-
摘要:
研究目的 白云鄂博超大型稀土矿床的形成与碳酸岩关系密切。在白云鄂博矿区外围，西矿区西南部中新生代沉积覆盖区，也存在一定规模的碳酸质岩石，其成因属性对白云鄂博矿床的形成具有启示意义。
研究方法 本文通过岩石学及矿物学研究发现，该碳酸质岩石实际为火成碳酸岩。
研究结果 碳酸岩总体受流体交代程度较弱，根据矿物组成，可分为白云石型和方解石型两种类型。岩石地球化学分析表明，碳酸岩样品富Sr（>4940×10-6），Mn（>2150×10-6）以及Ba（>106×10-6），REE平均含量为938×10-6，远高于本区沉积碳酸盐岩；样品全岩δ13CV-PDB和δ18OV-SMOW值范围分别为：-3.7‰~-4.2‰和6.7‰~7.7‰，为典型原始火成碳酸岩特征；岩石具有较均一的Sr同位素组成，87Sr/86Sr=0.702815~0.703185，表明它们为地幔来源且受地壳污染的可能性较小。此外，对碳酸岩中白云石、方解石、磷灰石的单矿物分析也均指示它们为岩浆成因。
结论 综上所述，覆盖区碳酸质岩石为火成碳酸岩，其对于白云鄂博矿床研究，以及本区大地构造演化研究均具有重要意义。
Abstract:This paper is the result of mineral exploration engineering.
Objective The formation of the giant Bayan Obo REE deposit is closely related to carbonatitic magmatism. Near the ore district, southwest of West Ore Body, there are carbonate rocks with a certain scale covered by Mesozoic-Cenozoic sediments, the genesis of which can indicate the formation process of the well-known Bayan Obo deposit.
Methods This contribution demonstrates that these rocks are actually igneous by the detailed study on petrology and mineralogy.
Results The rocks were little affected by fluid metasomatism and can be divided into dolomite type and calcite type according to their mineral compositions. Bulk rock analysis shows that these carbonatites are rich in Sr (>4940×10-6), Mn (>2150×10-6) and Ba (>106×10-6), and the average REE content are 938×10-6, much higher than that of sedimentary carbonates. The δ13CV-PDB and δ18OV-SMOW of the rock samples are-3.7‰--4.2‰ and 6.7‰-7.7‰, respectively, typical of primary igneous carbonatite. They have relatively homogeneous Sr isotopic compositions (87Sr/86Sr=0.702815-0.703185), indicating the mantle-derived rocks were contaminated by the crust limitedly. In addition, the mineral chemical features of dolomite, calcite and apatite also indicate an igneous origin.
Conclusions The identification of these carbonatites is of great significance for the comparative study on the Bayan Obo deposit and tectonic evolution of the area.
-
Key words:
- petrogeochemistry /
- mineral chemistry /
- C-O-Sr isotopes /
- carbonatite /
- mineral exploration engineering /
- Bayan Obo /
- Inner Mongolia
-
-
图 4 ZK106-3和ZK9-1中样品CaO-MgO-TFe2O3+MnO分类图解（修改自Woolley and Kempe, 1989）
Figure 4.
图 5 ZK106-3和ZK9-1中样品微量元素原始地幔标准化蛛网图（a）与稀土元素球粒陨石标准化配分图（b）（标准化值据Sun and McDonough, 1989；McDonough and Sun, 1995）
Figure 5.
图 6 方解石碳酸岩中磷灰石稀土元素球粒陨石标准化配分模式图（标准化值据McDonough and Sun, 1995）
Figure 6.
图 7 样品中白云石和方解石SrO-MnO图解（虚线值根据Yang and Le Bas, 2004）
Figure 7.
图 8 方解石碳酸岩样品中磷灰石Y-Sr（a）和Mn-Sr（b）图解（底图据Belousova et al., 2002）
Figure 8.
图 9 白云石碳酸岩样品碳、氧同位素组成（原始火成碳酸岩范围据Taylor et al., 1967）
Figure 9.
表 1 ZK106-3和ZK9-1中样品主量元素含量（%）
Table 1. Major element contents (%) of samples from ZK106-3 and ZK9-1
下载: 导出CSV
表 2 ZK106-3和ZK9-1中样品微量与稀土元素含量（10-6）
Table 2. Trace and REE element contents (10-6) of samples from ZK106-3 and ZK9-1
下载: 导出CSV
表 3 白云石和方解石碳酸岩样品中的白云石和方解石主量元素含量（%）
Table 3. Major element contents (%) of dolomite and calcite in dolomite-carbonatite and calcite-carbonatite samples
下载: 导出CSV
表 4 方解石碳酸岩样品中磷灰石的主量元素含量（%）
Table 4. Major element contents (%) of apatite grains in calcite-carbonatite samples
下载: 导出CSV
表 5 覆盖区方解石碳酸岩样品中磷灰石的微量与稀土元素含量（10-6）
Table 5. Trace element contents (10-6) of apatite grains in calcite-carbonatite samples
下载: 导出CSV
表 6 白云石碳酸岩样品碳、氧同位素组成（‰）
Table 6. Carbon and oxygen isotopic compositions (‰) of dolomite-carbonatite samples
下载: 导出CSV
表 7 白云石碳酸岩样品的Sr同位素数据
Table 7. Strontium isotopic compositions of dolomite-carbonatite samples
下载: 导出CSV
-
Bai Ge, Yuan Zhongxin, Wu Chengyu, Zhang Zhongqing, Zheng Lixuan. 1996. Demonstration on the Geological Features and Genesis of the Bayan Obo Ore Deposit[M]. Beijing: Geological Publishing House, 1-104 (in Chinese).
Belousova E A, Griffin W L, O'Reilly S Y, Fisher N I. 2002. Apatite as an indicator mineral for mineral exploration: Trace-element compositions and their relationship to host rock type[J]. Journal of Geochemical Exploration, 76(1): 45-69. doi: 10.1016/S0375-6742(02)00204-2
Brooker R A, Kjarsgaard B A. 2011. Silicate-carbonate liquid immiscibility and phase relations in the system SiO2-Na2O-Al2O3-CaO-CO2 at 0.1-2.5 GPa with applications to carbonatite genesis[J]. Journal of Petrology, 52: 1281-1305. doi: 10.1093/petrology/egq081
Campbell L S, Compston W, Sircombe K, Wilkinson C C. 2014. 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, 168: 1040-1062. doi: 10.1007/s00410-014-1040-4
Chakhmouradian A, Reguir E P, Zaitsev A N. 2016. Calcite and dolomite in intrusive carbonatites. Ⅰ. Textural variations[J]. Mineralogy and Petrology, 110(2/3): 333-360.
Fan H R, Hu F F, Yang K F, Pirajno F, Liu X, Wang K Y. 2014. Integrated U-Pb and Sm-Nd geochronology for a REE-rich carbonatite dyke at the giant Bayan Obo REE deposit, Northern China[J]. Ore Geology Reviews, 63: 510-519. doi: 10.1016/j.oregeorev.2014.03.005
Fan H R, Yang K F, Hu F F, Liu S, Wang K Y. 2016. The giant Bayan Obo REE-Nb-Fe deposit, China: Controversy and ore genesis[J]. Geoscience Frontiers, 7(3): 335-344. doi: 10.1016/j.gsf.2015.11.005
Feng M, Song W L, Kynicky J, Smith M P, Cox C, Xu C, Kopriva M, Brtnicky M, Fu W, Wei C W. 2020. Primary rare earth element enrichment in carbonatites: Evidence from melt inclusions in Ulgii Khiid carbonatite, Mongolia[J]. Ore Geology Reviews, 117: 103294. doi: 10.1016/j.oregeorev.2019.103294
Hao Zhiguo, Wang Xibin, Li Zhen, Xiao Guowang, Zhang Tairong. 2002. Petrological study of alkaline basic dyke and carbonatite dyke in Bayan Obo, Inner Mongolia[J]. Acta Petrologica et Mineralogica, 21(4): 429-444 (in Chinese with English abstract).
Hou Z Q, Liu Y, Tian S H, Yang Z M, Xie Y L. 2015. Formation of carbonatite-related giant rare-earth-element deposits by the recycling of marine sediments[J]. Scientific Reports, 5: 10231. doi: 10.1038/srep10231
Hu L, Li Y K, Wu Z J, Bai Y, Wang A J. 2019. 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, 172: 56-65. doi: 10.1016/j.jseaes.2018.08.022
Hu L, Li Y K, Chuan M S, Li R P, Ke C H, Wu Z J. 2020. Post-magmatic fluids dominate the mineralization of dolomite carbonatitic dykes next to the giant Bayan Obo REE deposit, Northern China[J]. Minerals, 10(12): 1117. doi: 10.3390/min10121117
Kynicky J, Smith M P, Song W L, Chakhmouradian A R, Xu C, Kopriva A, Galiova M V, Brtnicky M. 2019. The role of carbonate-fluoride melt immiscibility in shallow REE deposit evolution[J]. Geoscience Frontiers, 10: 527-537. doi: 10.1016/j.gsf.2018.02.005
Le Bas M J, Yang X M, Taylor, R N, Spiro B, Milton J A, Peishan Z. 2007. New evidence for the magmatic origin of the Bayan Obo ore-bearing dolomite marble, Inner Mongolia, China, from a calcite-dolomite carbonatite dyke[J]. Mineralogy and Petrology, 90: 223-248. doi: 10.1007/s00710-006-0177-x
Li Jiankang, Bai Ge, Yuan Zhongxin, Ying Lijuan, Zhang Jian. 2008. Evolvement and ore-forming process of carbonatite magma[J]. Geological Review, 54(6): 793-800 (in Chinese with English abstract).
Li X C, Zhou M F. 2015. Multiple stages of hydrothermal REE remobilization recorded in fluorapatite in the Paleoproterozoic Yinachang Fe-Cu-(REE) deposit, Southwest China[J]. Geochimica et Cosmochimica Acta, 166: 53-73. doi: 10.1016/j.gca.2015.06.008
Li Shenghu, Yu Xuefeng, Tian Jingxiang, Shan Wei, Shen Kun. 2021. Research status and prospect of the evolution mechanism of ore-forming fluids for carbonatite-hosted REE deposits[J]. Geology in China, 48(2): 447-459 (in Chinese with English abstract).
Liu Y L, Ling M X, Williams I S, Yang X Y, Wang C Y, Sun W D. 2018. The formation of the giant Bayan Obo REE-Nb-Fe deposit, North China, Mesoproterozoic carbonatite and overprinted Paleozoic dolomitization[J]. Ore Geology Reviews, 92: 73-83. doi: 10.1016/j.oregeorev.2017.11.011
Mao M, Rukhlov A S, Rowins S, Spence J, Coogan L A. 2016. Apatite trace element compositions: A robust new tool for mineral exploration[J]. Economic Geology, 111(5): 1187-1222. doi: 10.2113/econgeo.111.5.1187
McDonough W F, Sun S S. 1995. The composition of the Earth[J]. Chemical Geology, 120(3/4): 223-253.
Pan Y, Fleet M E. 2002. Compositions of the apatite-group minerals: Substitution mechanisms and controlling factors[J]. Reviews in Mineralogy and Geochemistry, 48: 13-49. doi: 10.2138/rmg.2002.48.2
Ren Yingchen, Zhang Yingchen, Zhang Zhongqing. 1994. Study on heat events of ore-forming Bayan Obo deposit[J]. Acta Geoscientica Sinica, (1/2): 95-101 (in Chinese with English abstract).
Smith M P, Campbell L S, Kynicky J. 2015. 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, 64: 459-476. doi: 10.1016/j.oregeorev.2014.03.007
Song Wenlei, Xu Cheng, Wang Linjun, Wu Min, Zeng Liang, Wang Lize, Feng Meng. 2013. Review of the metallogenesis of the endogenetic rare earth elements deposits related to carbonatite-alkaline complex[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 49: 725-740 (in Chinese with English abstract).
Song W L, Xu C, Smith M P, Chakhmouradian A, Brenna M, Kynicky J, Chen W, Yang Y H, Deng M, Tang H Y. 2018. Genesis of the world's largest rare earth element deposit, Bayan Obo, China: Protracted mineralization evolution over 1 b.y[J]. Geology, 46(4): 323-326. doi: 10.1130/G39801.1
Sun Jian. 2013. The Origin of the Bayan Obo Ore Deposit, Inner Mongolia, China: The Iron and Magnesium Isotope Constraint[D]. Beijing: China University of Geosciences (Beijing) (in Chinese with English abstract).
Sun Jian, Fang Nan, Li Shizhen, Chen Yuelong, Zhu Xiangkun. 2012. Magnesium isotopic constraints on the genesis of Bayan Obo ore deposit[J]. Acta Petrologica Sinica, 28(9): 2890-2902 (in Chinese with English abstract).
Sun S S, McDonough W F. 1989. Chemical and isotopic systematics of oceanic basalt: Implications for mantle composition and process[C]//Saunders A D, Norry M J(eds. ). Magmatism in the Ocean Basins. Geological Society, London, Special Publication, 42: 313-345.
Taylor H P, Frechen J, Degens E T. 1967. Oxygen and carbon isotope studies of carbonatites from the Laacher See district, West Germany and the Alno district, Sweden[J]. Geochimica et Cosmochimica Acta, 31: 407-430. doi: 10.1016/0016-7037(67)90051-8
Veizer J. 1983. Trace elements and isotopes in sedimentary carbonates[J]. Reviews in Mineralogy, 11: 265-199.
Veksler I V, Petibon C, Jenner G A, Dorfman A M, Dingwell D B. 1998. Trace element partitioning in immiscible silicate-carbonate liquid systems: An initial experimental study using a centrifuge autoclave[J]. Journal of Petrology, (11/12): 11-12.
Wallace M E, Green D H. 1998. An experimental determination of primary carbonatite magma composition[J]. Nature, 335: 343-346.
Wang Kaiyi, Fan Hongrui, Xie Yihan. 2002. Geochemistry of REE and other trace elements of the carbonatite dykes at Bayan Obo: Implication for its formation[J]. Acta Petrologica Sinica, 18(3): 340-348 (in Chinese with English abstract).
Wang Kaiyi, Zhang Jien, Fang Aimin, Dong Ce, Hu Fuyou. 2018. Genesis of the Bayan Obo deposit, Inner Mongolia: The fenitized mineralization in the ore bodies and its relation to the ore-bearing dolomite[J]. Acta Petrologica Sinica, 34(3): 785-798 (in Chinese with English abstract).
Wang K Y, Zhang J E, Yu L J, Fang A M, Dong C, Hu F Y. 2018. Fenitized wall rock geochemistry of the first carbonatite dyke at Bayan Obo, Inner Mongolia, China[J]. Acta Geologica Sinica (English Edition), 92(2): 180-193.
Weidendorfer D, Schmidt M W, Mattsson H B. 2017. A common origin of carbonatite magmas[J]. Geology, 45(6): 507-510. doi: 10.1130/G38801.1
Weng Z, Jowitt S, Mudd G, Haque N. 2015. A detailed assessment of global rare earth element resources: Opportunities and challenges[J]. Economic Geology, 110(8): 1925-1952. doi: 10.2113/econgeo.110.8.1925
Woolley A R, Kempe D R C. 1989. Carbonatites: Nomenclature, average chemical compositions, and element distribution[C]//Carbonatites: Genesis and Evolution; Bell, K, Ed.; Unwin Hyman: London, UK, pp. 1-14.
Xie Yuling, Qu Yunwei, Yang Zhanfeng, Liang Pei, Zhong Richeng, Wang Qiwei, Xia Jiaming, Li Bicheng. 2019. Giant Bayan Obo Fe-Nb-REE deposit: Progresses, controversaries and new understandings[J]. Mineral Deposits, 38: 983-1003 (in Chinese with English abstract).
Yang K F, Fan H R, Santosh M, Hu F F, Wang K Y. 2011. Mesoproterozoic mafic and carbonatitic dykes from the northern margin of the North China Craton: Implications for the final breakup of Columbia supercontinent[J]. Tectonophysics, 498: 1-10. doi: 10.1016/j.tecto.2010.11.015
Yang K F, Fan H R, Pirajno F, Li X C. 2019. The Bayan Obo (China) giant REE accumulation conundrum elucidated by intense magmatic differentiation of carbonatite[J]. Geology, 47: 1198-1202.
Yang Xiaoyong, Lai Xiaodong, Ren Yisu, Ling Mingxing, Liu Yulong, Liu Jianyong. 2015. Geological characteristics and their scientific problems of the Bayan Obo Fe-REE-Nb deposit: Discussion on the origin of Bayan Obo super-large deposit[J]. Acta Geologica Sinica, 89(12): 2323-2350 (in Chinese with English abstract). doi: 10.3969/j.issn.0001-5717.2015.12.010
Yang Xueming, Yang Xiaoyong, Le Bas M J. 1998. Geological and geochemical characteristics of carbonatites and their implication for tectonic settings[J]. Advance in Earth Sciences, 13(5): 457-466(in Chinese with English abstract).
Yang X M, Le Bas M J. 2004. Chemical compositions of carbonate minerals from Bayan Obo, Inner Mongolia, China: Implications for petrogenesis[J]. Lithos, 72: 97-116. doi: 10.1016/j.lithos.2003.09.002
Yang X Y, Lai X D, Pirajno F, Liu Y L, Ling M X, Sun W D. 2017. Genesis of the Bayan Obo Fe-REE-Nb formation in Inner Mongolia, North China Craton: A perspective review[J]. Precambrian Research, 288: 39-71. doi: 10.1016/j.precamres.2016.11.008
Ying Y C, Chen W, Simonetti A, Jiang S Y, Zhao K D. 2020. Significance of hydrothermal reworking for REE mineralization associated with carbonatite: Constraints from in situ trace element and C-Sr isotope study of calcite and apatite from the Miaoya carbonatite complex (China)[J]. Geochimica et Cosmochimica Acta, 280: 340-359. doi: 10.1016/j.gca.2020.04.028
Zhang S H, Zhao Y, Liu Y. 2017. 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, 291: 202-219. doi: 10.1016/j.precamres.2017.01.024
Zheng Yongfei, Chen Jiangfeng. 2000. The Stable Isotope Geochemistry[M]. Beijing: Science Press, 1-316 (in Chinese).
Zhu X K, Sun J, Pan C X. 2015. Sm-Nd isotopic constraints on rare-earth mineralization in the Bayan Obo ore deposit, Inner Mongolia, China[J]. Ore Geology Reviews, 64: 543-553. doi: 10.1016/j.oregeorev.2014.05.015
白鸽, 袁忠信, 吴澄宇, 张宗清, 郑立煊. 1996. 白云鄂博矿床地质特征和成因论证[M]. 北京: 地质出版社, 1-104.
郝梓国, 王希斌, 李震, 肖国望, 张台荣. 2002. 白云鄂博碳酸岩型REE-Nb-Fe矿床——一个罕见的中元古代破火山机构成岩成矿实例[J]. 地质学报, 76(4): 525-540. doi: 10.3321/j.issn:0001-5717.2002.04.010
李建康, 白鸽, 袁忠信, 应立娟, 张建. 2008. 富氟钡型碳酸岩岩浆的演化机制及其成矿效应[J]. 地质论评, 54(6): 793-800.
李胜虎, 于学峰, 田京祥, 单伟, 沈昆. 2021. 碳酸岩型稀土矿床成矿流体演化机制研究现状及展望[J]. 中国地质, 48(2): 447-459. http://geochina.cgs.gov.cn/cn/article/doi/10.12029/gc20210207
任英忱, 张英臣, 张宗清. 1994. 白云鄂博稀土超大型矿床的成矿时代及其主要地质热事件[J]. 地球学报, (1/2): 95-101.
宋文磊, 许成, 王林均, 吴敏, 曾亮, 王丽泽, 冯梦. 2013. 与碳酸岩-碱性杂岩体相关的内生稀土矿床的矿化特征及稀土富集机制评述[J]. 北京大学学报(自然科学版), 49: 725-740.
孙剑. 2013. 白云鄂博矿床成因再研究——铁镁同位素制约[D]. 北京: 中国地质大学(北京).
孙剑, 房楠, 李世珍, 陈岳龙, 朱祥坤. 2012. 白云鄂博矿床成因的Mg同位素制约[J]. 岩石学报, 28(9): 2890-2902.
王凯怡, 范宏瑞, 谢奕汉. 2002. 白云鄂博碳酸岩墙的稀土和微量元素地球化学及对其成因的启示[J]. 岩石学报, 18(3): 340-348.
王凯怡, 张继恩, 方爱民, 董策, 胡辅佑. 2018. 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, 34(3): 275-288.
谢玉玲, 曲云伟, 杨占峰, 梁培, 钟日晨, 王其伟, 夏加明, 李必成. 2019. 白云鄂博铁、铌、稀土矿床: 研究进展、存在问题和新认识[J]. 矿床地质, 38(5): 983-1003.
杨晓勇, 赖小东, 任伊苏, 凌明星, 刘玉龙, 柳建勇. 2015. 白云鄂博铁-稀土-铌矿床地质特征及其研究中存在的科学问题——兼论白云鄂博超大型矿床的成因[J]. 地质学报, 89(12): 2323-2350.
杨学明, 杨晓勇, Le Bas M J. 1998. 碳酸岩的地质地球化学特征及其大地构造意义[J]. 地球科学进展, 13(5): 457-466.
郑永飞, 陈江峰. 2000. 稳定同位素地球化学[M]. 北京: 科学出版社, 1-316.
-
图(9)
表(7)
计量
- 文章访问数: 1173
- PDF下载数: 60
- 施引文献: 0