In-situ microchronology and elemental analysis of pitchblende in the Pajiang uranium deposit, northern Guangdong: Implications for uranium mineralization

doi:10.13745/j.esf.sf.2023.11.70

Abstract

Abstract:

The Pajiang uranium deposit is located in the southern Taoshan-Zhuguang uranium metallogenic belt of the southwestern Fogang pluton. It is a typical granite-related U deposit, the only one found in the Fogang pluton, and uranium mineralization is strictly controlled by fault structures. In this paper, the mineralogy, microgeochemistry and chronology of pitchblende and pyrite in the Pajiang uranium deposit are studied by means of petrography, scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and in-situ laser ablation inductively coupled technique (LA-ICP-MS). In-situ LA-ICP-MS U-Pb dating of pitchblende yielded a weighted mean age of 49.70 ± 0.1 Ma, which corresponds to the Late Cretaceous, and is within the main metallogenic epoch (75-50 Ma) of South China. This indicates that the formation of the Pajiang uranium deposit is consistent with regional metallogeny and belongs to a regional metallogenic event. The total rare earth element (REE) content in pitchblende was (311.5-368.3)×10^-6 and the U/Th ratio was 17067-26524, suggesting that the uranium deposit is of medium-low-temperature hydrothermal origin. The TE_1,3 value of REE was 0.95-1.01, with quasi tetrad effect characteristics, indicating fluorine enrichment in the ore-forming fluids. In addition, the Co/Ni ratio of pyrite ranged between 5-26 in the Pajiang uranium deposit, suggesting the uranium deposit is of hydrothermal origin. Based on the above analysis, it is considered that the Pajiang uranium deposit is of medium-low-temperature hydrothermal type.

Key words: pitchblende, pyrite, chronology, geochemistry, Pajiang uranium deposit

CLC Number:

LI Haidong, TIAN Shihong, LIU Bin, HU Peng, WU Jianyong, CHEN Zhengle. In-situ microchronology and elemental analysis of pitchblende in the Pajiang uranium deposit, northern Guangdong: Implications for uranium mineralization[J]. Earth Science Frontiers, 2024, 31(2): 270-283.

Figures/Tables 12

Fig.1 Geotectonic location, deep and large fractures and uranium ore distribution sketch of the study area. Adapted from [14].

Fig.2 Geological sketch of Pajiang uranium deposit((a)According to Research Institute No.290, CNNC[17];(b)According to No.705 Geological Party[18])

Fig.3 Borehole profile of Zone 2 of the Pajiang uranium deposit (According to No.705 Geological Party[18])

Fig.4 Characteristics of gangue minerals in ore minerals of Pajiang uranium deposit (a,b: mineral hand specimen; c: reflected light; d,e: transmitted light; f-h: backscattered photos)

Table 1 LA-ICP-MS U-Pb dating results of Pitch uranium ore in Pajiang uranium deposit

Fig.5 In situ U-Pb age harmony diagram of pitchblende in Pajiang uranium deposit (a) and 207Pb corrected 206Pb*/238U weighted average age (b)

Table 2 Analysis results of major elements of pitchblende in Pajiang uranium deposit

Table 3 Rare earth element analysis results of pitchblende in Pajiang uranium deposit

Table 4 Analysis results of trace and rare earth elements of pyrite in Pajiang uranium deposit

Fig.6 Two dimensional diagram of major elements of pitchblende in Pajiang uranium deposit

Fig.7 Distribution diagram of surrounding rock and mineral rare earth elements of Pajiang uranium deposit

Fig.8 Two dimensional Co-Ni covariance map of pyrite in Pajiang uranium deposit

References 42

[1]	钟福军, 严杰, 夏菲, 等. 粤北长江花岗岩型铀矿田沥青铀矿原位U-Pb年代学研究及其地质意义[J]. 岩石学报, 2019, 35(9): 2727-2744.
[2]	骆金诚, 石少华, 陈佑纬, 等. 铀矿床定年研究进展评述[J]. 岩石学报, 2019, 35(2): 589-605.
[3]	郑国栋, 罗强, 刘文泉, 等. 粤北书楼丘铀矿床沥青铀矿原位U-Pb年龄和元素特征及其地质意义[J]. 地球科学: 中国地质大学学报, 2020, 46(6): 2172-2187.
[4]	BONNETTI C, LIU X D, MERCADIER J, et al. The genesis of granite-related hydrothermal uranium deposits in the Xiazhuang and Zhuguang ore fields, North Guangdong Province, SE China: insights from mineralogical, trace elements and U-Pb isotopes signatures of the U mineralisation[J]. Ore Geology Reviews, 2018, 92: 588-612.
[5]	石少华, 胡瑞忠, 温汉捷, 等. 桂北沙子江铀矿床成矿年代学研究: 沥青铀矿U-Pb同位素年龄及其地质意义[J]. 地质学报, 2010, 84(8): 1175-1182.
[6]	陈佑纬, 胡瑞忠, 骆金诚, 等. 桂北沙子江铀矿床沥青铀矿原位微区年代学和元素分析: 对铀成矿作用的启示[J]. 岩石学报, 2019, 35(9): 2679-2694.
[7]	叶丽娟, 肖志斌, 涂家润, 等. LA-ICPMS与EPMA结合测定铀矿物微区原位U-Pb年龄[J]. 地球学报, 2019, 40(3): 479-482.
[8]	毕献武, 胡瑞忠, 彭建堂, 等. 黄铁矿微量元素地球化学特征及其对成矿流体性质的指示[J]. 矿物岩石地球化学通报, 2004(1): 1-4.
[9]	ZHAO H X, FRIMMEL H E, JIANG S Y, et al. LA-ICP-MS trace element analysis of pyrite from the Xiaoqinling gold district, China: implications for ore genesis[J]. Ore Geology Reviews, 2011, 43: 142-153.
[10]	ZHENG Y, ZHANG L, CHEN Y, et al. Metamorphosed Pb-Zn-(Ag) ores of the Keketale VMS deposit, NW China: evidence from ore textures, fluid inclusions, geochronology and pyrite compositions[J]. Ore Geology Reviews, 2013, 54: 167-180.
[11]	ZHANG J, DENG J, CHEN H Y, et al. LA-ICP-MS trace element analysis of pyrite from the Chang’an gold deposit, Sanjiang Region, China: implication for ore-forming process[J]. Gondwana Research, 2014, 26(2): 557-575.
[12]	刘斌, 陈卫锋, 高爽, 等. 相山铀矿田黄铁矿微量元素、硫同位素特征及其地质意义[J]. 矿床地质, 2019, 38(6): 1321-1335.
[13]	姚振凯. 我国铀矿床的大地构造类型及其主要特征[J]. 大地构造与成矿学, 1983 (2): 117-125
[14]	孙立强. 南岭诸广山地区中生代花岗岩成因及其对铀成矿作用的启示[D]. 南京: 南京大学, 2018.
[15]	李四光. 地壳构造与地壳运动[J]. 中国科学: A辑, 1973, 3(4): 400-429.
[16]	范洪海, 庞雅庆, 何德宝, 等. 华南花岗岩型铀矿成矿作用及成矿预测[J]. 地球学报, 2022, 44(5): 887-896.
[17]	郭新文, 江卫兵, 许幼. 广东省仁化县塘湾地区铀矿地质普查报告[R]. 韶关: 核工业二九○研究所, 2023.
[18]	钟乙周, 唐启能, 梁富辉. 广东省清远县261地区良安-迳头地段铀矿地质普查报告[R]. 韶关: 七○五地质大队, 1978.
[19]	LIU Y S, HU Z C, GAO S. In-situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[J]. Chemical Geology, 2008, 257(1/2): 34-43.
[20]	ZONG K Q, CHEN J Y, HU Z C, et al. In-situ U-Pb dating of uraninite by fs-LA-ICP-MS[J]. Science China: Earth Sciences, 2015, 58(10): 1731-1740.
[21]	胡瑞忠, 骆金诚, 陈佑纬, 等. 华南铀矿床研究若干进展[J]. 岩石学报, 2019, 35(9): 2625-2636.
[22]	张龙, 陈振宇, 汪方跃. 华南花岗岩型铀矿床主要特征与成矿作用研究进展[J]. 岩石学报, 2021, 37(9): 2657-2676.
[23]	张伟盟, 严杰, 钟福军, 等. 粤北石角围花岗岩型铀矿床沥青铀矿LA-ICP-MS原位U-Pb定年研究[J]. 岩矿测试, 2019, 38(4): 449-460.
[24]	陈琪, 谭双, 万建军, 等. 苗儿山中段向阳坪铀矿床沥青铀矿U-Th-Pb化学定年及其地质意义[J]. 东华理工大学学报(自然科学版), 2021, 44(6): 519-526.
[25]	EVRON R, KIMMEL G, EYAL Y. Thermal recovery of self-radiation damage in uraninite and thorianite[J]. Journal of Nuclear Materials, 1994, 217: 54-66.
[26]	DEDITIUS A, UTSUNOMIYA S, EWING R. Alteration of UO₂₊_x under oxidizing conditions, Marshall pass, Colorado, USA[J]. Journal of Alloys and Compounds, 2007, 444-445: 584-589.
[27]	FRIMMEL H E, SCHEDEL S, BRÄTZ H. Uraninite chemistry as forensic tool for provenance analysis[J]. Applied Geochemistry, 2014, 48: 104-121.
[28]	MERCADIER J, CUNEY M, LACH P, et al. Origin of uranium deposits revealed by their rare earth element signature[J]. Terra Nova, 2011, 23(4): 264-269.
[29]	IRBER W. The lanthanide tetrad effect and its correlation with K/Rb, Eu/Eu^*, Sr/Eu, Y/Ho, and Zr/Hf of evolving peraluminous granite suites[J]. Geochimica et Cosmochimica Acta, 1999, 63(3/4): 489-508.
[30]	KERRICH R, SAID N, MANIKYAMBA C, et al. Sampling oxygenated Archean hydrosphere: implications from fractionations of Th/U and Ce/Ce^* in hydrothermally altered volcanic sequences[J]. Gondwana Research, 2013, 23(2): 506-525.
[31]	LING H F, CHEN X, LI D, et al. Cerium anomaly variations in Ediacaran-earliest Cambrian carbonates from the Yangtze Gorges area, South China: implications for oxygenation of coeval shallow seawater[J]. Precambrian Research, 2013, 225: 110-127.
[32]	ZHANG Y Y, ZHONG F J G, LIU J, et al. Genesis of the Mianhuakeng uranium deposit, South China: constraints from in-situ sulfur isotopes and trace elements of pyrite[J]. Applied Geochemistry, 2022, 140: 105302.
[33]	夏毓亮. 中国铀成矿地质年代学[M]. 北京: 中国原子能出版社, 2019.
[34]	肖为, 范洪海, 陈东欢, 等. 桂北广子田铀钨矿床成因: 沥青铀矿原位U-Pb定年、矿物地球化学证据[J]. 地质论评, 2022, 68(3): 831-844.
[35]	刘汉彬, 金贵善, 韩娟, 等. 华东南地区热液型铀矿成矿年代[J]. 地质学报, 2015, 89(增刊): 157-159.
[36]	郭春影, 秦明宽, 徐浩, 等. 广西苗儿山铀矿田张家铀矿床成矿时代: 沥青铀矿微区原位测定[J]. 地球科学, 2020, 45(1): 72-89.
[37]	胡瑞忠, 毕献武, 彭建堂, 等. 华南地区中生代以来岩石圈伸展及其与铀成矿关系研究的若干问题[J]. 矿床地质, 2007, 26(2): 139-152.
[38]	骆金诚, 齐有强, 王连训, 等. 粤北下庄铀矿田基性岩脉Ar-Ar定年及其与铀成矿关系新认识[J]. 岩石学报, 2019, 35(9): 2660-2678.
[39]	李杰, 黄宏业, 刘子杰, 等. 诸广中段鹿井地区辉绿岩⁴⁰Ar-³⁹Ar年代学特征[J]. 吉林大学学报(地球科学版), 2021, 51(2): 442-454.
[40]	张熠阳, 钟福军, 潘家永, 等. 赣南黄沙铀矿区辉绿岩成因及其与铀成矿关系[J]. 地球科学, 2022, 47(1): 206-223.
[41]	钟福军, 夏菲, 王玲, 等. 诸广中部鹿井铀矿田辉绿岩磷灰石U-Pb年龄、地球化学特征及其与铀成矿关系[J]. 地质学报, 2023, 97(8): 1-19.
[42]	何德宝, 范洪海, 孟艳宁, 等. 粤北下庄铀矿田不同类型矿床成矿流体对比研究[J]. 地质与勘探, 2015, 51(2): 303-311.