the ore-forming mechanism.
-
Key words:
- hydrothermal biotite /
- Electron Microprobe /
- physico-chemical condition /
- porphyry deposit /
- Bangpu
-
-
表 1 邦铺矿床钾硅酸盐化蚀变带内热液黑云母电子探针分析结果
Table 1. Electron microprobe analyses of hydrothermal biotite in the potassic alteration of the Bangpu deposit
下载: 导出CSV
表 2 国内外典型斑岩型矿床中热液黑云母成分对比
Table 2. Typical hydrothermal biotite compositions in porphyry deposits at home and abroad
矿床名称 矿床规模 矿化类型 含矿斑岩岩性 云母类型 样品 数量 元素含量比值 参考 文献 Mg/Fe Al/Fe K/Na Al2O3/TiO2 Si/Al Dalli 大型 Cu-Mo-Au 英安玢岩 镁质黑云母 6 2.17 1.56 19.37 2.82 2.16 [1] Kahang 大型 Cu-Mo 花岗闪长斑岩 镁质黑云母 18 2.2 1.42 18.85 2.92 5.01 [3] Santa Rita 大型 Cu 黑云母花岗闪长斑岩 镁质黑云母 65 1.93 1.37 29.67 4.56 2.34 [18] Maher-Abad 大型 Cu-Au 花岗闪长岩 镁质黑云母 3 2.49 1.68 25.3 5.44 2.06 [19] 多宝山 大型 Cu-Mo 花岗闪长岩 镁质黑云母 12 0.52 0.7 - 7.5 2.08 [14] 雄村 大型 Cu-Au 石英闪长玢岩 镁质黑云母-金云母 17 3.86 2.64 48.15 33.62 0.51 [20] 邦铺 大型 Mo(Cu) 闪长玢岩 镁质黑云母 30 2.13 1.38 82.52 10.29 2.44 本文 注：多宝山矿床相关数据引自文献[14]，该文献中未给出K/Na值。
下载: 导出CSV
-
[1] Ayati F,Yavuz F,Noghreyan M,et al.Chemical Characteristics and Composition of Hydrothermal Biotite from the Dalli Porphyry Copper Prospect,Arak,Central Province of Iran[J].Mineralogy Petrology,2008,94(1):107-122. http://cn.bing.com/academic/profile?id=2048894950&encoded=0&v=paper_preview&mkt=zh-cn
[2] Bath A B,Walshe J L,Cloutier J,et al.Biotite and Apatite as Tools for Tracking Pathways of Oxidized Fluids in the Archean East Repulse Gold Deposit,Australia[J].Economic Geology,2013,108(4):667-690. doi: 10.2113/econgeo.108.4.667
[3] Afshooni S Z,Mirnejad H,Esmaeily D,et al.Mineral Chemistry of Hydrothermal Biotite from the Kahang Porphyry Copper Deposit (NE Isfahan),Central Province of Iran[J].Ore Geology Reviews,2013,54(32):214-232. http://cn.bing.com/academic/profile?id=2013860458&encoded=0&v=paper_preview&mkt=zh-cn
[4] Parsapoor A,Khalili M,Tepley F,et al.Mineral Chemistry and Isotopic Composition of Magmatic,Re-equilibrated and Hydrothermal Biotites from Darreh-Zar Porphyry Copper Deposit,Kerman (Southeast of Iran)[J].Ore Geology Reviews,2015,66:200-218. doi: 10.1016/j.oregeorev.2014.10.015
[5] Beane R E.Biotite Stability in the Porphyry Copper Environment[J].Economic Geology,1974,69(2):241-256. doi: 10.2113/gsecongeo.69.2.241
[6] Wones D R,Eugster H P.Stability of Biotite:Experiment,Theory and Application[J].American Mineralogist,1965,50(9):1228-1272. http://www.minsocam.org/ammin/AM50/AM50_1228.pdf
[7] 赵晓燕,杨竹森,刘英超,等.西藏邦铺斑岩矽卡岩矿床二长花岗斑岩Sr-Nd-Pb-Hf同位素及闪锌矿黄铁矿Rb-Sr等时线年龄研究[J].地质学报,2015,89(3):522-533.
Zhao X Y,Yang Z S,Liu Y C,et al.Sr-Nd-Pb-Hf Isotope of Porphyritic Monzogranite and Rb-Sr Isochron Age of Sphalerite-Pyrite at the Bangpu Porphyry-Skarn Deposit[J].Acta Geology Sinica,2015,89(3):522-533.
[8] 王立强,唐菊兴,王登红,等.西藏墨竹工卡县邦铺钼(铜)矿床辉钼矿稀土-微量元素特征及对成矿流体性质的指示[J].地质论评,2012,58(5):887-892. http://www.cnki.com.cn/Article/CJFDTOTAL-DZLP201205011.htm
Wang L Q,Tang J X,Wang D H,et al.Rare Earth Element and Trace Element Features of Molybdenite in Bangpu Mo(Cu) Deposite,Maizhokunggar,Xizang (Tibet),and Their Constraints on the Nature of Ore-forming Fluid[J].Geological Review,2012,58(5):887-892. http://www.cnki.com.cn/Article/CJFDTOTAL-DZLP201205011.htm
[9] Wang L Q,Tang J X,Cheng W B,et al.Origin of the Ore-forming Fluids and Metals of the Bangpu Porphyry Mo-Cu Deposit of Tibet,China:Constraints from He-Ar,H-O,S and Pb Isotopes[J].Journal of Asian Earth Sciences,2015,103(1):276-287. http://cn.bing.com/academic/profile?id=2044872059&encoded=0&v=paper_preview&mkt=zh-cn
[10] 周雄,温春齐,霍艳,等.西藏墨竹工卡地区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. http://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD201007012.htm
Zhou X,Wen C Q,Huo Y,et al.Characteristics of Ore-forming Fluid of Bangpu Molybdenum-Copper Polymetallic Deposit, Maizhokunggar Area,Tibet,China[J].Geological Bulletin of China,2010,29(7):1039-1048. http://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD201007012.htm
[11] 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. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXB201204013.htm
Luo M C,Mao J W,Wang L Q,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. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXB201204013.htm
[12] 赵晓燕,杨竹森,周金胜,等.西藏邦铺斑岩矽卡岩矿床成矿流体特征——来自流体包裹体及C-H-O同位素的制约[J].岩石矿物学杂志,2015,34(4):475-492. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201504003.htm
Zhao X Y,Yang Z S,Zhou J S,et al.Characteristics of Ore-forming Fluids in the Bangpu Porphyry-Skarn Deposit:Evidence from Fluid Inclusions and Stable Isotope Compositions[J].Acta Petrologica et Mineralogica,2015,34(4):475-492. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201504003.htm
[13] Yavuz F.Evaluating Micas in Petrologic and Metallo-genic Aspect:Ⅰ-Definitions and Structure of the Computer Program Mica+[J].Computer & Geoscience,2003,29(10):1203-1213.
[14] 秦克章,张连昌,丁奎首,等.东天山三岔口铜矿床类型、赋矿岩石成因与矿床矿物学特征[J].岩石学报,2009,25(4):845-861. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200904010.htm
Qin K Z,Zhang L C,Ding K S,et al.Mineralization Type,Petrogenesis of Ore-bearing Intrusions and Mineralogical Characteristics of Sanchakou Copper Deposits in Eastern Tishan[J].Acta Petrologica Sinica,2009,25(4):845-861. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200904010.htm
[15] Foster M D.Interpretation of the Composition of Triocta-hedral Micas[R].Virginia:United States Geological Survey,1960,354-B:1-146.
[16] Stone D.Temperature and Pressure Variations in Suites of Archean Felsic Plutonic Rocks,Berens River Area,Northwest Superior Province,Ontario,Canada[J].The Canadian Mineralogist,2000,38:455-470. doi: 10.2113/gscanmin.38.2.455
[17] 于玉帅,杨竹森,高原,等.西藏尼雄矿田滚纠铁矿花岗闪长岩成因的矿物化学证据[J].地质与勘探,2013, 49(5):897-906. http://www.cnki.com.cn/Article/CJFDTOTAL-DZKT201305011.htm
Yu Y S,Yang Z S,Gao Y,et al.Genesis of Granodiorite in the Gunjiu Iron Deposit of the Nixiong Ore Field,Tibet: Evidence from Mineral Chemistry[J].Geology and Exploration,2013,49(5):897-906. http://www.cnki.com.cn/Article/CJFDTOTAL-DZKT201305011.htm
[18] Jacobs D C,Parry W T.Geochemistry of Biotite in the Santa Rita Porphyry Copper Deposit,New Mexico[J].Economic Geology,1979,74(4):860-887. doi: 10.2113/gsecongeo.74.4.860
[19] Siahcheshm K,Calagari A A,Abedini A,et al.Halogen Signatures of Biotites from the Maher-Abad Porphyry Copper Deposit,Iran:Characterization of Volatiles in Syn- to Post-Magmatic Hydrothermal Fluids[J].International Geology Review,2012,54(12):1353-1368. doi: 10.1080/00206814.2011.639487
[20] 谢富伟,唐菊兴,郎兴海.西藏雄村矿区Ⅰ号矿体斑岩含矿性研究——来自热液蚀变矿物和副矿物的证据[J].岩石矿物学杂志,2015,34(1):51-64. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201501005.htm
Xie F W,Tang J X,Lang X H.Ore Potential of the Porphyry in No.Ⅰ Deposit of the Xiongcun Ore District,Tibet:Evidence from Hydrothermal and Accessory Minerals[J].Acta Petrologica et Mineralogica,2015,34(1):51-64. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201501005.htm
[21] Boomeri M,Nakashima K,Lentz D R.The Sarcheshmeh Porphyry Copper Deposit,Kerman,Iran:A Mineralogical Analysis of the Igneous Rocks and Alteration Zones including Halogen Element Systematics Related to Cu Mineralization Processes[J].Ore Geology Reviews,2010,38(4):367-381. doi: 10.1016/j.oregeorev.2010.09.001
[22] Wones D R.Significance of the Assemblage Titanite+Magnetite+Quartz in Granitic Rocks[J].American Mineralogist,1989,74(7):744-749. http://www.minsocam.org/ammin/AM74/AM74_744.pdf
[23] Albuquerque A C.Geochemistry of Biotites from Granitic Rocks,Northern Portugal[J].Geochimica et Cosmochimica Acta,1973,37(7):1779-1802. doi: 10.1016/0016-7037(73)90163-4
[24] Rusk B G,Reed M H,Dilles J H.Fluid Inclusion Evidence for Magmatic-Hydrothermal Fluid Evolution in the Porphyry Copper-Molybdenum Deposit at Butte,Montana[J].Economic Geology,2008,103(2):307-334. doi: 10.2113/gsecongeo.103.2.307
[25] Sillitoe R H.Porphyry Copper Systems[J].Economic Geology,2010,105(1):3-41. doi: 10.2113/gsecongeo.105.1.3
[26] 刘彬,马昌前,刘园园,等.鄂东南铜山口铜(钼)矿床黑云母矿物化学特征及其对岩石成因与成矿的指示[J].岩石矿物学杂志,2010,29(2):151-165. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201002004.htm
Liu B,Ma C Q,Liu Y Y,et al.Mineral Chemistry of Biotites from the Tongshankou Cu-Mo Deposit:Implications for Petrogenesis and Mineralization[J].Acta Petrologica et Mineralogica,2010,29(2):151-165. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW201002004.htm
[27] 弥佳茹,袁顺达,原垭斌,等.湘南宝山矿床花岗闪长斑岩中黑云母的矿物学特征及其指示意义[J].矿床地质,2014,33(6):1357-1365. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ201406014.htm
Mi J R,Yuan S D,Yuan Y B,et al.Mineral Chemistry of Biotites in Baoshan Granodiorite-Porphyry,Southern Hunan Province:Implications for Petrogenesis and Mineralization[J].Mineral Deposits,2014,33(6):1357-1365. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ201406014.htm
-
图(3)
表(2)
计量
- 文章访问数: 986
- PDF下载数: 27
- 施引文献: 0