CAJ | 학술논문

辽宁眼前山铁矿位于鞍山地区南北向和东西向铁矿构造变形带的复合部位，为鞍山地区鞍山式铁矿床的典型代表。本文对眼前山铁矿的岩石学、矿物学进行了研究，对该区铁建造和围岩的主量和微量元素地球化学进行了分析。该区铁建造以条带状为主，少量为块状，其顶底板围岩及矿体夹层主要为太古宇鞍山群千枚岩。主量分析结果表明，铁矿石主要由SiO2和铁的氧化物组成，Al2O3含量较低，LOI较大。矿石微量元素分配曲线属于右倾型，强不相容元素和大离子亲石元素富集，具有显著的Eu正异常，是海底高温热液(>300℃)与海水混合的结果，表明了该区BIF形成与海底热液活动关系密切。该区BIF中富集重稀土元素，Y/Ho大于26，La和Eu具有正异常。由于缺少陆源碎屑物质，要形成稳定的条带状构造，推断该区的BIF形成于海水深度大于200 m的浅海环境，形成机制应该是富含铁的海底热液运移到相对浅水区发生氧化沉积所致。通过A-C-FM原岩恢复，结合Zr/TiO2-Ni图解可知千枚岩为变质沉积岩；Sm/Nd比值也显示了沉积岩的特点。该区千枚岩中Th的变化范围为7.9×10-6~22.5×10-6，平均为15.8×10-6；La的变化范围为17.9×10-6~71.7×10-6，平均为38.4×10-6；La/Sc的平均值为2.3；Th/Sc的平均值为1.0；La/Th的平均值为2.4。这些值都接近大陆岛弧沉积岩特征。综合分析认为，眼前山铁矿成矿环境相当于弧后盆地。
료녕안전산철광위우안산지구남북향화동서향철광구조변형대적복합부위，위안산지구안산식철광상적전형대표。본문대안전산철광적암석학、광물학진행료연구，대해구철건조화위암적주량화미량원소지구화학진행료분석。해구철건조이조대상위주，소량위괴상，기정저판위암급광체협층주요위태고우안산군천매암。주량분석결과표명，철광석주요유SiO2화철적양화물조성，Al2O3함량교저，LOI교대。광석미량원소분배곡선속우우경형，강불상용원소화대리자친석원소부집，구유현저적Eu정이상，시해저고온열액(>300℃)여해수혼합적결과，표명료해구BIF형성여해저열액활동관계밀절。해구BIF중부집중희토원소，Y/Ho대우26，La화Eu구유정이상。유우결소륙원쇄설물질，요형성은정적조대상구조，추단해구적BIF형성우해수심도대우200 m적천해배경，형성궤제응해시부함철적해저열액운이도상대천수구발생양화침적소치。통과A-C-FM원암회복，결합Zr/TiO2-Ni도해가지천매암위변질침적암；Sm/Nd비치야현시료침적암적특점。해구천매암중Th적변화범위위7.9×10-6~22.5×10-6，평균위15.8×10-6；La적변화범위위17.9×10-6~71.7×10-6，평균위38.4×10-6；La/Sc적평균치위2.3；Th/Sc적평균치위1.0；La/Th적평균치위2.4。저사치도접근대륙도호침적암특정。종합분석인위，안전산철광성광배경상당우호후분지。
Located in the central eastern part of Liaoning Province, the Yanqianshan iron deposit is a typical iron deposit of this area. The authors studied the petrographic and mineralogical characteristics of the Yanqianshan iron deposit, and analyzed the major and trace element geochemical characteristics of the iron formation and rocks. The iron formation is mainly the banded iron formation (BIF) and contains a small amount of lump ore, with its roof and floor rock as well as orebody interbed being mainly Archean Anshan Group phyllite. Analyses of major elements show that the iron ore is mainly composed of SiO2 and iron oxides, with low Al2O3 content and high LOI. The trace element distribution curve of the ore is of the right-oblique type, with the enrichment of the highly incompatible elements and LILE. There is a significant positive Eu anomaly, which resulted from the mixture of the seafloor hydrothermal fluid (>300℃) with the seawater. It is shown that the BIF formation of this area was closely related to the seafloor hydrothermal activity. The HREE are abundant in the BIF in this area, the Y/ Ho ratios are greater than 26, and La and Eu have positive anomalies. Due to lack of terrigenous material, the authors infer that the BIF formed in shallow water with the depth greater than 200m, and the iron-rich hydrothermal fluids migrated to relatively shallow water area and then experienced oxidation and precipitation to form a stable banded structure. A-C-FM restoration of the original rock in combination with Zr/TiO2-Ni diagram shows that phyllite is a kind of metasedimentary rock, and Sm/Nd ratios also suggest the characteristics of sedimentary rocks. Th values vary from 7.9 to 22.5×10-6 with an average of 15.8×10-6, La values vary from 17.9 to 71.7×10-6 with an average of 38.4 ×10-6, the average of La/Sc ratios is 2.3, the average of Th/Sc ratios is 1.0, and the average of La/Th ratios is 2.4 in the phyllite of this area. These data suggest the continental island arc sedimentary characteristics. It is thus concluded that the metallogenic environment of the Yanqianshan iron deposit was a back-arc basin around the Archean craton.