Download Field Trip Report 1 - Society of Economic Geologists

LondonStudentChapter
UniversityofWesternOntario
SocietyofEconomicGeologists–LondonStudentChapter
DetachmentFaultSettingsoftheLowerColorado
RiverandDeathValley
February11–20,2016
Objective:
Theprimaryobjectiveofthistripistoviewpost‐Laramidemid‐Tertiarydetachment
faults,thecharacterofsyn‐extensionmagmatism,andthenatureofassociated
preciousmetalepithermalandIOCGstylesofmineralization.
TripParticipants:
Dr.BobLinnen–UWOProfessor&TripLeader(Driver)
Dr.NeilBanerjee–UWOProfessor&TripLeader(Driver)
JessicaStromberg–GradStudent,TripLeader,SEGStudentChapterVice‐President
(Driver)
DianaZylik–UndergraduateStudent&SEGLondonStudentChapterSecretary
JonO’Callaghan–GraduateStudent
ConnorDavis–GraduateStudent
DiegoUribe–GraduateStudent
SarahCoDyre–GraduateStudent
AlexanderMunro–UndergraduateStudent
ScottHutchinson–UndergraduateStudent
AdamDemedeiros–UndergraduateStudent
NeeraSundaralingam–UndergraduateStudent
DylanLangille–UndergraduateStudent
PovilasGrigutis–UndergraduateStudent
MatthewDeGasperis–UndergraduateStudent
Thursday,February11th
LeftLondonat2AM.DrivetoDetroit,Michigan(DTW).SpiritAirlinesFlight111
departsDTWat6:50AM,arrivesinLasVegas,Nevada(LAS)at8:19AM.Drivesouth
toHooverDam,KingmanPeachSpringTuff,andviewNewberryDetachmentbefore
overnightinginLaughlin,NVattheAquariusHotel.
Figure1.WaterlevelswerelowattheHooverDam.
Figure2.TheMioceneagePeachSpringTuff(aweldedashflow)formerly
blanketedaminimumareaof2,000squaremileswheniteruptedfromtheSilver
CreekCaldera
Friday,February12th
TouroftheFriscoMine&MossMinenearBullheadCity.Visitthehistorictownof
OatmanandtheOatmanEpithermalDistrict.CampneartheMossMineinGrapevine
Canyon.
Figure3.TheFriscoMineisapastproducingepithermalgoldandsilvermine
discoveredin1894andminedintermittentlyuntil1935withbothundergroundand
cutandfillworkings.Thegoldandsilveriscontainedinquartz‐calciteveins.The
veinsarestrikingroughly055anddipping12,alongthecontactbetweenthe
NeoproterozoicKatherineGraniteandthePlioceneGoldenDoorVolcanics.The
mineralizationformsinstringerveins,withamaximumwidthof5.5m.
Figure4.GoldenVertex’sMossMineisanAu‐Agepithermal,brecciated,low
sulphidationquartz‐calciteveinandstockworksystemextendingoverastrike
lengthof1.4km.ThegeneralmanageroftheMossProject,JoeBardwichandtwo
otheremployeesgaveusatourofthepit,oldmineworkings,aswellastheir
cyanideheapleachsystemandassaylab.
Saturday,February13th
DeparttheBlackMountainsafterlookingattheGoldRoadVeinandSitgreavesPass.
HeadfortheghosttownofSwanseaandit’saccompanyingIOCGdeposits.Wehada
flattireuponleavingtheblackmountains,sohadtoforegotheGoldRoadVeinand
SitgreavespassandinsteaddrivestraighttoSwansea.
Figure5.DesertsunsetfromourcampsiteintheSwanseaghosttown.TheSwansea
minewasanundergroundCu‐Fe‐Ag‐AuminelocatedinArizona.Themineralization
wasofoxidizedcopperores,mixedinwithquartzandchlorite,withtheorebodies
locatedonandimmediatelysurroundingadetachmentsurfacerelatedtopost‐
LaramideOligocene‐Mioceneextension.Originallyprospectedinthe1880s,the
mineproducedintermittentlyuntil1944.
Sunday,February14th
ExploreabitaroundSwanseabeforeheadingsouthtoYuma.StopinQuartziteto
visittheQuartziteGoldShow.OvernightinYumaattheTravelodge.Inquartzite,
studentswerealsointroducedtotheprocessofgemcuttingandsettingwithavisit
totheworkshopofalocallapidary.
Figure6.ThedetachmentsurfaceatSwanseahasagreaterthan55kmoffset,and
theextendedandfractureduppercrusthostsacomplexhydrothermalsystem.The
SwanseadistrcitislocatedinadepressedbasinadjacenttotheBucksinmountains,
andthepresenceofsiltstone,sandstoneandlimestonesuggestitwasonceflooded.
ThissmallhermitdwellingdugintoawashcanyoninMineralWashissituatedinK‐
metasomatizedbasaltvolcanics.ThisK‐metasomatismreducedtheFeOcontent,
withconservativeestimatesgivingFeliberationat4x106tofmetallicFe.Similar
estimatesforCusuggesttheremovalof14700tofCu.
Monday,February15th
GeologyoftheCargoMuchachos,withvisitstoLincolnMining’sOroCruzproperty
andtheoldAmericanGirlMine.CampintheChocolateMountains.
Figure7.TheAmericanGirlopenpit.TheCargoMuchacho‐Tumcodistrictwas
discoveredbytheSpaniardsandminedasearlyas1780‐81.Thedistrictisbelieved
tohaveproducedthefirstgoldmineinCalifornia.Americansbeganminingthe
districtattheendoftheMexican‐AmericanWarin1848.TheCargoMuchacho,
Tumco,PasadenaandAmericanGirlMinescomprisethemajorgoldproducersof
theCargoMuchachoDistrict.Thisdistrictisbelievedtobethenorthwestern
extensionofthefamousgoldbeltoftheAltarDistrictofSonora,Mexico.Although
essentiallyagoldminingdistrictsomecopperwasproducedasabyproductofgold
mininghere,mainlyattheAmericanGirlMine.Oreinthisdistrictcontainsfree‐
millinggoldorgoldindisseminatedpyrite.Goldaloneandinassociationwithsilver
andcopper,andsomesericiteandkyanitearetheonlymineralsextractedfromthe
CargoMuchachos,thelattertwomineralshavebeenproducedmainlysince1930.
Thequartzveinsareupto8feetthickinthisregionandcontainthehighestgradeof
goldorefoundinImperialCounty.”
Figure8.TouringtheabandonedTumcominingtown.
Tuesday,February16th
TourofNewGold’sWesternMesquiteMine.LunchattheAlgodonesDunes.Visitthe
rhyolitedomesattheSaltonSeaandpossiblestopatPaintedCanyonbefore
overnightinginJoshuaTreeNationalParkwherewehadanotherflattire.
Figure9.SunriseoverourcampsiteintheChocolateMountainsneartheMesquite
Mine.
Figure10.InthepitatNewGoldsMesquiteMinewhereSEGmemberJessica
Strombergsetoffadailyproductionblast.Sincethecommencementofcommercial
productionin1985,theMesquiteminehasproducedmorethan4millionouncesof
gold.TheMesquiteMinecomprisesaseriesofgolddepositslocalizedalongtwosub‐
parallelzonesofnorthwesterlytrendingfaultingthatoverprintsasequenceof
gneissichostrocksandlocallyintrudinggranites.MuchoftheMesquitedistrictis
coveredbyaveneerofunconsolidatedpost‐mineralsandandgraveldepositsthat
varyfromafewtoseveraltensofmetresinthickness.Goldmineralizationat
Mesquitewasdepositedinanepithermalsetting,within150to300metresofthe
paleo‐surfacesubsequenttoamphibolitegrademetamorphism.Thebulkofthegold
mineralizationoccursasdisseminationsandveinsdevelopedalonganorthwesterly
trendingsystemofmoderatelytosteeplydippingfaultsandfractures.Gold
primarilyoccursasnativegold,ranginginsizefromverycoarsetosubmicron
disseminations.
Figure11.TheAlgodonesDunesisalargeerg(sanddunefield)locatedinthe
southeasternportionoftheU.S.stateofCalifornia,neartheborderwithArizonaand
theMexicanstateofBajaCalifornia.Thefieldisapproximately45mileslongby6
mileswideandextendsalonganorthwest‐southeastlinethatcorrelatestothe
prevailingnortherlyandwesterlywinddirections.
Wednesday,February17th
TouraroundtheJoshuaTreearea.OvernightinJoshuaTree.
Figure12.BobLinnendiscussinggranitetypeswhilehikingtheCottonwoodtrailto
theMastadonMine.MiningisanintegralpartofthehistoryoftheJoshuaTree
NationalParkregion.Thereare288abandonedminingsitesinJoshuaTreeNational
Parkwith747mineopenings.1Goldwasthecommodityofgreatestinterest.
Figure12.TheabandonedMastodonMine.
Figure13.TheviewfromthehistoricDesertQueenMine.TheDesertQueenMine
isdevelopedintheWhiteTankmonzogranite,southofthecontactwiththe
PalmsQuartzMonzonite.Goldisdescribedasbeinginpocketsassociated
withdikesofpegmatite,aplite,andesite,andveinsofgoldbearingquartz.
Minorveinletsofmalachiteandazurite,pyrolusitedendrites,andprobable
turquoiseoccurinfracturesinsomeofthemineralizedpocketsintheaplite
andquartzveins.Wasterockpilesarestainedwiththesesecondaryminerals.
Thursday,February18th
DrivefromJoshuaTreetoDeathValley,stoppingatMojaveGold’sTelegraphMine
explorationsite.CampatFurnaceCreekinDeathValleyNationalPark.An
impromptustopatAmboycraterwasalsomade.
Figure14.SunriseinJoshuaTree.
Figure16.ViewfromtherimoftheAmboyCrater,anextinctcinderconetype
ofvolcanothatrisesabovea70‐square‐kilometer(27sqmi)lavafield.Thiscinder
coneisestimatedtobe79,000yearsold(+/‐5,000years)andwasformedinlayers
ofmostlyvesicularpahoehoe–duringthePleistocenegeologicalperiod.The
interiorhasalavalake.LavaflowsasoldasAmboyCrateritselfblanketthe
surroundingarea.Themostrecenteruptionwasapproximately10,000yearsago.
Figure17.MorecarissuesattheTelegraphMineExplorationsite.TheTelegraph
Mineisalow‐sulfidation(quartz‐adularia)epithermalgold&silverdeposit.Gold‐
andsilver‐bearingepithermalbreccia‐veins,whichconsistofquartz‐sericite‐
adularia‐pyriteandquartz‐carbonate,cuttheinformallynamedCretaceous
Teutoniaadamellite.
Friday,February19th
GeologytourofDeathValleyNationalPark.DrivetoLasVegas.
Figure18.DantesView.Fromthisvantagepointyoucanviewdistant11049ft.
TelescopePeaktoBadwater,thelowestpoint(‐282ft.)intheWesternHemisphere.
Thisdifferenceinelevationisastaggering11,331feet(3455m)—thegreatest
topographicreliefintheconterminousU.S.Thisstrikingtopographyisaproductof
DeathValley'sveryactivetectonics.
Figure19.SEGmembersJessicaStromberg,DianaZylikandJonO’Callaghanatthe
Badwaterbasin,55mbelowsealevel.
Figure20.DeathValleywasina“superbloom”duringourvisit.
Figure21.Onefinaldesertsunset.
Saturday,February20th
HiketheGoldstrikeCanyonHotSpringstrail.FlybacktoDetroitfromLasVegas.
Figure22.HikingtheGoldstrikeCanyontrail.
st
Sunday,February21 ArriveinDetroitanddrivebacktoLondon.