汪小妹;焦养泉;杜远生;周琦;崔滔;计波;雷志远;翁申富;金中国;熊星;

• 1:中国地质大学资源学院
• 2:中国地质大学构造与油气资源教育部重点实验室
• 3:中国地质大学生物地质与环境地质国家重点实验室
• 4:贵州省地质矿产勘查开发局

摘要(Abstract)：

选取新模向斜的一个钻孔剖面,对铝土矿的矿物组成及稀土元素地球化学特征进行了研究。铝土矿矿石矿物以一水硬铝石为主,另有少量一水软铝石。其次为高岭石、绿泥石等黏土矿物,以及少量重矿物。此外,在含矿岩系近底部还发现有富集Ce元素的矿物氟菱钙铈矿[Ce2Ca(CO3)3F2]。从剖面顶部至底部,铝土矿中稀土元素含量呈逐渐增加的趋势,且稀土元素参数LaN/YbN、LaN/SmN和GdN/YbN的数值均随深度逐渐增大。说明从剖面顶部至底部,稀土元素的淋滤迁出逐渐减弱,且稀土元素间存在一定的分异。稀土元素间的分异可能由不同的含稀土元素矿物抗风化淋滤差异所致。铝土矿稀土元素配分模式表现为LREE明显富集、MREE中等-弱富集、HREE相对平坦的特征,且具有明显的正Ce异常。δCe异常值随深度增加逐渐减小,接近含矿岩系底部,δCe异常值再次增大。含矿岩系上部的Ce异常是由氧化条件下Ce3+向Ce4+转变并形成方铈矿(CeO2)所致。随着深度的增加,含矿岩系的氧化性逐渐减弱,从而δCe异常值逐渐减小。接近含矿岩系底部,由于氟菱钙铈矿[Ce2Ca(CO3)3F2]的形成,导致δCe异常值再次增大。氟菱钙铈矿的沉淀可通过氟化物络合物(CeF2+或CeCO3F0)与Ca2+和HCO3-发生反应来完成。

关键词(KeyWords)： 铝土矿;稀土元素;地球化学;务正道地区

Abstract:

Keywords:

基金项目(Foundation): 贵州省地勘基金项目“贵州务正道地区铝土矿基础地质与成矿规律研究”;; 国家自然科学基金项目(41202114);; 中国博士后科学基金项目(2012M521499);; 中央高校基本科研业务费专项资金项目(CUGL100253)

作者(Author): 汪小妹;焦养泉;杜远生;周琦;崔滔;计波;雷志远;翁申富;金中国;熊星;

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DOI:

参考文献(References)：

• [1]Duddy L R.Redistribution and fractionation of rare-earth andother elements in a weathering profile[J].Chemical Geology,1980,30:363-381.
• [2]Maksimovic Z,Panto G.Contribution to the geochemistry ofthe rare earth elements in the karst-bauxite deposits of Yugo-slavia and Greece[J].Geoderma,1991,51:93-109.
• [3]Banfield J F,Eggleton R A.Apatite replacement and rareearth mobility,fractionation,and fixation during weathering[J].Clay Miner.,1989,37:113-127.
• [4]刘巽锋.论黔北铝土矿的古喀斯特-红土型成因[J].地质学报,1990,(3):238-247.
• [5]章柏盛.贵州石炭纪铝土矿沉积相标志及沉积环境分析[J].中国地质科学院矿床地质研究所所刊,1990,1:23-55.
• [6]韩忠华.贵州道真县大塘铝土矿沉积相特征[J].矿产与地质,2008,22(5):428-432.
• [7]刘平.论黔北-川南石炭系大竹园组[J].中国区域地质,1996,15(2):123-130.
• [8]黄兴,张雄华,杜远生,等.黔北地区铝土矿形成的地质时代[J].地质科技情报,2012,31(3):49-54.
• [9]汪生杰,陈有能,杨文会.贵州遵义铝土矿扫描电镜、电子探针及射线衍射研究[J].矿物岩石,1987,7(4):18-24.
• [10]叶霖,潘自平,程增涛.贵州修文小山坝铝土矿中镓等伴生元素分布规律研究[J].矿物学报,2008,28(2):105-111.
• [11]殷科华.黔北务正道铝土矿的成矿作用及成矿模式[J].沉积学报,2009,27(3):452-457.
• [12]武国辉,刘幼平,张应文.黔北务-正-道地区铝土矿地质特征及资源潜力分析[J].地质与勘探,2006,42(2):39-43.
• [13]刘平.黔北务-正-道地区铝土矿地质概要[J].地质与勘探,2007,43(5):29-33.
• [14]Sun S S,McDonough W F.Chemical and isotopic systematicsof oceanic basalts:Implications for mantle composition andprocesses[C]∥Saunders A D,Norry M J.Magmatism in o-cean basins.[S.l.]:Geol.Soc.Spec.Publ.,1989:313-345.
• [15]Braun J J,Pagel M,Muller J P,et al.Cerium anomalies in lat-eritic profiles[J].Geochim.Cosmochim.Acta,1990,54:781-795.
• [16]Ji H B,Wang S J,Ouyanga Z Y,et al.Geochemistry of redresidua underlying dolomites in karst terrains of Yunnan-Guizhou Plateau II.The mobility of rare earth elements duringweathering[J].Chemical Geology,2004,203:29-50.
• [17]Ji H B,Wang S J,Ouyang Z Y,et al.Geochemistry of red re-sidua underlying dolomites in karst terrains of Yunnan-GuizhouPlateau.I.The formation of the Pingba profile[J].ChemicalGeology,2004,203:1-27.
• [18]Karada M M,Küpeli爦,Ark F,et al.Rare earth element(REE)geochemistry and genetic implications of the Morta爧bauxite deposit(Seydi爧ehir/Konya-Southern Turkey)[J].Chemie der Erde,2009,69:143-159.
• [19]Aubert D,Stille P,Probst A.REE fractionation during gran-ite weathering and removal by waters and suspended loads:Srand Nd isotopic evidence[J].Geochim.Cosmochim.Acta,2001,65:387-406.
• [20]Humphris S.The mobility of the rare earth elements in thecrust[C]∥Henderson P.Rare earth geochemistry.Develop-ments in geochemistry.[S.l.]:[s.n.],1984:317-342.
• [21]van der Weijden C H,van der Weijden R D.Mobility of ma-jor,minor and some redox-sensitive trace elements and rare-earth elements during weathering of four granitoids in centralPortugal[J].Chemical Geology,1995,125:149-167.
• [22]Wang Q F,Deng J,Liu X F,et al.Discovery of the REEminerals and its geological significance in the Quyang bauxitedeposit,West Guangxi,China[J].Journal of Asian Earth Sci-ences,2010,39:701-712.
• [23]Nyakairu G W A,Koeberl C,Kurzweil H.The Buwambo ka-olin deposit in Central Uganda:Mineralogical and chemicalcomposition[J].Geochem.J.,2001,35:245-256.
• [24]Mongelli G.Ce-anomalies in the textural components of UpperCretaceous karst bauxites from the Apulian carbonate platform(southern Italy)[J].Chemical Geology,1997,140:69-79.
• [25]Johannesson K H,Lyons W B.Rare earth element geochemis-try of Colour lake,an acidic freshwater lake on axel HeibergIsland,Northwest Territories,Canada[J].Chemical Geolo-gy,1995,119:209-223.
• [26]Johannesson K H,Stetzenbach K J,Hodge V F,et al.Rareearth element complexation behavior in circumneutral ground-waters:Assessing the role of carbonate and phosphate ions[J].Earth Planet.Sci.Lett.,1996,139:305-319.
• [27]Ngwenya B T.Hydrothermal rare earth mineralization in car-bonatites of the Tundulu complex,Malawi:Processes at thefluidrrock interface[J].Geochim.Cosmochim.Acta,1994,58:2061-2072.
• [28]Williams-Jones A E,Wood S A.A preliminary petrogeneticgrid for REE fluorocarbonates and associated minerals[J].Geochim.Cosmochim.Acta,1992,56:725-738.