摘要
弓长岭铁矿床二矿区位于华北板块东北端、弓长岭背斜的北翼、寒岭断裂与老岭断裂之间,以鞍山式富铁矿闻名,其中黑云母变粒岩层(K层)贯穿全区,为二矿区的标志层。重点对二矿区黑云变粒岩的微量稀土元素特征及其指示意义进行了分析和讨论。分析认为,二矿区黑云母变粒岩稀土配分模式为右倾轻稀土富集型,LREE/HREE比值为6.50~12.88.64,(La/Yb)_(N)比值为5.72~15.23,轻、重稀土分异明显,显示较高的分异程度,具较弱的δEu负异常和极弱的δCe负异常,总体显示较高的分馏程度,微量元素方面亏损高场强元素Nb、P和大离子亲石元素Ba、Sr。黑云变粒岩矿物特征、稀土元素La/Yb-REE图解和主量元素[(Al+Fe+Ti)/3-K]-[(Al+Fe+Ti)/3-Na]图解显示其原岩为杂砂岩,且V/Cr、Ni/Co和U/Th指标以及Sr/Ba值分别反映了氧化沉积环境和陆相沉积特征。w(Th)、w(U)、Zr/Th和w(La)等元素特征值和构造环境La/Sc-Ti/Zr判别图结果均显示弓长岭铁矿床二矿区黑云母变粒岩原岩形成于大陆岛弧环境。综上,黑云母变粒岩稀土微量元素特征显示其原岩为陆相沉积杂砂岩,沉积环境为大陆岛弧氧化环境。
No.2 Mine Lot of Gongchangling iron deposit is located at the northeast end of North China Plate,north wing of Gongchangling anticline.It is between Hanling fault and Laoling fault.The mine lot is famous for Anshan type iron ore,especially its rich iron ore.The biotite granular layer(K layer)runs through the whole area,which is the marker layer of No.2 diggings.This paper focuses on the analysis of the characteristics and indication of REE and trace elements of biotite granularities in No.2 mine lot of Gongchangling iron deposit.According to the analysis,REE distribution pattern of biotite granulotites in No.2 diggings was right-leaning LREE enrichment type.LREE/HREE ratio was 6.50~12.88,(La/Yb)_(N) ratio was 5.72~15.23.LREE and HREE differentiation was obvious.It shows high degree of differentiation,weak Eu negative anomaly and very weak Ce negative anomaly.In general,the fractionation degree was high and the trace elements Nb,P and Ba,Sr were depleted.The mineral characteristics,La/Yb-REE diagram and main elements[(Al+Fe+Ti)/3-K]-[(Al+Fe+Ti)/3-Na]diagram show that the original rock was greywacke.The V/Cr,Ni/Co,U/Th and Sr/Ba values reflect the characteristics of oxidized sedimentary environment and continental sedimentary facies respectively.The characteristic values of w(Th),w(U),Zr/Th and w(La)and the discriminant map of La/Sc-Ti/Zr in the tectonic environment all show that the biotite granulotite protolists in No.2 mine lot of Gongchangling iron deposit were formed in continental island arc environment.In conclusion,REE and trace element characteristics of biotite granulite show that the protoliths were continental sedimentary graywacke and the sedimentary environment was continental island arc oxidation environment.
作者
吴明刚
夏建明
WU Minggang;XIA Jianming(School of Marine Geosciences,Ocean University of China,Qingdao,Shandong 266100,China;Yantai Gold College,Yantai,Shandong 265401,China;School of Resource and Materials,Northeastern University at Qinhuangdao,Hebei 066004,China)
出处
《中国锰业》
2022年第5期68-74,共7页
China Manganese Industry
关键词
弓长岭铁矿床二矿区
黑云母变粒岩
稀土微量元素特征
氧化沉积环境
陆相沉积
No.2 diggings of Gongchangling iron deposit
Biotite granulite
Characteristics of REE and trace elements
Oxidized sedimentary environment
Continental sedimentary facies
