Geochemical characteristics of the Bayan Obo giant REE-Nb-Fe deposit: Constraints on its genesis

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• 作者：Xiaodong Lai ; Xiaoyong Yang ; ^{xyyang555@163.com}
• 关键词：Dolomite ; REE&ndash ; Nb&ndash ; Fe mineralization ; Element geochemistry ; Sulfur isotope ; Bayan Obo ; Inner Mongolia
• 刊名：Journal of South American Earth Sciences
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：41
• 期：Complete
• 页码：99-112
• 全文大小：2275 K

文摘

Geochemical characteristics of different dolomites in the Bayan Obo giant REE-Nb-Fe deposit in Inner Mongolia have been studied. Intensively REE-mineralized dolomites (total REE over 800?ppm) show similar geochemical characteristics to associated carbonatite dykes, with Ba, Th, REE enrichments and Sr, Nb, Ti, Cu depletions, which is different from those of dolomites in the deposit with low REE contents (total REE less than 800?ppm). The low REE dolomites display some transitional characteristics between carbonatite dyke and sedimentary carbonate, with La depletion and Nb enrichment. This indicates that the genesis of the REE-mineralized dolomites might be related to both carbonatite magma and sedimentary carbonates. Sulfur isotope data indicates two sulfur sources, a mantle source (¦Ä³⁴S c.a. 0¡ë) and seawater (¦Ä³⁴S c.a.?+25¡ë). It is proposed that mineralized dolomites in the Bayan Obo giant REE-Nb-Fe deposit are the product of sedimentary carbonate hydrothermally metasomatised by carbonatite magma and/or associated fluids. These dolomites formed the large-scale rare earth mineralization in the unique Bayan Obo REE-Nb-Fe deposit.