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郭剑衡(1992-),女,甘肃张掖人,博士研究生,从事矿物学、岩石学和矿床学专业研究工作。124322611@qq.com |
收稿日期: 2019-06-28
修回日期: 2019-08-03
网络出版日期: 2019-11-07
基金资助
国家重点研发计划项目“青藏高原大陆碰撞斑岩铜—钼—金矿系统结构与形成机制”(2016YFC0600305)
国家自然科学基金项目“滇西北中甸岛弧印支期斑岩铜矿床的保存与剥蚀程度研究:低温年代学制约”(41373051)
Trace Elemental Compositions of Iron Oxides from the Lannitang Porphyry Cu-Au Deposit in the Zhongdian Region (Northwest) and the Geological Significances:A LA-ICP-MS Study
Received date: 2019-06-28
Revised date: 2019-08-03
Online published: 2019-11-07
烂泥塘斑岩铜金矿床位于云南省西北部的中甸地区,矿体主要以细脉—浸染状、网脉状产于石英二长斑岩和石英闪长玢岩之中。矿区热液蚀变作用发育,围绕矿体由深部至浅部依次发育钾化带、绿泥石—绢云母化带、绢云母化带和泥化带。钾化带中发育3种不同产状的磁铁矿,根据磁铁矿产出状态与脉体之间的相互穿插关系,将其划分为浸染状分布的磁铁矿(Ⅰ类)、单一脉状磁铁矿(Ⅱ类)和石英—硫化物脉中的磁铁矿(Ⅲ类)。此外,矿区常见产于成矿期后白云石—石英大脉中的镜铁矿。采用激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)对上述铁氧化物进行了原位微区成分测试。结果表明:3类磁铁矿均富集Ti、V、Cr、Ni、Co、Al、Mg、Mn、Ga和Zn等微量元素。早期Ⅰ类磁铁矿含有钛铁矿出溶体,与Ⅱ、Ⅲ类磁铁矿相比,相对富集Mg、Ni和V等元素,属于岩浆磁铁矿;Ⅱ类磁铁矿相对富集Mn、Zn、Sn和Sc等元素,属于热液磁铁矿。岩浆磁铁矿(Ⅰ类磁铁矿)与后期脉状磁铁矿(Ⅱ类和Ⅲ类)相比,Ti、Al和Cr等元素含量相差不大。这可能是由于后期热液蚀变对Ⅰ类磁铁矿的强烈改造,导致其中Ti、Al和Cr等元素含量降低(通常岩浆磁铁矿比热液磁铁矿更富集Ti、Al和Cr)。Ⅱ、Ⅲ类脉状磁铁矿属于热液磁铁矿且二者微量元素含量差别不大,说明它们属于同一期流体中沉淀的产物。与磁铁矿相比,镜铁矿中的Ti、Al和V元素含量相差不大,而Cr、Ga、Ni和Co等元素含量比磁铁矿低一个数量级。结合前人资料,认为Al、Mn、Mg和Sc元素在磁铁矿中主要以类质同象形式存在,而Ca、S、Cu、Ba、Sr和Zr等元素主要以显微包裹体形式存在。钾化带中广泛发育的磁铁矿—赤铁矿共生组合、镜铁矿以及磁铁矿中异常低的Mn含量表明,烂泥塘矿区成矿流体的氧逸度高达赤铁矿—磁铁矿缓冲线。
郭剑衡 , 冷成彪 , 张兴春 , 张伟 , 尹崇军 , 张陆佳 , 田振东 . 滇西北烂泥塘斑岩铜金矿床铁氧化物LA-ICP-MS微量元素特征及其地质意义[J]. 黄金科学技术, 2019 , 27(5) : 659 -677 . DOI: 10.11872/j.issn.1005-2518.2019.05.659
The Zhongdian area, located in northwestern Yunnan, is an important porphyry belt in China. It hosts a large number of Triassic intermediate-felsic porphyritic intrusions and porphyry deposits such as Pulang porphyry Cu-Au, Xuejiping porphyry Cu, Chundu porphyry Cu, Langdu Cu skarn and Lannitang porphyry Cu-Au deposit. The Lannitang porphyry Cu-Au deposit is located in west belt of the Zhongdian area. The magnetite in Lannitang porphyry Cu-Au deposit is widespread and it occurred as disseminated and vein types in potassic and chlorite-sericite alteration zone.Specularite is also observed frequently in the post-mineralization dolomite-quartz coarse veins.We conducted the petrography and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to determine the texture and composition of iron oxides (magnetite and specularite). In this study, we identified three types of magnetite. Type-Ⅰ magnetite is disseminated in potassic alteration of deposit. It is generally contains ilmenite lamellas. Type-Ⅱ and Type-Ⅲ magnetite are occurred in magnetite single vein and magnetite-bearing quartz stockwork vein separately. Type-Ⅱ and Type-Ⅲ are distributed in potassic and chlorite-sericite alteration zone. The LA-ICP-MS analyses show that Type-Ⅰ magnetite is relatively rich in V, Ni and Mg than other two types of magnetite. Type-Ⅱ and Type-Ⅲ magnetite are more enriched in Mn, Zn, Sn, Sc and high-Ni/Cr ratio than Type-Ⅰ magnetite.Type-Ⅱ and Type-Ⅲ magnetite has similar content of many trace elements. The concentration of Cr,Ga,Ni and Co in specularite is obviously lower than those of magnetite. The ilmenite lamellae and low-Ni/Cr(Ni/Cr<1) ratio revealed that Type-Ⅰ magnetite belongs to igneous magnetite. Type-Ⅱ and Type-Ⅲ are distributed in veinlets and displayed high-Ni/Cr ratio (Ni/Cr>1). We suggested that they are hydrothermal magnetite. Type-Ⅰ magnetite (igneous) is intergrown with hydrothermal minerals including chlorite and sericite and it has quiet similar contents of Ti, Al and Cr with the other two hydrothermal magnetite.We suggest that Type-Ⅰ magnetite (igneous) experienced late-stage fluid alteration, which induced the loss of Ti, Al and Cr.The similar content of trace element between Type-Ⅱ and Type-Ⅲ magnetite indicated that they may precipitate from same period of fluid.In combination with previous studies, we propose that the presence of elements such as Al, Mn, Mg and Sc are in solid solution within magnetite (and/or specularite),but the Ca, S, Cu, Ba, Sr and Zr may be present in micro-/nano-scale mineral inclusions.The widespread presence of magnetite-hematite and specularite in the potassic alteration zone and low Mn concentration of magnetite indicates a high oxygen fugacity of the Lannitang porphyry Cu-Au deposit (magnetite-hematite buffer).
成文过程得到了中国地质科学院地球化学研究所陈伟研究员的指导,在此表示衷心感谢!
| 1 |
陈华勇,韩金生 .磁铁矿单矿物研究现状、存在问题和研究方向[J].矿物岩石地球化学通报,2015,34(4):724-730.
|
| 2 |
|
| 3 |
|
| 4 |
|
| 5 |
|
| 6 |
邱检生,张晓琳,胡建,等 .鲁西碳酸岩中磷灰石的原位激光探针分析及其成岩意义[J].岩石学报,2009,25(11):2855-2865.
|
| 7 |
贾泽荣,詹秀春,何红蓼,等 .激光烧蚀—等离子体质谱结合归一定量方法原位线扫描检测石榴石多种元素[J].分析化学,2009,37(5):653-658.
|
| 8 |
张乐骏,周涛发,范裕,等 .宁芜盆地陶村铁矿床磷灰石的LA-ICP-MS研究[J].地质学报,2011,85(5):834-848.
|
| 9 |
|
| 10 |
|
| 11 |
|
| 12 |
胡浩,段壮,
|
| 13 |
|
| 14 |
|
| 15 |
|
| 16 |
|
| 17 |
|
| 18 |
|
| 19 |
侯增谦,莫宣学 .“三江”地区义敦岛弧的构造—岩浆演化特征[C]//青藏高原地质文集. 北京:地质出版社,1991.
|
| 20 |
曾普胜,莫宣学,喻学惠,等 .滇西北中甸地区中—酸性斑岩及其含矿性初步研究[J].地球学报,1999,20:359-366.
|
| 21 |
曾普胜,王海平,莫宣学,等 .中甸岛弧带构造格架及斑岩铜矿前景[J].地球学报,2004,25(5):535-540.
|
| 22 |
杨岳清,侯增谦,黄典豪,等 .中甸弧碰撞造山作用和岩浆成矿系统[J].地球学报,2002,23(1):17-24.
|
| 23 |
李文昌,尹光候,卢映祥,等 .中甸普朗复式斑岩体演化及40Ar-39Ar同位素依据[J].地质学报,2009,83(10):1421-1429.
|
| 24 |
侯增谦,杨岳清,曲晓明,等 .三江地区义敦岛弧造山带演化和成矿系统[J].岩石学报,2004,78(1):109-120.
|
| 25 |
李建康,李文昌,王登红,等 .中甸弧燕山晚期成矿事件的Re-Os定年及成矿规律研究[J].岩石学报,2007,23(10):2415-2422.
|
| 26 |
冷成彪,张兴春,王守旭,等 .滇西北中旬松诺含矿斑岩的锆石SHRIMP U-Pb年龄及地质意义[J].大地构造与成矿学,2008,32(1):124-130.
|
| 27 |
王守旭,张兴春,冷成彪,等 .滇西北普朗斑岩铜矿锆石离子探针U-Pb年龄:成矿时限及地质意义[J].岩石学报,2008,24(10):2313-2321.
|
| 28 |
庞振山,杜杨松,王功文,等 .云南普朗复式岩体锆石U-Pb年龄和地球化学特征及其地质意义[J].岩石学报,2009,25(1):159-165.
|
| 29 |
任江波,许继峰 ,陈建林 .中甸岛弧成矿斑岩的锆石年代学及其意义[J].岩石学报,2011,27(9):2591-2599.
|
| 30 |
|
| 31 |
|
| 32 |
|
| 33 |
|
| 34 |
紫金矿业集团西南矿产勘察院 .云南香格里拉县烂泥塘及外围地勘项目2013年地质年报[R].云南:紫金矿业集团西南矿产勘察院,2013.
Southwest Mineral Exploration Institute of Zijin Group.Geological annual report of Lannitang and peripheral area in Shangri-la County ,Yunnan Province[R].Yunnan:Southwest Mineral Exploration Institute of Zijin Group,2013.
|
| 35 |
|
| 36 |
|
| 37 |
|
| 38 |
|
| 39 |
|
| 40 |
潘兆橹 .结晶学与矿物学[M].北京:地质出版社,1984:67-71.
|
| 41 |
段士刚,董满华,张作衡,等 .西天山敦德铁矿床磁铁矿原位LA-ICP-MS元素分析及意义[J].矿床地质,2014,33(6):1325-1337.
|
| 42 |
|
| 43 |
|
| 44 |
|
| 45 |
|
| 46 |
芮宗瑶,黄崇轲,齐国明,等 .中国斑岩铜(钼)矿床[M].北京:地质出版社,1984.
|
| 47 |
|
| 48 |
|
| 49 |
|
| 50 |
|
| 51 |
|
| 52 |
|
| 53 |
|
| 54 |
|
| 55 |
|
| 56 |
|
| 57 |
|
| 58 |
林师整 .磁铁矿矿物化学、成因及演化的探讨[J].矿物学报,1982(3):166-174.
|
| 59 |
|
| 60 |
|
| 61 |
|
/
| 〈 |
|
〉 |