岩石学报  2022, Vol. 38 Issue (2): 371-392, doi: 10.18654/1000-0569/2022.02.05   PDF    
江西崇义铁木里碱长花岗岩中铌和稀土元素的富集机制
郭娜欣1, 刘善宝1, 陈振宇1, 蒋胜雄2, 李宏伟2     
1. 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室, 北京 100037;
2. 中国地质大学(北京)地球科学与资源学院, 北京 100083
摘要: 华南是我国重要的战略性矿产资源基地,以花岗岩相关的稀有和稀土金属成矿作用而举世瞩目。其中,铌的成矿作用一般与过铝质高分异花岗岩有关,稀土元素则随岩浆演化程度增强而富集程度降低,而江西铁木里含黑云母碱长花岗岩体同时富集铌和稀土元素,矿化组合极具特色。本文在详细的矿物岩相学研究基础上,利用电子探针、飞秒激光电感耦合等离子质谱对铌和稀土矿物进行了矿物地球化学分析,借此对铁木里碱长花岗岩中铌和稀土元素的富集机制进行探讨。铁木里岩体由肉红色含黑云母碱长花岗岩(r-G)和灰白色含黑云母碱长花岗岩(g-G)组成,发育暗色包体。r-G中的铌矿物主要为岩浆期形成的铌铁金红石,稀土矿物包括岩浆期形成的硅钛铈矿、独居石、磷灰石和热液期形成的独居石和氟碳(钙)铈矿。g-G中的铌矿物包括岩浆期形成的铌铁金红石和热液期形成的铌铁金红石、易解石、铌铁矿,稀土矿物包括岩浆期磷灰石和热液期磷灰石、独居石、氟碳(钙)铈矿。暗色包体为岩浆混合成因,内含磷灰石、独居石和零星的硅钛铈矿、金红石。矿物组合特征显示,铁木里碱长花岗岩中的铌和稀土元素经过了岩浆和热液两个时期的富集。应用金红石、磷灰石、绿泥石等矿物成分特征约束了岩浆-热液演化过程中体系的物理化学状态,反演了铌和稀土元素的富集过程。在岩浆结晶阶段(688~500℃)铌形成铌铁金红石,稀土元素形成磷灰石、独居石、硅钛铈矿,部分稀土元素进入云母类矿物。在岩浆期后热液阶段,铌主要在高温阶段(500~486℃)形成热液金红石、易解石、铌铁矿,稀土元素发生活化、迁移,在中温热液阶段(~280℃)形成热液独居石、氟碳铈矿、氟碳钙铈矿等稀土矿物。岩浆体系处于高氧逸度状态,随着演化程度的增高,温度、氧逸度均呈下降趋势,热液体系处于低氧逸度的还原状态。流体温度和氧逸度的降低以及岩浆演化及岩浆与碳酸盐岩围岩反应导致的成分变化是造成稀土元素活化、迁移、沉淀的重要因素。铁木里碱长花岗岩体发育岩浆-热液型铌-稀土矿化,可作为该类资源综合评价的重要靶区。
关键词: 铌和稀土元素    铁木里    岩浆-热液    白垩纪    南岭东段    
Mechanism of Nb and REE enrichment in the Tiemuli alkali-feldspar granite, Chongyi County, Jiangxi Province
GUO NaXin1, LIU ShanBao1, CHEN ZhenYu1, JIANG ShengXiong2, LI HongWei2     
1. MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;
2. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
Abstract: South China is an important critical metal mineral resources base, and it is remarkable for widespread granites and extensive rare and rare-earth metal metallogeny. Niobium mineralization is closly assosicated with highly differentiated peraluminous granites, while the REEs decrease as magma evolves. The Early Cretaceous Tiemuli granitic pluton, located in Chongyi County, Jiangxi Province, eastern Nanling metallogenic belt, is mainly composed of flesh red and grey metaluminous-peraluminous biotite-bearing alkali-feldspar granites (r-G and g-G in short, respectively) which are chemically distinctive with high contents of niobium and rare earth elements. In this paper, detailed mineral analyses were carried out to probe into the enrichment mechanism of Nb and REEs in this intrusion. Niobium minerals in r-G mainly compose ilmenorutile, while rare earth minerals compose magmatic chevkinite, monazite, apatite and hydrothermal monazite, bastnaesite and parasite. Niobium minerals in g-G contain magmatic ilmenorutile and hydrothermal ilmenorutile, aeschynite and columbite, while magmatic apatite and hydrothermal apatite, monazite, bastnaesite, parasite comprise the REE minerals in g-G. Enclaves in the granites were caused by mixing of mafic and acidic magmas and contain apatite, monazite, a little rutile and chevkinite. Mineral assemblage characteristics indicate that Nb and REEs of the Tiemuli alkali-feldspar granite were concentrated during the magmatic and hydrothermal stages. Physicochemical conditions of the magmatic-hydrothermal system have been constrainted by rutile, apatite, chlorite, etc. And the enrichment mechanism of Nb and REEs has been delineated. Niobium was accommodated into ilmenorutile during the magmatic crystallization at temperature of 688~500℃, and be contained by hydrothermal rutile, aeschynite and niobite during the hydrothermal stage at temperature of 500~486℃. The rare earth elements were mainly taken into apatite, monazite, chevkinite, while some were reserved into biotite during the magmatic crystallization, and then turned to be moblizied and were migrated by hydrothermal fluid. The REEs were mainly deposited at temperature of ~280℃ with forms of monazite, bastnaesite and parasite. The melt had high oxygen fugacity while postmagmaic hydrothermal fluid turned to be reductive. The temperature and oxygen fugacity declined following the evolution. Variation of temperature, oxygen fugacity, and composition caused by magma evolution and reaction between magma and carbonate wall rocks during the hydrothermal stage are the critical factors for the mobilization, migration and deposition of REEs. The Tiemuli alkali-feldspar granite is characterized by magmatic-hydrothermal Nb-REE mineralization, and might be comprehensivly evaluated for granite-type Nb and REEs resources.
Key words: Niobium and rare earth elements    Tiemuli    Magmatic-hydrothermal evolution    Cretaceous    Eastern Nanling metallogenic belt    

华南是我国稀有、稀土资源基地,前人关于华南花岗岩及其成矿关系的研究结果表明,Nb的成矿作用一般与过铝质高分异花岗岩密切相关,铌以铌铁矿、细晶石等矿物形式富集于复式岩体晚阶段的富硅、富碱、富挥发份岩相中(邹天人,1985夏卫华等,1989Linnen and Cuney, 2005Hu et al., 2017Li et al., 2017Zhao et al., 2021);REE在岩浆演化过程中的行为则与Nb不同,对于某些特定的花岗岩体而言,REE含量随岩浆演化程度的增强呈现降低的趋势,如西华山、大吉山、九龙脑、姑婆山、佛冈、新丰等岩体(吴宗絮,1985陈毓川等,1989谷湘平,1989b夏卫华等,1989李福春等,2002华仁民等,2007Guo et al., 2012)。因此,一般认为花岗质岩浆系统中Nb和REE的富集发生在岩浆演化程度不同的岩体或复式岩体的不同阶段,很少在同一岩体或同一岩浆阶段内富集而共生(洪大卫,1982周瑞文,1982华仁民等,2007Moreno et al., 2016Guo et al., 2018Zhao et al., 2018a)。相应地,对华南地区铌和稀土成矿作用的研究也是相对独立的。对铌矿的研究多集中在成矿花岗岩的分异程度上(华仁民等,2007陈骏等,2008),对稀土矿的研究则主要侧重风化过程中稀土元素的迁移富集(赵芝等,2014Denys et al., 2021)。针对花岗质岩浆-热液演化过程中二者富集过程的研究相对较少。

铁木里岩体位于华南内部南岭成矿带东段赣南崇义地区(图 1),成岩时代为早白垩世,地球化学特征显示其为壳源沉积物重熔成因(Lu et al., 2018)。铁木里岩体的岩性主要为准铝质-弱过铝质的含黑云母碱长花岗岩,岩石中Nb的平均含量为96.3×10-6,最高可达328×10-6,与华南地区几个典型铌钽矿成矿岩体的Nb含量相当;REE平均含量为569×10-6,最高可达1878×10-6,显著高于南岭地区成稀土矿花岗岩的REE含量(表 1)。铁木里岩体同时富集Nb和REE,这在南岭地区非常具有成矿特色。针对其富集机制,本文对铁木里碱长花岗岩开展了铌矿物和稀土矿物的岩相学和矿物化学研究,约束了其形成时体系的物理化学条件,并探讨了其成矿潜力。

图 1 铁木里岩体大地构造位置图(a,据杨明桂和王光辉,2019)和铁木里岩体地质图(b,据江西省地质矿产局,1984修改) Fig. 1 Schematic tectonic framework of South China showing the location of Tiemuli pluton (a, after Yang and Wang, 2019) and geological map of the Tiemuli granitic pluton (b)

① 江西省地质矿产局. 1984.1:50000麟潭圩幅地质图

表 1 铁木里岩体与华南地区部分稀有、稀土成矿岩体中铌和稀土元素含量(×10-6) Table 1 Nb and REE contents of the Tiemuli and some representative granites related to rare and rare earth mineralization in South China (×10-6)
1 区域背景

华南以大面积分布的花岗质岩石和中生代成矿大爆发闻名(华仁民和毛景文,1999Zhou et al., 2006)。虽然自中生代以来,华南内部存在周期性的岩石圈伸展(张岳桥等,2012),但碱性岩及相关的Nb、REE共生矿床少见。华南地区的Nb和REE矿多与过铝质花岗岩有关,且二者的富集成矿多发生在岩浆演化的不同阶段。与Nb成矿相关的主要为高度分异演化的钠长石花岗岩或花岗伟晶岩(陈骏等,2008),集中分布在南岭成矿带和江南成矿带,江南成矿带的Nb矿主要形成于燕山晚期,南岭成矿带的Nb矿以燕山早期为主(李建康等,2019)。成矿岩体多为复式岩体的晚阶段岩相,呈小岩株、岩枝、岩盖状,在似层状岩相分带的上部和/或顶部带发育,Nb常以铌铁矿、细晶石等单矿物形式浸染状分布于岩石中。南岭地区的REE矿以离子吸附型为主(赵芝等,2014),少数内生REE矿(如西华山、姑婆山、新丰)则主要富集在花岗质岩浆演化的早期阶段,REE赋存在云母、独居石、榍石、褐帘石等矿物中(洪大卫,1982谷湘平, 1989a, b)。

华南内部南岭成矿带东段的崇(义)-(大)余-(上)犹地区为赣南地区有色、稀有、稀土成矿集中区,发育一系列钨、锡、钼、银、铅锌、铌钽、稀土矿床,具有多矿种共生,多类型共存的特征,成矿作用与印支-燕山期花岗质岩浆活动密切相关(王登红等,2016王浩洋等,2017王少轶等,2017赵正等,2017; Zhao and Zhou, 2018Zhao et al., 2018b)。铁木里岩体为该地区发育相对较少的燕山晚期岩浆岩。

2 岩体地质特征

铁木里岩体出露于江西崇义县城西北约20km处,大地构造上位于华夏块体腹地,属于南岭成矿带东段(图 1a)。岩体呈小岩株状产出,出露面积约1.2km2,侵位于上寒武统水石组浅变质岩(浅变质长石石英细砂岩夹薄层状板岩,局部有硅质石英砂岩、含钙砂岩及透镜状不纯灰岩)、下奥陶统茅坪组和中奥陶统对耳石组浅变质岩(粉砂质板岩、含碳板岩、硅质板岩等)和湖洋凹正长斑岩中(图 1b),岩性主要为肉红色和灰白色含黑云母碱长花岗岩,二者呈侵入接触,内部常见暗色包体。后期有碱性辉绿玢岩呈脉状侵入(郭娜欣等,2021)。

肉红色含黑云母碱长花岗岩(后文以r-G表示)呈细粒结构,主要由石英(~40%)、碱性长石(~50%)、黑云母(~5%)、磁铁矿(~5%)组成,副矿物主要有锆石、萤石、硅钛铈矿、独居石、金红石等。石英呈他形粒状,粒径0.5~1mm,部分石英内包裹有金红石、磁铁矿,显示其结晶较晚。碱性长石主要为正长石和条纹长石,正长石呈自形-半自形板状,粒径2mm×0.6mm左右;条纹长石呈他形板状,粒径1.5mm×1mm左右。黑云母呈自形-半自形片状,粒径1mm×0.4mm~2mm×0.5mm,单偏光下呈褐色。磁铁矿呈自形-半自形粒状,粒径约0.2mm,多与黑云母镶嵌生长(图 2a-c)。

图 2 铁木里含黑云母碱长花岗岩及暗色包体的岩相学特征 (a-c)肉红色含黑云母碱长花岗岩;(d-f)灰白色含黑云母碱长花岗岩;(g-i)暗色包体. Ab-钠长石;Ap-磷灰石;Bt-黑云母;Fl-萤石;Kfs-钾长石;Mag-磁铁矿;Mnz-独居石;Qtz-石英;Zrn-锆石 Fig. 2 Petrographic characteristics of the Tiemuli biotite-bearing alkali-feldspar granites and enclaves (a-c) flesh red biotite-bearing alkali-feldspar granites; (d-f) grey biotite-bearing alkali-feldspar granite; (g-i) enclave. Ab-albite; Ap-apatite; Bt-biotite; Fl-fluorite; Kfs-potassium feldspar; Mag-magnetite; Mnz-monazite; Qtz-quartz; Zrn-zircon

灰白色含黑云母碱长花岗岩(后文以g-G表示)主要呈中细粒-中粒结构,主要由石英(20%~30%)、碱性长石(60%~70%)、黑云母(3%~5%)、萤石(1%~2%)组成,副矿物主要有锆石、萤石、金红石、磷灰石、独居石、氟碳铈矿、氟碳钙铈矿等。石英呈半自形-他形粒状,粒径1~4mm,与长石、黑云母等矿物镶嵌生长。碱性长石以条纹长石为主,呈自形-半自形板状,粒径2mm×4mm,部分可达5~6mm。部分条纹长石被熔蚀呈眼球状,边部被石英、钠长石交代。黑云母呈他形填隙状,多已蚀变为绿泥石或白云母。萤石呈自形-半自形状,粒径0.1~0.6mm,内部常包含微粒锆石、钍石、易解石等(图 2d-f)。

暗色包体主要由细粒的黑云母(40%)、钠长石(40%)、石英(20%)组成,粒径0.1~0.8mm, 局部黑云母聚集呈团状。包体中见萤石、钍石、锆石、硅钛铈矿、独居石等副矿物,与黑云母密切共生。局部富硅,形成石英内部包含大量微粒黑云母的现象。此外包体中普遍发育针状磷灰石,有时还见有捕获的斜长石斑晶(成分为中-拉长石),呈自形板状,粒径可达6mm×1.2mm,指示存在岩浆混合作用(图 2g-i)。

3 铌、稀土矿物的岩相学特征

r-G中的铌、稀土矿物主要有铌铁金红石、磷灰石、独居石、硅钛铈矿、氟碳铈矿、氟碳钙铈矿。g-G中的铌、稀土矿物主要有铌铁金红石、易解石、铌铁矿、钛铁矿、独居石、磷灰石、氟碳铈矿、氟碳钙铈矿。暗色包体中铌矿物少见,主要见磷灰石、独居石等稀土矿物,偶见硅钛铈矿。

3.1 铌矿物

铁木里碱长花岗岩中的铌矿物主要为铌铁金红石和易解石,此外还有零星的铌铁矿和钛铁矿。

金红石主要见于g-G中,按产状可分为四类:(1)与磁铁矿、钛铁矿共生(图 3a);(2)与易解石共生(图 3b);(3)与稀土矿物共生(图 3c);(4)随机分布在黑云母、磁铁矿的内部或粒间(图 3d)。r-G中仅见与磁铁矿、钛铁矿共生的金红石(图 3a)。与磁铁矿、钛铁矿、易解石共生的金红石呈半自形粒状,粒径10~20μm(图 3a)。与稀土矿物紧密共生的金红石多呈他形粒状,粒径约为20μm,部分可达70μm。相对独立产出的金红石多产于绿泥石化黑云母中,呈自形柱状,粒径60~150μm。

图 3 铁木里碱长花岗岩中的金红石 (a)肉红色含黑云母碱长花岗岩中与磁铁矿、钛铁矿共生的金红石;(b)灰白色含黑云母碱长花岗岩中与易解石共生的金红石;(c)灰白色含黑云母碱长花岗岩中与氟碳铈矿、氟碳钙铈矿共生的金红石;(d)灰白色含黑云母碱长花岗岩中分布在磁铁矿内的金红石. Aes-易解石;Bast-氟碳铈矿;Ilm-钛铁矿;Par-氟碳钙铈矿;Rt-金红石;Xen-磷钇矿 Fig. 3 Rutiles in the Tiemuli alkali-feldspar granites (a) rutile accompanying with magnetite and ilmenite in r-G; (b) rutile accompanying with aeschynite in g-G; (c) rutile accompanying with bastnaesite and parasite in g-G; (d) rutile encompassed by magnetite in g-G. Aes-aeschynite; Bast-bastnaesite; Ilm-ilmenite; Par-parasite; Rt-rutile; Xen-xenotime

易解石属于含稀土的钛铌钽酸盐矿物,化学通式为AB2X6,A包括ΣCe、ΣY、Th、U、Ca、Mg、Fe2+、Mn、Na、Pb等,B包括Ti、Nb、Ta、Fe3+、Al、Si等,阴离子有O2-、OH-、F-等(张静,1988)。铁木里碱长花岗岩中的易解石主要见于g-G中,呈半自形-自形板状,发育裂纹,与金红石、锆石、萤石等共生,常被铌铁矿交代(图 4)。有时在萤石中观察到有易解石的微细粒包体(图 3b)。易解石的产出特征显示其为热液成因。

图 4 铁木里灰白色含黑云母碱长花岗岩中的易解石Clb-铌铁矿 Fig. 4 Aeschynites in the Tiemuli grey biotite-bearing alkali-feldspar granites Clb-columbite

铌铁矿见于g-G中,呈他形交代易解石(图 4b, c),为热液成因。钛铁矿在r-G和g-G中均为零星出现,有两种产状:(1)呈自形粒状包裹于造岩矿物,如石英中,粒径~50μm;(2)呈不规则状、微细脉状分布在磁铁矿、金红石边部,或穿入磁铁矿内部(图 3a)。钛铁矿的产出特征显示其形成于岩浆阶段。

3.2 稀土矿物

铁木里碱长花岗岩中的稀土矿物主要可以分为稀土磷酸盐、稀土氟碳酸盐、稀土钛硅酸盐三类。

稀土磷酸盐矿物以磷灰石和独居石为主,磷钇矿仅零星见于g-G中。磷灰石主要见于g-G及暗色包体中。g-G中的磷灰石可分为2类:内部不含独居石包体的自形柱状磷灰石(Ap-Ⅰ)(图 5c)、内部含独居石包体的磷灰石(Ap-Ⅱ)(图 5e, f)。暗色包体中的磷灰石呈细长柱状、针状(Ap-Ⅲ)(图 5a, b)。

图 5 铁木里碱长花岗岩及暗色包体中的磷灰石 (a、b)暗色包体中的磷灰石;(c-f)灰白色含黑云母碱长花岗岩中的磷灰石. Chev-硅钛铈矿;Chl-绿泥石 Fig. 5 Apatites in the Tiemuli alkali-feldspar granites and enclaves (a, b) apatite in enclaves; (c-f) apatite in g-G. Chev-chevkinite; Chl-chlorite

独居石在r-G、g-G及暗色包体中均有产出。r-G中的独居石有的呈半自形粒状包裹于其他矿物(如黑云母、石英)内,部分颗粒发育平直的晶面并显示环带结构,显示岩浆成因(图 6a, b);有的与绿泥石共生,显示热液成因(图 6c)。g-G中的独居石主要呈不规则状散布于其他矿物(如磷灰石)内(图 5e, f),或呈他形粒状与氟碳(钙)铈矿、萤石、锆石、金红石等矿物共生(图 6d),显示热液成因。暗色包体中的独居石分布在石英内,与针状磷灰石共生(图 2i)。

图 6 铁木里碱长花岗岩中的独居石 (a-c)肉红色含黑云母碱长花岗岩中的独居石;(d)灰白色含黑云母碱长花岗岩中的独居石Bast-Par-氟碳铈矿-氟碳钙铈矿交生体 Fig. 6 Monazites in the Tiemuli alkali-feldspar granites (a-c) monazite in r-G; (d) monazite in g-G. Bast-Par-intergrowth of bastnaesite and parasite

稀土氟碳酸盐矿物主要为氟碳铈矿和氟碳钙铈矿,见于r-G和g-G中。二者相间交生,但前者占优势,背散射图像下呈明(氟碳铈矿)、暗(氟碳钙铈矿)相间条纹状(图 3c图 5d图 6d)。氟碳铈矿和氟碳钙铈矿的粒径在20~200μm之间不等,与萤石、热液锆石、独居石、绿泥石、石英等矿物共生,穿入造岩矿物长石或磷灰石的晶体内部或间隙中,显示为热液阶段产物。

稀土钛硅酸盐矿物主要为硅钛铈矿,主要见于r-G中,呈自形短柱状,粒径30~50μm,与磁铁矿、锆石共生或包裹在其他矿物,如石英、钠长石、黑云母内部(图 7a-e),显示其为岩浆阶段较早结晶的矿物。部分硅钛铈矿显示遭受热液交代作用,从矿物边缘向内交代作用增强(图 7c-e)。暗色包体中的黑云母内也偶见硅钛铈矿(图 7f)。

图 7 铁木里碱长花岗岩及暗色包体中的硅钛铈矿 (a-e)肉红色含黑云母碱长花岗岩中的硅钛铈矿;(f)暗色包体中的硅钛铈矿. To-钍石 Fig. 7 Chevkinites in the Tiemuli alkali-feldspar granites and enclaves (a-e) chevkinite in r-G; (f) chevkinite in enclave. To-thorite

根据矿物结构及共生组合关系可以看出,r-G中岩浆期矿物组合为碱性长石-石英-黑云母-磁铁矿-锆石-硅钛铈矿-独居石-金红石-钛铁矿,热液期矿物组合为石英-钠长石-绿泥石-独居石-氟碳(钙)铈矿-钍石;g-G中岩浆期矿物组合为碱性长石-石英-黑云母-锆石-磷灰石-钛铁矿-磷钇矿-金红石,热液期矿物组合为石英-萤石-方解石-绿泥石-白云母-锆石-磷灰石-独居石-氟碳(钙)铈矿-金红石-易解石-铌铁矿-钍石;暗色包体中斜长石斑晶及针状磷灰石等显示岩浆混合特征。铁木里碱长花岗岩中的铌和稀土元素经过了岩浆结晶和岩浆期后热液交代两个阶段的富集过程,且g-G的热液交代作用比r-G要强(图 8)。

图 8 铁木里岩体的矿物组合特征 线条粗细表示矿物相对含量的多少,不代表绝对含量 Fig. 8 Mineral assemblage of the Tiemuli alkali-feldspar granites Thickness of lines represents the relative proportion instead of absolute proportion of minerals
4 分析测试方法

本次工作在铁木里矿区坑道内采集样品,对铌、稀土矿物进行了电子探针分析和LA-ICP-MS原位微量元素分析。电子探针测试工作在中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室完成,仪器型号为JXA-8230,测试时加速电压为15kV,激发电流为20nA,根据矿物粒度大小,电子束斑直径选择5μm或1μm。测试过程中稀土矿物标样采用人造稀土五磷酸盐,如五磷酸镧、五磷酸铈等。

矿物的LA-ICP-MS原位微量元素分析在国家地质实验测试中心完成,测试仪器为ASJ-200 343nm飞秒激光剥蚀系统和X-Series电感耦合等离子质谱仪。测试时使用氦气作为载气,激光能量密度为5J/cm2,剥蚀束斑直径30μm,激光频率8Hz。分析中所用标样为人工合成硅酸盐玻璃SRM610、SRM612。实验过程中,每测10个点,加测一次标样(2个SRM610,1个SRM612)。内标采用SiO2,外标采用SRM610和SRM612。数据处理采用ICPMSDatacal 10.8软件完成。

5 测试结果 5.1 铌矿物

金红石的TiO2含量为71.07%~97.92%,FeOT含量为0.73%~6.04%,Nb2O5含量为2.20%~19.79%,还有少量的Ta2O5(0.03%~1.40%)、WO3(0%~7.40%)、SnO2(0%~1.99%)(表 2)。图 9显示,Ti与Nb、FeT显示显著的负相关,说明金红石中主要发生了Nb、Fe对Ti的类质同象置换,置换方式为2Nb5++Fe2+→3Ti4+,且这种类质同象置换是不均匀的,使得金红石在背散射图像下呈明暗相间的不规则状(图 3b, c)。金红石的稀土元素含量低,ΣREE值为161×10-6~2136×10-6(表 3)。

表 2 铁木里碱长花岗岩中金红石的电子探针分析结果(wt%) Table 2 EPMA analysis results of rutiles in the Tiemuli alkali-feldspar granites (wt%)

图 9 金红石的化学成分特征 Fig. 9 Geochemical features of the rutiles in Tiemuli alkali-feldspar granites

表 3 铁木里碱长花岗岩中金红石的LA-ICP-MS分析结果(×10-6) Table 3 LA-ICP-MS analysis results of rutiles in the Tiemuli alkali-feldspar granites (×10-6)

易解石中Nb2O5含量为21.18%~43.44%(平均值31.62%),Ta2O5含量为1.08%~11.66%(平均值5.19%),TiO2含量为7.40%~19.64%(平均值14.06%),UO2含量为7.93%~27.88%(平均值18.04%)(表 4),属于铀-易解石,并且铀含量远高于一般铀-易解石中的铀含量(5%~7%,王濮等,1982)。此外,还含有不同数量的SiO2(1.04%~7.67%)、Al2O3(0.16%~0.29%)、FeOT(1.12%~16.97%)、CaO(1.91%~11.40%)、BaO(0.45%~6.23%)、ThO2(0.51%~4.67%)、WO3(0.40%~1.10%)、SnO2(0%~3.80%)、F(0.10%~0.65%)。值得注意的是,铀-易解石中稀土元素含量低,一个点的分析结果显示其ΣRe2O3仅为1.42%,且表现为富轻稀土贫重稀土的特征,ΣLRe2O3/ΣHRe2O3为1.90。易解石的化学成分特征表明存在U、Th、Ti对Nb、REE的类质同象置换作用,置换方式为(U, Th)4++Ti4+→Nb5++REE3+

表 4 铁木里碱长花岗岩中易解石的电子探针分析结果(wt%) Table 4 EPMA analysis results of aeschynites in the Tiemuli alkali-feldspar granites (wt%)

铌铁矿中Nb2O5含量为66.30%~71.28%,Ta2O5含量为3.48%~6.81%,此外含少量的TiO2(3.64%~3.94%)、MnO(4.08%~4.59%)、WO3(1.28%~1.51%)、SnO2(0.27%~0.56%)、UO2(0.66%~1.14%)、ThO2(0.15%~0.65%)。钛铁矿中Nb2O5含量为1.49%~2.42%,Ta2O5为0.13%~0.23%,MnO含量为3.27%~3.63%,MgO含量很低(表 5)。

表 5 铁木里碱长花岗岩中铌铁矿、钛铁矿的电子探针分析结果(wt%) Table 5 EPMA analysis results of columbites and ilmenites in the Tiemuli alkali-feldspar granites (wt%)
5.2 稀土矿物

电子探针分析结果表明,铁木里碱长花岗岩中磷灰石的F含量为1.98%~3.70%,属于氟磷灰石(表 6)。g-G中内部不含独居石包体的自形柱状磷灰石(Ap-Ⅰ)的P2O5含量为40.04%~41.15%,CaO含量为50.88%~55.77%,F含量为2.74%~2.97%;有独居石包体的磷灰石(Ap-Ⅱ)的P2O5含量为40.15%~42.97%,CaO含量为54.27%~55.33%,MnO含量为0.04%,F含量为1.98%~3.70%。暗色包体中针状、细长柱状的磷灰石(Ap-Ⅲ)的P2O5含量为38.57%~42.57%,CaO含量为53.59%~55.18%,MnO含量为0.52%~0.62%,F含量为2.23%~2.61%。此外,磷灰石中还含有少量的SiO2和Na2O。三种磷灰石的各氧化物平均值相比,Ap-Ⅲ具有中等的CaO、P2O5含量,最高的Na2O、SiO2、MnO含量和最低的F、Cl含量;Ap-Ⅱ具有最高的CaO、P2O5含量,最低的SiO2含量和中等的F、Cl含量(图 10表 6)。对Ap-Ⅱ和Ap-Ⅲ进行了原位微量元素测试(表 7),其球粒陨石标准化稀土元素配分图均呈右倾型,但Ap-Ⅱ具有更高的稀土元素含量,更显著的铕负异常(δEu=0.08 ~ 0.09)和更强烈的轻重稀土元素分馏(图 11)。Ap-Ⅲ具有显著的铈正异常(δCe=1.47 ~ 1.81)。此外,AP-Ⅱ具有较高的Rb、Sr、Zr、Hf、Nb、Ta、Th、U、Ba等微量元素(表 7)。

表 6 铁木里碱长花岗岩中磷灰石的电子探针分析结果(wt%) Table 6 EPMA analysis results of apatites in the Tiemuli alkali-feldspar granites (wt%)

图 10 铁木里碱长花岗岩中的磷灰石成分特征 空心符号代表测试值,实心符号代表平均值 Fig. 10 Geochemical feature of the apatites in Tiemuli alkali-feldspar granites Hollow symbols mean analysis values, and solid symbols stand for average values

表 7 铁木里碱长花岗岩中磷灰石的微量元素分析结果(×10-6) Table 7 Trace elements contents of apatites in the Tiemuli alkali-feldspar granites (×10-6)

图 11 铁木里碱长花岗岩中的磷灰石球粒陨石标准化稀土元素配分图(标准化值据Sun and McDonough, 1989) Fig. 11 Chondrite-normalized REE patterns of apatites in Tiemuli alkali-feldspar granites (normalization values from Sun and McDonough, 1989)

r-G中岩浆成因独居石的稀土元素含量低(ΣRe2O3=48.81%~53.96%),ThO2(12.61%~17.90%)、SiO2(1.99%~3.20%)含量高(表 8)。两种花岗岩中热液独居石的稀土元素含量高(ΣRe2O3=58.76%~65.15%),ThO2(4.33%~6.99%)、SiO2(0.79%~1.15%)含量低(表 8)。暗色包体中独居石的化学成分与热液独居石相近,但变化范围更大(图 12)。独居石中ThO2与SiO2呈良好的正相关,与ΣRe2O3呈负相关,说明存在阳离子Th4+代替Ce3+、络阴离子[SiO4]2-代替[PO4]3-的类质同象替换,其替代方式为Th4++Si4+→Ce3++P5+,且岩浆成因独居石中这种类质同象替代程度显著高,说明岩浆富Si、Th。在稀土元素球粒陨石标准化配分曲线图上,各类独居石均呈右倾型。r-G中的岩浆、热液独居石的稀土元素球粒陨石标准化配分曲线形态一致;g-G中的热液独居石中重稀土元素(Er、Tm、Yb、Lu)呈现富集特征;暗色包体中的独居石的重稀土元素(Er、Tm、Yb、Lu)较r-G中独居石高,较g-G中独居石低(表 9图 12d)。

表 8 铁木里碱长花岗岩中独居石的电子探针分析结果(wt%) Table 8 EPMA analysis results of monazites in the Tiemuli alkali-feldspar granites (wt%)

图 12 铁木里碱长花岗岩中独居石的化学成分特征及球粒陨石标准化稀土元素配分图(标准化值据Sun and McDonough, 1989) Fig. 12 Geochemical features and chondrite-normalized REE patterns (normalization values from Sun and McDonough, 1989) of monazites in the Tiemuli alkali-feldspar granites

表 9 铁木里碱长花岗岩中独居石的微量元素分析结果(×10-6) Table 9 Trace elements contents of monazites in the Tiemuli alkali-feldspar granites (×10-6)

氟碳铈矿的稀土氧化物含量(ΣRe2O3)为74.51%~79.11%,F含量为4.16%~6.04%,与理论值(王濮等,1982)十分接近。氟碳钙铈矿的ΣRe2O3含量为63.75%~71.89%,F含量为2.50%~2.89%,CaO含量为6.50%~10.57%,F含量较理论值略微偏低。此外,氟碳铈矿与氟碳钙铈矿均含有少量Th、U、Fe,二者相比,氟碳铈矿的ThO2(0.50%~1.08%)、UO2(0.05%)较高,氟碳钙铈矿的FeOT(0.16%~0.46%)较高(表 10)。

表 10 铁木里碱长花岗岩中氟碳铈矿、氟碳钙铈矿的电子探针分析结果(wt%) Table 10 EPMA analysis results of bastnaesite and parisite in the Tiemuli alkali-feldspar granites (wt%)

r-G中硅钛铈矿的ΣREE含量为39031×10-6~581107×10-6,SiO2含量为12.81%~16.74%,TiO2含量为9.10%~12.11%,FeOT含量为2.54%~12.68%,CaO含量为0.95%~2.13%,Nb2O5含量为3.36%~5.17%,ThO2含量为3.05%~4.72%(表 11表 12)。遭受蚀变后,硅钛铈矿的SiO2、CaO、FeOT降低,Nb、Th、REE增高。暗色包体中硅钛铈矿的化学成分与受到热液影响的硅钛铈矿相似(图 13)。在球粒陨石标准化稀土元素配分图上,r-G中的硅钛铈矿具有相似的配分曲线,轻重稀土元素分馏强,显示有明显负铕异常的右倾型;暗色包体中硅钛铈矿具有弱的铕负异常,重稀土元素分馏弱(图 13d)。

表 11 铁木里碱长花岗岩中硅钛铈矿的电子探针分析结果(wt%) Table 11 EPMA analysis results of chevkinites in the Tiemuli alkali-feldspar granites (wt%)

表 12 铁木里碱长花岗岩中硅钛铈矿的微量元素含量(×10-6) Table 12 Trace elements contents of chevkinites in the Tiemuli alkali-feldspar granites (×10-6)

图 13 铁木里碱长花岗岩中硅钛铈矿的化学成分特征及球粒陨石标准化稀土元素配分图(标准化值据Sun and McDonough, 1989) Fig. 13 Geochemical features and chondrite-normalized REE patterns (normalization values from Sun and McDonough, 1989) of chevkinites in Tiemuli alkali-feldspar granites
6 讨论 6.1 铁木里碱长花岗岩中铌、稀土矿物形成时的物理条件

金红石中Zr的含量主要受温度控制,受压力影响较小,可用于计算其结晶时体系的温度。根据Watson et al.(2006)的经验公式:log(Zr金红石)=(7.36±0.10)-(4470±120)/T(K),计算出黑云母中的金红石(TML-1-12-2)以及与易解石共生的金红石TML-1-5-4具有较高的结晶温度(688℃),代表了岩浆成因金红石的结晶温度,结晶温度较低的金红石为受到热液影响的金红石或者直接是从热液中结晶出来的(<500℃)(表 2表 3)。也就是说,铌主要在岩浆阶段和高温热液阶段以金红石-易解石-铌铁矿的形式结晶沉淀。绿泥石作为中-低温条件下稳定存在的热液矿物,其成分可以反演体系的温度和氧逸度。Foster(1962)提出,在利用绿泥石的成分数据时,首先根据Na2O+K2O+CaO值判断数据的可靠性,若该值大于0.5%,表明绿泥石成分存在混染,需要剔除。以此为标准,本文得到了绿泥石的有效成分(表 13)。根据Cathelineau(1988)的经验公式:T(℃)=321.98Al/2-61.9,计算出g-G中由黑云母蚀变而成的绿泥石(Chl-Ⅰ,图 2d)的形成温度为346~387℃;r-G中与萤石、钍石、硅钛铈矿、氟(碳)钙铈矿、独居石等热液矿物共生的绿泥石(Chl-Ⅱ,图 5f图 6a-c)的形成温度为283~ 284℃,暗色包体中绿泥石(Chl-Ⅲ,图 5a)的形成温度为226~299℃。

表 13 铁木里碱长花岗岩中绿泥石的电子探针分析结果(wt%) Table 13 EPMA analysis results of chlorites in the Tiemuli alkali-feldspar granites (wt%)

在长英质岩石中,硅钛铈矿的稳定域随氧逸度的增加而扩展(Scaillet and Macdonald, 2001)。r-G中硅钛铈矿的出现说明体系具有相对较高的氧逸度,而硅钛铈矿后期受到热液交代分解的现象表明可能存在氧逸度的降低。实验研究表明,绿泥石的Fe/(Fe+Mg)值与环境的氧逸度有关,环境的还原性越强,形成的绿泥石Fe/(Fe+Mg)值越大(Bryndzia and Scott, 1987)。Chl-Ⅰ、Chl-Ⅱ、Chl-Ⅲ三种绿泥石的Fe/(Fe+Mg)值分别为0.82~0.88、0.94~0.95、0.88~ 0.89,说明它们均形成于还原性的热液流体环境。中酸性岩浆岩中磷灰石内Mn的含量与其结晶时体系的氧逸度存在相关性(Miles et al., 2014),根据Miles et al.(2014)的经验公式:logfO2=-0.0022(±0.0003)Mn(×10-6)-9.75(±0.46),计算出g-G中有独居石包体的磷灰石Ap-Ⅱ形成时的氧逸度为10-10.5~10-10.4;暗色包体中磷灰石Ap-Ⅲ结晶时的氧逸度为10-20.3~10-18.6。此外,黑云母的化学成分也显示花岗岩中黑云母形成时的氧逸度在磁铁矿-赤铁矿(Fe3O4-Fe2O3,HM)缓冲线附近,暗色包体中黑云母形成时的氧逸度在自然镍-绿镍矿(Ni-NiO,NNO)缓冲线附近(另文发表)。暗色包体相对较低的氧逸度可能是由还原性的镁铁质岩浆混入造成的,这与包体中存在中-拉长石斑晶的现象一致。因此,对铁木里花岗质岩浆-热液体系而言,从岩浆期到热液期,体系由高氧逸度向低氧逸度的还原状态演化,这与西华山、骑田岭、大湖塘等花岗岩体的演化过程一致(Xie et al., 2010李洁等,2013韩丽等,2016)。

综上,铌矿物主要形成于岩浆结晶阶段(金红石)和岩浆期后高温热液阶段早期(热液金红石、易解石、铌铁矿)(688~486℃);稀土元素主要在岩浆结晶阶段形成磷灰石、独居石、硅钛铈矿,部分进入黑云母,这些矿物在岩浆期后热液阶段发生稀土元素的活化、迁移,并在中温热液阶段结晶形成热液独居石、氟碳铈矿、氟碳钙铈矿等稀土矿物(283~284℃)。从岩浆阶段到岩浆期后热液阶段,铁木里花岗质岩浆-热液体系的温度和氧逸度均呈现降低趋势,这可能是导致稀土元素活化、迁移的重要因素。

6.2 铁木里碱长花岗岩中铌、稀土矿物形成时体系的化学成分特征

在铁木里碱长花岗岩中,岩浆结晶阶段即有铌铁金红石、钛铁矿、硅钛铈矿、磷灰石、独居石等铌、稀土矿物形成,说明岩浆本身富集Ca、Ti、Fe、Nb、REE、P、F等。岩浆结晶的硅钛铈矿受到热液交代后,SiO2、FeOT降低,REE、Th、Ca、F增高;易解石中铀含量高(7.93%~27.88%)。以上特征说明流体与岩浆相比更富REE、Th、U、Ca、F,贫Si、Ti。

在过铝质花岗岩体系中,结晶分异过程可以富集大部分的稀土元素。REE3+与Ca2+的离子半径接近,含钙的造岩矿物(如斜长石、黑云母)和副矿物(如硅钛铈矿、磷灰石、独居石、榍石、萤石等)富集了体系中绝大部分的稀土元素,上述矿物的分离结晶使残余熔体及岩浆期后的气成热液中稀土元素贫化(刘英俊等,1986赵振华等,1999李福春等,2002)。铁木里碱长花岗岩中的斜长石属于钠长石,含钙造岩矿物主要为黑云母,因此体系中的稀土元素绝大部分在岩浆结晶分异过程中进入了黑云母、硅钛铈矿、磷灰石、独居石等矿物中。随着结晶分异的进行,残余岩浆向富碱、富挥发份的方向演化。当岩浆中水达到饱和或过饱和时,在一定的物理化学条件下会分异出富挥发份(H2O、F、Cl、B、P等)的富碱贫硅流体(李建康等,2008)。富碱流体可将早期结晶的含钙矿物中的稀土元素置换出来,F等卤素可显著提高高场强元素矿物在热液中的溶解度(Migdisov et al., 2011Tanis et al., 2016Timofeev et al., 2017)。这一过程使得铁木里碱长花岗岩中岩浆阶段结晶的磷灰石、硅钛铈矿、独居石和黑云母中的稀土元素被迁移出来。当体系的物理化学条件,如温度、氧逸度、流体成分等发生变化时,络合物溶解度降低,成矿元素沉淀(Salvi et al., 2000Williams-Jones et al., 2000Trofanenko et al., 2016刘琰等,2017)。铁木里碱长花岗岩中磷灰石内的稀土元素在热液阶段被活化迁移,部分在磷灰石内部发生再沉淀形成独居石,说明稀土元素被迁移出磷灰石晶格后很快与[PO4]3-结合,其余稀土元素在热液中与F-、CO32-形成络合物稳定留存在热液中。岩浆热液与碳酸盐岩围岩反应使Ca2+和CO2等加入热液。Ca2+的加入一方面可以使硅钛铈矿、独居石变得不稳定而部分或全部溶解(Li and Zhou, 2017),另一方面可与F-结合形成萤石。萤石的沉淀会显著影响F-的活度,造成稀土-氟化物络合物活性急剧下降,稀土-氟化物络合物失稳,氟碳铈矿、氟碳钙铈矿沉淀。CO2的加入会降低金红石的溶解度,形成与稀土矿物共生的贫REE和Nb的热液金红石。此外,普遍观察到热液锆石与热液阶段形成的氟碳铈矿、氟碳钙铈矿、独居石、萤石等矿物共生(图 6d),说明体系中也有锆的富集,实验岩石学研究也表明锆在富氟的碱性流体中可以被有效溶解并搬运(Migdisov et al., 2011)。

6.3 铁木里碱长花岗岩的稀有、稀土元素成矿潜力

综上所述,铁木里岩体是一个发育岩浆-热液型铌-稀土矿化的碱长花岗岩体,并伴有钍、铀、锆等高场强元素的富集。国内外许多与碱性岩有关的岩浆-热液型稀有稀土矿床都表现为深部岩体型矿化与浅部热液脉型矿化模式,如加拿大Thor Lake的Nechalacho岩体深部为岩浆型铌钽矿化,浅部为热液型铌钽矿化(Timofeev and Williams-Jones, 2015);我国冕宁-德昌稀土成矿带中牦牛坪稀土矿深部为伟晶岩型-岩浆型稀土矿化,浅部为热液脉型稀土矿化(Xie et al., 2015)。铁木里岩体位于华南腹地,是白垩纪华南地区软流圈上涌、岩石圈拉张减薄构造背景下的产物,花岗岩为经历多次陆内造山作用的老地壳重熔而成(Lu et al., 2018),与其同期的碱性辉绿玢岩为软流圈地幔减压熔融并萃取岩石圈地幔富集组分形成(郭娜欣等,2021)。壳幔物质混合导致岩浆中铌和稀土元素的初始富集,充分的结晶分异及岩浆期后热液作用使成矿物质再次活化富集。目前铁木里地表露头见大量围岩捕掳体,即剥蚀作用仅影响到岩体顶部,岩体主体均尚保留。虽然其矿化尚未达到工业矿体标准,但可以作为岩浆-热液型铌-稀土矿产资源综合评价的一个重要靶区。

7 结论

(1) 铁木里碱长花岗岩中的铌和稀土元素经过了岩浆结晶和岩浆期后热液两个阶段的富集过程。岩浆阶段具有较高的氧逸度,岩浆期后热液阶段则为低氧逸度的还原状态。在岩浆-热液演化过程中,体系的温度和氧逸度均呈下降趋势。

(2) 铌在岩浆结晶阶段主要形成铌铁金红石,在岩浆期后高温热液阶段早期(>486℃)形成热液铌铁金红石、易解石、铌铁矿等。

(3) 稀土元素在岩浆结晶阶段形成氟磷灰石、独居石、硅钛铈矿等,在岩浆期后热液阶段发生活化、迁移,并在中温热液阶段(~280℃)沉淀形成热液独居石、氟碳铈矿、氟碳钙铈矿等。

(4) 铁木里碱长花岗岩体发育岩浆-热液型铌-稀土矿化,可以作为该类资源综合评价的重要靶区。

参考文献
Bryndzia LT and Scott SD. 1987. The composition of chlorite as a function of sulfur and oxygen fugacity: An experimental study. American Journal of Science, 287(1): 50-76 DOI:10.2475/ajs.287.1.50
Cathelineau M. 1988. Cation site occupancy in chlorites and illites as a function of temperature. Clay Minerals, 23(4): 471-485 DOI:10.1180/claymin.1988.023.4.13
Chen J, Lu JJ, Chen WF, Wang RC, Ma DS, Zhu JC, Zhang WL and Ji JF. 2008. W-Sn-Nb-Ta-bearing granites in the Nanling range and their relationship to metallogengesis. Geological Journal of China Universities, 14(4): 459-473 (in Chinese with English abstract)
Chen YC, Pei RF, Zhang HL, Lin XD, Bai G, Li CY, Hu YJ, Liu GQ and Xian BQ. 1989. The Geology of Non-Ferrous and Rare Metal Deposits Related to Mesozoic Granitoids in Nanling Region. Beijing: Geological Publishing House, 1-508 (in Chinese)
Cui YY. 2014. Geochronology, geochemistry and petrogenesis of the granitoids in the Sanming-Ganzhou area, South China. Master Degree Thesis. Beijing: China University of Geosciences (Beijing) (in Chinese with English abstract)
Denys A, Janots E, Auzende AL, Lanson M, Findling N and Trcera N. 2021. Evaluation of selectivity of sequential extraction procedure applied to REE speciation in laterite. Chemical Geology, 559: 119954 DOI:10.1016/j.chemgeo.2020.119954
Foster MD. 1962. Interpretation of the composition and a classification of the chlorites. Washington: United States Government Printing Office, A1-A33
Gu XP. 1989a. Allanite as the indicator of the oxygen fugacity of granite magmas. Minerals and Rocks, 9(3): 26-32 (in Chinese with English abstract)
Gu XP. 1989b. Characteristics of the rare earth composition of allanite and their geological implications in Xinfeng granite. Mineral Resources and Geology, 3(3): 47-50 (in Chinese with English abstract)
Guo CL, Chen YC, Zeng ZL and Lou FS. 2012. Petrogenesis of the Xihuashan granites in southeastern China: Constraints from geochemistry and in-situ analyses of zircon U-Pb-Hf-O isotopes. Lithos, 148: 209-227 DOI:10.1016/j.lithos.2012.06.014
Guo NX, Zhao Z, Gao JF, Chen W, Wang DH and Chen YC. 2018. Magmatic evolution and W-Sn-U-Nb-Ta mineralization of the Mesozoic Jiulongnao granitic complex, Nanling Range, South China. Ore Geology Reviews, 94: 414-434 DOI:10.1016/j.oregeorev.2018.02.015
Guo NX, Liu SB and Zhao Z. 2021. Geochronology, geochemistry and geological implications of diabase porphyrite in Tiemuli W-Fe deposit, Chongyi County, Jiangxi Province. Earth Science, 46(2): 460-473 (in Chinese with English abstract)
Han L, Huang XL, Li J, He PL and Yao JM. 2016. Oxygen fugacity variation recorded in apatite of the granite in the Dahutang tungsten deposit, Jiangxi Province, South China. Acta Petrologica Sinica, 32(3): 746-758 (in Chinese with English abstract)
Hong DW. 1982. Biotites and mineralogical facies from granitic rocks of South China and their relation to the series of mineralization. Acta Geologica Sinica, 56(2): 149-164 (in Chinese with English abstract)
Hu RZ, Chen WT, Xu DR and Zhou MF. 2017. Reviews and new metallogenic models of mineral deposits in South China: An introduction. Journal of Asian Earth Sciences, 137: 1-8 DOI:10.1016/j.jseaes.2017.02.035
Hua RM and Mao JW. 1999. A preliminary discussion on the Mesozoic Metallogenic Explosion in East China. Mineral Deposits, 18(4): 300-307 (in Chinese with English abstract)
Hua RM, Zhang WL, Gu SY and Chen PR. 2007. Comparison between REE granite and W-Sn granite in the Nanling region, South China, and their mineralizations. Acta Petrologica Sinica, 23(10): 2321-2328 (in Chinese with English abstract)
Huang WT, Wu J, Liang HY, Zhang J, Ren L and Chen XL. 2020. Ages and genesis of W-Sn and Ta-Nb-Sn-W mineralization associated with the Limu granite complex, Guangxi, China. Lithos, 352-353: 105321 DOI:10.1016/j.lithos.2019.105321
Jia XH, Wang XD, Yang WQ and Niu ZJ. 2014. Formation age, geochemistry and petrogenesis of Xueshanzhang A-type granite in nrthern Guangdong. Journal of Mineralogy and Petrology, 34(3): 40-49 (in Chinese with English abstract)
Li FC, Zhu JC, Qi L, Rao B and Pan GX. 2002. Experimental study on evolution of REE in magmatic fluid phase in the F-rich granite system. Geological Journal of China Universities, 8(1): 9-15 (in Chinese with English abstract)
Li J, Zhong JW, Yu Y and Huang XL. 2013. Insights on magmatism and mineralization from micas in the Xihuashan granite, Jiangxi Province, South China. Geochimica, 42(5): 393-404 (in Chinese with English abstract)
Li JK, Zhang DH, Wang DH and Zhang WH. 2008. Liquid immiscibility of fluorine-rich granite magma and its diagenesis and metallogeny. Geological Review, 54(2): 175-183 (in Chinese with English abstract)
Li JK, Li P, Wang DH and Li XJ. 2019. A review of niobium and tantalum metallogenic regularity in China. Chinese Science Bulletin, 64(15): 1545-1566 (in Chinese) DOI:10.1360/N972018-00933
Li SH, Li JK, Chou IM, Jiang L and Ding X. 2017. The formation of the Yichun Ta-Nb deposit, South China, through fractional crystallization of magma indicated by fluid and silicate melt inclusions. Journal of Asian Earth Science, 137: 180-193 DOI:10.1016/j.jseaes.2016.11.016
Li XC and Zhou MF. 2017. Hydrothermal alteration of monazite-(Ce) and chevkinite-(Ce) from the Sin Quyen Fe-Cu-LREE-Au deposit, northwestern Vietnam. American Mineralogist, 102(7): 1525-1541 DOI:10.2138/am-2017-5970
Linnen RL and Cuney M. 2005. Granite-related rare-element deposits and experimental constraints on Ta-Nb-W-Sn-Zr-Hf mineralization. In: Linnen RL and Samson IM (eds. ). Rare-Element Geochemistry and Mineral Deposits. Ottawa: Geological Association of Canada, 45-67
Liu Y, Chen C, Shu XC, Guo DX, Li ZJ, Zhao HX and Jia YH. 2017. The formation model of the carbonatite-syenite complex REE deposits in the east of Tibetan Plateau: A case study of Dalucao REE deposit. Acta Petrologica Sinica, 33(7): 1978-2000 (in Chinese with English abstract)
Liu YC, Li JK, Zou TR, Jiang SY, Ding X and Wang X. 2017. Constraints of fluid evolution on Nb and Ta enrichment of the Daping granite porphyry in Yongding, Fujian. Acta Geologica Sinica, 91(5): 1052-1065 (in Chinese with English abstract)
Liu YJ, Cao LM, Li ZL, Wang HN, Chu TQ and Zhang JR. 1986. Geochemistry of Elements. Beijing: Science Press, 1-548 (in Chinese)
Lu L, Liang T, Zhao Z and Liu SB. 2018. A unique association of scheelite and magnetite in the Tiemuli W-Fe skarn deposit: Implications for Early Cretaceous metallogenesis in the Nanling Region, South China. Ore Geology Reviews, 94: 136-154 DOI:10.1016/j.oregeorev.2018.01.028
Migdisov AA, Williams-Jones AE, van Hinsberg V and Salvi S. 2011. An experimental study of the solubility of baddeleyite (ZrO2) in fluoride-bearing solutions at elevated temperature. Geochimica et Cosmochimica Acta, 75(23): 7426-7434 DOI:10.1016/j.gca.2011.09.043
Miles AJ, Graham CM, Hawkesworth CJ, Gillespie MR, Hinton RW, Bromiley GD and EMMAC. 2014. Apatite: A new redox proxy for silicic magmas?. Geochimica et Cosmochimica Acta, 132: 101-119 DOI:10.1016/j.gca.2014.01.040
Moreno JA, Molina JF, Bea F, Abu Anbar M and Montero P. 2016. Th-REE-and Nb-Ta-accessory minerals in post-collisional Ediacaran felsic rocks from the Katerina Ring Complex (S. Sinai, Egypt): An assessment for the fractionation of Y/Nb, Th/Nb, La/Nb and Ce/Pb in highly evolved A-type granites. Lithos, 258-259: 173-196
Salvi S, Fontan F, Monchoux P, Williams-Jones AE and Moine B. 2000. Hydrothermal mobilization of high field strength elements in alkaline igneous systems: Evidence from the Tamazeght Complex (Morocco). Economic Geology, 95(3): 559-576
Scaillet B and Macdonald R. 2001. Phase relations of peralkaline silicic magmas and petrogenetic implications. Journal of Petrology, 42(4): 825-845 DOI:10.1093/petrology/42.4.825
Sun SS and McDonough WF. 1989. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. In: Saunders AD and Norry MJ (eds.). Magmatism in the Ocean Basins. Geological Society, London, Special Publication, 42(1): 313-345
Tanis EA, Simon A, Zhang YX, Chow P, Xiao YM, Hanchar JM, Tschauner O and Shen GY. 2016. Rutile solubility in NaF-NaCl-KCl-bearing aqueous fluids at 0. 5~2.79GPa and 250~650℃. Geochimica et Cosmochimica Acta, 177: 170-181 DOI:10.1016/j.gca.2016.01.003
Timofeev A and Williams-Jones AE. 2015. The origin of niobium and tantalum mineralization in the Nechalacho REE deposit, NWT, Canada. Economic Geology, 110(7): 1719-1735 DOI:10.2113/econgeo.110.7.1719
Timofeev A, Migdisov AA and Williams-Jones AE. 2017. An experimental study of the solubility and speciation of tantalum in fluoride-bearing aqueous solutions at elevated temperature. Geochimica et Cosmochimica Acta, 197: 294-304 DOI:10.1016/j.gca.2016.10.027
Trofanenko J, Williams-Jones AE, Simandl GJ and Migdisov AA. 2016. The nature and origin of the REE mineralization in the Wicheeda carbonatite, British Columbia, Canada. Economic Geology, 111(1): 199-223 DOI:10.2113/econgeo.111.1.199
Wang DH, Zhao Z, Liu SB, Guo NX, Liang T, Chen W and Zhou XP. 2016. Patterns of metallogenesis of Jiulongnao orefield in the east section of the Nanling region and direction for prospecting. Acta Geologica Sinica, 90(9): 2399-2411 (in Chinese with English abstract)
Wang HY, Zhao Z, Chen W, Zhou H, Chen ZY, Hou KJ and Li C. 2017. Geological characteristics, rock and ore forming age and prospecting of Meishuping tungsten-molybdenum deposit in Jiangxi. Earth Science Frontiers, 24(5): 109-119 (in Chinese with English abstract)
Wang HZ, Zhao YD, Chen PR, Ling HF and Wu JQ. 2018. Petrogenesis of the Zhulanbu composite pluton and its implications for tectonic setting. Acta Petrologica et Mineralogica, 37(2): 175-196 (in Chinese with English abstract)
Wang LZ, Xu C, Zhao Z, Song WL and Kynicky J. 2015. Petrological and geochemical characteristics of Zhaibei granites in Nanling region, Southeast China: Implications for REE mineralization. Ore Geology Reviews, 64: 569-582 DOI:10.1016/j.oregeorev.2014.04.004
Wang P, Pan ZL and Weng LB. 1982. Systematic Mineralogy (Volume Ⅲ). Beijing: Geological Publishing House, 1-734 (in Chinese)
Wang SY, Zhao Z, Fang GC, Ouyang X, Chen ZY and Hou KJ. 2017. Mineralogical and geochronological characteristics of the Zhang(dongkeng)-Jiu(longnao) tungsten polymetallic deposit, southern Jiangxi Province, and its geological implications. Earth Science Frontiers, 24(5): 120-130 (in Chinese with English abstract)
Watson EB, Wark DA and Thomas JB. 2006. Crystallization thermometers for zircon and rutile. Contributions to Mineralogy and Petrology, 151(4): 413-433 DOI:10.1007/s00410-006-0068-5
Williams-Jones AE, Samson IM and Olivo GR. 2000. The genesis of hydrothermal fluorite-REE deposits in the Gallinas Mountains, New Mexico. Economic Geology, 95(2): 327-341 DOI:10.2113/gsecongeo.95.2.327
Wu ZX. 1985. Geochemical characteristics of some rare element bearing granites in southeast China and the physicochemical condition of their formation. Acta Petrologica Sinica, 1(1): 34-48 (in Chinese with English abstract)
Xia WH, Zhang JT, Feng ZW and Chen ZY. 1989. Geology of Granite-Type Rare Metal Deposits in Nanling Region. Beijing: China University of Geosciences Press (in Chinese)
Xie L, Wang RC, Chen J and Zhu JC. 2010. Mineralogical evidence for magmatic and hydrothermal processes in the Qitianling oxidized tin-bearing granite (Hunan, South China): EMP and (MC)-LA-ICPMS investigations of three types of titanite. Chemical Geology, 276(1-2): 53-68 DOI:10.1016/j.chemgeo.2010.05.020
Xie YL, Li YX, Hou ZQ, Cooke DR, Danyushevsky L, Dominy SC and Yin SP. 2015. A model for carbonatite hosted REE mineralisation: The Mianning-Dechang REE belt, western Sichuan Province, China. Ore Geology Reviews, 70: 595-612 DOI:10.1016/j.oregeorev.2014.10.027
Yang MG and Wang GH. 2019. Formation and evolution of the plate activity and the structural system in the South China continental region. Acta Geologica Sinica, 93(3): 528-544 (in Chinese with English abstract)
Zhang J. 1988. Chemical characteristics of aeschynite group minerals. Journal of the Chinese Rare Earth Society, 6(2): 63-67 (in Chinese with English abstract)
Zhang YQ, Dong SW, Li JH, Cui JJ, Shi W, Su JB and Li Y. 2012. The new progress in the study of Mesozoic tectonics of South China. Acta Geoscientica Sinica, 33(3): 257-279 (in Chinese with English abstract)
Zhao WW and Zhou MF. 2018. Mineralogical and metasomatic evolution of the Jurassic Baoshan scheelite skarn deposit, Nanling, South China. Ore Geology Reviews, 95: 182-194 DOI:10.1016/j.oregeorev.2018.01.032
Zhao Z, Wang DH, Chen ZY, Guo NX, Liu XX and He HH. 2014. Metallogenic specialization of rare earth mineralized igneous rocks in the estern Nanling region. Geotectonica et Metallogenia, 38(2): 255-263 (in Chinese with English abstract)
Zhao Z, Wang DH, Chen YC, Liu SB, Fang GC, Liang T, Guo NX, Wang SY, Wang HY, Liu ZQ, Zeng ZL, Ding M, Chen W and Zhou XP. 2017. "Jiulongnao metallogenic model" and the demonstration of deep prospecting: The extended application of "Five levels+Basement" exploration model. Earth Science Frontiers, 24(5): 8-16 (in Chinese with English abstract)
Zhao Z, Liu C, Guo NX, Zhao WW, Wang PA and Chen ZH. 2018a. Temporal and spatial relationships of granitic magmatism and W mineralization: Insights from the Xingguo orefield, South China. Ore Geology Reviews, 95: 945-973 DOI:10.1016/j.oregeorev.2018.03.022
Zhao Z, Zhao WW, Lu L and Wang HY. 2018b. Constraints of multiple dating of the Qingshan tungsten deposit on the Triassic W(-Sn) mineralization in the Nanling region, South China. Ore Geology Reviews, 94: 46-57 DOI:10.1016/j.oregeorev.2018.01.009
Zhao Z, Zhou XP, Guo NX, Zhang HY, Liu ZY, Zheng YL, Zeng ZL and Chen YC. 2018c. Superimposed W and Ag-Pb-Zn (-Cu-Au) mineralization and deep prospecting: Insight from a geophysical investigation of the Yinkeng orefield, South China. Ore Geology Reviews, 93: 404-412 DOI:10.1016/j.oregeorev.2018.01.017
Zhao Z, Fu TY, Gan JW, Liu C, Wang DH, Sheng JF, Li WB, Wang PA, Yu ZF and Chen YC. 2021. A synthesis of mineralization style and regional distribution and a proposed new metallogenic model of Mesozoic W-dominated polymentallic deposits in South China. Ore Geology Reviews, 133(1-3): 104008
Zhao ZH, Xiong XL and Han XD. 1999. Discussion on mechanism of rare earth elements tetrad effect in granites: A case study of Qianlishan and Ba'erzhe granites. Science in China (Series D), 29(4): 331-338 (in Chinese)
Zhou RW. 1982. Relationship between alkali feldspar granites and REE-Nb-Ta mineralization. Geology and Exploration, 18(12): 12-15, 22 (in Chinese)
Zhou XM, Sun T, Shen WZ, Shu LS and Niu YL. 2006. Petrogenesis of Mesozoic granitoids and volcanic rocks in South China: A response to tectonic evolution. Episodes, 29(1): 26-33 DOI:10.18814/epiiugs/2006/v29i1/004
Zhu JC, Zhang PH, Xie CF, Zhang H and Yang C. 2006. The Huashan-Guposhan A-type granitoid belt in the western part of the Nanling Mountains: Petrology, geochemistry and genetic interpretations. Acta Geologica Sinica, 80(4): 529-542 (in Chinese with English abstract)
Zhu JC, Wang RC, Lu JJ, Zhang H, Zhang WL, Xie L and Zhang RQ. 2011. Fractionation, evolution, petrogenesis and mineralization of Laiziling granite pluton, southern Hunan Province. Geological Journal of China Universities, 17(3): 381-392 (in Chinese with English abstract)
Zhu ZY, Wang RC, Marignac C, Cuney M, Mercadier J, Che XD and Lespinasse MY. 2018. A new style of rare metal granite with Nb-rich mica: The Early Cretaceous Huangshan rare-metal granite suite, northeast Jiangxi Province, southeast China. American Mineralogist, 103(10): 1530-1544 DOI:10.2138/am-2018-6511
Zou TR. 1985. On the rare granites of three magmatic series and their REE distribution patterns in China. Journal of Kunming Institute of Technology, 10(1): 15-19, 21-27 (in Chinese with English abstract)
Zuo ML. 2016. The research of differences of the rare-metal granites mineralization between Yichun Yashan and Quannan Dajishan in Jiangxi Province. Master Degree Thesis. Beijing: China University of Geosciences (Beijing) (in Chinese with English abstract)
陈骏, 陆建军, 陈卫锋, 王汝成, 马东升, 朱金初, 张文兰, 季峻峰. 2008. 南岭地区钨锡铌钽花岗岩及其成矿作用. 高校地质学报, 14(4): 459-473. DOI:10.3969/j.issn.1006-7493.2008.04.001
陈毓川, 裴荣富, 张宏良, 林新多, 白鸽, 李崇佑, 胡永嘉, 刘姤群, 冼柏琪. 1989. 南岭地区与中生代花岗岩类有关的有色及稀有金属矿床地质. 北京: 地质出版社.
崔圆圆. 2014. 华南三明-赣州地区花岗岩类年代学、地球化学及岩石成因. 硕士学位论文. 北京: 中国地质大学(北京)
谷湘平. 1989a. 花岗岩岩浆氧逸度定量指示剂——褐帘石. 矿物岩石, 9(3): 26-32.
谷湘平. 1989b. 广东新丰稀土花岗岩中褐帘石的稀土组成特点及其地质意义. 矿产与地质, 3(3): 47-50.
郭娜欣, 刘善宝, 赵正. 2021. 江西崇义铁木里钨铁矿区内辉绿玢岩的年代学、地球化学特征及地质意义. 地球科学, 46(2): 460-473.
韩丽, 黄小龙, 李洁, 贺鹏丽, 姚军明. 2016. 江西大湖塘钨矿花岗岩的磷灰石特征及其氧逸度变化指示. 岩石学报, 32(3): 746-758.
洪大卫. 1982. 华南花岗岩的黑云母和矿物相及其与矿化系列的关系. 地质学报, 56(2): 149-164.
华仁民, 毛景文. 1999. 试论中国东部中生代成矿大爆发. 矿床地质, 18(4): 300-307. DOI:10.3969/j.issn.0258-7106.1999.04.002
华仁民, 张文兰, 顾晟彦, 陈培荣. 2007. 南岭稀土花岗岩、钨锡花岗岩及其成矿作用的对比. 岩石学报, 23(10): 2321-2328. DOI:10.3969/j.issn.1000-0569.2007.10.001
贾小辉, 王晓地, 杨文强, 牛志军. 2014. 粤北雪山嶂A型花岗岩的形成时代、地球化学特征及其成因. 矿物岩石, 34(3): 40-49.
李福春, 朱金初, 漆亮, 饶冰, 潘根兴. 2002. 富氟花岗岩体系岩浆流体内稀土元素演化规律的实验研究. 高校地质学报, 8(1): 9-15. DOI:10.3969/j.issn.1006-7493.2002.01.002
李洁, 钟军伟, 于洋, 黄小龙. 2013. 赣南西华山花岗岩的云母成分特征及其对岩浆演化与成矿过程的指示. 地球化学, 42(5): 393-404.
李建康, 张德会, 王登红, 张文淮. 2008. 富氟花岗岩浆液态不混溶作用及其成岩成矿效应. 地质论评, 54(2): 175-183. DOI:10.3321/j.issn:0371-5736.2008.02.004
李建康, 李鹏, 王登红, 李兴杰. 2019. 中国铌钽矿成矿规律. 科学通报, 64(15): 1545-1566.
刘琰, 陈超, 舒小超, 郭东旭, 李自静, 赵海璇, 贾玉衡. 2017. 青藏高原东部碳酸岩-正长岩杂岩体型REE矿床成矿模式——以大陆槽REE矿床为例. 岩石学报, 33(7): 1978-2000.
刘英俊, 曹励明, 李兆麟, 王鹤年, 储同庆, 张景荣. 1986. 元素地球化学. 北京: 科学出版社.
刘永超, 李建康, 邹天人, 江善元, 丁欣, 王娴. 2017. 福建永定大坪铌钽矿化花岗斑岩体的流体演化对铌钽富集的制约. 地质学报, 91(5): 1052-1065. DOI:10.3969/j.issn.0001-5717.2017.05.007
王登红, 赵正, 刘善宝, 郭娜欣, 梁婷, 陈伟, 周新鹏. 2016. 南岭东段九龙脑矿田成矿规律与找矿方向. 地质学报, 90(9): 2399-2411. DOI:10.3969/j.issn.0001-5717.2016.09.019
王浩洋, 赵正, 陈伟, 周辉, 陈振宇, 侯可军, 李超. 2017. 江西梅树坪钨钼矿床地质、成岩成矿时代与找矿方向. 地学前缘, 24(5): 109-119.
王洪作, 赵友东, 陈培荣, 凌洪飞, 吴俊奇. 2018. 赣南珠兰埠复式岩体成因及其构造意义. 岩石矿物学杂志, 37(2): 175-196. DOI:10.3969/j.issn.1000-6524.2018.02.001
王濮, 潘兆橹, 翁玲宝. 1982. 系统矿物学. 北京: 地质出版社.
王少轶, 赵正, 方贵聪, 欧阳翔, 陈振宇, 侯可军. 2017. 赣南樟(东坑)-九(龙脑)钨多金属矿床矿物学、年代学特征及其地质意义. 地学前缘, 24(5): 120-130.
吴宗絮. 1985. 华南某些含稀有元素花岗岩的地球化学特征及其形成的物理化学条件. 岩石学报, 1(1): 34-48. DOI:10.3321/j.issn:1000-0569.1985.01.005
夏卫华, 章锦统, 冯志文, 陈紫英. 1989. 南岭花岗岩型稀有金属矿床地质. 北京: 中国地质大学出版社.
杨明桂, 王光辉. 2019. 华南陆区板块活动与构造体系的形成演化——纪念李四光先生诞辰130周年. 地质学报, 93(3): 528-544.
张静. 1988. 易解石族矿物的化学特征. 中国稀土学报, 6(2): 63-67. DOI:10.3321/j.issn:1000-4343.1988.02.013
张岳桥, 董树文, 李建华, 崔建军, 施炜, 苏金宝, 李勇. 2012. 华南中生代大地构造研究新进展. 地球学报, 33(3): 257-279.
赵振华, 熊小林, 韩小东. 1999. 花岗岩稀土元素四分组效应形成机理探讨——以千里山和巴尔哲花岗岩为例. 中国科学(D辑), 29(4): 331-338.
赵正, 王登红, 陈毓川, 刘善宝, 方贵聪, 梁婷, 郭娜欣, 王少轶, 王浩洋, 刘战庆, 曾载淋, 丁明, 陈伟, 周新鹏. 2017. "九龙脑成矿模式"及其深部找矿示范: "五层楼+地下室"勘查模型的拓展. 地学前缘, 24(5): 8-16.
赵芝, 王登红, 陈振宇, 郭娜欣, 刘新星, 何晗晗. 2014. 南岭东段与稀土矿有关岩浆岩的成矿专属性特征. 大地构造与成矿学, 38(2): 255-263.
周瑞文. 1982. 钾长-碱长花岗岩与稀土铌钽成矿的关系. 地质与勘探, 18(12): 12-15, 22.
朱金初, 张佩华, 谢才富, 张辉, 杨策. 2006. 南岭西段花山-姑婆山A型花岗质杂岩带: 岩石学、地球化学和岩石成因. 地质学报, 80(4): 529-542. DOI:10.3321/j.issn:0001-5717.2006.04.007
朱金初, 王汝成, 陆建军, 张辉, 张文兰, 谢磊, 章荣清. 2011. 湘南癞子岭花岗岩体分异演化和成岩成矿. 高校地质学报, 17(3): 381-392. DOI:10.3969/j.issn.1006-7493.2011.03.003
邹天人. 1985. 论中国三个岩浆系列的稀有金属花岗岩及其稀土分布型式. 昆明工学院学报, 10(1): 15-19, 21-27.
左梦璐. 2016. 江西雅山与大吉山两类稀有金属花岗岩成矿差异性研究. 硕士学位论文. 北京: 中国地质大学(北京)