Genesis of the Bayan Obo Fe-REE-Nb formation in Inner Mongolia, North China Craton: A perspective review
Genesis of the Bayan Obo Fe-REE-Nb formation in Inner Mongolia, North China Craton: A perspective review
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DOI：
10.1016/j.precamres.2016.11.008
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发表时间：
2017
影响因子：
3.8
通讯作者：
Xiaoyong Yang;Xiaodong Lai;F. Pirajno;Yulong Liu;M. Ling;Wei-dong Sun
中科院分区：
文献类型：
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作者：
Xiaoyong Yang;Xiaodong Lai;F. Pirajno;Yulong Liu;M. Ling;Wei-dong Sun
内蒙古巴彦鄂博存款矿床是世界上最大的稀土资源。由于元素、矿物组成复杂，加之多期地质事件的活动，其成矿机制至今仍存在争议。本文对前人的研究成果进行了总结，为巴彦鄂博存款的进一步研究提供了参考。通过野外观察和显微镜观察，总结了巴彦鄂博矿区不同类型的铁-稀土-铌矿化，并将其划分为9种类型。本文通过对大量已发表地球化学资料的整理和重新评价，为巴彦鄂博存款是由沉积岩与碳酸盐岩岩浆作用形成的提供了确凿的证据。研究结果表明，铁矿石的形成是沉积作用（Pt 1）的结果，而稀土矿化白云岩的形成可能与碳酸盐岩岩浆和/或伴生流体与沉积碳酸盐岩的相互作用和反应有关，含稀土碳酸盐岩岩浆经历了强烈的分馏富集过程。C-O-S-Fe-Mg同位素特征表明，稀土铌矿化来自沉积碳酸盐岩交代作用（长石蚀变）。提出了这一独特的稀土铌成矿作用的新模式，认为它与早古生代以来西伯利亚板块俯冲到华北板块之下有关。我们认为，巴彦鄂博Fe-REE-Nb矿床及其块状贫容矿H8白云岩是由来自于大陆岩石圈地幔（SCLM）的碳酸盐岩岩浆与沉积碳酸盐岩相互作用的结果。
The Bayan Obo deposit in Inner Mongolia, North China Craton (NCC) is the largest rare-earth element (REE) resource in the world. Due to the complex element and mineral compositions and the activity of several geological events, the ore-forming mechanism is still controversial. Previous models are reviewed here to provide information for further investigation on the Bayan Obo deposit. In this study, we summarize all different types of Fe-REE-Nb mineralization using field observations and microscope work, in which we recognize 9 types of Fe-REE-Nb ores in the Bayan Obo ore district. By compiling and re-evaluating a large number of published geochemical data, this paper provides solid evidence that the Bayan Obo deposit formed through interaction between sedimentary rocks and carbonatite magmatism. From the results of our review, it can be conjectured that the formation of iron ores was originated from sedimentation (Pt1), whereas the formation of REE mineralized dolomite might be related to interaction and reaction between the carbonatite magmas and/or associated fluids with sedimentary carbonate rocks, with the REE-bearing carbonatite magmas having undergone intense fractionation enrichment process. The C-O-S-Fe-Mg isotopes indicate that the REE-Nb mineralization was derived from metasomatism (fenitic alteration) of sedimentary carbonate. A new model is proposed for this unique REE-Nb mineralization, which is related to the subduction of Siberian Craton beneath the North China Craton since Early Paleozoic period. We interpret that the Bayan Obo Fe-REE-Nb ore deposits and their massive barren host, H8 dolomite, were generated as a result of interaction of fluids expelled from a subcontinental lithospheric mantle (SCLM)-derived carbonatite magma with sedimentary carbonates.