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新疆西天山查岗诺尔铁矿床磁铁矿和石榴石微量元素特征及其对矿床成因的制约
引用本文:洪为,张作衡,蒋宗胜,李凤鸣,刘兴忠.新疆西天山查岗诺尔铁矿床磁铁矿和石榴石微量元素特征及其对矿床成因的制约[J].岩石学报,2012,28(7):2089-2102.
作者姓名:洪为  张作衡  蒋宗胜  李凤鸣  刘兴忠
作者单位:1. 中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037
2. 中国地质大学地球科学与资源学院,北京100083;新疆维吾尔自治区地质矿产勘查开发局,乌鲁木齐830000
3. 新疆维吾尔自治区地质矿产勘查开发局第三地质大队,库尔勒,841000
基金项目:本文受国家重点基础研究发展计划(2012CB416803)、国家科技支撑计划(2011BAB06B02)和地质矿产调查评价项目(1212011085060)联合资助.
摘    要:查岗诺尔大型磁铁矿床位于西天山阿吾拉勒东段,赋存于下石炭统大哈拉军山组安山岩及安山质火山碎屑岩之中,主体矿底板夹透镜状的大理岩,矿体主要为层状、似层状、透镜状。根据矿石组构和矿物共生特征,可以划分为岩浆期和热液期两个成矿期,后者包括矽卡岩和石英-硫化物两个亚成矿期,进一步可以细分为6个成矿阶段。岩浆期的磁铁矿∑REE很低,稀土配分模式大致呈轻稀土、重稀土较富集而中稀土亏损的U型,富Ti、V、Cr,表明铁质可能来自安山质岩浆的结晶分异作用; 矽卡岩亚成矿期的磁铁矿∑REE极低,略微富集LREE,其它稀土元素亏损强烈,贫Ti、V,略富集Ni、Co和Cu。矽卡岩亚期的含矿和无矿矽卡岩中的石榴石的稀土配分模式类似,∑REE含量相对较高,呈HREE富集、LREE亏损、弱正Eu异常的分布型式,显示了交代成因石榴石的特征,暗示与其共生的磁铁矿也是通过热液流体与围岩地层的交代反应生成的,铁质来自围岩。结合矿床地质与微量元素地球化学,认为查岗诺尔铁矿可能是岩浆型和矽卡岩型(主要)的复合叠加矿床。

关 键 词:铁矿床  微量元素  稀土元素  磁铁矿  石榴石  查岗诺尔  西天山
收稿时间:2012/1/16 0:00:00
修稿时间:2012/3/13 0:00:00

Magnetite and garnet trace element characteristics from the Chagangnuoer iron deposit in the western Tianshan Mountains, Xinjiang, NW China: Constrain for ore genesis
HONG Wei,ZHANG ZuoHeng,JIANG ZongSheng,LI FengMing and LIU XingZhong.Magnetite and garnet trace element characteristics from the Chagangnuoer iron deposit in the western Tianshan Mountains, Xinjiang, NW China: Constrain for ore genesis[J].Acta Petrologica Sinica,2012,28(7):2089-2102.
Authors:HONG Wei  ZHANG ZuoHeng  JIANG ZongSheng  LI FengMing and LIU XingZhong
Institution:MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Faculty of Geosciences and Resources, China University of Geosciences, Beijing 100083, China;The Bureau of Geology and Mineral Resources Development of Xinjiang, Urumqi 830000, China;No.3 Unit of the Bureau of Geology and Mineral Resources Development of Xinjiang, Korla 841000, China
Abstract:Located in the eastern Awulale metallogenic belt of western Tianshan Mountains, the large-scale Chagangnuoer iron deposit is hosted in the andesite and andesitic volcaniclastics of the Lower Carboniferous Dahalajunshan Formation, with one lentoid marble as footwall rock beneath the main ore bodies which exhibit as lamellar, stratoid and lenticular. The alteration zonation is similar with typical hydrothermal deposits. According to ore fabric and mineral paragenesis, this deposit can be divided into two ore-forming stages, which are magmatic stage and hydrothermal stage (included prograde sub-stage and quarts-sulfide sub-stage). In the magmatic stage, REE in magnetite is very low, rich in LREE and HREE but depleted in MREE with a "U" type pattern. In addition, this kind of magnetites has a higher Ti, V, Cr, indicating that Fe might come from the crystallization differentiation of andesitic magma. On the other hand, in the prograde sub-stage, magnetites have a lower REE content, a bit rich in LREE but other REE strongly depleted. Compared with the magnetites in magmatic stage, these magnetites are poor in Ti, V but a bit abundant in Ni, Co and Cu content. Garnets in barren and ore-bearing skarn distribute the same REE patterns, having a relatively high REE content, enriched in HRRE but depleted in LREE, and with a not pronounced positive Eu anomaly, which displays the feature of garnet with metasomatic origin in the calcic skarn. And this hints that the magnetites, which have a paragenesis relationship with ore-bearing garnets, should be also a product of hydrothermal fluid replacement with wall rocks, and most of the mineralizing materials (Fe) probably are derivate from andesitic strata. In combination geological characteristics with trace element geochemistry, we hold that the Chagangnuoer iron ore is probably one polygenetic deposit with the skarn type (predominated) superposition upon the magmatic type.
Keywords:Iron ore  Trace element  REE  Magnetite  Garnet  Chagangnuoer  Western Tianshan
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