Bayan Obo deposit (Bayun-Obo deposit; Baiyunebo deposit), Bayan Obo, Bayan Obo Mining District, Baotou League (Baotou Prefecture), Inner Mongolia Autonomous Region, China
|Latitude & Longitude (WGS84):||41° 47' 45'' North , 109° 58' 10'' East|
|Latitude & Longitude (decimal):||41.79583,109.96944|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
Superlarge polygenic REE-Fe-Nb deposit (Bayan-Obo type), discovered as an iron deposit in 1927. REE minerals were discovered in 1936, and Nb-bearing ores in the late 1950s. Reserves are estimated at more than 40 million tons of REE minerals grading at 3-5.4% REE (70% of world's known REE reserves), 1 million tons of Nb2O5 and 470 million tons of iron. The deposit also contains a vast amount of fluorite, which is contained in all ore types; reserves are estimated at 130 million tons.
Bayon Obo is the world's largest REE deposit. The fluorite content of the ores also makes it the world's largest fluorite deposit.
The deposit occurs in an east-west trending Mesoproterozoic rift zone along the northern margin of the Sino-Korean Craton. Host strata are quartzite, slate, limestone, and dolomite. The latter is also the main host rock. The orebodies are stratiform and lenticular, with masses, bands, layers, veins, and disseminations. Besides clear features of hot water sedimentation, the deposit also exhibits Mg, Fe, Na and F metasomatism. Sm-Nd monazite isochron age for bastnaesite and riebeckite is 1200 to 1300 Ma, whereas Th-Pb and Sm-Nd age of Ba-REE-F carbonates and aeschynite is 474 to 402 Ma.
Aegirine from metamorphic rocks associated with the ore is peculiar in being colourless in thin section, possibly due to the lack of charge transfer transitions.
Mineral ListMineral list contains entries from the region specified including sub-localities
128 valid minerals. 15 (TL) - type locality of valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
252.17 - 541 Ma
|Paleozoic intrusive and metamorphic terranes|
Age: Paleozoic (252.17 - 541 Ma)
Comments: Mixtures of metamorphic and intrusive or plutonic rocks, tracts known as crystalline, migmatitic terranes, moderately to highly metamorphosed rocks of unknown origin with or without intrusions. This classification is inherently prone to variable interpretation, as other compilers might distinguish some packages by their metamorphic or gneissic protoliths, and the associated age ranges may be more variable.
Lithology: Intrusive and metamorphic terranes
Reference: Geological Survey of Canada. Generalized geological map of the world and linked databases. doi:10.4095/195142. Open File 2915d. 
Localities in this Region
Zonglin Hou (1982): Discussion on a symbiotic sedimentary-metamorphic origin of the Bayan Obo deposit. Geology and Prospecting 18(8), 24-29, 52 (in Chinese).
Ren Yingchen, Ximen Lulu, and Peng Zhizhong (1983): Daqingshanite: A new mineral recently discovered in China. Geochemistry 2(2), 180-84 (in English).
Jutian Qiu and Tiegeng Liu (1986): On the genesis of the Bayan Obo carbonatites. Geology and Prospecting 22(8), 35-40 (in Chinese).
Zhang, P. and Tao, K. (1986): Bayan Obo mineralogy. Science Publishers, Beijing, 208 pp. (in Chinese with English abstract)
Tiegeng Liu, Guanxin Wang, and Jiwen Gong (1987): A study of brockite found in China. Acta Mineralogica Sinica 7(2), 177-182.
Zonglin Hou (1989): The Bayan Obo Fe-Nb-REE deposit: its basic geological features, metallogenesis and genetic model. Geology and Prospecting 25(7), 1-5, 22 (in Chinese with English abstract).
Youbin Liang (1990): The Discovery and Study of Strontianiferous Aragonite. Acta Petrologica et Mineralogica 9(1).
Drew, L.J., Qingrun Meng, and Weijun Sun (1990): The Bayan Obo iron-rare-earth-niobium deposits, Inner Mongolia, China. Lithos, 26, 43-65.
Le Bas, M.J., Kellere, J., Tao Kejie, Wall, F., William, C.T., and Zhang Peishan (1992): Carbonatite dykes at Bayan Obo, Inner Mongolia, China. Mineralogy and Petrology 46(3), 195-228.
Wenmei Wang and Yongfu Yu (1993): A study on aegirine from Baiyun Obo ore deposit. Acta Mineralogica Sinica 13(2), 169-173.
Zhang Peishan, Yang Zhuming, Tao Kejie, and Yang Xueming (1996): "Mineralogy and Geology of Rare Earths in China", Science Press (Beijing), 226 pp.
Zhongxin Yuan and Ge Bai (1997): Distribution of alkaline intrusive rocks and related metallic ore deposits of China. Geology and Prospecting 33(1), 42-48 (in Chinese with English abstract).
Tu Guangchi and Wang Kaiyi (1997): Factors Constraining the Formation of the Superlarge Bayan-Obo REE-Fe-Nb Deposit. In: Pei Rongfu (ed.): Proceedings of the 30th International Geological Congress, Vol.9, VSP (Utrecht, Tokyo), pp. 83-90.
Chao, E.C.T., Back, J.M., Minkin, J.A., Tatsumoto, M., Wang Junwen, Conrad, J.E., McKee, E.H., Hou Zonglin, Meng Qingrun, and Huang Shengguang (1997): The Sedimentary Carbonate-Hosted Giant Bayan Obo REE-Fe-Nb Ore Deposit of Inner Mongolia, China: A Cornerstone Example for Giant Polymetallic Ore Deposits of Hydrothermal Origin. USGS Bulletin 2143.
Jiyuan Gao, Yixian Wang, Yuzhuo Qiu, and Qian Zhang (1999): Origin of the ore-bearing dolomite in Baiyun Obo ore deposit. Acta Sedimentologica Sinica 17(s1), 675-680.
Smith, M.P., Henderson, P., and Peishan, Z. (1999): Reaction relationships in the Bayan Obo Fe-REE-Nb deposit Inner Mongolia, China: implications for the relative stability of rare-earth element phosphates and fluorocarbonates. Contributions to Mineralogy and Petrology 134, 294-310.
Smith, M.P., Henderson, P., and Campbell, L.S. (2000): Fractionation of the REE during hydrothermal processes: constraints from the Bayan Obo Fe-REE-Nb deposit, Inner Mongolia, China. Geochimica et Cosmochimica Acta 64(18), 3141-1360.
Orris, G.J., and Grauch, R.I. (2002): USGS Open-File Report 02-189.
Zhongxin Yuan, Ge Bai, and Zongqing Zhang (2004): Autometasomatic phenomena of host rocks in the Bayan Obo ore deposit and their significance. Acta Petrologica et Mineralogica 23(1), 19-25.
Zhuming Yang, Rengui Song, Kejie Tao, and Peishan Zhang (2003): Rare earth compositional variation of aeschynite group minerals. Journal of the Chinese Rare Earth Society 21(6), 716-720.
Hongrui Fan, Yihan Xie, Kaiyi Wang, and Wilde, S.A. (2004): Methane-rich fluid inclusions in skarn near the giant REE–Nb–Fe deposit at Bayan Obo, Northern China. Ore Geology Reviews 25, 301-309.
Jinsha Xu and Ganfu Shen (2005): Mineralogical study on fluorophlogopite from the Bayan Obo ore deposit. Acta Mineralogica Sinica 25(3), 213-216.
Gupta, C.K., and Krishnamurthy, N. (2005): Extractive Metallurgy of Rare Earths. CRC Press (Boca Raton), 484 pp.
Zhanfeng Yang and Jianyong Liu (2007): Necessity and feasability of Baiyunebo rare earth deposit prospecting. Chinese Rare Earths 28(6), 84-87.
Jinsha Xu, Guaming Yang, Guowu Li, Zhilan Wu, Ganfu Shen (2008): A new mineral, Dingdaohengite-(Ce): the polymorph of Perrierite-(Ce) and a titanium analog at the C(1) site of Chevkinite sub-group. Acta Mineralogica Sinica 28(3), 237-243.
Berger, V.I., Singer, D.A., and Orris, G.J. (2009): Carbonatites of the World. Explored Deposits of Nb and REE - Database and Grade and Tonnage Models. USGS Open-File Report 09-1139.
Jindrich Kynicky, Martin P. Smith and Cheng Xu (2012): Diversity of Rare Earth Deposits: The Key Example of China. Elements 8, 361-367.
Ribeiro Da Costa, I., Rodrigues, C.R., Barriga, F.J.A.S., Rona, P.A., Nunes, C.D., Vaz, P.D. (2014): Colourless aegirine in metamorphic rocks from Bayan Obo (Inner Mongolia): lack of charge transfer transitions as possible explanation. European Journal of Mineralogy: 25(6): 987-993.