辽冀地区条带状铁建造地球化学特征：Ⅱ．稀土元素特征  

Geochemical characteristics of Banded Iron Formations in Liaoning-eastern Hebei area: Ⅱ. Characteristics of rare earth elements

作　　者：姚通[1,2] 李厚民[2] 杨秀清[2,3] 李立兴[2] 陈靖[2] 张进友[4] 刘明军 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]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 [3]北京大学地球与空间科学学院,北京100871 [4]河北省地质矿产勘查开发局第五地质大队,唐山063004 [5]辽宁省冶金地质勘查局地质勘查研究院,鞍山114002

出　　处：《岩石学报》2014年第5期1239-1252,共14页Acta Petrologica Sinica

基　　金：国家“973”项目(2012CB416801);国土资源部公益性行业科研专项经费项目(200911007-15、201111002);地质矿产调查评价项目(1212011120988)联合资助

摘　　要：辽冀地区（鞍山-本溪地区和冀东地区）位于华北克拉通北东部，是我国早前寒武纪条带状铁建造（BIFs）最重要的分布区，主要为新太古代Algoma型。本文系统对比了辽冀地区28个铁矿床200件铁矿石样品的稀土元素特征。结果表明：（1）所有样品的稀土元素特征比较相似：稀土元素总量较低，Y／Ho比值较高；经太古宙后平均澳大利亚页岩（PAAS）标准化后呈现重稀土相对富集、轻稀土相对亏损的配分模式，La异常不明显，强烈的Eu正异常和明显的Y正异常，暗示研究区铁矿石成矿物质主要来源于海底高温热液和海水的混合溶液；与冀东地区BIFs相比，鞍本地区Eu异常更为明显，说明鞍本地区BIFs显示更多的热液特征；（2）铁矿石的Ce／Ce＊变化范围为0．77～1．09，缺乏明显的Ce负异常，说明其沉积于还原的海水环境；（3）辽冀地区BIFs的稀土元素总量、Eu异常、Y异常和Y／Ho比值变化范围均比较大，可能与BIFs沉积过程中碎屑物质的加入有关；与鞍本地区相比，冀东地区BIFs的Eu正异常、Y正异常程度均小于鞍本地区，热液和海水特征均不明显。Y／Ho比值更接近球粒陨石（26—28），可能暗示冀东地区有更多的碎屑物质的加入。The Early Precambrian Banded Iron Formations （BIFs） are the most important iron ore resources type in China, and account for approximately 64% of the total identified resources. In China, BIFs are mainly distributed in greenstone belts of the North China Craton, such as Anshan-Benxi （ in Liaoning Province）, Jidong （ in Hebei Province） -Miyun （ in Beijing）, Wutai （ in Shanxi Province）, Wuyang （in Henan Province）, Huoqiu （in Anhui Province）, and Luxi （in Shandong Province）. Liaoning-eastern Hebei area （ including Anshan-Benxi area and eastern Hebei area） is the study area, which accounts for more than 34% of overall iron ore reserves in China. Anshan-Benxi area includes Anshan, Benxi, and Liaoyang and so on, which is composed of the supracrustal rock （about 30% ） and granitic rock （about 70% ）. Archean Anshan Group is the major ore stratum, iron ore mainly occurs in the Middle and Upper Anshan Group. The rocks have undergone greenschist to amphibolite facies metamorphism. Eastern Hebei area includes Zunhua, Qianxi, Kuaneheng, Qinglong, Qianan and so on, which is composed of the crystalline basement and sedimentary cover. Iron ore mainly hosted in the Qianxi Group, Zunhua Group, Luanxian Group and Zhuzhangzi Group. The rock have been strongly migmatized, and metamorphosed to the greenschist to granulite facies. Based on field geological and microscopic studies, we found that there are many differences exist on the ore type, degree of metamorphism, ore formation, and mineral combination between the Anshan- Benxi and the eastern Hebei area. In this study, we mainly report rare earth elements of 200 samples of iron ore from 28 iron deposits in Liaoning-eastern Hebei area. The results show that ： （ 1 ） All samples show very similar characteristics of total contents of REE and Y ： the total contents of REE are very low, but Y/Ho ratios are high. After normalized by Post Archean Australian Shale （ PAAS）, REE and Y patterns display depletion of light REE relative to h

关 键 词：条带状铁建造 稀土元素 鞍山-本溪地区 冀东地区 华北克拉通 

分 类 号：P595[天文地球—地球化学] P618.31[天文地球—地质学]