Typomorphic characteristics of magnetite and prediction of deep iron-rich orebody in the Bayan Obo ore deposit

doi:10.13745/j.esf.sf.2022.10.45

Abstract

Abstract:

The Bayan Obo rare earth-niobium-iron ore deposit contains a large amount of iron resources, among which magnetite has been widely studied as an ore mineral. Typomorphic characteristics of magnetite can be used to explore the genesis, metallogenic regularity and deep prospecting of the ore deposit, however, they have not been commonly studied in the Bayan Obo ore deposit. In this paper, the total iron data of 22 exploration lines were used, and mineral micro-zone composition testing was performed on 45 samples from 10 exploration lines covering 600 × 600 meters in area and 800 meters in depth, using energy dispersive spectroscopy (EDS) and electron probe (EPMA) methods. The Bayan Obo magnetite can be divided into magmatic and hydrothermal magnetites, indicating both are formed or modified in the ore deposit. Combined with thermometric data, it can be seen that wherever magnetites are enriched, the local total iron content is also higher, and iron-rich orebodies are easy to form at formation temperatures ranging between 350-650℃. Under such observation, deep iron-rich orebodies are likely to form in the eastern direction of Line 12 and 13 and may be connected to the eastern deep ore deposit, which is worthy of further research and exploitation.

Key words: Bayan Obo deposit, magnetite, typomorphic mineral, hydrothermal, magma, prospecting

CLC Number:

P618.31

XU Zhihao, YAN Guoying, YANG Zongfeng, WANG Zhaojing, SHEN Junfeng, ZHANG Mengmeng, LI Peipei, XU Kexin. Typomorphic characteristics of magnetite and prediction of deep iron-rich orebody in the Bayan Obo ore deposit[J]. Earth Science Frontiers, 2023, 30(2): 426-439.

Figures/Tables 11

Fig.1 Regional geological map of the Bayan Obo deposit. Base map modified after [54-55].

Fig.2 Horizontal distribution map of different ore and sampling locations in Bayan Obo main mine. Base map modified after [2].

Table 1 Data table of total iron, REE2O3, Nb2O5 in Bayan Obo deposit

Fig.3 Diagram of sampling points in Bayan Obo main deposit

Table 2 Major element of Bayan Obo magnetite

Fig.4 Longitudinal projection contour map of the contents of major elements (wB/%) in magnetite in Bayan Obo deposit

Fig.5 Comparison of SEM-EDS data and EPMA data in magnetite of some samples

Fig.6 Genetic classification of BayanObo magnetite. Base map adapted from [32].

Fig.7 Longitudinal projection contour map of proportion of hydrothermal magnetite (%)

Fig.8 Longitudinal projection isotherm (℃) of magnetite

Fig.9 Longitudinal projection isotherm (℃) of magmatic magnetite (A) and longitudinal projection isotherm (℃) of hydrothermal magnetite (B)

References 74

[1]	SMITH M P, CAMPBELL L S, KYNICKY J. A review of the genesis of the world class Bayan Obo Fe-REE-Nb deposits, Inner Mongolia, China: multistage processes and outstanding questions[J]. Ore Geology Reviews, 2015, 64: 459-476. DOI URL
[2]	郝美珍, 赵永岗, 张顺, 等. 白云鄂博超大型Nb-Fe-REE矿床主矿矿体形态变化及深部找矿方向的探讨[J]. 地质调查与研究, 2018, 41(3): 167-175.
[3]	王凯怡, 张继恩, 郝美珍, 等. 白云鄂博赋矿白云岩的稀土地球化学及对稀土矿化的制约[J]. 地质科学, 2020, 55(2): 439-458.
[4]	YANG X Y, LAI X D, PIRAJNO F, et al. Genesis of the Bayan Obo Fe-REE-Nb formation in Inner Mongolia, North China Craton: a perspective review[J]. Precambrian Research, 2017, 288: 39-71. DOI URL
[5]	高计元, 王一先, 裘愉卓, 等. 白云鄂博矿床含矿白云岩的成因探讨[J]. 沉积学报, 1999, 17(增刊1): 675-680.
[6]	章雨旭, 吕洪波, 张绮玲, 等. 微晶丘成因新认识[J]. 地球科学进展, 2005, 20(6): 693-700. DOI
[7]	章雨旭, 彭阳, 乔秀夫, 等. 白云鄂博矿床赋矿白云岩成因新认识[J]. 地质论评, 1998, 44(1): 70-76.
[8]	魏菊英, 上官志冠. 内蒙古白云鄂博铁矿床中磁铁矿和赤铁矿的氧同位素组成[J]. 地质科学, 1983, 18(3): 217-224.
[9]	LE BAS M J, XUEMING Y, TAYLOR R N, et al. New evidence from a calcite-dolomite carbonatite dyke for the magmatic origin of the massive Bayan Obo ore-bearing dolomite marble, Inner Mongolia, China[J]. Mineralogy and Petrology, 2007, 90(3/4): 223-248. DOI URL
[10]	ZHANG S H, ZHAO Y, LIU Y S. A precise zircon Th-Pb age of carbonatite sills from the world’s largest Bayan Obo deposit: implications for timing and genesis of REE-Nb mineralization[J]. Precambrian Research, 2017, 291: 202-219. DOI URL
[11]	DENG M, XU C, SONG W L, et al. REE mineralization in the Bayan obo deposit, China: evidence from mineral paragenesis[J]. Ore Geology Reviews, 2017, 91: 100-109. DOI URL
[12]	HU L, LI Y K, WU Z J, et al. Two metasomatic events recorded in apatite from the ore-hosting dolomite marble and implications for genesis of the giant Bayan Obo REE deposit, Inner Mongolia, Northern China[J]. Journal of Asian Earth Sciences, 2019, 172: 56-65. DOI URL
[13]	KUEBLER C, SIMONETTI A, CHEN W, et al. Boron isotopic investigation of the Bayan Obo carbonatite complex:insights into the source of mantle carbon and hydrothermal alteration[J]. Chemical Geology, 2020, 557: 119859. DOI URL
[14]	LAI X D, YANG X Y, SANTOSH M, et al. New data of the Bayan Obo Fe-REE-Nb deposit, Inner Mongolia:implications for ore genesis[J]. Precambrian Research, 2015, 263: 108-122. DOI URL
[15]	LIU S, DING L, FAN H R, et al. Hydrothermal genesis of Nb mineralization in the giant Bayan Obo REE-Nb-Fe deposit (China):implicated by petrography and geochemistry of Nb-bearing minerals[J]. Precambrian Research, 2020, 348: 105864. DOI URL
[16]	LIU S, FAN H R, GROVES D I, et al. Multiphase carbonatite-related magmatic and metasomatic processes in the genesis of the ore-hosting dolomite in the giant Bayan Obo REE-Nb-Fe deposit[J]. Lithos, 2020, 354/355: 105359. DOI URL
[17]	LIU S, FAN H R, YANG K F, et al. Fenitization in the giant Bayan obo REE-Nb-Fe deposit: implication for REE mineralization[J]. Ore Geology Reviews, 2018, 94: 290-309. DOI URL
[18]	WANG K Y, FANG A M, ZHANG J E, et al. Genetic relationship between fenitized ores and hosting dolomite carbonatite of the Bayan obo REE deposit, Inner Mongolia, China[J]. Journal of Asian Earth Sciences, 2019, 174: 189-204. DOI URL
[19]	邓淼, 韦春婉, 许成, 等. 白云鄂博超大型稀土矿床成因评述[J]. 地学前缘, 2022, 29(1): 14-28. DOI
[20]	王凯怡, 张继恩, 方爱民, 等. 白云鄂博矿床成因: 矿体内霓长岩化成矿作用与赋矿白云岩的联系[J]. 岩石学报, 2018, 34(3): 785-798.
[21]	柯昌辉, 孙盛, 赵永岗, 等. 内蒙古白云鄂博超大型稀土-铌-铁矿床控矿构造特征及深部找矿方向[J]. 地质通报, 2021, 40(1): 95-109.
[22]	李以科, 柯昌辉, 王登红, 等. 白云鄂博矿区深边部铁矿床勘查突破及启示[J]. 矿床地质, 2022, 41(1): 202-206.
[23]	CAMPBELL L S, COMPSTON W, SIRCOMBE K N, et al. Zircon from the East Orebody of the Bayan Obo Fe-Nb-REE deposit, China, and SHRIMP ages for carbonatite-related magmatism and REE mineralization events[J]. Contributions to Mineralogy and Petrology, 2014, 168(2):1041. DOI URL
[24]	KE C H, LI Y K, WU Z J. The first discovery of the earlypalaeozoic carbonatite in the Bayan obo deposit, Inner Mongolia, China: evidence from zircon U-Pb geochronology[J]. Acta Geologica Sinica (English Edition), 2018, 92(6): 2440-2442.
[25]	LAI X D, YANG X Y, LIU Y L, et al. Genesis of the Bayan obo Fe-REE-Nb deposit: evidences from Pb-Pb age and microanalysis of the H8 formation in Inner Mongolia, North China Craton[J]. Journal of Asian Earth Sciences, 2016, 120: 87-99. DOI URL
[26]	NI P, ZHOU J, CHI Z, et al. Carbonatite dyke and related REE mineralization in the Bayan Obo REE ore field, North China: evidence from geochemistry, CO isotopes and RbSr dating[J]. Journal of Geochemical Exploration, 2020, 215: 106560. DOI URL
[27]	ZHANG H D, ZHAI M G, WANG D Q, et al. Dating of monazite-apatite-allanite-epidote corona from the Bayan Obo Group in the northern margin of the North China Craton: implications for the time of regional Au and REE mineralization[J]. Science Bulletin, 2022, 67(3): 236-239. DOI URL
[28]	ZHU X K, SUN J, PAN C X. Sm-Nd isotopic constraints on rare-earth mineralization in the Bayan Obo ore deposit, Inner Mongolia, China[J]. Ore Geology Reviews, 2015, 64: 543-553. DOI URL
[29]	刘玉龙, 陈江峰, 李惠民, 等. 白云鄂博矿床白云石型矿石中独居石单颗粒U-Th-Pb-Sm-Nd定年[J]. 岩石学报, 2005, 21(3): 881-888.
[30]	张宗清, 唐索寒, 王进辉, 等. 白云鄂博矿床白云岩的Sm-Nd、Rb-Sr同位素体系[J]. 岩石学报, 2001, 17(4): 637-642.
[31]	朱祥坤, 孙剑. 内蒙古白云鄂博矿床的稀土矿化时代与期次[J]. 地球学报, 2012, 33(6): 845-856.
[32]	DARE S A S, BARNES S J, BEAUDOIN G, et al. Trace elements in magnetite as petrogenetic indicators[J]. Mineralium Deposita, 2014, 49(7): 785-796. DOI URL
[33]	GRIGSBY J D. Detrital magnetite as a provenance indicator[J]. Journal of Sedimentary Research, 1990, 60(6): 940-951.
[34]	DUPUIS C, BEAUDOIN G. Discriminant diagrams for iron oxide trace element fingerprinting of mineral deposit types[J]. Mineralium Deposita, 2011, 46(4): 319-335. DOI URL
[35]	NADOLL P, MAUK J L, HAYES T S, et al. Geochemistry of magnetite from hydrothermal ore deposits and host rocks of the mesoproterozoic belt supergroup, United States[J]. Economic Geology, 2012, 107(6): 1275-1292. DOI URL
[36]	BOUTROY E, DARE S A S, BEAUDOIN G, et al. Magnetite composition in Ni-Cu-PGE deposits worldwide: application to mineral exploration[J]. Journal of Geochemical Exploration, 2014, 145: 64-81. DOI URL
[37]	CHEN W T, ZHOU M F, LI X C, et al. In-situ LA-ICP-MS trace elemental analyses of magnetite: Cu-(Au, Fe) deposits in the Khetri copper belt in Rajasthan Province, NW India[J]. Ore Geology Reviews, 2015, 65: 929-939. DOI URL
[38]	GENNA D, GABOURY D. Deciphering the hydrothermal evolution of a VMS system by LA-ICP-MS using trace elements in pyrite: an example from thebracemac-McLeod deposits, Abitibi, Canada, and implications for exploration[J]. Economic Geology, 2015, 110(8): 2087-2108. DOI URL
[39]	HU H, LENTZ D, LI J W, et al. Reequilibration processes in magnetite from iron skarn deposits[J]. Economic Geology, 2015, 110(1): 1-8. DOI URL
[40]	YI L W, GU X P, LU A H, et al. Major and trace elements of magnetite from the qimantag metallogenic belt: insights into evolution of ore-forming fluids[J]. Acta Geologica Sinica - English Edition, 2015, 89(4): 1226-1243. DOI URL
[41]	ZHAO W W, ZHOU M F. In-situ LA-ICP-MS trace elemental analyses of magnetite: the Mesozoic Tengtie skarn Fe deposit in the Nanling Range, South China[J]. Ore Geology Reviews, 2015, 65: 872-883. DOI URL
[42]	李伟, 谢桂青, 朱乔乔, 等. 鄂东南程潮铁矿多世代叠加成矿作用: 磁铁矿证据[J]. 岩石学报, 2016, 32(2): 471-492.
[43]	NADOLL P, ANGERER T, MAUK J L, et al. The chemistry of hydrothermal magnetite: a review[J]. Ore Geology Reviews, 2014, 61: 1-32. DOI URL
[44]	HUANG X W, ZHOU M F, QIU Y Z, et al. In-situ LA-ICP-MS trace elemental analyses of magnetite: the Bayan Obo Fe-REE-Nb deposit, North China[J]. Ore Geology Reviews, 2015, 65: 884-899. DOI URL
[45]	SHE H D, FAN H R, YANG K F, et al. In situ trace elements of magnetite in the Bayan Obo REE-Nb-Fe deposit: implications for the genesis of mesoproterozoic iron mineralization[J]. Ore Geology Reviews, 2021, 139: 104574. DOI URL
[46]	CHEN W, YING Y C, BAI T, et al. In situ major and trace element analysis of magnetite from carbonatite-related complexes: implications for petrogenesis and ore genesis[J]. Ore Geology Reviews, 2019, 107: 30-40. DOI URL
[47]	HUANG X W, BEAUDOIN G. Nanoinclusions in zoned magnetite from the Sossego IOCG deposit, Carajás, Brazil: implication for mineral zoning and magnetite origin discrimination[J]. Ore Geology Reviews, 2021, 139: 104453. DOI URL
[48]	NIELSEN R L, FORSYTHE L M, GALLAHAN W E, et al. Major and trace-element magnetite-melt equilibria[J]. Chemical Geology, 1994, 117(1/2/3/4): 167-191. DOI URL
[49]	TOPLIS M J, CARROLL M R. An experimental study of the influence of oxygen fugacity on Fe-Ti oxide stability, phase relations,and mineral—melt equilibria in Ferro-basaltic systems[J]. Journal of Petrology, 1995, 36(5): 1137-1170. DOI URL
[50]	王凯怡, 范宏瑞, 杨奎锋, 等. 白云鄂博碳酸岩的方解石-白云石地质温度计[J]. 岩石学报, 2010, 26(4): 1141-1149.
[51]	CANIL D, LACOURSE T. Geothermometry using minor and trace elements in igneous and hydrothermal magnetite[J]. Chemical Geology, 2020, 541: 119576. DOI URL
[52]	YUAN Z X, BAI G, WU C Y, et al. Geological features and genesis of the Bayan Obo REE ore deposit, Inner Mongolia, China[J]. Applied Geochemistry, 1992, 7(5): 429-442. DOI URL
[53]	王凯怡, 杨奎峰, 范宏瑞, 等. 白云鄂博矿床研究若干问题的探讨[J]. 地质学报, 2012, 86(5): 687-699.
[54]	YANG K F, FAN H R, SANTOSH M, et al. Mesoproterozoic carbonatitic magmatism in the Bayan Obo deposit, Inner Mongolia, North China: constraints for the mechanism of super accumulation of rare earth elements[J]. Ore Geology Reviews, 2011, 40(1): 122-131. DOI URL
[55]	张克信, 潘桂棠, 何卫红, 等. 中国构造-地层大区划分新方案[J]. 地球科学: 中国地质大学学报, 2015, 40(2): 206-233.
[56]	ZHAO G C, SUN M, WILDE S A, et al. Assembly, accretion and breakup of the paleo-mesoproterozoic Columbia supercontinent: records in the North China Craton[J]. Gondwana Research, 2003, 6(3): 417-434. DOI URL
[57]	ZHAO G C, SUN M, WILDE S A, et al. A paleo-mesoproterozoic supercontinent: assembly, growth and breakup[J]. Earth-Science Reviews, 2004, 67(1/2): 91-123. DOI URL
[58]	周建波, 郑永飞, 杨晓勇, 等. 白云鄂博地区构造格局与古板块构造演化[J]. 高校地质学报, 2002, 8(1): 46-61.
[59]	郭聪祥, 刘云. 白云鄂博铁矿深部探矿分析[J]. 包钢科技, 2015, 41(4): 5-7.
[60]	REN Y S, YANG X Y, WANG S S, et al. Mineralogical and geochemical study of apatite and dolomite from the Bayan Obo giant Fe-REE-Nb deposit in Inner Mongolia: new evidences for genesis[J]. Ore Geology Reviews, 2019, 109: 381-406. DOI URL
[61]	白鸽, 袁忠信, 吴澄宇, 等. 白云鄂博矿床地质特征和成因论证[M]. 北京: 地质出版社, 1996.
[62]	中国科学院地球化学研究所. 白云鄂博矿床地球化学[M]. 北京: 科学出版社, 1988.
[63]	张培善, 陶克捷. 白云鄂博矿物学[M]. 北京: 科学出版社, 1986.
[64]	闫国英, 孙丽军, 常剑, 等. 白云鄂博铁矿东矿境界外露天开采可行性分析[J]. 现代矿业, 2018, 34(7): 77-78, 84.
[65]	于俊芳, 沈茂森, 杨波, 等. 白云鄂博东矿白云石型矿石特征分析[J]. 包钢科技, 2022, 48(3): 10-13, 81.
[66]	于俊芳, 闫国英, 彭章旷. 白云鄂博东矿条带型矿石特征分析[J]. 现代矿业, 2022, 38(7): 106-109.
[67]	CHAO E C T, BACK J M, MINKIN J A, et al. 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[R]. US Geological Survey, 1997.
[68]	高海洲. 白云鄂博矿区稀土稀有矿产资源综合评述(一)[J]. 包钢科技, 2009, 35(5): 1-6.
[69]	NEWBURY D E, RITCHIE N W M. Is scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) quantitative?[J]. Scanning, 2013, 35(3): 141-168. DOI PMID
[70]	NEWBURY D E, RITCHIE N W M. Measurement of trace constituents by electron-excited X-ray microanalysis with energy-dispersive spectrometry[J]. Microscopy and Microanalysis, 2016, 22(3): 520-535. DOI PMID
[71]	TANG D M, QIN K Z, MAO Y J, et al. Magnetite geochemistry and iron isotope signature of disseminated and massive mineralization in the Kalatongke magmatic Cu Ni sulfide deposit, northwest China[J]. Chemical Geology, 2022, 605: 120965. DOI URL
[72]	XIE H, HUANG X W, MENG Y M, et al. Discrimination of mineralization types of skarn deposits by magnetite chemistry[J]. Minerals, 2022, 12(5): 608. DOI URL
[73]	ZHAO L J, SHAO Y J, ZHANG Y, et al. Differentiated enrichment of magnetite in the Jurassic W-Sn and Cu skarn deposits in the Nanling Range (South China) and their ore-forming processes:an example from the Huangshaping deposit[J]. Ore Geology Reviews, 2022, 148: 105046. DOI URL
[74]	王昭静. 白云鄂博主矿区稀土-铌-铁矿化趋势分析及启示意义[C]// 中国稀土学会2021学术年会论文摘要集, 成都, 2021.