Processes Governing Alkaline Groundwater Chemistry within a Fractured Rock (Ophiolitic Mélange ...

22 Pages·2017·7.48 MB·English

Hindawi
Geofluids
Volume 2017, Article ID 3153924, 21 pages
https://doi.org/10.1155/2017/3153924
Research Article
Processes Governing Alkaline Groundwater Chemistry
within a Fractured Rock (Ophiolitic Mélange) Aquifer
Underlying a Seasonally Inhabited Headwater Area in
the AladaLlar Range (Adana, Turkey)
CüneytGüler,1GeoffreyD.Thyne,2HidayetTaLa,1andÜmitYJldJrJm1
1JeolojiMu¨hendislig˘iBo¨lu¨mu¨,MersinU¨niversitesi,C¸iftlikko¨yKampu¨su¨,33343Mersin,Turkey
2ScienceBasedSolutions,2317MountainShadowLane,Laramie,WY82070,USA
CorrespondenceshouldbeaddressedtoCu¨neytGu¨ler;[email protected]
Received 12 January 2017; Accepted 27 April 2017; Published 15 August 2017
AcademicEditor:TobiasP.Fischer
Copyright©2017Cu¨neytGu¨leretal.ThisisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense,
whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline
groundwaterwithinafracturedrock(ophioliticme´lange)aquiferunderlyingaseasonallyinhabitedheadwaterareaintheAladag˘lar
Range(Adana,Turkey).Inthisaquifer,spatiotemporalpatternsofgroundwaterflowandchemistrywereinvestigatedduringdry
(October 2011) and wet (May 2012) seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow,
rock,andsoilwerecollectedandanalyzedtoconstrainthePHREEQCinversegeochemicalmodelsusedforsimulatingwater-
rockinteraction(WRI)processes.HydrochemistryoftheaquifershowsastronginterseasonalvariabilitywhereMg–HCO3 and
Mg–Ca–HCO3watertypesareprevalent,reflectingtheinfluenceofophioliticandcarbonaterocksonlocalgroundwaterchemistry.
R-modefactoranalysisofhydrochemicaldatahintsatgeochemicalprocessestakingplaceinthegroundwatersystem,thatis,WRI
involvingCa-andSi-bearingphases;WRIinvolvingamorphousoxyhydroxidesandclayminerals;WRIinvolvingMg-bearing
phases;andatmospheric/anthropogenicinputs.ResultsfromthePHREEQCmodelingsuggestedthathydrogeochemicalevolution
isgovernedbyweatheringofprimaryminerals(calcite,chrysotile,forsterite,andchromite),precipitationofsecondaryminerals
(dolomite,quartz,clinochlore,andFe/Croxides),atmospheric/anthropogenicinputs(halite),andseasonaldilutionfromrecharge.
1.Introduction intheliterature,thereisnocleardefinitionastowhatconsti-
tutesa“headwaterarea”[4,8].Itisgenerallyagreeduponthat
Achievement of a sustainable aquifer management requires theseareasareuniqueandfragilerechargeenvironmentsnear
animprovedunderstandingofthecomplexnaturalprocesses thetopographicaldrainagedivideswhereflowlinesofzero-
generating the observed composition of groundwater, as tofirst-ordercatchmentsoriginate[7,9].Yet,becauseofthe
well as all anthropogenic activities hindering its safe use problemofscaledependency,mostoftheselow-orderstream
andavailability[1].Thisiscriticallyimportant,especiallyin channels are rarely documented on the topographic maps
headwaterareas,sincetheytypicallyconstitute70–80%ofthe [4,10];hence,theyarefrequentlyomittedfromtheordering
total catchment area [2] and represent starting point of the schemes (e.g., [11, 12]). In reality, these montane headwater
terrestrialwatercycle[3].Ourunderstandingofthemoun- systemsserveasthetransportmediumfordeliveringwater,
tainousheadwatersystemsandtheimpactsofanthropogenic sediment, nutrients, and other materials to downstream
activities on headwater-scale has been largely impeded by areas, especially during intermittent rainfall and snowmelt
their small size, large numbers, remote locations, rugged events [4, 6, 10]. Recently, Bishop et al. [5] called aptly this
terrain, harsh climate conditions, and lack of road access, understudied and ignored realm as “Aqua Incognita,” the
logistics,andavailabledata[4–7].Despitetheirimportance, unknownwaters.Anumberofstudies(e.g.,[2,6,10,13–15])
2 Geofluids
have shown that hydrological and hydrogeochemical pro- meansealevel(msl),anditischaracterizedbytopographic
∘ ∘
cesses occurring in headwater systems have critical control gradients between 0.13 and 45.9 (with a mean slope of
∘
onthequantityandbiophysicochemicalqualityoftheunder- 16.6 and E-SE aspect). The climate is continental to some
lying shallow groundwater and downstream systems, all of extent [19] and influenced by both the Mediterranean and
which are intimately linked through the hydrologic cycle. central Anatolian weather systems, bringing temperate, dry
Furthermore, these areas and associated hyporheic zones summers, and cold, wet winters to the area [20]. Based on
have also importantecosystem functions,providing unique theavailableclimatedata(1960–1991)recordedatthePozantı
habitatsfordiverseflora,fauna,andmicrobiota[16–18]that meteorological station (see Figure1(b)), the average annual
∘
areimperativeforafullyfunctioningsystem. air temperature is 13.5 C and temperatures occasionally
During the last several decades, relatively poorly devel- exceed31∘Cinsummerandrarelydropbelow−6∘Cinwinter
opedandremotehighlandsoftheAladag˘larRangeofeastern [32].Theareareceivesanaverageannualprecipitationslightly
Taurides have become increasingly valued for their clima- higherthan725mmand85%ofitoccursbetweenNovember
tological and bioecological diversity (e.g., [19–21]), near- andMay[32].Theprecipitationoccursinwinter,asrainand
pristine water and air quality (e.g., [21, 22]), scenic and snowfall,butinsummerasoccasionalthunderstorms.
aestheticbeauty(e.g.,[20]),andrecreational/touristicoppor- InKızılgediksite,thereare85individualhousesaccom-
tunities(e.g.,[23]).Longbeforetherecentappreciationofall modating some 300 people during the peak season (June
thesenaturaltreasures/qualities,thesehighlandareas(called to September). However, population remains insignificant
yayla)wereoccupiedessentiallyassummercampinggrounds during the rest of the year (i.e., off-season). Currently, the
bythenomadicpeople(calledYo¨ru¨k)whocommonlymade area does not have a sewerage network and each property
their living by livestock rearing (primarily goat) and to a has its own cesspit in the garden. Traditionally, cesspits
lesser extent small-scale family farming [24, 25]. While the are built square in form (dimensions: 2m × 2m × 1.5m)
pure nomadic lifestyle is still alive in some areas, currently, and lined with loose-fitting stones allowing wastewater to
yaylas are mostlyfrequentedby thecity dwellers, especially percolate into the ground (Figure2). There was no piped
duringthesummerseason,duetotheircomfortableclimate watersupplyuntil2011,wheremajorityoftheresidentsstill
(e.g.,coolandlesshumid)ascomparedtotheMediterranean rely on large-diameter hand-dug wells (HDWs) (Figure2)
coastalzone(i.e.,C¸ukurovaregion)[19,21].Asaresponseto for their domestic water needs and irrigation. Typical of
thisnewtrend,numerousseasonalsettlementswerecreated serpentiniticterrains,thenaturalvegetationinthesettlement
in the headwater areas, which in turn have not only sig- area is limited to sparse shrubs and herbaceous vegetation
nificantlyaltereddemographic,cultural,andsocioeconomic (a.k.a.serpentinebarrens[35]),whereasdomesticatedplants
characteristicsoftheregion[21]butalsohadamarkedimpact andtreesaremainlyfoundaroundresidentialhouses.Addi-
onthenaturalenvironment[23,24,26–28]. tionally,patchesofmixedconiferforests(e.g.,pine,juniper,
RecentmodelingstudiesconductedintheSeyhanRiver larch,fir,andcedar)areoftenfoundinthehillssurrounding
basin also raised concerns over the anthropogenic climate thesettlementarea.
change, which is projected to aggravate the pressure on the
hydrologicsystemintheforthcomingdecades[29–31].This 2.2.GeologicalandHydrogeologicalSetting. Thestudyareais
paperpresentsthefirstdetailedanalysisofhydrologicaland situated in the east of the relatively isolated Karsantı basin
hydrochemical data obtained from two snapshot sampling (see Figure1(b)), which formedduringOligocene time[34,
campaignscarriedoutintheKızılgedikseasonalsettlement, 36–38]withinthewesternmostpartoftheeasternTaurides
which is located in a serpentinized ophiolitic terrain in the [33,39],immediatelytothenorthoftheextensivelystudied
headwatersoftheSeyhanRiverbasin.Thespecificobjectives Adanabasin[40–45].Thegeologicalformationsfoundinthe
ofthepresentstudywere(i)todefinethemineralogyandgeo- regionrangeinagefromMesozoictoCenozoicandrepresent
chemistryoftherocksandsoilsfoundinthearea;(ii)todeter- highlycomplextectonicandstratigraphicrelationships[36,
mine water levels and groundwater flow directions in the 46] (Figures 3(a) and 3(b)). Mesozoic rocks include the
ophioliticcomplexaquifer;(iii)toinvestigatepossibleeffects Late Triassic-Early Jurassic Etekli formation (megalodon-
of anthropogenic inputs to the underlying shallow aquifer; bearing limestone) [36], Late Cretaceous Kızılcadag˘ ophi-
and(iv)toshedlightonthepredominanthydrogeochemical oliticme´lange(serpentinizedduniteandharzburgite,serpen-
processesusinginversegeochemicalmodelingapproach. tinite, radiolarite, chert, and exotic blocks) [47], and Late
Cretaceous Pozantı-Karsantı ophiolite (harzburgite, dunite,
2.StudyArea pyroxenite,gabbro,diabasedykes,andmetamorphicrocks)
[48,49].TheKızılcadag˘ophioliticme´lange,tectonicallyover-
2.1.PhysiographicSetting,Climate,andLandUse. Thestudy lainbythePozantı-Karsantıophiolite,containsthrustslices
area,located∼100kmnorthoftheMediterraneanSeacoast- composedofEtekliformation[36].Theophioliticme´langeis
line in Adana province (Turkey), lies within the Aladag˘lar madeupofblocksofheterogeneousandstronglydeformed
Range of eastern Taurides (Figures 1(a) and 1(b)) and is a lithologies(i.e.,exoticblocksdecimetertoseveralhundreds
2
partoftheSeyhanRiverbasin(area21,700km ).Thespecific of meters in size) set in a variably altered serpentinitic
∘ 󸀠 󸀠󸀠
area studied is bounded by the latitudes 37 31 55.50 N matrix[50].Mostoftheserpentiniteshaveprobablyformed
∘ 󸀠 󸀠󸀠 ∘ 󸀠 󸀠󸀠
and 37 32 28.70 N, and longitudes 35 25 10.75 E and duringsuboceanichydrothermalalterationofultramaficpro-
∘ 󸀠 󸀠󸀠
35 25 52.51 E.Thisareaencompassesaruggedmountainous toliths(e.g.,harzburgiteanddunite)priortotheiremplace-
terrain, with altitudes ranging from 1030 to 1310m above mentonland.Pozantı-Karsantıophioliteformedwithinthe
Geofluids 3
26∘E 45∘E
42∘N Black Sea Russia Camardi Feke W N E
Greece Istanbul NAF Georgia Ulukisla KarsBaanstiin Aladağ Andirin S
Armenia Pozanti Study area Kozan Kadirli
36∘N Aegean Sea N IzmMierditerrWanTeasetuaerirndn eSseaKFAnkarTCaaeTunurtizdr aLelsTaTkuLeFrkeSEFtyudAyd aarneaa EAF SEyarsBtieaornrder FoBldSsZ TauriLdaekse VIarnaqIran CamMliyearyslain TarsuKsarAaisdSaealyiRhniavnaer CeyhanRiverYumCuerythaIlaminkamoglu OsmaDnuiyzieci
W E 0 180 360(km) Erdemli Karatas 0 20(km)
S Lebanon Mediterranean Sea
(a) (b)
Figure1:(a)ThebroadgeographicalsubdivisionoftheTaurides(after[33])andmajortectonicstructuresinTurkey(KF=KırkkavakFault,
EF=Ecemi¸sFault,TLF=TuzLakeFault,EAF=EastAnatolianFault,NAF=NorthAnatolianFault,BSZ=BitlisSutureZone)(modified
from[34])and(b)locationoftheKızılgedikstudyareainAladag˘(Adana,Turkey).
prevalenceofsinkholes.Adetailedsynthesisofbothregional
and local tectonic frameworkand evolutionof the Karsantı
basincanbefoundin[34,38].
Hydrologically,thestudyarearesideswithinseveralzero-
order catchments that lie at the ultimate extremes of the
Soil localdrainagenetwork,whereoverlandflowisonlyseenafter
heavy rainfall events and during snowmelt episodes in ill-
defined surface flow paths (e.g., rills, gullies, and swales).
The aquifers within the study area can be classified into
two primary groups based on host rock and structural
characteristics,asfollows:(i)carbonaterockaquiferand(ii)
ophioliticcomplexaquifer.Groundwateroccurrencewithin
Not to scale
thecarbonaterocksisnotknownduetoabsenceofmonitor-
Figure2:Schematicdrawingshowingtypicaldesignsofhand-dug ingwells,butsecondaryporositycreatedbyfractures/faults,
wellsandcesspitsinthestudyarea. together with karstic features such as sinkholes, may allow
significant groundwater circulationand enhanced recharge.
Groundwater found within the ophiolitic complex aquifer
Neo-TethysOceanintheMiddletoLateCretaceous[51,52]. isofutmostimportanceforthelivelihoodoftheheadwater
Much of the large-scale deformation is related to regional environment and local residents, although ophiolitic rocks
compressionaleventsthatoccurredduringLateEocene[34]. of this region have been considered impermeable in earlier
In the study area, Cenozoic sedimentation begins with studies [57, 58]. In the study area, the ophiolitic complex
the Oligocene-Late Miocene Karsantı formation (terrestrial aquifer is compartmentalized by a distinct set of faults,
and lacustrine pebbly sandstone, mudstone, coaly clay- trending in SW–NE direction. In this aquifer, groundwater
stone, and marl) [43]. This formation is separated from istappedfromthehighlyfracturedportionoftheophiolitic
the underlying Mesozoic tectonostratigraphic units by a me´langebyshallowHDWswithdepthsnotexceeding10m.
distinct unconformity [53]. This nonmarine deposition Inthestudyarea,rechargetotheaquiferstakesplacethrough
ended in the Early Miocene by a transgression from the several ways, such as (i) infiltration from the runoff from
Adana basin [54]. The Early-Middle Miocene (Aquitanian- precipitationandsnowmeltevents;(ii)lateralanddownwards
Burdigalian) Kaplankaya formation (shallow marine marl, groundwater flow from the overlying geological formations
claystone,sandstone,andsandylimestone)[45]recordsthe (mostly karstic in nature); (iii) infiltration from irrigation
first marine transgression in the Karsantı basin [37]; the water; and (iv) wastewater percolation from the cesspits.
base of this unit also lies above an irregular unconformity The main recharge areas are positioned to the N and SW
surface[55].Kaplankayaformationispartlyoverlainbyand of the study area (Figures 3(a) and 3(b)). Water levels in
passeslaterallyintotheEarly-MiddleMiocene(Burdigalian- the ophiolitic complex aquifer respond relatively quickly
Serravallian) Karaisalı formation (fossiliferous reefal lime- to the recharge events, due to highly fractured nature of
stone)[43,56].Karaisalıformationoccupiestopographically theupperportionsoftheophioliticme´lange.Thedischarge
higher parts of the study area (e.g., Korum Mountain) and from the aquifers occurs in different ways, including (i)
is highly susceptible to karstification, as evidenced by the subsurface outflow to adjacent valleys that moves through
4 Geofluids
35∘24㰀30㰀㰀E 35∘25㰀00㰀㰀E 35∘25㰀30㰀㰀E 35∘26㰀00㰀㰀E A㰀
B
37∘32㰀30㰀㰀N
37∘32㰀00㰀㰀N
37∘31㰀30㰀㰀N
A B㰀
0 0.2 0.4 0.6 (km)
Scale
Geological formations
Tka Karaisalı formation (Early-Middle Miocene) Formation boundary
Transitional Fault
Tkp Kaplankaya formation (Early-Middle Miocene) Overthrust
Angular unconformity Road
Tk Karsantı formation (Oligocene-Late Miocene) A A㰀 Cross section line
Nonconformity Settlement
Kk Pozantı-Karsantı ophiolite (Late Cretaceous)
Overthrust
TRJe Etekli formation (Late Triassic-Early Jurassic)
Overthrust
Kkm Kızılcadağ ophiolitic mélange (Late Cretaceous)
(a)
A Korum Mountain A㰀
Study area
m) 1250
e ( 1150
d
u 1050
Altit 950
850
B Study area B㰀
m) 1150
e ( 1050
d
u 950
Altit 850
0 500(m)
Scale
Etekli formation (Triassic-Jurassic) Kaplankaya formation (Early-Middle Miocene)
Kızılcadağ ophiolitic mélange (Late Cretaceous) Karaisalı formation (Early-Middle Miocene)
Pozantı-Karsantı ophiolite (Late Cretaceous)
(b)
Figure3:(a)Detailedgeologicalmap(adaptedfrom[36])oftheregionsurroundingtheKızılgediksite(shownintheredbox)overlaidon
󸀠
adigitalelevationmodel(DEM)withagridsizeof10mand(b)generalizedgeologicalcrosssectionsalongthelinesA–A (SWtoNE)and
󸀠
B–B (NWtoSE)in(a)showingthesubsurfacelithologyandmajortectonicstructures(faultsshowninredcolor).
Geofluids 5
Oct 2011 May 2012
N N
W E W E
S S
0 80 160 0 80 160
(m) (m)
Scale Scale
Geological formations Geological formations
Tka Karaisalı formation (Early-Middle Miocene) Tka Karaisalı formation (Early-Middle Miocene)
Tkp Kaplankaya formation (Early-Middle Miocene) Tkp Kaplankaya formation (Early-Middle Miocene)
Kkm Kızılcadağ ophiolitic mélange (Late Cretaceous) Kkm Kızılcadağ ophiolitic mélange (Late Cretaceous)
TRJe Etekli formation (Late Triassic-Early Jurassic) TRJe Etekli formation (Late Triassic-Early Jurassic)
Topographic contour Topographic contour
Formation boundary Formation boundary
Fault Fault
Overthrust Overthrust
1120 Groundwater level (m) 1120 Groundwater level (m)
Groundwater flow direction Groundwater flow direction
Hand-dug well location Hand-dug well location
K22 K22
Cesspit location Cesspit location
Rock/soil sampling location Rock/soil sampling location
(a) (b)
Figure4:HydrogeologicalmapoftheKızılgedikstudyarea(seeredboxinFigure3(a))showinglocationsofgroundwater(𝑛 = 25),rock
(𝑛 = 10), and soil (𝑛 = 8) sampling sites. The hand-dug well (HDW) codes (i.e., K1–K25) refer to both water table measurement and
groundwatersamplingsites.Thewatertableelevationsaregivenatintervalsof2mabovemeansealevel(msl)forboth(a)dryseason(October
2011)and(b)wetseason(May2012).Arrowsdepictthegeneraldirectionofshallowgroundwaterflowinthefracturedophioliticcomplex
aquifer.
fractures/faults; (ii) discharge by springs and seeps; (iii) samples (𝑛 = 8) were collected at a depth of 0–15cm with
evaporation of shallow groundwater; (iv) transpiration by a stainless steel spatula, after removing stones, plant/root
plants;and(v)groundwaterabstractionfromHDWs. debris, and foreign objects. At each soil sampling site (i.e.,
S1–S8), representative composite samples were obtained by
3.MaterialsandMethods pooling four subsamples (∼250g) taken on the corners of
2
a 1m square [59]. All samples were placed in labeled self-
3.1.Rock/SoilSamplingandAnalyticalMethods. Arockand locking polyethylene bags and transferredto the laboratory
soil sampling campaign was carried out in November 2013 for further processing. In the laboratory, the rock and soil
inordertorelatethegroundwaterchemistrywithlithology. sampleswereair-driedatroomtemperatureforseveraldays,
Selectionofthesamplingsites(seeFigure4)waslargelybased disintegratedandhomogenizedinanagatemortarandthen
onspatialdistributionofthemajorgeologicalunitsandfield passed througha2mmsieve. SamplesforX-raydiffraction
observations made during prioron-site surveys. Fresh rock (XRD),wavelengthdispersiveX-rayfluorescence(WDXRF),
samples (𝑛 = 10) were collected at various locations (i.e., and loss-on-ignition (LOI) analyses were prepared by the
R1–R10), generally as composite chip samples (∼1kg) from usualpowdermethodproceduresasdescribedbyBuhrkeet
available outcrops with a rock hammer. Topsoil composite al.[60].Rockandsoilsamplesweregroundtopowderand
6 Geofluids
homogenizedbyRS200tungstencarbidevibratorydiscmill spatialinterpolationalgorithmavailableintheGeostatistical
(Retsch,Germany)andthenfinegrindingwasaccomplished AnalystextensionoftheArcGIS9.3.1software[64].
usinganagatemortarandpestle.
Themainmineralphasesoccurringintherockandsoil 3.3. Water Sampling and Analytical Methods. Groundwater
sampleswerecharacterizedbypowderXRDtechniqueusing samples were collected from identical HDWs (𝑛 = 25) in
a Rigaku SmartLab X-ray diffractometer (Rigaku Corpora- dry and wet seasons (Figure4). In this study, well purging
tion,Japan)withCuK𝛼radiationatanacceleratingvoltage wasnotattemptedduetopresenceoflargevolumeofwater
of 40kV and a tube current of 30mA. XRD patterns in in the HDWs. Groundwater samples were collected from a
diffractograms were obtained from 5∘ to 60∘ in 2𝜃 with a depth of a few meters below the water table by lowering a
step width of 0.02∘, at a scanning speed of 4∘min–1, using plastic bailer into the HDWs. Additionally, snow samples
1mmreceivingslits,a10mmlengthlimitingslit,anda2/3∘ were collected shortly after two major snowfall events on
incident slit. The software PDXL and the PDF-2 database January2012(𝑛=6)andFebruary2013(𝑛=5)fromvarious
(http://www.icdd.com) were employed for mineral phase locationsofthesiteforphysicochemicalcharacterizationof
identification. The chemical composition of the rock and the precipitation. Sampling and analytical techniques fol-
soil samples were determined by a Rigaku ZSX Primus II lowedthesuggestionsbyAPHA-AWWA-WEF[65]andwere
WDXRF spectrometer (Rigaku Corporation, Japan) with a similartothosedescribedearlierintheliterature[1,66].The
4kWrhodiumtarget,usinganaccelerationvoltageof30kV fieldparameters(pH,redoxpotential(Eh),dissolvedoxygen
and a current of 100mA. The major oxides (SiO2, TiO2, (DO), electrical conductivity (EC), and temperature) were
Al2O3,Fe2O3,MnO,MgO,CaO,Na2O,K2O,P2O5,andSO3) measuredinsituusingaWTWMulti340i/SETmultiparam-
and trace elements (Co, Cr, Ni, and Sr) in bulk solids were eter instrument (Wissenschaftlich-Technische Werksta¨tten,
quantifiedusingthestandardlessanalysisprogramSQX[61]. Germany).Theprobeswerecalibrateddailyinthefieldusing
WDXRF analyses were carried out on pressed-powder standard procedures before sampling as per manufacturer’s
pellets that were prepared by thoroughly mixing 10g of instructions.Groundwatersampleswereimmediatelyfiltered
eachsamplewith4gofcellulosebinder(SPEXSamplePrep on site through a disposable nylon membrane syringe filter
PrepAid(cid:2),USA)withaparticlesizeof≤20𝜇m.Themixture (Econofilter)withaporesizeof0.45𝜇m(AgilentTechnolo-
was pressed into 38mm diameter pellets using a manually gies, Germany). In brief, at each site, two 250mL aliquots
operated hydraulic press. After pressing, the pellets were were collected in clean HDPE bottles for cation and anion
driedinovenat100∘Cfor12h,beforetheWDXRFanalysis. analyses.Aliquotstakenforcationanalysiswereacidifiedat
TheLOIwasdeterminedastheweightlosspercentageafter thefield(belowpH2.0)with65%extrapureHNO3(Merck,
burning 4g of powdered dry sample in an electric muffle Germany)topreventbiologicalactivityandprecipitationof
furnaceat950∘Cfor1h[62,63].Allanalyseswereperformed cationic species. All the samples were stored in an icebox
attheAdvancedTechnologyEducation,ResearchandAppli- containinggel-filledicepackstopreventpossibleevaporation
cationCenter(ME˙ITAM),MersinUniversity(Turkey). effects. Then, they were transported to the laboratory and
∘
refrigeratedat4 Cuntilanalysis.
3.2.GroundwaterLevelMeasurement. Thegroundwatersam- Analysesfortotalconcentrationsoffivemajorelements
plecollectionandwaterlevelmeasurementswerecompleted (Ca,Mg,Na,K,andSi)and17traceelements(Al,As,B,Ba,
within two days, in two separate field campaigns, covering Br,Co,Cr,Cu,Fe,Li,Mn,Mo,Ni,Sr,Ti,V,andZn)inthe
all the wells. The field campaigns took place in October acidifiedaliquotswerecarriedoutintheME˙ITAM,Mersin
2011andMay2012.Forconvenience,theterms“dryseason” University(Turkey)byAgilent7500ceICP-MS(AgilentTech-
and “wet season” will be used throughout the rest of the nologies, Japan) equipped with Octopole Reaction System.
paper to refer to measurements/sampling made on shallow ThepurityofargongasusedintheICP-MSwas99.998%or
hand-dugwells(HDWs)duringOctober2011andMay2012, higher.Theexternalstandardcalibrationmethodwasapplied
6 45 72 89 115 159
respectively. The wells found in the area are typically large- toalldeterminationsusing Li, Sc, Ge, Y, In, Tb,
209
diameter(ca.0.8–1.2m)HDWsrangingindepthsfrom3.29 and Biinternalstandardmix.Five-pointcalibrationcurves
to9.54m.Allthewellsaredirectlycompletedinthehighly were created by analyzing NIST single-element reference
fracturedupperportionoftheKızılcadag˘ophioliticme´lange standardspreparedbyserialdilutionofstocksolutions.The
+ −
and none was identified to have a casing or lining within concentrations of ammonia (NH4 ), nitrate (NO3 ), nitrite
− 2− 3−
the saturated zone (Figure2). These relatively shallow wells (NO2 ), sulfate (SO4 ), orthophosphate (PO4 ), chloride
− −
are generally equipped with hand pumps and exploited for (Cl ), and fluoride (F ) in the unacidified aliquots were
domestic purposes and/or irrigation water supply, chiefly determinedattheMersinUniversityGeologicalEngineering
during summer months. The depth to water in the HDWs Department with Hach Lange DR 2800 spectrophotometer
(𝑛 = 25) was determined manually by means of a flat (Hach Lange GmbH, Germany). Carbonate (CO32−) and
−
tapewaterlevelsounder(AkımHydrometry,Turkey)witha bicarbonate (HCO3 ) in water samples were determined
precisionof1mm.Watertableelevations(withrespecttomsl) by volumetric titration with 0.01N standard H2SO4 using
were calculated in a Geographic Information System (GIS) phenolphthalein and methyl orange indicator solutions,
environment by subtracting depth to water measurements respectively. The ultrapure water (obtained from the ELGA
from the topographic elevations obtained from the digital Purelab UHQ system; Veolia Water Solutions, UK) used in
elevationmodel(DEMwithagridsizeof10m).Groundwater the analytical processes had a resistivity of 18.2MΩcm at
level maps were created by employing the ordinary kriging roomtemperature.Theaccuracyoftheanalyticalresultswas
Geofluids 7
estimated by calculating the percent charge balance errors
(%CBE),asdescribedbyFreezeandCherry[67].Calculated
%CBEaverage−0.55forthedryseasondatasetand−0.30for
Fractured serpentinite
thewetseasondataset,withstandarddeviationsof0.86and
0.40,respectively.Nosamplesinthedatabasehavea%CBE Chrysotile
greaterthan±2.31.
3.4.StatisticalAnalysisandDataProcessing. Thewaterchem-
Dolomite
istrydataweresubjectedtobasicandmultivariatestatistical
analyses utilizing the open source statistical software R ver.
3.1.2 [68]. The basic statistical analyses include descriptive
statistics(minimum,maximum,mean,median,andstandard
deviation),Pearsonproduct-momentcorrelationcoefficient
(𝑟), and Kolmogorov–Smirnov (K–S) test. K–S test [69, 70]
was used to assess normality of data variables. R-mode Figure5:Fieldimageofalargefracturesystem(crosscuttingthe
factor analysis (R-mFA) was employed for the multivariate highlyfracturedserpentiniterockinKızılcadag˘ophioliticme´lange)
statistical analysis of the water chemistry data. R-mFA can filled/sealed with chrysotile (i.e., fibrous asbestos) and secondary
help in extraction of hidden information on the factors dolomite.Hammerforscaleis33cmlong.
controllinggroundwaterchemistry,byonlyretainingthekey
components of the dataset. As a data reduction technique,
R-mFA reduces a large number of variables to a minimum Livermore National Laboratory thermodynamic database,
number of uncorrelated (i.e., orthogonal) new variables thatis,LLNL.dat[79].
calledfactorsbylinearlycombiningmeasurementsmadeon
theoriginalvariables[71].Onlynormalizedandstandardized 4.ResultsandDiscussion
variables were utilized in the R-mFA as suggested by Gu¨ler
et al. [72]. In R-mFA, rotation of factors was carried out 4.1.Rock/SoilMineralogyandGeochemistry. Themineralog-
usingthe“varimaxraw”method,whereKaisercriterion[73] icalandchemicalcompositionofrocksandsoilsfoundinthe
was utilized to determine the number of factors. Detailed study area may imprint a unique character to the regional
technicaldescriptionofR-mFAtechniqueandbestpractices groundwater and will be used to constrain the selection of
canbefoundelsewhere[71,74–77]. mineral phases that will be utilized in WRI modeling [80].
The GIS spatial database used in this study was created Results from XRD analyses (Table1) were compared with
using (i) 1:25,000-scale geological maps published by Alan the results from WDXRF analyses (Table2) to provide a
etal.[36];(ii)1:25,000-scaletopographicmapsheet(Adana reliable characterization of the mineral phases in the rock
M34c3)publishedbyTurkishMinistryofNationalDefense; andsoilsamples.XRDanalysisofserpentiniterocksmaking
(iii) high-resolution (2.44m) QuickBird satellite imagery up the Kızılcadag˘ ophiolitic me´lange (i.e., samples R1, R2,
acquired in 2012; and (iv) geographic coordinate measure- and R3) revealed that lizardite is the dominant mineral
mentsmadeduringon-sitesurveysusingaMagellanTriton phase with trace amounts of antigorite, olivine, chromite,
2000 GPS unit. The spatial data layers were georeferenced calcite, and phlogopite (Table1), whereas XRD analysis of
within GIS environment using the WGS84 datum (UTM exoticblocks(i.e.,samplesR7,R8,andR9)dispersedinthe
Zone36N),thenintegrated,manipulated,analyzed,andvisu- ophioliticme´langeshowsthepresenceoffourpredominant
alizedusingArcGIS9.3.1softwareanditsextensions,namely, mineralphases,suchaslizardite,quartz,calcite,anddolomite
3DAnalyst,GeostatisticalAnalyst,andSpatialAnalyst[64]. (Table1). These exotic blocks (i.e., limestone, siltstone, and
sandstone)arealsoassociatedwithminorandtraceamounts
3.5.GeochemicalModeling. ThegeochemicalcodePHREEQC of secondary mineral phases, such as hematite, ankerite,
Interactive ver. 3.1.4 [78] was used for determination of magnesite,dickite,andvermiculite(Table1).Asreflectedin
aqueous speciation and saturation indices, as well as for XRD results, carbonate rocks of the Early-Middle Miocene
performing inverse modeling calculations related to repre- Kaplankaya and Karaisalı formations (samples R4 and R5,
sentativeend-memberwatertypes.Thesaturationindex(SI) resp.)arecomposedalmostentirelyofcalcite,whereasthose
ofamineralphaseisdefinedusing of Late Triassic-Early Jurassic Etekli formation (sample R6)
𝐼𝐴𝑃 arecomposedpredominantlyofcalcite,withtraceamounts
SI=log( ), (1) of dolomite. Chrysotile (i.e., fibrous asbestos) is the most
𝐾
𝑇 common mineral phase found in veins and shear zones
where 𝐼𝐴𝑃 is the ion activity product for a given mineral crosscutting the serpentinite rocks (Figure5), along with
phase and 𝐾𝑇 is the equilibrium constant of its solubility dolomiteandtraceamountsofclinochlore(i.e.,sampleR10).
productattemperature𝑇.TheSIparameterdescribesthree In the study area, dolomite mostly occurs as white to pink
saturation states. These are (i) undersaturated (SI < 0), (ii) veinswhichshowfracture-sealtexture(Figure5).Notethat
in equilibrium (SI = 0), and (iii) supersaturated (SI > 0) sampling of chrysotile veins was intentionally avoided due
states. All geochemical calculationsand water-rock interac- tohazardousnatureofthismineral;therefore,chrysotilewas
tion (WRI) modeling were performed using the Lawrence notdetectedintheXRDanalysis.
8 Geofluids
Table1:Mineralogicalcompositionoftheselectedrock(R1–R10)andsoil(S1–S8)samplesfromtheKızılgedikareaasdeterminedbyX-ray
a
diffraction(XRD)analysis .
b c
Samplenumber Lithology Source Lz Atg Ol Qz Chr Cal Dol Ank Mgs Hem Dck Kln Vrm Clc Di Phl
R1 Kkm Serpentinite +++ + + +
R2 Kkm Serpentinite +++ +
R3 Kkm Serpentinite +++ +
R4 Tkp Limestone +++
R5 Tka Limestone +++
R6 TRJe Limestone +++ +
R7 Kkm Exoticblock +++
R8 Kkm Exoticblock ++ ++ +++ + + +
R9 Kkm Exoticblock +++ +++ ++ +
R10 Kkm Fracturefill +++ +
S1 Kkm Serpentinite ++ + ++ ++ + + + +
S2 Kkm Serpentinite +++ + ++
S3 Kkm Serpentinite +++ +++ +
S4 Kkm Serpentinite +++ +
S5 Kkm Serpentinite +++ ++
S6 Kkm Serpentinite ++ +++ ++ ++ + + +
S7 Kkm Serpentinite +++ + +
S8 Kkm Exoticblock + ++ +++
a
AbbreviationsfornamesofmineralphasesarefromWhitneyandEvans[85].Lz=lizardite,Atg=antigorite,Ol=olivine,Qz=quartz,Chr=chromite,Cal=
calcite,Dol=dolomite,Ank=ankerite,Mgs=magnesite,Hem=hematite,Dck=dickite,Kln=kaolinite,Vrm=vermiculite,Clc=clinochlore,Di=diopside,
andPhl=phlogopite.Plusesindicaterelativeabundanceofmineralphases(+++=major,++=minor,and+=trace)asjudgedfromXRDpeakintensities.
b c
Lithologyreferstotheprincipalgeologicalformationexposedatthesurfaceinthesamplingsite(seeFigure3forgeologicalformationdescriptions). Source
referstotheprincipalrocktypeorparentmaterialoccurringinthesamplingsite.
The soils found in the area are generally shallow in (2487–3857ppm) (Table2), which is typical of ultramafic
depth (ca. 0–30cm) and discontinuous and mostly direct rocksfoundinthearea(see[84]),whereasWDXRFanalysis
weatheringproductoftheserpentiniteandcarbonaterocks resultsofexoticblocks(i.e.,samplesR7,R8,andR9)dispersed
underneath. The mineralogy of serpentinitic soils (samples intheophioliticme´langearecharacterizedbyhighlyvariable
S1–S7),identifiedbyXRD,wasdominatedbymineralphases amountsofoxides(Table2),astheyarecomposedofdifferent
such as lizardite and antigorite (Table1). In some sam- lithologicunits(i.e.,limestone,siltstone,andsandstone).
ples, in addition to these mineral phases, secondary phases ThesamplesR4,R5,R6,andR7(alllimestoneformations)
such as quartz, hematite, magnesite, kaolinite, vermiculite, composedalmostentirelyofcalcite(Table1)arefoundtobe
clinochlore,anddiopsidewerepresent(Table1).Thepresence lowinSiO2,Al2O3,Fe2O3,MnO,MgO,K2O,P2O5,andSO3
of vermiculite and lack of smectites in the upper parts of and high in CaO (59.39–70.86wt.%) (Table2). The sample
the soil profiles indicate that soils are well drained and takenfromafracturefillmaterial(R10),determinedbyXRD
have been formed under temperate climate conditions [81]. tohavedolomiteasthemajormineralphase(Table1),ischar-
Additionally,presenceofexpansiveclays,suchasvermiculite, acterized by high CaO (34.97wt.%) and MgO (15.99wt.%)
in the soil matrix implies high level of cation exchange concentrations (Table2). As reflected by WDXRF analysis,
capacity[82,83]ofserpentiniticsoils.Ontheotherhand,a serpentine soils (samples S1–S7) show very similar major
soilsample(i.e.,S8)takenfromanareaoverlyinganexotic oxide compositions, which depleted in CaO, K2O, MnO,
blockfoundwithintheKızılcadag˘ophioliticme´langeshows TiO2, Na2O, P2O5, and SO3, and contain high levels of
the presence of dolomite as the main phase, with lesser SiO2,MgO,Fe2O3,andAl2O3 andareenrichedintraceele-
amountsofcalciteandquartz. mentssuchasCr(1647–11603ppm)andNi(2615–6493ppm)
The rock and soil samples were also analyzed by (Table2).ThedistinctdifferencesinCrandNiconcentrations
WDXRF technique to reveal their chemical composition betweensoilscanbetakenasanindicationofdifferencesin
(Table2). Chemical analysis results of serpentinite rocks degree of weathering and/or mineralogical compositions of
making up the Kızılcadag˘ ophiolitic me´lange (i.e., samples the parent rocks [83, 86]. Cr most commonly occurs as an
R1, R2, and R3) show that SiO2 (35.80–38.52wt.%) and accessory mineral (e.g., chromite) in serpentinites, whereas
MgO(33.03–37.73wt.%)arethemostabundantoxides,along Ni primarily exists as impurity on the crystal structure of
withFe2O3 (9.68–11.03wt.%).Inthesesamples,oxidessuch mineralphasesinserpentine[87,88].Ontheotherhand,S8
as CaO, MnO, Al2O3, TiO2, and K2O show relatively low sample,determinedbyXRDtocontaindolomite,calcite,and
but highly variable concentrations. Serpentinite rocks also quartz (Table1), shows high concentrations of CaO, MgO,
containhigh concentrationsofCr (1864–2982ppm) and Ni andSiO2(Table2),confirmingthepresenceofthesemineral
Geofluids 9
XRF)analysis. nts(ppm)NiSr2487983857bdl3640bdl164701bdl1192bdl207bdl24011714914132bdl3211173385bdl2615784410bdl3716bdl6493bdl4672bdl4671bdl761147 parentmaterial
D me or
nce(W aceeleCr298218642618514bdlbdlbdl8528700bdl11603553816472217322095392308bdl cktype
X-rayfluoresce TrTotalCo99.14bdl99.18bdl99.07bdl99.84bdl99.87bdl99.99bdl99.96bdl99.67bdl98.2028999.29bdl97.83bdl98.78bdl99.1031399.09bdl98.6734398.0036898.9326699.64bdl theprincipalro
o
persive cLOI13.5312.6712.4530.3830.9239.9528.2135.499.1841.298.348.3413.1312.9112.8510.0611.9440.62 referst
s e
ngthdi SO30.710.060.230.080.060.020.030.060.06bdl0.100.080.150.070.160.120.100.07bSourc
ele ns).
erminedbywav KOPO2250.020.02bdlbdlbdlbdl0.060.040.040.05bdlbdlbdl0.01bdlbdl0.03bdlbdlbdl0.140.050.460.030.110.020.04bdl0.060.020.090.030.050.020.360.11 mationdescriptio
asdet NaO2bdlbdlbdlbdlbdlbdlbdlbdlbdlbdlbdl0.10bdlbdlbdlbdlbdlbdl calfor
edikarea s(wt.%)CaO4.100.130.3462.3166.3959.3970.8630.060.4434.973.664.420.340.480.750.680.4429.04 orgeologi
g e f
heKızıl oroxidMgO33.0337.7335.902.070.820.510.5118.8428.0615.9924.3815.7728.5035.2729.3723.2030.648.37 Figure3
sfromt MajMnO0.190.080.170.09bdlbdlbdl0.200.090.410.210.250.240.160.240.260.210.13 site(seeonlimit.
dsoil(S1–S8)sample AlOFeO23231.949.680.1310.040.4311.030.381.710.190.340.010.040.050.100.033.181.1314.710.521.434.3415.227.4116.591.3014.681.309.930.8917.692.6619.071.0312.504.736.00 urfaceinthesampling%);bdl=belowdetecti
R10)an TiO20.12bdlbdlbdlbdlbdlbdlbdlbdlbdl0.140.230.06bdl0.040.10bdl0.29 atthesdinwt.
ock(R1– SiO235.8038.3438.522.721.060.070.1911.8144.504.6841.2545.1040.5738.9336.6041.7342.009.92 nexposedn(reporte
r oo
oftheselected bSource SerpentineSerpentineSerpentineLimestoneLimestoneLimestoneExoticblockExoticblockExoticblockFracturefillSerpentineSerpentineSerpentineSerpentineSerpentineSerpentineSerpentineExoticblock ologicalformati=loss-on-igniti
composition aLithology KkmKkmKkmTkpTkaTRJeKkmKkmKkmKkmKkmKkmKkmKkmKkmKkmKkmKkm heprincipalgecLOIplingsite.
Table2:Chemical Samplenumber R1R2R3R4R5R6R7R8R9R10S1S2S3S4S5S6S7S8aLithologyreferstotoccurringinthesam
10 Geofluids
phases. The concentrations of oxides such as Na2O, K2O, information in Table A.1 (Supplementary Material available
P2O5,andSO3aregenerallyverylow(<0.10wt.%)inalltypes online at https://doi.org/10.1155/2017/3153924). The average
of rock and soil samples (Table2), reflecting the nutrient- electricalconductivity(EC)valuesandtotaldissolvedsolids
poorcharacteroftheserpentiniticterrain.Theresultsfrom (TDS)contentsofshallowgroundwaterare419𝜇Scm−1 and
XRDandWDXRFanalysessuggestthatoccurrenceofmin- 288.2mgL−1 in dry season, whereas the average values of
eralphasesandelevatedconcentrationsofsomeelementsin these parameters decline over 10% and 28% in wet season,
thesoilsofthestudyareaismostlyduetogeogenicsources respectively (Table3). Dissolved oxygen (DO) and redox
andrepresentativeofthegeologicalformationsoccurringin potential (Eh) measurements indicate predominantly oxi-
thearea. dizing conditions during both dry and wet seasons, with a
tendencytowardsslightlyreducingconditionsindryseason
4.2. Groundwater Levels and Flow Directions. Water level (Table3). The pH values vary from 7.9 to 9.4 in dry season
mapsfordryseasonandwetseasonarepresentedinFigures and from 7.4 to 9.3 in wet season (Table3), indicating the
4(a) and 4(b), where average depths to groundwater were slightly to very alkaline nature of the groundwater. The pH
4.83 and 2.79m below ground surface (bgs), respectively. values display somewhat lower values in wet season due to
Thedecreaseinaveragedepthtowater(2.04mbgs)between supply of low pH recharge water from rain and snowmelt
dry season and wet season can be attributed to increased (e.g., mean snow pH = 5.78). Groundwater temperature of
recharge through precipitation, as well as snowmelt, and shallow HDWs vary slightly (depending on the depth to
insignificant amount of groundwater extraction during the water)andrangefrom12.6to20.2∘Cindryseasonandfrom
off-season(SeptembertoMay).Eventhoughthegroundwa- 11.0to16.6∘Cinwetseason(Table3).
ter levels in individual HDWs show significant fluctuations In the ophiolitic complex aquifer, a significant seasonal
(from 0.74 to 5.31m) between dry season and wet season, variation in groundwater trace element and major ion
no discernible spatiotemporal variations were observed on chemistry is evident from the summary statistics (Table3).
groundwater flow directions and gradients (Figures 4(a) Generally speaking, the concentration values were higher
and4(b)).Equipotentialmapsconstructedfortheophiolitic in the dry season than in the wet season (except for Ca2+,
complex aquifer indicate the direction of the groundwater − 3−
Cl ,PO4 ,Br,andCr),indicatingrelativelyrapidrecharge
movementtobemainlyfromNtoNE/SEnearwellK2and
from precipitation events. At this site, trace elements could
fromSWtoNEnearwellK6(Figures4(a)and4(b)),bothof be divided into low (<1.0𝜇gL−1; Co, Mo, Cu, V, and As),
whicharelocatednearthelocalrechargeareas.Thehydraulic moderate (1.0–10𝜇gL−1; Ba, Cr, Li, Ni, and Mn), and high
gradients calculated from equipotential maps vary between (>10𝜇gL−1; Zn, Al, B, Sr, Ti, Br, and Fe) concentration
0.047–0.235m/m for dry season and 0.043–0.223m/m for
rangesaccordingtotheiraverageabundancesintheshallow
the wet season, showing no significant seasonal gradient
groundwater,consideringthe entiredataset (e.g., combined
changes in the study area. Steep hydraulic gradients are
dryandwetseasonsamples).Therelativeabundanceoftrace
restrictedtotheSWmountainouspart(nearwellK6),where
elements was ranked (considering median concentrations)
highlyfracturedKızılcadag˘ophioliticme´langeisoverlainby
relativelythin(∼3m)andlowhydraulicconductivityaquitard in the order B > Fe > Ti > Br > Sr > Zn > Al > Li >
Ba > Ni > Mn > Cr > As > Mo > V > Cu > Co for dry
(i.e., Kaplankaya formation) composed of shallow marine
season samples, whereas they ranked in the order Br > Sr
marl,claystone,sandstone,andsandylimestone(Figures4(a)
> Ti > B > Al > Zn > Fe > Ni > Cr > Li > Ba > As > V
and4(b)).Aninterestingfeatureintheareaisthedepression
> Cu > Mn > Co > Mo for wet season samples (Table3).
coneformedaroundwellK14,wheremostoftheupgradient
The concentrations of major cations and anions found in
flow appears to be directed towards the depression (during
dryseasonandwetseasongroundwatersamples(alongwith
bothdryandwetseasons),eventhoughnoheavypumping
mean snow composition) are plotted on the Piper diagram
ofgroundwatereveroccurredinornearthiswell.Thedepth
[90] in order to determine main water types and depict
towaterinwellK14wasrecordedas5.22and3.49mbgsin
the hydrogeochemical evolution path (Figure6). From this
dryseasonandwetseason,respectively.WellK14islocated
near (∼60m) a major fault zone juxtaposing Kızılcadag˘ figure, 2it+is ev2+ident that the−dominant ions in all samples
ophiolitic me´lange and carbonate rocks of Etekli formation are Mg , Ca , and HCO3 , which is typical of ophiolitic
and carbonate terrains [91, 92]. Nevertheless, many of the
(Figures 4(a) and 4(b)), where open fractures and karstic
+ − −2
featuresdevelopedwithintheseunitsmighthavecollectively groundwatersamplescontainedverylowNa ,Cl ,andSO4
concentrations,bothindryandwetseasons(seeTableA.1)
providedhighlyconductivepathwaysforsubsurfaceoutflow
(SupplementaryMaterial).
underneath the adjacent dry valley. Interestingly, the same
BasedonPiperdiagram,threehydrochemicalfacieshave
faultzoneactsasaflowbarrieratSWpartofthestudyarea,
as evidenced by groundwater flow direction that is aligned been identified, including Mg–HCO3, Mg–Ca–HCO3, and
parallel to the fault zone, displaying a combined conduit- Ca–Mg–HCO3 (Figure6). About 72% and 40% of ground-
barrierbehavior(e.g.,see[89]). watersamplesfromdryseasonandwetseason,respectively,
belong to Mg–HCO3 type. The rest of the groundwater
4.3.HydrochemicalCharacteristicsoftheWaterSamples. The samplesweremostlyclassifiedasMg–Ca–HCO3type,except
summary statistics of the seasonal physicochemical com- for two wet season samples (e.g., K7 and K16), which were
position of groundwater and snow samples are presented classified as Ca–Mg–HCO3 type. The linear scattering of
in Table3 and complete dataset is provided as supporting the wet season water samples along the Ca-Mg axis in the