| 沙 鑫.北祁连西段卡瓦铁矿的地球化学特征及其地质意义[J].地质与勘探,2016,52(4):657-666 |
| 北祁连西段卡瓦铁矿的地球化学特征及其地质意义 |
| Geochemical features of the Kawa iron ore deposit in the western section of the North Qilian Mountains |
| 投稿时间：2016-01-30 修订日期：2016-06-02 |
| DOI： |
| 中文关键词: 北祁连西段 卡瓦铁矿 物质来源 成矿环境 |
| 英文关键词: Western North Qilian, Kawa iron ore deposit, source, metallogenic environment |
| 基金项目:甘肃省2014年省级矿产资源补偿费地质勘查项目（甘财建[2014] 99号）、中央高校基本科研业务费项目（Lzu-Jbky-2012-128）和兰州大学甘肃省西部矿产资源重点实验室基金项目联合资助 |
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| 中文摘要: |
| 卡瓦铁矿位于北祁连造山带西段，是新近发现的沉积变质型铁建造。矿石全铁(Fe2O3T，平均45.28%)含量最高，其次为SiO2含量（平均40.50%），并具有较高的亲生物化合物P2O5（平均0.73%）及陆缘碎屑组分Al2O3（平均4.69%）、TiO2（平均0.31%）；Ba以及对氧化还原敏感的元素U、Th相对富集，Nb、Ta、Sr、Zr、Hf相对亏损；稀土总量较高，LREE亏损、HREE富集，弱的La正异常，无Eu、Ce、Y异常，Sr/Ba、Y/Ho比值与陆源沉积物相近。综合分析认为卡瓦铁矿是中元古代早期海洋化学沉积的产物，在形成过程中伴有较多陆缘碎屑物质的加入。此外，卡瓦铁矿缺乏Ce负异常，U、Th的相对富集，表明铁矿沉积于低氧的环境。 |
| 英文摘要: |
| The Kawa iron ore deposit is located in the west section of the North Qilian orogenic belt, which is a newly discovered sedimentary metamorphic iron formation. In the average major compositions of its iron ore, total Fe2O3T is highest (44.22% on average)，next is SiO2 (40.50%), with relative enrichment of P2O5(0.73%), Al2O3(4.69%) and TiO2(0.31%). Trace elements show that Ba and redox-sensitive trace elements (U, Th) are relatively enriched, while Ta, Nb, Sr, Zr and Hf are relatively depleted. The total rare earth element contents are high, and the PAAS-normalized REE patterns display depletion of light REE relative to heavy REE; La positive anomalies, non-significant positive anomalies of Eu, Ce, Y and low Sr/Ba, Y/Ho values. These characteristics demonstrate that the iron source of the Kawa iron ore deposit are the product of Early Proterozoic ocean chemical deposition, with much addition of continental margin clastic material during its formation. In addition, the Kawa iron ore deposit lacka Ce negative anomalies and has relative enrichment of U and Th, implying the oxygen fugacity was relatively low in its depositional environment． |
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