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1 第 45 卷第 5 期 Vol.45, No.5, 年 9 月 GEOCHIMICA Sept., 2016 陈金勇 1,2*, 范洪海 1,2, 王生云 1,2, 顾大钊 1,2 (1., ; 2., ) 摘要 :,,,, :,, Eu, U Pb Th Co Rb Sr Ni Sb Cs Zr Hf REE, ;,, Eu, U Pb Th Sc Cr Co Zn Nb Mo Ta Yb HREE 关键词 : ; ; ; ; ; ; 中图分类号 : P595; P611 文献标识码 : A 文章编号 : (2016) Trace element and REE geochemical characteristics of alaskites and their relations with uranium mineralization around Gaudeanmus, Namibia CHEN Jin-yong 1,2*, FAN Hong-hai 1,2, WANG Sheng-yun 1,2 and GU Da-zhao 1,2 1. Beijing Research Institute of Uranium Geology, China National Nuclear Corporation, Beijing , China; 2. Key Laboratory of Uranium Resource Exploration and Evaluation Technology, China National Nuclear Corporation, Beijing , China Abstract: This paper focuses on the effect of later hydrotherm on mineralized alaskites and the stages of uranium mineralization. Here, we have reviewed the trace element and REE geochemical characteristics of alaskites and their relations with uranium mineralization in the Gaudeanmus area, Namibia. The results show that there is a significantly increasing amount of rare-earth elements from non-mineralized to mineralized alaskites, indicating the synchronization of REE enrichment and uranium mineralization. There are at least two stages of uranium mineralization: firstly, due to magmatic crystallization differentiation, the REE pattern is characterized by the right-inclining type with obvious Eu negative abnormity and LREE enrichment. This is the main mineralization stage, and uranium enrichment may have close relations with Pb, Th, Co, Rb, Sr, Ni, Sb, Cs, Zr, Hf and REE in this area, so they are evidently of homology; secondly, due to superimposed hydrothermal alteration, the REE pattern manifests as the left-inclining type with obvious Eu negative abnormity and HREE enrichment. At this stage, the correlations between U and Pb, Th, Sc, Cr, Co, Zn, Nb, Mo, Ta, Yb, HREE are excellent. Key words: rare-earth element; trace element; uranium mineralization; hydrotherm; alaskite; Gaudeanmus area; Namibia 收稿日期 (Received): ; 改回日期 (Revised): ; 接受日期 (Accepted): 基金项目 : 作者简介 : (1984 ),,, * 通讯作者 (Corresponding author): CHEN Jin-yong, jinyong @163.com; Tel:

2 第 5 期陈金勇等 : 纳米比亚欢乐谷地区白岗岩微量元素稀土元素地球化学特征及与铀矿化关系 487 0,, (Rössing) [1], (Valencia) (Rössing South) Ida Dome Goanikontes (Gaudeanmus) [2 11] U-Pb, (509±1) Ma, [12 13] (508±2) Ma, Nex et al. [13], ; Herd [14], [10 11] ;,, ( ) [15 19],,,, 1,, ( ) ( Ma), Kalahari Congo Rio de la Plata [20], Okahandja [21 22] [23] [24] ( 1) ( ) [25] : (Abbabis ) Nosib Swakop Nosib (Etusis) (Khan); Swakop (Rössing) (Chuos) (Karibib) (Kuiseb) Abbabis,,,, (2093±51) Ma (1038±58) Ma (U-Pb SHRIMP) [26] Abbabis,,,, Hoffmann et al. [27] (746±2) Ma, (746±2) Ma,,, ( ),, :, Sturtian, 710 Ma [28], 2, 0.1~200 m ( 2),, (497±5.5) Ma (LA-ICPMS U-Pb ) [29], : CHEN Jin-yong et al.: Trace element and REE geochemical characteristics of alaskites and their relations with U mineralization

3 年 Fig.1 1 Geological diagram of the Gaudeanmus area, Namibia, showing the location of significant uranium anomalies

绢云母化绿泥石化(图 3d) 黄铁矿化(图 3e) 具有强烈的蚀变(图 3a), 蚀变类型有钠长石化(图和赤铁矿化(图 3a)等图3 纳米比亚欢乐谷地区白岗岩岩石学矿物学及其蚀变特征 Fig.

4 第5期陈金勇等: 纳米比亚欢乐谷地区白岗岩微量元素稀土元素地球化学特征及与铀矿化关系图2 Fig 纳米比亚欢乐谷地区 18 号矿化带西部地质剖面图 Geological section of western mineralization zone 18 in the Gaudeanmus area Namibia 晶作用所形成, 二是由后期热液叠加改造作用所形 3c) 硅化白云母化伊利石化(图 3b) 高岭石化(图成, 该期铀矿化主要发育在构造破碎带处, 白岗岩 3a) 绢云母化绿泥石化(图 3d) 黄铁矿化(图 3e) 具有强烈的蚀变(图 3a), 蚀变类型有钠长石化(图和赤铁矿化(图 3a)等图3 纳米比亚欢乐谷地区白岗岩岩石学矿物学及其蚀变特征 Fig.3 Petrologic and uranium mineral characteristics of alaskite in Gaudeanmus, Namibia (a) 矿化白岗岩发生高岭土化褐铁矿化等; (b) 矿化白岗岩发生伊利石化; (c) 白岗岩发生钠长石化(Ab); (d)黑云母发生绿泥石化(chl), 在绿泥石中含硅钙铀矿(Urp); (e) 在钾长石(Kf)裂隙中充填黄铁矿脉(Py); (f)白岗岩发育蠕英石(my)现象; (g)晶质铀矿(ur)与锆石(zr)共生, 黄铁矿 (Py) 充填其反射性晕圈内; (h) 黄铁矿(Py)边缘见有脉状的沥青铀矿(Ptc)和铀石(Cof); (i) 沥青铀矿(Ptc)分布于黄铁矿(Py)周围, 并伴生硅钙铀矿(Urp) 锆石(Zr)和独居石(Mnz) CHEN Jin-yong et al.: Trace element and REE geochemical characteristics of alaskites and their relations with U mineralization

5 年,,,, ( 3f),,,,,, [10 11] ( 3g) ( 3h, 3i), μm 5 mm,,, ( 3i), 69%, 31%,, [10] 3, 6 [13],, 13, (ZK ZK ZK20-1-3) (ZK ZK ZK80-9-2) (ZK ZK ZK ZK ZK LS-1 ZK15-2-7), 18 ( 1), Finnigan-MAT HR-ICP-MS(Element Ⅰ), DZ/T , 20 30%, 10 μg/g 5%, 10 μg/g 10%, [30] 4 1, 13.9~ ~ ~21053 μg/g Rb/Sr 1.07~7.53, 4.29, (0.31) (0.32) [31 32], Nb/Ta 8.22~35.8, 15.2; Zr/Hf 27.8~33.7, 30.8( ZK ), Th/U 0.07~1.22, 0.47( ZK20-1-3, ),, Ba/Rb , 0.43, Ba/Rb 0.5~1.52, 0.87,, Ba/Rb ( 4),, Rb Th U Pb, Ti P Sr, Ba, Ta Ti, [33] 5 2, (ΣREE) 222~377 μg/g ( 303 μg/g) 385~1763 μg/g ( 878 μg/g) 109~5994 μg/g ( 1926 μg/g),, ( 5) : Eu ( 5a); Eu ( 5b) Eu (δeu 0.03~0.47, 0.22),

6 第 5 期陈金勇等 : 纳米比亚欢乐谷地区白岗岩微量元素稀土元素地球化学特征及与铀矿化关系 491 CHEN Jin-yong et al.: Trace element and REE geochemical characteristics of alaskites and their relations with U mineralization

7 年 4 ( [33]) Fig.4 The primitive mantle-normalized spider diagram of trace elements in Gaudeanmus, Namibia (The data of primitive mantle are from Sun et al. [33] ) (a) ; (b) (ZK ZK ZK15-2-7), LREE/ HREE 6.63~25.11, 13.6,, δeu 0.03~0.39, 0.18, δce 0.91~1.01, 0.96, (La/Yb) N 6.95~43.79, 25.15,, ; (La/Sm) N 2.88~8.49, 4.90, ; (Gd/Yb) N 1.17~4.96, 2.87, (ZK ZK ZK LS-1), LREE/HREE 0.6~2.31, 1.35, (La/Yb) N 0.19~1.79, 0.89,, δeu 0.14~0.47, 0.31, δce 1.01~1.20, 1.07 (La/Sm) N 0.32~1.98, 1.16, ; (Gd/Yb) N 0.53~0.77, 0.63, 6 6.1,, SPSS R, U 3,, U, 5 ( [33]) Fig.5 Chondrite-normalized REE distribution patterns of the alaskites in Gaudeanmus, Namibia (data of chondrite are from Sun et al. [33] ) (a) ; (b)

8 第 5 期陈金勇等 : 纳米比亚欢乐谷地区白岗岩微量元素稀土元素地球化学特征及与铀矿化关系 493 CHEN Jin-yong et al.: Trace element and REE geochemical characteristics of alaskites and their relations with U mineralization

9 年表 3 纳米比亚欢乐谷地区白岗岩中铀与微量元素的相关系数 Table 3 Correlation coefficients of U and trace elements in alaskites from Gaudeanmus, Namibia Sc Cr Co Ni Cu Zn Rb Sr Nb Mo Sb Cs Ba Ta W Pb Th Zr Hf Yb ΣREE LREE HREE (La/Yb) N , U U ( 3, 6),, U : Sc Co Ni Rb Sr Nb Sb Cs Ta Pb Th Zr Hf Yb REE; : Cr Cu Zn Mo 6 U Fig.6 Correlations between U and other elements in alaskites from Gaudeanmus, Namibia

10 第 5 期陈金勇等 : 纳米比亚欢乐谷地区白岗岩微量元素稀土元素地球化学特征及与铀矿化关系 495 Ba W, U Pb Th( 6a) Co Rb Sr Ni Sb Cs Zr( 6b) Hf REE, 0.805~0.995, U Pb Th Zr Hf REE, U (La/Yb) N, LREE (0.839) HREE (0.764), U Rb/Sr ( 6e),, Rb/Sr, U,, U : Sc Cr Co Ni Cu Zn Nb Mo Ta W Pb Th Yb REE; : Rb Sr Sb Cs Ba Zr Hf, U Pb Th( 6a) Sc Cr Co Zn Nb Mo Ta Yb HREE( 6d), , U Co Zn Mo HREE U Rb/Sr ( 6e), U (La/Yb) N,, U HREE (0.973) LREE (0.256)( 6c, 6d),,, 6.2, 143 Nd/ 144 Nd ( ~ ) 87 Sr/ 86 Sr ( ~ ) Abbabis 143 Nd/ 144 Nd ( ~ ) 87 Sr/ 86 Sr ( ~ ) [35 37],, Abbabis, - [38] (Rb Ba Sr K), [35] ( 7) 7 Fig.7 LILE variations in alaskites from Gaudeanmus, Namibia CHEN Jin-yong et al.: Trace element and REE geochemical characteristics of alaskites and their relations with U mineralization

11 年 ( 3), ( 6f),, [39 41] : (1),,,,, LREE HREE ; (2) REE U, UO 2 (CO 3 ) 2 2 UO 2 (CO 3 ) 4 3 [42 44], CO 2, CO 2 [45], UO 2 (CO 3 ) 2 2 UO 2 (CO 3 ) 4 3 HCO 3, U Th HREE, LREE [44],, HREE LREE 7 (1), ΣREE = 222~377 μg/g, 303 μg/g; ΣREE = 385~1763 μg/g, 878 μg/g; ΣREE = 109~5994 μg/g, 1926 μg/g,, δeu 0.03~0.47, 0.22, (2) Rb Th U Pb, Ti P Sr Ba, U Pb Th Co Rb Sr Ni Sb Cs Zr Hf REE, 0.805~0.995, U Pb Th Zr Hf REE, U Pb Th Sc Cr Co Zn Nb Mo Ta Yb HREE, 0.906~0.999, U Co Zn Mo HREE (3) :, 71%,, Eu ;, 31%,, Eu 参考文献 (References): [1] Berning J, Cooke R, Hiemstra S A, Hoffman U. The Rössing uranium deposit, South West Africa[J]. Econ Geol, 1976, 71(1): [2] Marlow A G. Remobilisation and primary uranium genesis in the Damaran Orogenic Belt, Namibia[D]. Leeds: University of Leeds, [3] Mouillac J L, Valois J P, Walgenwitz F. The Goanikontes uranium occurrence in South West Africa/Namibia[M]// Anhaeusser C R, Maske S. Mineral Deposits of Southern Africa (Volume ). Johannesburg: Geological Society of South Africa, 1986: [4] Nex P A M, Kinnaird J A. Granites and their mineralisation in the Swakop River area around Goanikontes, Namibia[J]. Comm Geol Surv Namibia, 1995, 10: [5] Nex P A M. Tectono-metamorphic setting and evolution of granitic sheets in the Goanikontes area, Namibia[D]. Ireland: National University of Ireland, [6] Söhnge G. Journal of a Geologist[M]. Stellenbosch: Stellenbosch University, 2001: 197p. [7] Kinnaird J A, Nex P A M. A review of geological controls on uranium mineralisation in sheeted leucogranites within the Damara Orogen, Namibia[J]. Trans Inst Min Metall B, 2007, 116(2): [8] Greenaway G. Valencia Uranium Pty Ltd: Valencia Project, Namibia-Resource Update[R]. Snowden Group, [9] Guy G F. Petrographic, Mineralogical and geochemical characterisation of granite-hosted uranium deposits of the central Damara Orogen, Namibia[D]. Johannesburg: University of the Witwatersrand, [10],,,,. [J]., 2013, 59(5): Chen Jin-yong, Fan Hong-hai, Chen Dong-huan, Gu Da-zhao, Wang Sheng-yun. Research on the characteristics of uranium minerals of alaskite-type uranium deposit in the Gaudeanmus area, Namibia[J]. Geol Rev, 2013, 59(5): (in Chinese

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km 5 km Pt 2 x 2 1 Au 65 ~ ~ km 5 km 10 km 2 Au Au

km 5 km Pt 2 x 2 1 Au 65 ~ ~ km 5 km 10 km 2 Au Au 38 1 2015 3 JOURNAL OF EAST CHINA INSTITUTE OF TECHNOLOGY Vol. 38 No. 1 Mar. 2015 doi 10. 3969 /j. issn. 1674-3504. 2015. 01. 002 1 2 1 2 3 1. 471000 2. 471000 3. 510640 9 P618. 51 A 1674-3504 2015 01-0012-11.