纳米比亚西北部朝斯组铁矿地质特征研究与初步经济评价  

Geological characteristics and preliminary economic evaluation of iron ore deposit within the Chuos formation in northwest of Namibia

作　　者：刘典波[1] 李利阳[2] 张传恒[1] LIU Dianbo;LI Liyang;ZHANG Chuanheng(School of Earth Sciences and Resources, China University of Geosciences (Beijing),Beijing 100083,China;No.4 Gold Geological Party of Chinese Armed Police Force,Liaoyang 111000,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]武警黄金第四支队,辽宁辽阳111000

出　　处：《中国矿业》2019年第6期29-35,共7页China Mining Magazine

摘　　要：纳米比亚西北部地区朝斯组中赋存大规模铁矿,该铁矿形成于新元古代约730 Ma时期,由于雪球地球的影响,全球在这一时期形成很多大的铁矿。本文通过对朝斯组铁矿岩芯的观察和对岩芯主量元素特征的分析可知朝斯组铁矿主要由Fe2O3和SiO2组成,铁矿中SiO2含量较高。微量元素特征表明铁矿中富集Co,相对亏损Rb。稀土元素特征表明铁矿中稀土总量均较低,具有相似的REE配分模式,轻稀土相对重稀土亏损,轻微的Eu正异常和明显的Ce负异常。地球化学分析表明铁矿的物质来源兼具陆源沉积物和海相沉积物的特征,Ce的轻微负异常反映了成矿时海水为低氧化环境,而Eu的轻微正异常说明海底低温热液参与了铁矿的成矿过程。朝斯组铁矿石资源量为20亿t,平均品位30%,潜在经济价值为700亿美元。纳米比亚对环境保护严格,采矿的征地成本很高,铁矿所在地区的基础设施非常差,从开采到铁矿运输的成本投入很高,这些都导致纳米比亚铁矿价格优势并不明显。本文认为,如果该地区未来不能发现其他价值更高的共伴生矿产,这些铁矿在目前技术经济条件下开采盈利的前景不明朗。There is a large scale of iron ore deposit within the Chuos formation in northwest of Namibia.The iron ore was formed in about 730 Ma of Neoproterozoic.Due to the influence of snowball earth,many large iron ores formed in the world during this period.By analyzing the major element of iron ore of Chuos formation,it consists mainly of Fe2O3 and SiO2,the SiO2 content is high.Tracing element characteristics indicates that Co is enriched in iron ore and Rb is relatively deficient.The characteristics of rare earth elements indicate that the total amount of rare earth elements in iron ore is relatively low,and there is a similar REE distribution model.The light rare earth has loss relative to heavy rare earth,slight positive Eu anomaly and obvious negative Ce anomaly.The source of iron ore is characterized by both terrestrial sources sediments and marine sedimentary deposits.The slight negative anomaly of Ce reflects the low oxidizing environment of seawater during mineralization,but the slight anomaly of Eu indicates that the undersea cryohydrothermal is involved in the deposit of iron ore.The iron ore resources amount to 2 billion tons,average grade 30%,potential economic value is 70 billion US dollars.There is strictly environmental protection law in Namibia,the cost of land acquisition for mining is high,the infrastructure is poor,and the costs for mining and the ore transportation will be high.All these lead to Namibia iron ore price advantage may not be obvious.This paper argues that if the region cannot find other,more valuable,co-associated minerals in the future,the prospect of the mining of these iron ores under the current technical and economic conditions is not clear.

关 键 词：纳米比亚 朝斯组铁矿 地质特征 经济评价 

分 类 号：P595[天文地球—地球化学] F407[天文地球—地质学]