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1、大学专业英语课件 Still waters run deep.流静水深流静水深,人静心深人静心深 Where there is life,there is hope。有生命必有希望。有生命必有希望Abstract:Processes of mineral alteration involving the mobilization and deposition of more than 30 chemical elements during bauxite formation and epigenesis have been studied on specimens from the Devon
2、ian Schugorsk bauxite deposit,Timan,Russia.Chemical analyses of the minerals were obtained by electron microprobe and element distribution in the minerals was studied by element mapping.Interpretation of these data also utilized high-resolution BSE and SE images.Specialized Vocabulary:Specialized Vo
3、cabulary:Mobilization mubilaizei-n n.动员;调动Formation f:mein n.构造,编队,形成Epigenesis epidenisis epidenisis n.n.渐成说渐成说;地地 外力变质外力变质;后成后成specimen spesimn n.样本,标本electron microprobe 电子微探针;电子显微探针;电子探针 The main rock-forming minerals of the Vendian parent rock are calcite,dolomite,feldspar,aegirine,riebeckite,m
4、ica,chlorite and quartz;accessory minerals are pyrite,galena,apatite,ilmenite,monazite,xenotime,zircon,columbite,pyrochlore,chromite,bastnaesite and some others.Typically,the grainsize of the accessory minerals in both parent rock and bauxite is from 1 to 40 mm.However,even within these rather small
5、 grains,the processes of crystal growth and alteration during weathering can be determined from the zonal distribution of the elements.The most widespread processes observed are:Specialized Vocabulary:Specialized Vocabulary:parent rock parent rock 母岩母岩Calcite klsait n.Calcite klsait n.矿矿 方解石方解石Dolom
6、ite dlmait n.Dolomite dlmait n.白云石白云石Feldspar feldsp:n.Feldspar feldsp:n.长石长石Aegirine ei,ri:n n.Aegirine ei,ri:n n.矿矿 霓石霓石riebeckiteri:bekait n.riebeckiteri:bekait n.钠闪石钠闪石mica maik n.mica maik n.云母云母chlorite kl:rait n.chlorite kl:rait n.绿泥石绿泥石quartz kw:ts n.quartz kw:ts n.石英石英accessory minerals acc
7、essory minerals 副矿物副矿物pyrite pairait n.pyrite pairait n.矿矿 黄铁矿黄铁矿galena li:n n.galena li:n n.矿矿 方铅矿方铅矿apatite ptait n.apatite ptait n.磷灰石磷灰石ilmenite ilmnaitn.ilmenite ilmnaitn.矿矿 钛铁钛铁矿矿Please follow the next page for Please follow the next page for the other Specialized Vocabulary the other Speciali
8、zed Vocabulary of this pageof this page (1)Decomposition of Ti-bearing (1)Decomposition of Ti-bearing minerals such as ilmenite,aegirine and minerals such as ilmenite,aegirine and riebeckite with the formation of riebeckite with the formation of leucoxene,which is the main leucoxene,which is the mai
9、n concentrator of Nb,Cr,V and W.concentrator of Nb,Cr,V and W.Crystal growth can be traced from the Crystal growth can be traced from the zonal distribution of Nb(up to 16 zonal distribution of Nb(up to 16 wt.%).Vein-like leucoxene is also wt.%).Vein-like leucoxene is also observed in association wi
10、th organics.observed in association with organics.(2)Weathering of columbite and (2)Weathering of columbite and pyrochlore:the source of Nb in pyrochlore:the source of Nb in leucoxene is now strongly weathered leucoxene is now strongly weathered columbite,while the alteration of columbite,while the
11、alteration of pyrochlore is expressed in the growth pyrochlore is expressed in the growth of plumbopyrochlore rims around Ca-of plumbopyrochlore rims around Ca-rich cores.rich cores.Specialized Vocabulary:Specialized Vocabulary:Monazite mnzait n.独居石xenotime zentaim n.磷钇矿zircon z:kn n.锆石columbite klm
12、bait n.钶铁矿；铌铁矿pyrochlore pairkl:n.矿烧绿石chromite krumait n.亚铬酸盐；铬铁矿bastnaesite n.氟碳铈矿grainsize n.粒度；粒径decomposition,di:kmpzin n.分解,腐败,变质Ti-bearing mineral;leucoxene lju:kksi:n n.白钛石；金红石；白榍石plumbopyrochlore.plumbopyrochlore.烧绿石烧绿石rim rim n.rim rim n.边边,轮缘轮缘,框框Please follow the next page for the Please
13、follow the next page for the other Specialized Vocabulary of this other Specialized Vocabulary of this pagepage(3)Dissolution of sulphide minerals(3)Dissolution of sulphide minerals and apatite and the formation of and apatite and the formation of crandallite group minerals:crandallite group mineral
14、s:crandallite crystals of up to 40 mm crandallite crystals of up to 40 mm size show a very clear zonation.size show a very clear zonation.From From the core to the rim of a crystal,the the core to the rim of a crystal,the following sequence of elements is following sequence of elements is observed:C
15、a?Ba?Ce?Pb?Sr?observed:Ca?Ba?Ce?Pb?Sr?Nd.Sulphur also shows a zoned but Nd.Sulphur also shows a zoned but more complicated distribution,while more complicated distribution,while the distribution of Fe is rather the distribution of Fe is rather variable.A possible source of REE is variable.A possible
16、 source of REE is bastnaesitebastnaesite from the parent rock.from the parent rock.More than twelve crandallite type More than twelve crandallite type cells can be identified in a single cells can be identified in a single crandallite grain.crandallite grain.Specialized Vocabulary:Specialized Vocabu
17、lary:sulphide slfaid n.sulphide slfaid n.硫化物硫化物apatite ptait n.apatite ptait n.磷灰石磷灰石crandallite krndlait n.crandallite krndlait n.纤磷钙铝纤磷钙铝石石zonation zunein zonation zunein n.n.成带；动植物的生物地理学的地成带；动植物的生物地理学的地带分布；带状配列带分布；带状配列Nb：Niobium naiubim n.化铌（41号元素，汉语发言n）Cr：chromium krumjm n.化铬（24号元素，汉语发音g)V：vanad
18、ium vneidim n.化钒（23号元素，汉语发音fn)W：tungsten tstn n.化 钨（74号元素，汉语发音w）Ca：calcium klsim n.化 钙（20号元素，汉语发音gi)Ba：barium brim n.化 钡（56号元素，汉语发音bi）Ce：cerium sirim n.化 铈（58号元素，汉语发音sh）(4)Alteration of stoichiometric zircon and xenotime with the formation of metamict solid solution of zircon and xenotime:altered zi
19、rcon rims also bear large amounts of Sc(up to 3.5 wt.%),Fe,Ca and Al in the form of as yet unidentified inclusions of 12 mm.Monazite seems to be the least altered mineral of the profile.In the parent rock,an unknown mineral of the composition(wt.%):ThO2 54.8;FeO 14.6;Y2O5 2.3;CaO 2.0;REE 1.8;SiO2 12
20、.2;P2O5 2.8;total 94.2(average from ten analyses)was determined.In bauxite,another mineral was found,which has the composition(wt.%):Specialized Vocabulary:Specialized Vocabulary:stoichiometric,stikimetrik stoichiometric,stikimetrik adj.adj.化学计算的；化学计量的化学计算的；化学计量的metamict metmikt n.蜕晶质Pb：lead li:d n.
21、化 铅（82号元素，汉语发音qin）Sr：strontium strnim n.化 锶（38号元素，汉语发音s）Sc：scandium skndim n.化 钪（21号元素，汉语发音kng）Fe：iron ain n.化 铁（26号元素，汉语发音ti）Ca：calcium klsim n.化 钙（20号元素，汉语发音gi)铝（13号元素，汉语发音l）Th：thorium:rim,n.化 钍（90号元素，汉语发音t）Cu：copper kp n.化 铜（29号元素，汉语发音tng）Cd：cadmium kdmim n.化 镉（48号元素，汉语发音g）Bi：bismuth bizm n.化 铋（8
22、3号元素，汉语发音b）ThO2 24.9;FeO 20.5;Y2O5 6.7;CaO 2.0;ZrO 17.6;SiO2 8.8;P2O5 5.4;total 89.3(F was not analysed;average from nine analyses).Presumably,the second mineral is the result of weathering of the first one.Although the Th content is very high,the mineral is almost free of Pb.However,intergrowths of
23、 galena and pyrite are observed around the partially decomposed crystals of the mineral.Another generation of galena is enriched in chalcophile elements such as Cu,Cd,Bi etc.,and is related to epigenetic alteration of the profile,as are secondary apatite and muscovite.Specialized Vocabulary:Speciali
24、zed Vocabulary:weathering weri n.风化intergrowth intru n.共生，交互生长pyrite pairait n.矿黄铁矿galena li:n n.矿方铅矿Decomposed a.已分解的,已腐烂的chalcophile klk,fail adj.【地球化学】亲铜的，亲硫的epigenetic,epidinetik adj.生外成的；后生的Muscovite,mskvait 白云母Al：aluminum,ljuminim,n.化 铝（13号元素，汉语发音l）Y：yttrium itrim n.化 钇（39号元素，汉语发音y）Si：silicon
25、silikn n.化 硅（14号元素，汉语发音gu）P：phosphorus fsfrs n.化 磷（15号元素，汉语发音ln）Zr：zirconium z:kunim n.化 锆（40号元素，汉语发音go）KEYWORDS:bauxite,laterite,weathering,geochemistry,mineralogy,trace elements,leucoxene,crandallite,zircon,xenotime,pyrochlore,galena.Specialized Vocabulary:Specialized Vocabulary:leucoxene lju:kksi
26、:n n.白钛石；金红石；白榍石Introduction The problem of trace elements in The problem of trace elements in bauxite profiles is important for a bauxite profiles is important for a number of reasons.Firstly,deep number of reasons.Firstly,deep chemical weathering is a geochemical chemical weathering is a geochemic
27、al process which is as important as process which is as important as magmatism,metamorphism or magmatism,metamorphism or sedimentation.In addition,principles sedimentation.In addition,principles of concentration and/or differentiation of concentration and/or differentiation of chemical elements duri
28、ng bauxite of chemical elements during bauxite formation differ from those typical for formation differ from those typical for magmatic,metamorphic and magmatic,metamorphic and sedimentary sedimentary processes.Specialized Vocabulary:Specialized Vocabulary:Bauxite b:ksait n.Bauxite b:ksait n.矾土矾土,铁铁
29、铝氧石铝氧石,化化 铝土矿铝土矿 MagmatismMagmatism：岩浆作用：岩浆作用Metamorphism metm:fiMetamorphism metm:fi zm n.zm n.变质作用变质作用Chemical weathering Chemical weathering 化学化学 风风化化,化学风化作用化学风化作用,化学气候化学气候 sedimentation sedimentein sedimentation sedimentein n.n.沉淀沉淀,沉降沉降Geochemical ,di:kemikl Geochemical ,di:kemikl adj.adj.地球化学的
30、地球化学的Sedimentary sedimentri Sedimentary sedimentri a.a.沉淀性的沉淀性的Secondly,only a few elements such as Ga and V are successfully extracted as by-products of Al production,although some other elements may show high concentrations within bauxite profiles.Thus,the nature of the minerals containing trace e
31、lements is an important key for the understanding of their behaviour during bauxite formation.The problem of mobility of chemical elements during deep weathering has been discussed for many years.However,the very small grain-size of bauxite(a few microns or even smaller)has hindered detailed investi
32、gations.Specialized Vocabulary:Specialized Vocabulary:extracted ikstrktid 萃取的by-product bai,prdkt n.副产品；附带产生的结果；意外收获mobility mubiliti mobility mubiliti n.n.可动性可动性,变动性变动性,情感不定情感不定Ga：gallium lim n.化镓镓（23号元素，汉语发音ji）V：vanadium vneidim n.化钒（23号元素，汉语发音fn)Al：aluminum,ljuminim,n.化 铝（13号元素，汉语发音l）The most wid
33、espread method used The most widespread method used to determine element mobility was a to determine element mobility was a comparison of its bulk content in the comparison of its bulk content in the parent rock and in the weathering parent rock and in the weathering profile,frequently using profile
34、,frequently using isovolumetric calculations.isovolumetric calculations.Bardossy and Aleva(1990)Bardossy and Aleva(1990)compared data on six bauxite compared data on six bauxite districts and concluded that there districts and concluded that there exist a number of elements for exist a number of ele
35、ments for which their chemical properties which their chemical properties unequivocally determine enrichment unequivocally determine enrichment or depletion in all lateritic-bauxite or depletion in all lateritic-bauxite districts(p.145).This conclusion districts(p.145).This conclusion needs explanat
36、ion.needs explanation.Specialized Vocabulary:Specialized Vocabulary:isovolumetric isovolumetric adj.adj.等容的，定容的等容的，定容的depletion dipli:n depletion dipli:n n.n.消耗消耗,罄尽罄尽,放血放血lateritic,ltritik lateritic,ltritik adj.adj.含有红土的；红壤的含有红土的；红壤的lateritic-bauxite：红土型铝土矿 This study on the mineralogy and geochemi
37、stry of trace elements in bauxite was carried out on samples from the Schugorsk bauxite deposit from the Middle Timan,Russia.Material from this deposit contains higher levels of certain elements than normal(Mordberg,1996,1997)and is hence suitable for a detailed mineralogical investigation.Specializ
38、ed Vocabulary:Specialized Vocabulary:mineralogy,minrldi mineralogy,minrldi 矿物学矿物学Geology Bauxite deposits of the Middle Timan are located in the North of European Russia,between the NE edge of the Russian Plate and the Pechorsk Depression(Fig.1).Specialized Vocabulary:Specialized Vocabulary:Plate pl
39、eit n.板块The geology of the bauxite region has been given in detail by Likhachev(1993)and Mordberg(1996,1997).Devonian bauxite deposits located within the Chetlass orogenic structure occur on folded,mostly carbonate strata of the Riphean.Deposits of both lateritic and karstic origin are found.The ove
40、rlying rocks are Upper Devonian volcanogenic and sedimentary sequences;in some instances the bauxite profile is covered directly by Late Devonian trap basalt.The Schugorsk bauxite deposit,the largest in the region,was formed over a Precambrian carbonate sequence which had been altered by alkali meta
41、somatic processes.Specialized Vocabulary:Specialized Vocabulary:Orogenic:adj.造山的；造山运动的carbonate k:bneit n.碳酸盐strata streit:n.层(地层,岩歧,阶层,薄片)lateritic,ltritik adj.含有红土的；红壤的karstic.adj.喀斯特的Upper Devonian:(地质学)晚泥盆世volcanogenic,vlkndenik volcanogenic,vlkndenik adj.adj.源于火山的；火山生成的源于火山的；火山生成的sedimentary se
42、quence:sedimentary sequence:沉积层序沉积层序Precambrian pri:kmbrin Precambrian pri:kmbrin n.n.前寒武纪前寒武纪,前塞武层前塞武层carbonate k:bneit n.carbonate k:bneit n.碳酸盐碳酸盐Alkali n.Alkali n.碱碱Metasomatic,metsumtik adj.地交代的Rock-forming minerals of the Rock-forming minerals of the metasomatite are dolomite,calcite and metas
43、omatite are dolomite,calcite and K-feldspars.PlK-feldspars.Plagioclaseagioclase,aegerine,aegerine,riebeckite,biotite and sericite are also riebeckite,biotite and sericite are also present in various amounts.The present in various amounts.The weathered profile attains a total depth weathered profile
44、attains a total depth here of 100-120 m,and the main ore-here of 100-120 m,and the main ore-forming minerals are boehmite,forming minerals are boehmite,kaolinite and hematite with nearly kaolinite and hematite with nearly monomineralic white boehmitic monomineralic white boehmitic bauxites being wid
45、espread within the bauxites being widespread within the deposit.The ratio of carbonate and deposit.The ratio of carbonate and silicate minerals in the parent rock silicate minerals in the parent rock varies broadly with an average of 1:1.varies broadly with an average of 1:1.Due to this heterogeneit
46、y,the deposit Due to this heterogeneity,the deposit cannot be treated as either the lateritic cannot be treated as either the lateritic or the karstic type.or the karstic type.Specialized Vocabulary:Specialized Vocabulary:Metasomatite:n.交代岩，换质岩dolomite dlmait n.白云石K-feldspars 钾长石plagioclase pleidikl
47、eis,-kleiz n.矿斜长石riebeckite ri:bekait n.矿钠闪石biotite baitait n.矿黑云母sericite serisait n.矿丝（绢）云母boehmite b:mait n.矿勃姆石（一种水软铝石）hematite hemtait,n.矿赤铁矿monomineralic mnu,mainrlik adj.单矿物的silicate silikit n.silicate silikit n.硅酸盐硅酸盐heterogeneity,hetrudini:iti heterogeneity,hetrudini:iti n.n.多相性多相性,异质性异质性la
48、teritic,ltritik adj.含有红土的；红壤的Material and methods Samples for the investigation were taken from drill cores.A part of each sample was powdered,and the levels present of 60 elements(including the major ones)were determined by XRF following standard methods at the Technical University of Berlin.A full
49、 description of the methods is given by Krumb(1998).The contents of elements in minerals were determined in polished sections using a wavlength-dispersive(WD)electron probe microanalyser(Cameca SX50)at the Natural History Museum,London.Specialized Vocabulary:Specialized Vocabulary:drill cores：岩心poli
50、shed plit polished plit a.a.擦亮的擦亮的,精练的精练的,优美的优美的MicroanalysermaikrunlaizMicroanalysermaikrunlaiz n.n.微量分析仪微量分析仪 International standards were used for calibration of each element.The analytical conditions used were 15 kV and 20 nA with counting times of 20 s for Zr,Ca,Ti,Nb,P,Sc,Pb,Mn,Fe,Hf,Na,Mg,Al