资源环境与城乡规划管理外文翻译文献.docx

资源环境与城乡规划管理外文翻译文献.docx

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资源环境与城乡规划管理外文翻译文献

资源环境与城乡规划管理外文翻译文献

（文档含中英文对照即英文原文和中文翻译）

Cyclicalsaltefflorescenceweathering:

aninvisiblethreattotherecoveryofundergroundmineenvironmentfortouristexploitation

J.MatíasPenàsCastejón•J.FranciscoMaciáSánchez•

MaPilarJiménezMedina•MaJesúsPenàlverMartínez

Received:

30April2013/Accepted:

25January2014/Publishedonline:

11February2014

Springer-VerlagBerlinHeidelberg2014

AbstractEnhancingthevalueofanundergroundmineenvironmentfortouristexploitationinvolvesalteringthephysico-chemicalbalanceofstonematerialswhoseoriginalmechanicalpropertiesguaranteedthestructuralstabilityofthesite’sgalleriesandchambers.Humidityandtemperaturechangescausedbythepublicexhibitionofthiskindofassetsarethemaincausesofsuchdisorders.AftertheinterventionintheAgrupa-VicentamineinLaUnion（Spain）therewerestillrunoff-waterleaksintothemine.Thesewaterrunoffsthroughthefaultandschistosityplanesoftheenclosingrockmassgiverisetosaltprecipitationovertime.Adaptingthismineandturningitintoamuseumhavemeantadecreaseinrelativeindoorshumidityandanincreaseintemperature.Thesevariationshavecausedrocks,whichwerestableintheoriginalconditions,toincreasetheirrateofphysico-chemicalweatheringduetothepolycyclicsupergenealterationofthemetalsulfidestheycontain.Theresultingreleaseofsulfatesintothesolutionandtheirsubsequentprecipitationassingleanddoublesaltefflorescencecauseshaloclasty,deterioratingtherock’smechanicalpropertiesanddiminishingthestructuralstabilityoftheoperation.Thispaperpresentstheresultsofcharacterizingthesupergenemineralphasesofsaltefflorescenceintherockbedenclosinganundergroundsulfideminevalueenhancedfortouristexploitation.Dangersforthestructuralstabilityofthistypeofarchitecturalintervention,associatedtotheformationofefflorescences,arealsoidentified;theseefflorescencesarecausedbytheweatheringofrocksthatmakeupitssupportingstructure.

KeywordsMineenvironment.Haloclasticweathering.Saltefflorescence.Geoindicators.Stonedecay.Agrupa-Vicentamine.LaUnio´n（Spain）

Introduction

Thewithdrawalfromminingactivityinmostlastcenturyminingareasandthesubsequenteconomicandsocialcrisisaffectingtheseabandonedindustrialareasarecurrentlyencouragingtherecoveryofminingheritagefortouristdevelopment（Hospers2002）.

Projectsforthepublicopeningofundergroundminesfacetwogreatchallenges:

（1）toguaranteethestabilityandstructuralsafetyofthegroundenclosure;and

（2）toachievethenecessaryconditionsofhabitabilityandcomfortofthepremises.Thedifficultiesoftacklingandexecutingsuchtechnicalprojectscomemainlyfromoperatinginadynamicenvironment,characterizedbythemutabilityofthephysico-chemicalpropertiesofitsconstituentmaterials.

Thenewventilationsystem,thenewlightingconditionsandtheaffluenceofpubliccausevariationsintheoriginalthermohygrometricbalanceconditions.Thesechangesgeneratetheappearanceofsaltefflorescencesandpolycyclicalchangesintheirmineralogicalphases.

Salineefflorescencemaycausethehaloclasticruptureoftherocksthatstructurallysupportmine’sgalleriesandchambers.Thiscallsforthedeterminationoftheoriginandnatureofsuchsalts,soastofindsuitablemechanismsthatinhibitweatheringprocessesfromtheverybeginning.Atpresent,differenttubbingsystemsarebeinggraduallybutpervasivelyintroducedtoavoidcollapserisksinthese‘‘museummines’’.

Therocksaboveandundertheexploitedmineralbedarecalledroofandbottomschists,respectively.TheroofoftheAgrupa-Vicentamineisformedbychloriticmicaschistsandquartzites,intenselyfoldedmetamorphicrocks,andthebottommaterialsaregraphiticschistsandgrayquartzites.Betweenbothlevels,astratiformmineralizationofsulfidesusedtobeexploited,mostlypyriteinsideachlorite（andsometimesgrenalite）gangue（MantecaandGarcı´a2005）（Fig.1）.

Despitetherelativeimpermeabilityoftherocksthatcoverthemine,theintenseriftingofthelandhasallowedfortheinfiltrationandundergroundflowofrainwateroverthecourseoftime.

Chemicalweatheringresultingfromthesupergenealterationofiron,leadandzincsulfidesinthemineralbedandintheschistsofthebottomandroofoftheminehascausedthereleaseofanionsandcationsintotheground-watersolutionthatcontinuouslycirculatesthroughthenetworkofpores,schistosityplanesandthefracturenet-work,afterrainperiods.

Whenthiswatercomesincontactwithpyriteandmarcasite,aseriesofchemicalreactionstakeplace,breakingdownthesemineralsandformingironsulfatesandacidminedrainage.

Asaresult,thefracturesinthepyritebedusuallypresentedopenholesstuffedwithironsulfate,‘‘melanterite’’（FeSO4·7H2O）.Sulphuricacidwasalsoreactingwithothercomponentsofthemineralbed（e.g.chlorite）,formingvarioushydratedsulfates-particularly‘‘epsomite’’（MgSO4·7H2O）whichwereprecipitatingonthebottomandroofofthemineintheformofneedle-shapedwhiteefflorescence.

Duringtheminingactivitytheworkingenvironmentforminerswasguaranteedthroughraiseventilation.Beforeopeningtheminetothepublic,microclimaticconditionsweremeasuredalong1year.Mediumtemperatureandrelativehumiditywere23.5℃and95.3%,respectively.

Afteropeningtheminetothepublic,itwasnecessarytoinstallthemandatoryairconditioningsystem.Thisauxiliaryventilationsystemtakesairfromtheflow-throughsystem（12,000m3/h）anddistributedittothemines’galleriesviatwomountedventilationfans.Ventilationsystemjustoperatesduringtimetablepublicvisits.

Asaconsequencenowadays,thenewmediumtemperatureandrelativehumidityvaluesare18.5℃and73.5%,respectively.Therefore,thehydrationanddehydrationcyclesofthesesaltsintensified.Theoversaturationofthesolutionalsoincreased,duetohigherevaporationproducedbythedescentinrelativehumidityandtheincreaseintemperature

insidethemain（Espinosa-MarzalandScherer2010）.

Allofthatimpliedanupsurgeintheaggressivenessoftherock’sphysicalweathering,asaresultofboththeincreaseincrystallizationpressureexertedbysaltsandalsooftheincreaseinthenumberofcycles.

Thus,thegoalsofourstudywere:

（1）tocharacterizethesaltsinvolvedinthephysicalweatheringofthebottomandroofschistsofthisundergroundmetalsulfidemine,asaresultofthecyclicalchangesoftemperatureandhumiditycausedbyitsopeningtothepublic;

（2）toidentifytherisksforthestructuralstabilityofthemine,comingfromsaltformation;and（3）toproposecorrectivemeasurementstominimizethoserisks.

Locationandgeology

TheAgrupa-VicentamineissituatedintheCuestadeLasLajasoftheSierraMineramountainrangeinLaUnio´n（Cartagena）.ThismountainridgerunsparalleltotheMediterraneanseafromEasttoWest,betweenthecityofCartagenaandCapePalos.Ithasanapproximatelengthof28kmandis5kmbroad.ItoncewasoneofthemostimportantminingdistrictsinSpainandthemostrepre-sentativeoftheMurciaRegion,duetoitsiron,leadandzincdeposits（Fig.2）.

Afterceasingitsminingactivityintheyear1991,thecityofLaUnio´nandthesurroundingvillageswereimmersedinadeepeconomicandsocialcrisis.

Localandregionalgovernmentshaverecentlyfocusedonpreserving,restoringandgivingmininganewmeaning.Effortshavebeenfocused,onkeepingminingheritageastheeconomicengineofthearea,althoughunderanewapproachthatpresentstheminingheritageasaculturalandtouristattraction（Conesaetal.2008）.Thus,in2006,theTownHallofLaUnio´ndecidedtotackletheadaptationoftheAgrupa-Vicentaundergroundmine,openingittothepublicin2009.

ThemineralizationpatternoftheSierraMineracorre-spondstothatoftheNevado-Fila´bridecomplex,possiblyformedbythehydrothermalreplacementofalevelofTriassicmarblelocatedneartheroofofthisformation.ThismineralizationpatternisthemostwidelyspreadintheSierraMinera,althoughitreceivesdifferentnamesaccordingtotheprevalentmineral:

pyritebed,sphaleritebedormagnetitebed.

Thewall-to-roofverticalsequenceofthegeologicmaterialsthatformtheSierraconformstothreesuperposedgeologicsets（MantecaandOvejero1992）:

Nevado-Fila´-brideComplex（CNF）,Alpuja´rrideComplex（CA）andNeogene（N）（Fig.3）.

TheCNFconsistsofintenselyfoldedmetamorphicrocks,withalowerbasementformedbygraphiteschistsfromthePaleozoic,andanuppercoverageformedbymicaschists,quartziteandPermo-Triasmarble.

TheCAisformedbylightlyfoldedmetamorphicmaterialsabovetheunderlyingCNF.Itshowsatleasttwosuperposedbedsoverthrust,calledlowerCA（alsoknownasSanGine´sunit）andupperCA（a.k.a.Portma´nunit）.Eachofthemhasadetriticbasaltract,phyllitesandquartzitesofPermo-Triasageandanuppercarbonatedtract,limestonesanddolostones,ofMiddleTriasage.

TheNeogeneismadeupoflightlyfoldedUpperMio-cenesedimentaryrocks,conglomerates,sandstonesandmarls,andofmagmaticrocksofUpperMiocene/Pliocene

age,whichtraversethewholeseries.Finally,modernalluvialsedimentsarefoundaccumulatedindepressions.

Geologically,theAgrupa-Vicentamineisontheeasternborderofa‘‘horst’’;i.e.arockmassdelimitedbyfaultsthathasrisenabovetheadjacentareas.Theeffectsoferosionafteritselevationeliminatedtheupperrockylevels,whichexplainswhythePaleozoicsubstratum,—themostancientmaterialsoftheSierra-