Journal of Geochemical Exploration 112 (2012) 93–106

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Journal of Geochemical Exploration

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Variation of mineralizing fluids and fractionation of REE during the emplacement ofthe vein-type fluorite deposit at Bozijan, Markazi Province, Iran

Farhad Ehya ⁎Department of Geology, Behbahan Branch, Islamic Azad University, Behbahan, Iran

⁎ Tel.: +98 671 4220105x8; fax: +98 671 4220109.E-mail address: ehya@behbahaniau.ac.ir.

0375-6742/$ – see front matter © 2011 Elsevier B.V. Alldoi:10.1016/j.gexplo.2011.08.005

a b s t r a c t

a r t i c l e i n f o

Article history:Received 17 December 2010Accepted 12 August 2011Available online 23 August 2011

Keywords:Fluid inclusionGeochemistryREEFluoritePrecious metalsIran

Fluorite vein mineralization occurs mainly in slates and phyllites of Lower Jurassic Shemshak Formation andscarcely in Triassic limestones in Bozijan, which is situated at the west of Mahallat city in the Markazi Prov-ince of Iran. The ore consists mainly of fluorite, quartz, calcite, and iron oxides. The subordinate componentsare galena, pyrite, manganese oxides, and malachite. Local wall-rock alterations include argilization and silic-ification. The nature of the mineralization and ore–host rock relationships indicate an epigenetic mode of for-mation for fluorite mineralization.Fluid inclusions in early fluorites and quartz consist of aqueous and aqueous-carbonic inclusions, therebyshowing that during deposition of bulk fluorites, two immiscible fluids are involved: aqueous and carbonic.The aqueous fluid is a mixture of two low- and high-salinity (b15 and N26.24 wt.% NaCl equivalent) H2O–NaCl–(CaCl2–KCl–MgCl2) brines, as is evidenced by Th-salinity plots. The aqueous inclusions are homoge-nized at temperatures between 152.5 and 312 °C. The aqueous-carbonic inclusions exhibit salinity and ho-mogenization temperature in ranges between 22.04 and 24.26 wt.% NaCl equivalent and between 253 and390.5 °C, respectively. Fluid inclusions in late fluorites show the fluorites were precipitated from a colder(102.4–175 °C) and less saline (15.96–24.45 wt.% NaCl equivalent) fluid than the early fluorites.Rare earth element (REE) analysis in fluorites revealed extremely low values in ranges between 2.87 and34.39 ppm for early fluorites and between 1.91 and 6.4 ppm for late fluorites, thus indicating that fluoriteshad been derived from a sedimentary environment. However, Tb/Ca and Y/Ho ratios invariably suggest a hy-drothermal origin for Bozijan fluorites. The Ce/Yb ratios and chondrite-normalized patterns revealed that thefluorites (early as well as late ones) are enriched in LREE (light rare earth element) relative to HREE (heavyrare earth element). This indicates that REE leaching from source rocks and fluid migration occurred underhigh-temperature and low-pH conditions. The enigmatic LREE-enriched late fluorites suggest that depositionof fluorites in Bozijan did not occur during a long-lived episode of mineralization. Europium represents pos-itive as well as negative anomalies that have been probably caused by fluorite precipitation from mixing twofluids possessing opposite Eu anomalies. The Ce/Ce* ratios portray persistent negative Ce anomalies, thus in-dicating reducing conditions in the hydrothermal fluids. In the (La/Yb)n–Eu/Eu* diagram, data points do notoverlap with the fields represented by fluorite-bearing Au–Ag deposits from elsewhere, thus indicating a verylow potential for precious-metal mineralization in the studied area. This interpretation is well in line with thelow contents of precious metals in the Bozijan deposit, thus suggesting that REE geochemistry is a reliabletool for exploring precious metals in fluorite deposits.The Bozijan deposit is classified here as an “unconformity-related fluorite deposit.” According to a conceptualmodel, mineralization occurred when the ascending hypersaline brines mixed with the less saline connatefluids in sediments of Triassic and predominantly Jurassic ages. The less saline connate brines were assumedto be the fluoride-bearing solutions, as suggested by the high F contents of the rocks containing them and REEpatterns.

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1. Introduction

Fluorite was first produced in Iran as a byproduct of lead mining in1960, and the first fluorite mine was started in 1968 (USGS, 2001).More than thirty fluorite deposits and prospects are currentlyknown in Iran; however, the majority of these deposits are small-sized. So, the total sum of the proved Iranian fluorite reserves is

94 F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

only 1.358 Mt, which comprises about 0.6% of the world's fluorite re-serves (Ghorbani, 2007). The largest fluorite deposit of Iran is atKamar Mehdi (0.124 Mt), which is located 165 km southwest ofTabas in the Southern Khorasan Province. The Iranian fluorite de-posits are viewed as being dominantly hydrothermal in origin(Qishlaqi and Moore, 2006).

The Bozijan, also known as Chekap, fluorite deposit is located37 km west of Mahallat city, close to the Bozijan village in theMarkazi Province of western Iran. The area around Mahallat citycomprises a fluorspar district, including Bozijan, Bagher Abad, DarrehBadam, and Atash Kuh deposits (Fig. 1). These deposits are apparentlysimilar in terms of their host rocks, mode of mineralization, and,somewhat, mineral paragenesis. Mineralization invariably occurs asveins in Lower Jurassic shales, slates, and phyllites and, in somecases, in limestones of the Triassic age. The above-mentioneddeposits, except for Atash Kuh, are currently being mined in openpits dug along veins.

Despite widespread fluorite deposits in Iran, only a few studies ontheir geology, geochemistry, and aspects of formation have been pub-lished (Moore et al., 1998; Qishlaqi and Moore, 2006; Rajabzadeh,2007). However, the detailed geology and genesis of fluorite depositslocated in the Mahallat district have not yet been studied. Moreover,the facts that fluorite deposits are hosted by sedimentary or slightlymetamorphosed sedimentary rocks and that mineralization is veinshaped provide an opportunity in Mahallat district to shed furtherknowledge on literature regarding the formation of vein-type fluoritedeposits in sedimentary settings, even though this type of fluoritedeposit is not uncommon worldwide (e.g., Dill et al., 2008; Dill,

Fig. 1. Simplified map showing the location of

2010). These fluorite deposits are commonly associated with hydro-thermal systems in which mineralizing fluids vented along fractureand fault zones that intersected hydraulic planes such as faults andunconformities. Debate is concerned, however, with the sources ofore-forming fluids and materials.

Geochemistry of rare earth elements (REEs) has been widely usedby numerous researchers to understand the geologic conditionsunder which fluorite is deposited (e.g., Castorina et al., 2008; Salletet al., 2005; Sánchez et al., 2010; Sasmaz et al., 2005a; Xiang et al.,2010). Moreover, many researchers (Constantopoulos, 1988; Heinet al., 1990; ƠConnor et al., 1993; Palmer and Williams-Jones,1996; Sasmaz and Yavuz, 2007; Strong et al., 1984; Williams-Joneset al., 2000) combined geochemical data with fluid inclusion studiesto unravel fluorite genesis. On the other hand, some workers appliedthe geochemistry of REE as an exploration tool to differentiate be-tween precious-metal-bearing fluorite deposits and barren de-posits (Constantopoulos, 1988; Eppinger and Closs, 1990; Hillet al., 2000; Sasmaz et al., 2005b). The aim of the currentstudy is to present the geological setting, petrographic andfluid inclusion findings, and geochemistry of REEs to constraina genetic model for the Bozijan fluorite deposit. The geochemistry ofREEs is also used to evaluate the potential of precious-metalmineraliza-tion in the Bozijan deposit and to reexamine this exploratory tool.

2. Geological setting

The Bozijan fluorite deposit is located at the southwestern edge ofthe Central Iran Zone in close vicinity to the border of the Sanandaj–

fluorite deposits in the Mahallat district.

95F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

Sirjan Zone. The studied area (Fig. 2) is constituted by rocks fromPrecambrian to Recent ages. Precambrian dolostones and Cambrianshales and sandstones are unconformably overlaid by Permian lime-stones and dolostones. This extensive stratigraphic gap is attributedto Caledonian epeirogenic events (Sheikholeslami, 2005). Post-Caledonian tectonic events began with an extension that led to theprogradation of the Permian sea, in which deposition took place con-tinuously until entire Triassic. Deposition of limestones and dolos-tones dominated this period. Some volcanic rocks (diabase)interbedded within dolostones and dolomitic limestones belonging

Fig. 2. Simplified geologic map of the Bozijan a

to the lower part of the Permian sediments were reported in a fewplaces out of the studied area (Sheikholeslami, 2005). The secondextensional event occurred during the Lower Jurassic, which causedTriassic sediments to be unconformably covered by Jurassic strata.Detrital sediments and carbonates constituted the major sedimentaryproducts of this event. The Jurassic sediments were subsequently de-formed during the Late Cimmerian deformational event (see below).

The Bozijan fluorite mineralization is dominantly hosted by LowerJurassic Shemshak Formation (Fig. 2), which covers vast areas to thewest and north of the studied area. Mineralization occurs mainly

rea (modified after Sheikholeslami, 2005).

96 F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

near the unconformable contact of Shemshak Formation with under-lying Triassic limestones; as seen in veins 1 and 3 (see Section 4.1)(Fig. 2), it extends for a few meters into the Triassic limestones.These rocks are composed of gray, brown, and yellow thin-beddedto massive fossiliferous limestone, dolomitic limestone, and dolostone.The thickness of Triassic strata ranges from 40 to 80 m (Sheikholeslami,2005). The Shemshak Formation is composed of silty shales with inter-calations of calcareous sandstones andmedium- to thick-bedded sandylimestones. The overall thickness of the Shemshak Formation is estimat-ed to be between 1500 and 2000 m (Sheikholeslami, 2005). In theminearea, this rock unit has experienced a slight regional metamorphism, sothat slate and phyllite having a perfect horizontal schistosity compriseits bulk lithology. This weak metamorphism is considered evidencefor the Late Cimmerian tectonic event, which influenced the region(Sheikholeslami, 2005).

The presence of numerous, commonly strike-slip faults displacingPermian and Triassic limestones, especially near the fluorite mineral-ization, is the most important structural feature in the studied area(Fig. 2). Minor faults with little displacement are also seen in thewall rocks of the ore bodies. Although the mineralized zones are notcontrolled or confined by the faults, the fact that fluorite veins followa trend similar to major faults present around them can be inter-preted as being suggestive of a genetic relationship between faultingand mineralization. The faults could provide channel ways for miner-alizing fluids to reach the site of ore deposition. The presence of local,brecciated wall rocks close to the veins supports the view that theveins are probably mineralized parts of pre-existing faults.

The Bozijan area is devoid of any magmatic activity. The nearestmagmatic activities to the fluorite mineralization are intrusions of al-kali gabbros that are located about 20 km southwest of the studiedarea in the Sanandaj–Sirjan Zone. These intrusive bodies are of post-Cretaceous, probably Paleocene, age (Sheikholeslami, 2005).

3. Samples and methods

In this study, thirty-five mineral and rock samples were collectedfrom all fluorite veins and host rocks cropping out in the mine pits,as well as thirteen mineral and rock samples were collected frommine dumps near each vein. In all cases, care was taken to select rep-resentative samples of fluorite mineralization and host rocks. Toavoid possible hydrothermal alteration, the host rock samples weretaken away from the veins where no evidence indicating wall-rock al-teration could be found. Routine mineral-optical examinations wereperformed on thin sections from seventeen ore samples using a pet-rographic microscope.

Eight fluorite and three quartz samples were subjected to fluid in-clusion studies. The paragenetic situations of the samples are given inTable 1. Since fluorites with massive and drusy aggregates have beenthe most frequent fluorites from early and late generations, respec-tively (see Section 4.1), only massive- and drusy-aggregated fluoriteswere selected for the purposes of this study. For the same reason, onlymassive-aggregated quartz samples were chosen. Fluid inclusionstudies were conducted on doubly polished wafers (~250 μm thick)using a Zeiss microscope equipped with a Linkam THMS-600

Table 1Summary of microthermometric data of fluid inclusions.

Hosted mineral Inclusion type Tm, carb Tm, clath Th, carb Te

(°C) (°C) (°C) (°C)

Early fluorite Aqueous (type II) −60/Late fluorite Aqueous (type II) −60/Q2 quartz Aqueous (type II) −60/Early fluorite Aqueous-carbonic −58.8/−57.5 −10/−7 28.1/30.9Early fluorite Aqueous (type III)

Tm, carb: first CO2 melting; Tm, clath: last clathrate melting; Th, carb: CO2 homogenization; Te: firsto liquid; Ts, NaCl: halite dissolution; N: number of measurements.

heating–freezing stage at the Iranian Mineral Processing ResearchCenter. The apparatus was calibrated using standard compounds (so-dium nitrate, cesium nitrate, and n-hexane), and its precision is±0.2 °C for freezing and ±0.6 °C for heating measurements. Freezingmeasurements were carried out on fluid inclusions until their com-plete freezing approached and phase transitions measured immedi-ately after heating. The salinity data of aqueous inclusions werecalculated from ice melting temperatures (Tm, ice) using the equationof Bodnar (1993), whereas those of halite-bearing inclusions werecalculated from the dissolution temperature (Ts, NaCl) using the equa-tion of Sterner et al. (1988). The salinities of aqueous-carbonic inclu-sions were calculated from clathrate melting temperatures (Tm, clath)using the method of Darling (1991). Densities of the CO2 phasewere calculated with the FlinCor program (Brown, 1989) using theequation of Brown and Lamb (1989). Isochores were constructedwith the help of the ISOC program, available in the FLUIDS package(Bakker, 2003). The equations of state of Knight and Bodnar (1989)and Bodnar and Vityk (1994) for aqueous inclusions, and those ofBowers and Helgesson (1983) and Bakker (1999) for aqueous-carbonic inclusions, were used.

Sixteen samples of early massive and late drusy fluorites with dif-ferent colors (see below) were subjected to chemical analysis. First,the samples were crushed, and then the fluorites were separated byhand picking under a binocular microscope. To have an estimate ofF and trace element contents of country rocks, four samples fromhost rocks (two samples of Shemshak Formation and two of Triassiclimestones) were also subjected to chemical analysis. Analyses formajor oxides were done using ICP-AES, for trace elements and rareearth elements using ICP-MS, and for F using Specific Ion Electrodeby commercial Acme Analytical Laboratories in Canada.

4. Results

4.1. Mineralogy of the fluorite mineralization

Fluorite mineralization occurs as east–west trending veins thatcrop out in three separate areas (Fig. 2). These three veins are re-ferred to as veins 1–3 in this study. The largest vein (vein 3) has alength of 500 m. The widths of the veins are very variable and rangefrom 1 to 4 m. The veins are either vertical or dipping up to 70° tothe north, and they intersect the host rock schistosity (Fig. 3a). Inplaces where fluorite veins occur in limestones, mineralizationtends to replace the host rocks. The points of contact between veinsand host rocks are sharp. The mineralogy of the deposits comprisesfluorite, quartz, calcite, iron oxides, minor galena, pyrite, manganeseoxides, and malachite. The paragenetic sequence is shown in Fig. 4.

Mineralization was preceded by local silicification (quartz Q1) andargilization of the host rocks. Fluorite precipitation was obviously themost important event in the sequence of mineral formation, occur-ring in two stages. Early fluorite (Fl 1) is commonly massive, sugargrained, scarcely colloform, and is either white or colorless (Fig. 3b).Sugar-grained fluorite is commonly brittle and is easily powderedunder hand force. Late fluorite (Fl 2) occurs dominantly as drusyand less frequently as open-space fillings and free-grown cubic

Tm, ice Th, total Th Ts, NaCl Salinity N

(°C) (°C) (°C) (°C) (wt.% NaCl eq.)

−49 −23.4/−9.5 166/295 13.40/24.58 34−49 −23.2/−12 102.4/175 15.96/24.45 17−49 −21.2/−10.5 152.5/220 14.46/23.18 23

272/390.5 22.04/24.26 8265/312 146/174 29.5/30.65 5

t ice melting; Tm, ice: last ice melting; Th, total: total homogenization; Th: homogenization

Fig. 3. (a) Near vertical fluorite vein cutting the schistosity of the host rocks slate and phyllite; (b) fluorite (Fl 1) intergrown with quartz (Q2) and calcite (Cal 1); secondary ironoxides are also seen; (c) colorless cubic fluorite (Fl 2) crystal grown in a vug; (d) photomicrograph showing the intergrowth of fluorite (Fl 1), calcite (Cal 1) and quartz (Q2). Notethe carbonate relics in fluorite and quartz (crossed polars); (e) photomicrograph of microveins consisting of small crystals of quartz (Q3) that cutting the fluorite (Fl 1) (crossedpolars); and (f) photomicrograph of fluorite (Fl 1) crystals surrounded by calcite (Cal 2) veinlets forming a netlike texture (crossed polars).

97F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

crystals with sizes of a fewmillimeters in vugs (Fig. 3c). Drusy fluoriteis mostly pale to deep violet in color. The color of the crystals rangesfrom colorless to pale violet. Quartz from the second generation (Q2)was simultaneously precipitated with early fluorite, as shown by itstight intergrowth (Fig. 3b). Similar to the accompanying fluorite,this quartz is commonly massive and milky to colorless. Small, unco-lored, hexagonal crystals of quartz are rarely found with fluorite crys-tals in cavities, thus suggesting a third generation of quartz (Q3).

Quartz is more common in the veins at upper levels, and its amountdecreases with increasing depth. The distribution of calcite is unevenand occurs commonly locally. In places where calcite is a commonmineral, it is found as light brown veinlets and patches with perfectrhombohedral cleavage. These calcites (Cal 1) are enclosed by mas-sive fluorite and Q2 quartz, indicating that they are coeval (Fig. 3b).Sulfides precipitated during early fluorite formation, as shown bythe presence of pyrite and galena enclosed by massive fluorite. Pyrite

Fig. 4. Simplified paragenetic sequence of the Bozijan deposit.

98 F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

is a rare mineral occurring locally as small cubic crystals. Galena isalso a minor mineral found as veinlets and small patches with perfectcubic cleavage.

Thin sections of representative ore samples were examined undera polarizing microscope. The studied samples are mineralogically andtexturally simple. The most common feature observed is the inter-grown crystals of fluorite (Fl 1), quartz (Q2), and sometimes calcite(Cal 1) (Fig. 3d). Fluorite is commonly observed as large patchesand rarely as small cubic crystals. Quartz occurs as fine- to medium-grained unhedral crystals intergrown always with fluorite. Some fluo-rite and quartz grains contain abundant fine carbonate relics, thus in-dicating the replacement of pre-existing carbonate-bearing rocks byfluorite and quartz (Fig. 3d). Calcite, where present, constitutescoarse-grained unhedral crystals, filling the spaces between fluoriteand quartz grains. Late fluorite (Fl 2) occurs rarely as veinlets inter-secting some quartz crystals from the second generation (Q2). In ad-dition, remobilization and recrystalization of calcite and quartz formveinlets of these minerals (Cal 2 and Q3) crosscutting earlier crystalsas well as extending along grain boundaries (Fig. 3e). In some places,

Fig. 5. Photomicrographs of different types of fluid inclusions hosted in early fluorite: (a) aq(c) aqueous multiphase liquid+daughter salt+vapor (L+S+V) type III; and (d) aqueous

fluorite crystals are surrounded by calcite veinlets, thereby resultingin the formation of a netlike texture (Fig. 3f).

Mineral formation ended with supergene minerals of iron oxides,manganese oxides, and malachite. Iron oxides and hydroxides arecommon (Fig. 3c), especially as small cubic crystals pseudomorphedafter pyrite. Manganese oxides are commonly found in fractures assmall dendrites in fluorite and quartz minerals. Malachite is rarely ob-served as veinlets in low-grade parts close to wall rocks.

4.2. Physical and chemical data of the mineralizing fluids

4.2.1. Petrography of fluid inclusionsStudies on fluid inclusions hosted in early and late fluorites as well

as in quartz (Q2) were conducted. Both primary and secondary fluid in-clusions have been recognized in the studied fluorite (both early andlate) and quartz samples according to the criteria of Roedder (1984).Primary fluid inclusions are found to be isolated and randomly distrib-uted, or rarely parallel to growth zones and crystal planes. In theorder of decreasing abundance, primary fluid inclusions have irregular,spherical, negative crystal, and elongated shapes. Necking down andleakage are relatively common. The studied samples usually containseveral primary inclusions; however, suitable inclusions for microther-mometric measurements (without necking down and leakage) are re-stricted. The size of inclusions ranges from 1 to 40 μm. Measured fluidinclusions in early and late fluorites have a size ranging from 5 to12 μm. The size of measured inclusions in quartz ranges between 5and 10 μm. Larger inclusions are rare and frequently leaked or necked,and, hence, they were not studied.

Primary fluid inclusions in early and late fluorites and quartz canbe grouped into two categories on the basis of their room-temperature appearance combined with heating and freezing behav-iors: aqueous and aqueous-carbonic fluid inclusions.

Three types of aqueous fluid inclusions are recognized in earlyfluorites on the basis of the number of phases present at room tem-perature: monophase liquid (L, type I), biphase liquid+vapor (L+V, type II), and multiphase liquid+daughter salt+vapor (L+S+V,

ueous monophase liquid (L) type I; (b) aqueous biphase liquid+vapor (L+V) type II;-carbonic multiphase liquid+liquid CO2+vapor (L+L CO2+V).

Table 2Trace- and REE concentrations in limestone and slate from Bozijan district.

Rock type Limestone Slate

Sample no. TLE1 TLE2 BSF2 BSF6

F 0.25 0.15 0.37 0.25Y 3.7 2.4 27.5 28.2La 3.9 2.8 41.3 41.4Ce 7.9 4.4 99.4 99.9Pr 0.89 0.51 9.53 9.61Nd 3.5 1.9 34.8 35.5Sm 0.77 0.40 6.72 6.92Eu 0.23 0.16 1.33 1.40Gd 0.84 0.36 5.64 5.91Tb 0.13 0.05 0.96 1.00Dy 0.68 0.25 5.14 5.44Ho 0.12 0.06 1.03 1.11Er 0.29 0.19 3.08 3.13Tm 0.05 0.02 0.47 0.46Yb 0.27 0.15 3.10 3.08Lu 0.04 0.02 0.46 0.46∑REE 19.61 11.27 212.96 215.32Ce/Yb 29.2 29.3 32.0 32.4Ce/Ce* 1.02 0.88 1.20 1.20Eu/Eu* 0.87 1.29 0.66 0.66

F in percent; trace- and rare earth elements in ppm; detection limits (%) are: F (0.01);(ppm) are: Nd (0.3); Y, La, Ce, (0.1); Sm, Gd, Dy, Yb (0.05); Er (0.03); Pr, Eu, Ho (0.02);and Tb, Tm, Lu (0.01). Eu=Eu� ¼ EuN=

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiSmN

�GdNp

and Ce=Ce� ¼ CeN=ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiLaN�PrN

p.

99F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

type III) inclusions (Fig. 5a, b and c). Type II inclusions are consider-ably more common than the other inclusions. The late fluorites(Fl 2) and quartz lack type III fluid inclusions, having only types Iand II inclusions. In quartz samples, type I inclusions are very rarecompared with type II ones. According to the habit and birefringenceof the solid phases, at least some of the daughter salts were recog-nized as halite. The degree of fill (Vl/Vl+Vv+Vs) ranges from 0.7 to0.9 in biphase and multiphase inclusions.

In sum, in early fluorites (Fl 1) and especially in quartz, theaqueous-carbonic inclusions are less common than the aqueousfluid inclusions. The aqueous-carbonic inclusions comprise threephases at room temperature (liquid water+liquid CO2+vapor CO2)(Fig. 5d). Liquid water is commonly the dominant phase. The CO2

content calculated from volumetric measurements ranges from20.38 to 28.76 wt.% in inclusions from early fluorites and quartz.The late fluorites lack aqueous-carbonic fluid inclusions.

Secondary fluid inclusions in early and late fluorites and quartz arefound in a line-oriented pattern including several fluid inclusions.Secondary inclusions are mostly monophase L and biphase L+V in-clusions with irregular shapes. Since secondary inclusions were in-variably too small (b5 μm) to yield reliable data, they were notstudied.

4.2.2. Microthermometric resultsMicrothermometric measurements were performed on aqueous as

well as aqueous-carbonic inclusions in the minerals hosting inclusions.In the case of aqueous inclusions, type II and a few type III inclusions inearly fluorite and only type II inclusions in late fluorite and Q2 quartzwere measured. A total of 65 fluid inclusions in early and late fluoritesand 24 inclusions in Q2 quartz were measured. Microthermometricresults and the abbreviations used in the text are given in Table 1. Infreezing studies, fluid inclusions were cooled to −100 to −110 °C toensure that they were completely frozen. All inclusions homogenizedto liquid phase during heating measurements.

First ice melting temperatures (Te) in aqueous type II fluid inclu-sions from fluorite generations as well as from quartz range between−60 and −49 °C, thus indicating the presence of multicomponentH2O–NaCl–(CaCl2–KCl–MgCl2) brines in fluid inclusions. Ice was thelast solid phase to melt in these inclusions, except for three inclusionsin early fluorite in which hydrohalite was the last melted solid. TheTm, ice for type II inclusions varies from−23.4 to−9.5 °C in early fluo-rite, from −23.2 to −12 °C in late fluorite, and from −21.2 to−10.5 °C in Q2 quartz. Salinities calculated from the Tm, ice rangefrom 13.40 to 24.58 (mean 21.32) wt.% NaCl equivalent in early fluo-rite, from 15.96 to 24.45 (mean 21.62) wt.% NaCl equivalent in latefluorite, and from 14.46 to 23.18 (mean 19.89) wt.% NaCl equivalentin Q2 quartz. Homogenization temperatures (Th) for type II fluid in-clusions range from 166 to 295 °C (mean 217 °C) in early fluorite,from 102.4 to 175 °C (mean 145 °C) in late fluorite, and from 152.5to 220 °C (mean 191 °C) in Q2 quartz.

In a few type III inclusions hosted in early fluorite, solid-phase(halite) dissolution occurred at a temperature range from 146 to174 °C, corresponding to a salinity range from 29.5 to 30.65 wt.%NaCl equivalent. The solid phase in one inclusion remainedunchanged even at N400 °C, suggesting that it was probably a trappedsolid. Total homogenization of the type III inclusions occurred at atemperature range from 265 to 312 °C.

In aqueous-carbonic inclusions, Th, carb occurs in a narrow rangefrom 28.1 to 30.9 °C in early fluorite and at 30.8 °C in only one mea-sured inclusion in Q2 quartz, thus corresponding to CO2 densities be-tween 0.53 and 0.65 g/cm3 in early fluorite and 0.54 g/cm3 in Q2quartz. The restricted range of Th, carb values indicates that the densityof the CO2-phase did not fluctuate considerably during the en-trapment of the mineralizing fluids. First CO2 melting temperatures(Tm, carb) range from −58.8 to −57.5 °C in early fluorite and Q2quartz. Tm, carb lower than that of pure CO2 (−56.6 °C) indicates

that CH4 is an additional component of the carbonic phase (Burruss,1981). Assuming that CH4 was the phase responsible for the depres-sion of the Tm, carb values, its amounts can be estimated from the rela-tionship between Tm, carb and Th, carb using the data of Thiéry et al.(1994). The results show that aqueous-carbonic inclusions fromearly fluorite and Q2 quartz are less than 0.1 in X CH4. Due to thepresence of low concentrations of CH4, less than 0.1 mol fraction,the effects of CH4 on clathrate melting can be considered unimpor-tant. Tm, clath values range from−10 to−7 °C, corresponding to salin-ities from 22.04 to 24.26 (mean 23.38) wt.% NaCl equivalent in earlyfluorite and 22.80 wt.% NaCl equivalent in Q2 quartz. Th, total occursbetween 272 and 390.5 °C (mean 313.7 °C) in early fluorite and at253 °C in Q2 quartz. Some aqueous-carbonic inclusions in fluoriteand quartz were decrepitated before reaching total homogenizationtemperatures.

4.3. Chemical composition

The results for analyses of selected samples from host rocks arelisted in Table 2. The F values of two slate samples are 0.25 and0.37% and of two limestone samples are 0.15 and 0.25%. Yttrium con-tents represent values from 27.5 to 28.2 ppm in slate and from 2.4 to3.7 in limestone samples. The total REE (∑REE) contents of slatesamples are 212.96 and 215.32 ppm and of limestone samples are11.27 and 19.61 ppm. The Ce/Yb ratios range from 29.2 to 29.3 inslate and from 32.0 to 32.4 in limestone samples, indicating thatthey are enriched in LREE. Both the slate samples exhibit positive Ceanomalies (Ce/Ce*=1.20), whereas the limestone samples exhibitnegative and slightly positive Ce anomalies (Ce/Ce*=0.88–1.02). Inthe case of Eu, slates exhibit negative anomalies (Eu/Eu*=0.66),whereas limestones exhibit negative as well as positive anomalies(Eu/Eu*=0.87–1.29).

The results for analyses of fluorite samples are listed in Table 3.The F concentrations range from 30.07 to 45.37% for early fluoritesand from 22.87 to 46.27% for late fluorites. The Ca concentrationsrange from 35.56 to 48.27% for early fluorites and from 47.12 to49.74% for late fluorites. The deviation from ideal concentrations ofF and Ca in fluorite is obviously due to the presence of other com-pounds that function as impurities within the analyzed samples. Thefact that SiO2 is the major impurity having values that range from

Table 3Major oxide, trace- and REE concentrations in fluorites from Bozijan deposit.

Generation Early Late

Color Colorless White Colorless Pale violet Violet

Sample no. TFE2 BFE2 BFE3 BFE7 BFE9 BFE10 BFE14 BFE18 BFE19 BFE21 TFE1 BFE6 BFE12 BFE5 BFE8 BFE17

Ca 36.74 47.51 48.24 48.10 47.13 45.38 46.82 46.09 47.38 43.88 35.56 49.08 47.12 49.74 47.41 47.81F 31.37 34.47 43.37 45.37 31.47 33.17 45.37 33.37 33.97 43.27 30.07 22.87 33.77 27.17 46.27 43.67SiO2 28.22 7.76 4.76 3.66 5.98 9.68 7.20 6.78 5.98 12.98 29.25 9.00 4.35 2.20 3.93 5.00Y 8.7 2.4 2.1 4.0 4.0 2.7 1.7 1.9 3.3 2.9 10.0 2.3 2.2 2.1 1.6 4.0Au bdl 1.5 bdl bdl bdl bdl bdl 1.0 0.9 1.0 0.7 bdl bdl bdl bdl bdlLa 4.7 3.9 1.0 1.9 1.9 1.3 1.4 0.9 2.8 2.7 6.6 0.6 0.8 0.5 0.8 2.0Ce 10.7 5.7 1.3 2.1 2.3 1.4 1.8 1.1 3.2 2.8 13.4 0.8 1.1 0.6 0.7 2.3Pr 1.42 0.51 0.13 0.26 0.26 0.17 0.17 0.10 0.32 0.31 1.74 0.15 0.12 0.09 0.08 0.23Nd 6.6 1.6 0.4 0.7 0.8 0.9 0.6 0.4 1.0 1.1 7.8 0.4 0.4 0.6 bdl 1.2Sm 0.96 0.18 0.09 0.17 0.15 0.14 0.08 0.09 0.14 0.10 1.28 0.11 0.09 0.08 bdl 0.10Eu 0.38 0.05 0.04 0.06 0.06 0.04 0.05 0.02 0.05 0.04 0.53 0.02 0.03 0.04 bdl 0.04Gd 1.02 0.19 0.17 0.25 0.24 0.18 0.14 0.12 0.15 0.13 1.45 0.07 0.10 0.09 0.15 0.17Tb 0.14 0.02 0.02 0.04 0.03 0.03 0.02 bdl 0.02 0.03 0.19 0.02 0.02 0.02 0.02 0.02Dy 0.66 0.17 0.15 0.23 0.19 0.14 0.07 0.06 0.13 0.14 0.88 0.13 0.14 0.08 0.08 0.12Ho 0.11 0.03 bdl 0.03 0.04 0.03 bdl bdl 0.03 0.03 0.12 0.02 0.03 bdl 0.03 0.04Er 0.18 0.05 0.04 0.11 0.05 0.08 bdl bdl 0.03 0.09 0.23 bdl 0.05 0.03 0.05 0.10Tm 0.01 0.01 bdl 0.01 bdl bdl bdl bdl bdl 0.01 0.02 bdl bdl bdl bdl bdlYb 0.08 bdl 0.07 bdl 0.07 0.07 bdl 0.07 0.09 0.06 0.14 bdl bdl 0.05 bdl 0.08Lu bdl bdl bdl bdl bdl bdl bdl bdl bdl bdl 0.01 bdl bdl bdl bdl bdl∑REE 26.96 12.41 3.41 5.86 6.09 4.48 4.33 2.86 7.96 7.54 34.39 2.32 2.88 2.18 1.91 6.4Y/Ho 79.0 80 – 133.3 100 90 – – 110 96.6 83.3 115 73.3 – 53.3 100Ce/Yb 133.7 – 18.5 – 32.8 20.0 – 15.7 35.5 46.6 95.7 – – 12.0 – 28.7Ce/Ce* 0.99 0.97 0.86 0.71 0.78 0.71 0.88 0.88 0.81 0.73 0.95 0.64 0.85 0.68 0.66 0.81Eu/Eu* 1.18 0.82 0.98 0.88 0.32 0.77 1.44 0.58 1.06 1.06 1.19 0.69 0.95 1.44 – 0.93Yb/La 0.01 – 0.07 – 0.03 0.05 – 0.07 0.03 0.02 0.02 – – 0.10 – 0.04(La/Yb)n 39.73 – 9.75 – 18.54 12.69 – 8.78 21.00 31.07 32.25 – – 7.00 – 16.97(Tb/Yb)n 7.76 – 1.27 – 1.90 1.90 – – 0.97 2.25 6.06 – – 1.82 – 1.10

Ca, F and SiO2 in percent; trace- and rare earth elements in ppm; Au in ppb; bdl: below detection limit; detection limits (%) are: Ca, SiO2 (0.01); and (ppb) is 0.5. Other detectionlimits and calculations of Ce and Eu anomalies are as in Table 2.

Fig. 6. Homogenization temperature versus salinity plot. Fluid inclusions in fluorite andquartz.

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3.66 to 29.25% for early fluorites and from 2.20 to 9.00% for late fluo-rites is evidenced in Table 3. As mentioned in Section 4.1, quartz is anabundant mineral tightly intergrown with fluorite, even on a micro-scopic scale. Yttrium represents values in a narrow range from 1.7to 10 ppm for early fluorites and from 1.6 to 4 ppm for late fluorites.Gold contents fall in a narrow range from 0.7 to 1.5 ppb for early fluo-rites and below the detection limit of 0.5 ppb for late fluorites.

The ∑REE contents range from 2.87 to 34.39 ppm for early fluo-rites and from 1.91 to 6.4 ppm for late fluorites (Table 3). The onlyfluorites with relatively high ∑REE contents are TFE1 and TFE2early fluorite samples (34.39 and 26.96 ppm, respectively); othersamples have very low∑REE, indicating that the REE concentrationsof two generations of fluorite are much alike. It is important to notethat these two samples were taken from vein 1 (Fig. 2), where thevein extends into the Triassic limestones. No meaningful relationshipcan be found between total REE contents in fluorites and their differ-ent colors. The fluorites display variable Y/Ho ratios in the rangesfrom 79 to 133.3 for early fluorites and from 53.3 to 115 for late fluo-rites (Table 3). All fluorites exhibit negative Ce anomalies (Ce/Ce*=0.73–0.99 for early fluorites and Ce/Ce*=0.64–0.85 for latefluorites), whereas they display negative as well as positive Eu anom-alies (Eu/Eu*=0.32–1.44 for early fluorites and Eu/Eu*=0.69–1.44for late fluorites). The Ce/Yb ratios fall in the wide ranges from 15.7to 133.7 for early fluorites and from 12 to 28.7 for late fluorites, indi-cating that fluorites are enriched in LREE with regard to HREE. TheYb/La ratios display narrow ranges from 0.01 to 0.07 for early fluoritesand from 0.04 to 0.1 for late fluorites.

5. Discussion

5.1. Fluid evolution

The Th-salinity plot for measured fluid inclusions is shown inFig. 6. The aqueous type II inclusions in early fluorite exhibit a wide

salinity range (13.40–24.58 wt.% NaCl eq.) as well as a wide rangeof Th (166–295 °C). The aqueous type II inclusions in Q2 quartz exhib-it a salinity range (14.46–23.18 wt.% NaCl eq.) similar to that seen inearly fluorite but have a slightly lower Th range (152.5–220 °C). Thislower Th range may indicate, as could not be recognized from petro-graphic evidence, that the precipitation of Q2 quartz commencedprobably somewhat later than the precipitation of early fluorite atlower temperatures. The aqueous-carbonic inclusions hosted inearly fluorite and Q2 quartz have higher Th values than aqueoustype II inclusions in both minerals. The aqueous type II inclusionsfrom late fluorite show a salinity range (15.96–24.45 wt.% NaCl eq.)similar to that seen in early fluorite and Q2 quartz but representa lower Th range (102.4–175 °C), thus indicating that late fluorite

Fig. 7. Intersection of isochores of aqueous inclusions and coexisting aqueous-carbonicinclusions from early fluorite. Thick isochores correspond to aqueous inclusions withminimum and maximum homogenization temperatures of 166 °C and 312 °C, respec-tively, as well as the mean (228 °C) of homogenization temperatures. Thin isochoreswere calculated for aqueous-carbonic inclusions with minimum, maximum and themean total homogenization temperatures of 272, 390.5 and 313.7 °C, respectively.See text for more explanation.

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was deposited from more evolved fluids at considerably lowertemperatures.

Mixtures of aqueous fluids with carbonic compounds are immisci-ble below 300–400 °C (Pichavant et al., 1982). The range of fluid im-miscibility extends to higher temperatures with increasing salinity, sothat fluid unmixing and the probability of trapping immiscible fluidsin such systems is extremely likely (Shepherd et al., 1985). Therefore,the presence of aqueous and aqueous-carbonic fluid inclusions in thestudied samples may be suggestive of the trapping of two immisciblefluids: aqueous and carbonic. The criteria indicating that fluid immisci-bility has probably occurred during fluorite mineralization in Bozijanare as follows: (1) the presence of high-salinity aqueous inclusions inearly fluorite argues fluid immiscibility (Sisson and Hollister, 1990);(2) the ranges of salinities for aqueous and aqueous-carbonic inclusionsoverlap, suggesting that they are genetically related (Ramboz et al.,1982); and (3) the aqueous-carbonic inclusions exhibit higher homog-enization temperatures than the aqueous inclusions, which is also inagreement with fluid immiscibility (Roedder, 1984). However, the ab-sence of primary or pseudosecondary carbonic inclusions in equilibriumwith aqueous and aqueous-carbonic inclusions is not common in casesof fluid immiscibility. A possible explanation for this is the fact that inthe case of immiscibility, any proportions of the end members can betrapped and it is possible that little or no CO2 was trapped as pure car-bonic inclusions. The abovementioned evidences lead to the conclusionthat fluid immiscibility was apparently an important process whichaffected hydrothermal fluids. Considering that aqueous and aqueous-carbonic inclusions are the results of a fluid immiscibility process,their microthermometric results can be used to estimate the true tem-peratures and pressures under which fluid inclusions were entrapped(see below).

The salinity ranges of aqueous type II inclusions in early fluoriteand Q2 quartz and of type III inclusions in early fluorite (Fig. 6) maysuggest the presence of two earlier parental aqueous fluids: onehypersaline (N26.24 wt.% NaCl equivalent, i.e. the minimum salinitythat one halite-bearing inclusion can possess, Sterner et al., 1988)and the other with relatively low salinity (b15 wt.% NaCl equivalent).The mixing of these two end-member fluids with different propor-tions could produce fluids of intermediate salinity represented by in-clusions having salinities between these two salinity extremes. Nomeaningful difference in temperature can be seen in the case ofthese two parental fluids, as evidenced by data points in Fig. 6. Onthe other hand, the restricted numbers of fluid inclusions with salin-ities b15 and N26.24 wt.% NaCl equivalent may reveal that the mixingof two end-member fluids was nearly complete, resulting in the factthat the majority of the inclusions possess intermediate salinities. Ifthis interpretation is true, then fluid mixing was yet another impor-tant process that occurred during the course of mineralization.

5.2. P–T reconstruction

The P–T (pressure and temperature) conditions of entrapment offluid inclusions were constrained by intersecting the isochores of in-clusions entrapped contemporaneously from two immiscible fluids(Roedder, 1984; Roedder and Bodnar, 1980; Shepherd et al., 1985).Since the isochores for aqueous and CO2-bearing inclusions have dif-ferent slopes, the intersection of the isochores provides an estimate ofthe P–T conditions of fluid trapping. In the studied samples, late fluo-rite did not contain aqueous-carbonic inclusions; hence, this methodcannot be used to determine the P–T conditions of trapping of inclu-sions hosted by late fluorite. The samples of early fluorite and Q2quartz contain aqueous as well as aqueous-carbonic inclusions. How-ever, since only one aqueous-carbonic inclusion was measured in Q2quartz, isochores were calculated only for inclusions hosted by earlyfluorite.

Isochores for the aqueous and aqueous-carbonic fluid inclusionswere calculated for inclusions representing the minimum and

maximum as well as the mean values of measured homogenizationtemperatures. Isochores for aqueous inclusions were calculated forinclusions having homogenization temperatures of 166, 312, and228 °C. For aqueous-carbonic inclusions, isochores for inclusionswith total homogenization temperatures of 272, 390.5, and 313.7 °Cwere calculated (Fig. 7). The intersections of the isochores define aP–T area in which fluid inclusions might get entrapped, shown asshaded in Fig. 7. This entrapment area determines a minimum trap-ping temperature and pressure of 240 °C and 160 MPa, respectively.The upper extreme of the entrapment area extends to temperaturesabove 500 °C. However, the geological setting of the fluorite mineral-ization, especially the fact that it is away from magmatic activities,makes these high temperatures seem unrealistic. According to theavailable data, therefore, it appears very probable that the P–T condi-tions of the lower extreme of the entrapment area are near the actualconditions of the entrapment for fluid inclusions hosted by earlyfluorite.

5.3. REE patterns

Geochemistry of REE is a useful tool in investigating hydrothermalmineralization and is extensively used to understand fluorite genesisin different geological environments (Schwinn and Markl, 2005). TheREE signature of a hydrothermal fluid is primarily controlled by phys-icochemical conditions governing the fluid during leaching of REEfrom source rocks, as well as during fluid migration. The leaching ofREE and fluid migration may occur under two different states:sorption- or complexation-dominated conditions (Bau and Möller,1991, 1992; Michard, 1989). With increasing pH and decreasing tem-perature, sorption decreases and the complexation prevails. Underconditions favored by sorption (i.e., high T and low pH), LREE-enriched patterns are produced in fluid, whereas under complexationconditions, LREE-depleted patterns are displayed as HREE are morestrongly complexed with F− ions than LREE (Haas et al., 1995;Wood, 1990a,b). The minerals accompanying a given mineral mayalso significantly affect its REE pattern, because they may competewith each other for uptake of the REE during crystallization. Thus,the REE abundance in mineralizing fluids may depend on the order

Fig. 9. Y/Ho ratios of Bozijan fluorites compared to hydrothermal fluorites and someother geological materials. C1, chondrite; PAAS, Post-Archaean Australian Shale(modified after Bau and Dulski, 1995).

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of deposition of the REE-absorptive minerals, regardless of the ulti-mate REE source (Castorina et al., 2008).

The∑REE contents in fluorite samples are low and display rangesfrom 2.87 to 34.39 ppm and from 1.91 to 6.4 ppm for early and latefluorites, respectively (Table 3). Calcite is the only competitor mineralfor REE in the Bozijan deposit. However, since calcite is much lessabundant than fluorite in Bozijan, considering that it has an importanteffect on the REE pattern of fluorite seems irrelevant. Fluorites withlow ∑REE contents are described as those that have been derivedfrom a sedimentary environment (Hill et al., 2000; Ronchi et al.,1993; Sasmaz et al., 2005a). This interpretation can also be true forBozijan fluorites, as the host rocks of the veins are either sedimentaryrocks or slightly metamorphosed sedimentary rocks. On the otherhand, the plots of Tb/Ca versus Tb/La ratios have been establishedby Möller et al. (1976) in the form of a discriminating diagram repre-senting different fluorite occurrences according to their sedimentary,hydrothermal, and pegmatitic affinities (Fig. 8). The Tb/Ca ratio is anindicator of the environment in which fluorite forms, whereas the Tb/La ratio is a criterion determining the degree of fluorite differentiationas crystallization proceeds (Möller et al., 1976; Möller and Morteani,1983). All data plot in the hydrothermal field (Fig. 8), thereby indicat-ing a hydrothermal origin for Bozijan fluorites. The fluorite samplesplotted in Fig. 8 include early as well as late fluorites. As expected,their corresponding data points should be distributed along both pri-mary crystallization and remobilization trends. This is well illustratedin Fig. 8 by data points of early fluorites distributed along the primarycrystallization trend, and by those of late fluorites along the remobili-zation trend. Moreover, Bau and Dulski (1995) suggested that hydro-thermal fluorites are characterized by variable and non-chondritic Y/Ho ratios of up to 200. The Y/Ho ratios of hydrothermal fluorites andsome geological materials are shown in Fig. 9 (Bau and Dulski, 1995).The Y/Ho ratios of Bozijan fluorites falling in the ranges from 79 to133.3 for early fluorites and from 53.3 to 115 for late fluorites(Table 3) overlap well with the hydrothermal fluorites in Fig. 9 andprovide another confirmation of hydrothermal origin for the studiedsamples.

As shown by the Ce/Yb ratios (Table 3) and the chondrite-normalized REE patterns (Fig. 10), the values of LREE are considerablyhigher than those of HREE in the studied fluorites. The fact that thefluorites are LREE-enriched indicates that leaching of REE and fluidmigration would occur under high-temperature and low-pH condi-tions. The relatively high temperature of the fluid is evidenced bythe true temperature of fluid entrapment (N240 °C) deduced fromfluid inclusions. The low pH of the fluid is implied by dissolutionand replacement of carbonate-bearing host rocks, as demonstrated

Fig. 8. Plots of Tb/Ca versus Tb/La ratios for the Bozijan fluorites. Primary crystallizationtrend represents degree of differentiation during fluorite crystallization, and remobili-zation trend represents remobilization of earlier-formed fluorites (after Möller et al.,1976; Möller and Morteani, 1983).

by field and petrographic studies. Moreover, according to Möller(1991), an enrichment of LREE in fluorites would indicate a Ca2+/Fratio N1 in the parent fluids. This means that the fluids did not origi-nate from an F-rich source or from mobilization of pre-existing fluo-rite mineralization in deeper parts of the crust (Lüders, 1991).Therefore, an origin by remobilization cannot be demonstrated forthe Bozijan fluorites.

It is well proved that the fluorites crystallized in the early stages ofmineralization are enriched in LREE, whereas those formed in thelate stages of the process of mineral formation are enriched in HREE(Constantopoulos, 1988; Ekambaram et al., 1986; Hill et al., 2000;Möller et al., 1976). All studied fluorites from Bozijan including bothearly and late ones are enriched in LREE (Table 3, Fig. 10). The prob-lem of LREE-enriched late fluorites remains unsolved. However, theenigmatic LREE-enriched late fluorites may suggest that the deposi-tion of fluorites in the Bozijan deposit did not occur during a long-lived episode of mineralization.

Although the REE patterns for fluorites and host rocks are not ex-actly the same, they exhibit a similar overall trend (Fig. 10), whichcan suggest a genetic relationship between them, especially regardingthe source of fluorine (see below). Another important feature ofchondrite-normalized REE patterns is that the limestone-hostedearly fluorites (TFE1 and TFE2 samples) have the highest REE values,and their patterns plot higher than the patterns for other samples,

Fig. 10. REE distribution patterns of fluorites and average country rocks. All samples arenormalized to chondrite (Boynton, 1984). Av. Lime., average limestone (n=2); Av. Slt.,average slate (n=2).

Fig. 11. (La/Yb)n ratio versus (Eu/Eu*)n ratio plot. All samples are normalized to chon-drite (Boynton, 1984). Data range for fluorite-bearing hydrothermal deposits in NewMexico (Eppinger and Closs, 1990), and Akdagmadeni fluorites in Turkey (Sasmazet al., 2005b) are shown.

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even higher than the pattern displayed by the average host rock lime-stone (Fig. 10). Hill et al. (2000) also found limestone-hosted fluoritesto be having the highest ∑REE values relative to other sediment-hosted fluorites. Although these deposits were in close vicinity to in-trusive rocks and these researchers considered a genetic associationbetween the intrusive rocks and fluorite deposits, the lack of igneousrocks in the Bozijan area indicates that the higher ∑REE values inlimestone-hosted fluorites is not necessarily related to the igneousrocks located near them.

The ratios of Eu/Eu* and Ce/Ce* in fluorites, which are indicators ofthe magnitudes of Eu and Ce anomalies, are given in Table 3. The Euand Ce anomalies are useful indicators for fluid temperature and ox-ygen fugacity (ƒO2). Thermochemical reduction of Eu3+ to Eu2+ canoccur at high temperatures; therefore, hydrothermal fluorite willshow the Eu anomaly of hydrothermal fluid only when it is crystal-lized below 200 °C (Schwinn and Markl, 2005). Since Eu2+ is moremobile than Eu3+, during REE leaching from host rocks, it accumu-lates in fluid, thereby resulting in a positive Eu anomaly in the fluidand a negative one in the leached rock (Castorina et al., 2008). Fur-ther, at temperatures higher than 200 °C, the size of Eu2+ preventsits substitution for Ca2+ in the fluorite structure, and the mineral ex-hibits a negative Eu anomaly (Bau, 1991; Möller, 1998; Möller andHolzbecher, 1998). Finally, the Eu anomaly in fluorite could be inher-ited from the parent fluid (Schwinn and Markl, 2005). Since fluid in-clusion studies reveal that early fluorites were formed attemperatures N240 °C, it can be suggested that their positive Euanomalies did not result from a crystal–chemical control during crys-tallization. Alternatively, it can be concluded that their positive Euanomalies were produced by a positive Eu anomaly in the mineraliz-ing fluid. Since slates, the major host rocks for fluorite mineralization,exhibited negative Eu anomalies (Table 2), and as the fluid tempera-ture was N200 °C, it can be assumed that leaching of REE from hostrocks under high temperatures resulted in a positive Eu anomaly inthe fluid and a negative Eu anomaly in the host rocks. The negativeEu anomalies exhibited by some fluorite samples can be explainedby precipitation either above 200 °C from a fluid with or without anEu anomaly or below 200 °C from a fluid having a negative Eu anom-aly (Castorina et al., 2008). Again, crystallization below 200 °C is notsupported by fluid inclusion evidences, thus rendering the former ex-planation more probable. Although pressure corrections were notdone for homogenization temperatures of fluid inclusions hosted inlate fluorites, these temperatures indicate that the late fluoriteswere crystallized at considerably lower temperatures than those ofearly ones, most probably below 200 °C. Therefore, their positiveand negative Eu anomalies could be caused by crystallization fromfluids with positive as well as negative Eu anomalies. In view of theabove explanations and considering that the presence of major differ-ences in the Eu anomaly in a single fluid seems unlikely, it seems rea-sonable that the positive and negative Eu anomalies displayed byfluorites were produced from the mixing of two fluids: one with apositive Eu anomaly and the other with a negative Eu anomaly. Thisassumed fluid-mixing model is supported by fluid inclusion evi-dences as previously discussed. Finally, the presence of sulfide min-erals in the Bozijan deposit shows that the fluids were reduced and,rather, Eu2+-enriched.

The negative Ce anomalies of the Bozijan fluorites indicate that themineralizing fluids deposited fluorite under reducing conditions(Möller et al., 1998), which is in agreement with the presence of sul-fides in the Bozijan deposit. Alternatively, the negative Ce anomaliescould be inherited from seawater (Castorina et al., 2008), and it canbe assumed as the major source of mineralizing fluids in the form ofbasinal brines (see below).

In the (La/Yb)n vs. Eu/Eu* diagram (Fig. 11), two samples of stud-ied fluorites overlap with the barren fluorite deposits (i.e., lackingprecious metals mineralization), and some samples do not overlapwith any deposit type. Some fluorite samples fall in the field occupied

by granitoid, skarn, and metamorphic-hosted Akdagmadeni fluoritesin Turkey (Sasmaz et al., 2005b). That the studied fluorite veins lackpotential for exploring Ag–Au mineralization is suggested in Fig. 11.The Ag content in all fluorites is below the detection limit of0.1 ppm (not included in Table 3), and the maximum Au content is1.5 ppb (Table 3). These worthless contents of precious metals areconsistent with Fig. 11, again confirming that the geochemistry ofREE is a creditable approach in the exploration of precious metalsmineralization in fluorite deposits. Although the positive Eu anomalyis considered an indicator for precious metals mineralization in fluo-rite deposits (Constantopoulos, 1988; Sasmaz et al., 2005b), the factthat Bozijan fluorites are devoid of precious metals suggests thatthis interpretation cannot be true in all cases.

5.4. Sources of ore-forming fluids and materials

The source of mineralizing fluids is nearly speculative. Neverthe-less, some thoughts are not very unrealistic, according to the resultsof microthermometric studies. Early fluorites were precipitated fromsolutions with moderate to high salinity (13.40 to 30.65 wt.% NaCleq.) under a minimum temperature of 240 °C and reducing condi-tions, as indicated by negative Ce anomalies. The salinity range offluids coincides well with that of basinal brines (Bodnar, 1999), buttheir temperature is somewhat higher than that of these hydrother-mal solutions. Although the relationship between mineralizationand host-rock metamorphism is not clearly conspicuous, the factthat fluorite veins crosscut their host-rock schistosity indicates thatthey were formed either during or after metamorphism. So, it seemsvery probable that this weak metamorphism caused basinal brines,acting as mineralizing fluids for early fluorites, having high tempera-tures (see also below). The carbonic content of the fluids might be de-rived from decarbonation of the metamorphosed host rocks (Barrieand Touret, 1999).

The source of F for fluorite mineralization is also not exactly clear.The average content of F in slate and limestone host rocks is 3100 and2000 ppm, respectively. The F content of host rocks is several timesgreater than its average in shale (680 ppm) and limestone(250 ppm) (Rose et al., 1979); hence, it is very probable that F wasderived from host rocks. Moreover, the similarity between the overalltrends of chondrite-normalized REE patterns for fluorites and hostrocks (Fig. 10) may mean that the host rocks are the source of REE(Schwinn and Markl, 2005) and, possibly, F. The lower mobility ofREE relative to F during leaching from the host rocks by percolatingsolutions probably caused the lower∑REE content of the hydrother-mal fluid and then of fluorites with respect to the slates (Sasmaz et al.,2005a).

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Decrease in temperature and/or pressure, fluid mixing, and reac-tion of hydrothermal fluid with wall rocks were suggested byRichardson and Holland (1979) as the main factors causing fluoriteto precipitate. Fluid inclusion studies on early fluorites provide evi-dence supporting fluid mixing. The relatively wide range of homoge-nization temperatures in early fluorite-hosted inclusions indicatesthat cooling was a precipitating mechanism for fluorite. On theother hand, local wall-rock alteration is indicative of the reaction ofhydrothermal solution with wall rocks, which probably triggeredfluorite deposition. Since limestone is more reactive than slate, thelatter mechanism probably has a more effective role when fluorite ishosted by limestone.

5.5. Classification and a genetic model for fluorite mineralization

In the light of the results obtained in this study, it is possible toclassify as well as to propose a conceptual genetic model for the Bozi-jan fluorite deposit. The facts that mineralization is vein type and thatit is associated with a set of faults clearly suggest that it belongs to thestructure-related class in the classification scheme proposed by Dill(2010) for fluorite deposits. Further, occurrence of mineralizationproximal to the unconformity between Triassic strata below andLower Jurassic Shemshak Formation at the top places the Bozijan de-posit into the unconformity-related subclass in the classificationscheme. From this point of view, the Bozijan deposit is, for example,similar to deposits occurring in Western and Central Europe such asStanislawów and Boguszów in Poland; Harrachov and Křišany inCzech Republic; Chaillac in France; Nabburg-Wölsendorf in Germany;and Asturias district in northern Spain (see Dill et al., 2008; Sánchezet al., 2009, for detailed descriptions).

The most important mineralizing process accepted in some vein-type fluorite districts in Europe is the mixing of fluoride-bearingbrines and low-salinity surficial or connate brines (Sánchez et al.,2009, and references therein). Among these fluorite deposits, the de-posits most similar to Bozijan are those from Asturias fluorspar dis-trict located within a Mesozoic basin in northern Spain. In theAsturias fluorspar district, fluorite mineralization occurs as vein andstratabound bodies in red beds and carbonates of Permo-Triassicand Carboniferous ages (Sánchez et al., 2009). Similar to the Bozijandeposit, the veins are associated with fault and fracture structuresand occur at or near the unconformity between the Paleozoic base-ment and Permo-Triassic sedimentary rocks. Except for the presenceof barite and dolomite in the Asturias district, the mineralogy of theAsturian and Bozijan deposits is also well comparable. Based onfluid inclusion studies, the mixing of two fluids with contrasting sa-linities (b8 wt.% NaCl equivalent and 7–13 wt.% NaCl+11–14 wt.%CaCl2) over the temperature range from 80 to 170 °C was consideredby Sánchez et al. (2009) as the dominant process during fluorite pre-cipitation. Fluid inclusion studies on the Bozijan deposit also indicatethat the mixing of two brines with contrasting salinities (b15 andN26.24 wt.% NaCl equivalent) occurred during the time of fluorite for-mation. Besides the geological similarities between the Asturian andBozijan deposits, the fact that the same processes are involved influid evolution in both deposits leads to the conclusion that a some-what similar genetic model can be proposed for the Bozijan deposit.

In a slightly modified model from that proposed for Asturias dis-trict (Sánchez et al., 2009, their Fig. 11), it can be said that the frac-tures and faults in the studied area facilitated the downwardpenetration of the saline fluids into the basement. While the fluidsdescended, their temperature and, probably, their salinity and metalcontent increased through water–rock interaction, and they finallyflowed up along faults connecting the Precambrian–Cambrian base-ment to the Mesozoic cover. Precipitation of fluorite occurred whenthe ascending brines encountered less saline, connate fluids trappedwithin sediments of Triassic and dominantly Jurassic ages (i.e., Trias-sic limestones and Shemshak Formation). In the Asturian model, the

deep basinal brines were considered fluoride-carrying solutions (Sán-chez et al., 2009). In the case of the Bozijan deposit, however, sincehost rocks themselves are F-enriched, it can be suggested that al-though the deep hypersaline fluids might have provided some fluo-ride budget, it seems more probable that the bulk of fluoride wassupplied by the less saline fluids. These fluids acquired their fluoridecontent as they moved through and leached the relatively F-enriched surrounding rocks. It is quite possible that the host rockmetamorphism caused these fluids having high temperatures toleach the rocks more effectively. As is evidenced by the shape of min-eralization and the fact that it is fault associated, the favorite places toprecipitate the ore are fractures and even faults existing in the hostrocks.

However, to confirm this model and clarify its details, includingthe brine-driving mechanisms and the relation between mineraliza-tion and geodynamic evolution of the studied area, more studies, es-pecially regarding the time of mineralization, should be done.

6. Summary and conclusions

Fluorite mineralization in the Bozijan deposit is hosted by slatesand phyllites of Lower Jurassic Shemshak Formation, as well as, in avery restricted extent, by Triassic limestones. The mineralization oc-curs as east–west trending, approximately vertical veins cuttingacross the schistosity of the slates and phyllites, and as replacementsof limestones. The main constituents of the veins are fluorite, quartz,calcite, and iron oxides with subordinate amounts of galena, pyrite,manganese oxides, and malachite. The metamorphosed host rockshave been locally argilized and silicified. The mode of mineralizationand its relationships to host rocks favor an epigenetic origin formineralization.

The presence of two immiscible fluids (aqueous and carbonic)during crystallization of the bulk of fluorites is evidenced by the oc-currence of aqueous and aqueous-carbonic inclusions in early fluo-rites and Q2 quartz. Microthermometric measurements on aqueousinclusions reveal that the trapped brines are multicomponent H2O–NaCl–(CaCl2–KCl–MgCl2) fluids with salinities from 13.40 to30.65 wt.% NaCl equivalent and Th between 152.5 and 312 °C. TheTh-salinity plots also indicate a mixing between aqueous H2O–NaCl–(CaCl2–KCl–MgCl2) brines of contrasting salinities (b15 andN26.24 wt.% NaCl equivalent). The values of Tm, carb and Th, carb showthat the carbonic fluid is nearly pure CO2 having less than 0.1 molfraction of CH4. The aqueous-carbonic inclusions display a salinityrange from 22.04 to 24.26 wt.% NaCl equivalent and a Th, total rangefrom 253 to 390.5 °C. The constructed isochores for aqueous andaqueous-carbonic fluid inclusions in early fluorite suggest a minimumtrapping temperature and pressure of 240 °C and 160 MPa, respec-tively. Fluid inclusions reveal that late fluorites were deposited froma colder and less saline fluid with Th from 102.4 to 175 °C and salin-ities between 15.96 and 24.45 wt.% NaCl equivalent. According tofluid inclusion findings, a basinal brine source can be assumed formineralizing fluids.

The ∑REE content of fluorites is low, and the highest values arefound in limestone-hosted early fluorites. The Tb/Ca and Y/Ho ratiosconfirm a hydrothermal origin for the fluorites. The studied fluorites,including both early and late ones, exhibit LREE enrichment, thus sug-gesting that leaching of REE from source rocks and fluid migration oc-curred under high-T and low-pH conditions, which is in agreementwith fluid inclusions and petrographic evidence. The mystic LREE-enriched late fluorites may be suggestive of fluorite deposition duringa short-lived episode of mineralization in Bozijan. The Eu/Eu* ratiosindicate positive as well as negative anomalies. These opposite Euanomalies are probably due to fluorite crystallization frommixing be-tween two fluids: one with positive and the other with negative Euanomalies. The Ce/Ce* ratios reveal persistent negative Ce anomaliesthat are indicative of reducing conditions in the mineralizing fluids.

105F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

The presence of sulfide minerals associated with fluorite is consistentwith this hypothesis.

From an REE geochemistry viewpoint, comparisons of the Bozijanfluorites with other deposits indicate that the studied fluorites aresimilar to fluorite-bearing barren veins in NewMexico and Akdagmadenifluorites in Turkey, and that the Bozijanfluorites have a very lowpotentialfor exploring preciousmetalsmineralization. The latter conclusion is con-sistent with the low contents of precious metals in the Bozijan deposit,thus confirming that the REE geochemistry is a useful tool in the explora-tion of precious metals in fluorite deposits.

The facts that mineralization is vein type and that it occurs nearthe unconformity between Triassic and Lower Jurassic strata classifythe Bozijan deposit as a structure-related class and anunconformity-related subclass in the classification scheme of Dill(2010). The genetic model proposed for the Bozijan deposit was mod-ified from that previously accepted in some European fluorite districts(e.g., Sánchez et al., 2009). In this conceptual model, the precipitationof fluorite was assumed to be caused by mixing between ascending,deep basinal hypersaline fluids and less saline, fluoride-carrying con-nate fluids trapped within overlying Mesozoic strata. Fluorite deposi-tion occurs when these two fluids come together, preferentially infractures and faults existing in the host rocks. The fluoride contentof less saline fluids was probably supplied dominantly by surroundingrocks of Jurassic age, as is evidenced from their high fluorine contentand REE patterns.

Acknowledgments

The author would like to thank the Research Council of BehbahanIslamic Azad University for financing this study (52153880325004).The author is indebted to the personnel of Poudrsazan Industrial &Mineral Group for offering facilities during field work. H.G. Dill andE. Vindel are also thanked for their careful reviews, which significant-ly improved the manuscript.

References

Bakker, R.J., 1999. Adaptation of the Bowers and Helgeson (1983) equation of state tothe H2O–CO2–CH4–N2–NaCl system. Chemical Geology 154, 225–236.

Bakker, R.J., 2003. Package FLUIDS 1. Computer programs for analysis of fluid inclusiondata and for modeling bulk fluid properties. Chemical Geology 194, 3–23.

Barrie, I.J., Touret, J.L.R., 1999. Fluid inclusion studies of gold-bearing quartz veins fromthe Yirisen deposit, Sula Mountains greenstone belt, Masumbiri, Sierra Leone. OreGeology Reviews 14, 203–225.

Bau, M., 1991. Rare-earth element mobility during hydrothermal and metamorphicfluid–rock interaction and the significance of the oxidation state of europium.Chemical Geology 93, 219–230.

Bau, M., Dulski, P., 1995. Comparative study of yttrium and rare-earth element behav-iours in fluorine-rich hydrothermal fluids. Contributions to Mineralogy and Petrol-ogy 119, 213–223.

Bau, M., Möller, P., 1991. REE systematics as source of information on minerogenesis.In: Pagel, M., Leroy, J.L. (Eds.), Source, Transport and Deposition of Metals. Balk-ema, Rotterdam, pp. 17–20.

Bau, M., Möller, P., 1992. Rare earth element fractionation in metamorphogenic hydro-thermal calcite, magnesite and siderite. Mineralogy and Petrology 45, 231–246.

Bodnar, R.J., 1993. Revised equation and table for determining the freezing point de-pression of H2O–NaCl solution. Geochimica et Cosmochimica Acta 57, 683–684.

Bodnar, R.J., 1999. Hydrothermal solutions. In: Marshall, C.P., Fairbridge, R.W.(Eds.), Encyclopedia of Geochemistry. Kluwer Academic Publishers, Lancaster,pp. 333–337.

Bodnar, R.J., Vityk, M.O., 1994. Interpretation of microthermometric data for H2O–NaClfluid inclusions. In: De Vivo, B., Frezzotti, M.L. (Eds.), Fluid Inclusions in Minerals:Methods and Applications, Short Course IMA, pp. 117–130.

Bowers, T.S., Helgesson, H.C., 1983. Calculation of the thermodynamic and geochemicalconsequences of nonideal mixing in the system H2O–CO2–NaCl on phase relationsin geologic systems: equation of state for H2O–CO2–NaCl at high pressures andtemperatures. Geochimica et Cosmochimica Acta 47, 1247–1275.

Boynton, W.V., 1984. Geochemistry of the rare earth elements: meteorite studies. In:Henderson, P. (Ed.), REE Geochemistry. Elsevier, Amsterdam, pp. 63–114.

Brown, P.E., 1989. FLINCOR: a computer program for the reduction and investigation offluid inclusion data. American Mineralogist 74, 1390–1393.

Brown, P.E., Lamb, W.M., 1989. P–V–T properties of fluids in the system H2O±CO2±NaCl: new graphical presentations and implications for fluid inclusion studies.Geochimica et Cosmochimica Acta 53, 1209–1221.

Burruss, R.C., 1981. Analysis of phase equilibria in C–O–H–S fluid inclusions. In: Hollis-ter, L.S., Crawford, M.L. (Eds.), Fluid Inclusions: Applications to Petrology: Mineral-ogical Association of Canada Short Course, 6, pp. 39–74.

Castorina, F., Masi, U., Padalino, G., Palomba, M., 2008. Trace-element and Sr–Nd isoto-pic evidence for the origin of the Sardinian fluorite mineralization (Italy). AppliedGeochemistry 23, 2906–2921.

Constantopoulos, J., 1988. Fluid inclusions and rare earth element geochemistry offluorite from south-central Idaho. Economic Geology 83, 626–636.

Darling, R.S., 1991. An extended equation to calculate NaCl contents from final clath-rate melting temperatures in H2O–CO2–NaCl fluid inclusions: implications for P–T isochore location. Geochimica et Cosmochimica Acta 55, 3869–3871.

Dill, H.G., 2010. The “chessboard” classification scheme of mineral deposits: mineralo-gy and geology from aluminum to zirconium. Earth-Science Reviews 100, 1–420.

Dill, H.G., Sachsenhofer, R.F., Grecula, P., Sasvári, T., Palinkaš, L.A., Borojevic-Šoštaric, S.,Strmic-Palinkaš, S., Prochaska, W., Garuti, G., Zaccarini, F., Arbouille, D., Schulz,H.M., 2008. Fossil fuels, ore and industrial minerals. In: McCann, T. (Ed.), Geologyof Central Europe. Geological Society of London, Special Publication, London,pp. 1341–1449.

Ekambaram, V., Brookins, D.G., Rosenburg, P.E., Emanuel, K.M., 1986. REE geochemistryof fluorite–carbonate deposits in Western Montana, USA. Chemical Geology 54,319–331.

Eppinger, R.G., Closs, L.G., 1990. Variation of trace elements and rare earth elements influorite: a possible tool for exploration. Economic Geology 85, 1896–1907.

Ghorbani, M., 2007. Economic Geology of Mineral and Natural Resources of Iran. ArianZamin. 492 pp. (in Farsi).

Haas, J.R., Shock, E.L., Sassani, D., 1995. Rare earth in hydrothermal systems: estimatesof standard partial molal thermodynamic of aqueous complexes of rare earth ele-ments at high pressures and temperatures. Geochimica et Cosmochimica Acta 21,4329–4350.

Hein, U.F., Lüders, V., Dulski, P., 1990. The fluorite vein mineralization of the southernAlps: combined application of fluid inclusions and rare earth element (REE) distri-bution. Mineralogical Magazine 54, 325–333.

Hill, G.T., Andrew, R.C., Philip, R.K., 2000. Geochemistry of southwestern New Mexicofluorite occurrences: implications for precious metals exploration in fluorite-bearing systems. Journal of Geochemical Exploration 68, 1–20.

Knight, C.L., Bodnar, R.J., 1989. Synthetic fluid inclusions. IX. Critical PVTX properties ofNaCl–H2O solutions. Geochimica et Cosmochimica Acta 53, 3–8.

Lüders, V., 1991. Formation of hydrothermal fluorite deposits of the Harz Mountains,Germany. In: Pagel, M., Leroy, J.L. (Eds.), Source, Transport and Deposition ofMetals. Balkema, Rotterdam, pp. 325–328.

Michard, A., 1989. Rare earth element systematics in hydrothermal fluids. Geochimicaet Cosmochimica Acta 53, 745–750.

Möller, P., 1991. REE fractionation in hydrothermal fluorite and calcite. In: Pagel, M.,Leroy, J. (Eds.), Source, Transport and Deposition of Metals. Balkema, Rotterdam,pp. 91–94.

Möller, P., 1998. Europium anomalies in hydrothermal minerals: kinetic versus ther-modynamic interpretation. Proceedings of the Ninth Quadrennial IAGOD Sympo-sium. Schweizerbart, Stuttgart, pp. 239–246.

Möller, P., Holzbecher, E., 1998. Eu anomalies in hydrothermal fluids and minerals: acombined thermochemical and dynamic phenomenon. Freiburger Forstliche For-schung Heft 475, 73–84.

Möller, P., Morteani, G., 1983. On the chemical fractionation of REE during the forma-tion of Ca-minerals and its application to problems of the genesis of ore deposits.In: Augustithis, S. (Ed.), The Significance of Trace Elements in Solving Petro-genetic Problems, pp. 747–791. Athens.

Möller, P., Parekh, P.P., Schneider, H.J., 1976. The application of Tb/Ca–Tb/La abundanceratios to problems of fluorspar genesis. Mineralium Deposita 11, 111–116.

Möller, P., Bau, M., Dulski, P., Lüders, V., 1998. REE and Y fractionation in fluorite andtheir bearing on fluorite formation. Proceedings of the 9th Quadrennial IAGODSymp. Schweizerbart, Stuttgart, pp. 575–592.

Moore, F., Sadeghi, M., Jami, M., 1998. Physico-chemical characteristics of mineralizingfluids at the Kamar–Mehdi mine, Tabas region. Iranian Journal of Science & Tech-nology 9, 245–253.

ƠConnor, P.J., Högelsberger, H., Feely, M., Rex, D.C., 1993. Fluid inclusion studies,rare-earth element chemistry and age of hydrothermal fluorite mineralizationin western Ireland—a link with continental rifting? Transactions of the Institu-tion of Mining and Metallurgy (Section B: Applied Earth Science) 102,B141–B148.

Palmer, D.A.S., Williams-Jones, A.E., 1996. Genesis of the carbonate-hosted fluorite de-posit at Amba Dongar, India: evidence from fluid inclusions, stable isotopes andwhole rock-mineral geochemistry. Economic Geology 91, 934–950.

Pichavant, M., Ramboz, C., Weisbrod, A., 1982. Fluid immiscibility in natural processes:use and misuse of fluid inclusion data. I. Phase equilibria analysis—a theoreticaland geometrical approach. Chemical Geology 37, 1–27.

Qishlaqi, A., Moore, F., 2006. Recognition of Pinavand fluorite mines occurrence basedon geochemistry and REE data. Iranian Journal of Crystallography and Mineralogy,No. 2, 325–338 (in Farsi).

Rajabzadeh, M.A., 2007. A fluid inclusion study of a large MVT barite–fluorite deposit:Komshecheh, Central Iran. Iranian Journal of Science & Technology 31, 73–87.

Ramboz, C., Pichavant, M., Weisbrod, A., 1982. Fluid immiscibility in natural processes:use and misuse of fluid inclusion data. II. Interpretation of fluid inclusion data interms of immiscibility. Chemical Geology 37, 29–48.

Richardson, C.K., Holland, H.D., 1979. The solubility of fluorite in hydrothermal solu-tions, an experimental study. Geochimica et Cosmochimica Acta 43, 1313–1325.

Roedder, E., 1984. Fluid inclusions. In: Ribbe, R.H. (Ed.), Review in Mineralogy, 12. Min-eralogical Society of America. 646 pp.

106 F. Ehya / Journal of Geochemical Exploration 112 (2012) 93–106

Roedder, E., Bodnar, R.J., 1980. Geologic pressure determinations from fluid inclusionstudies. Annual Review of Earth & Planetary Science 8, 263–301.

Ronchi, L.H., Tauray, J.C., Michard, A., Dardenne, M.A., 1993. The Ribeira fluorite district,Southern Brazil: geological and geochemical (REE, Sm–Nd isotopes) characteris-tics. Mineralium Deposita 28, 240–252.

Rose, A.W., Hawkes, H.E., Webb, J.S., 1979. Geochemistry in Mineral Exploration, 2nded. Academic Press, New York. 657 pp.

Sallet, R., Moritz, R., Fontignie, D., 2005. The use of vein fluorite as probe for paleofluidREE and Sr–Nd isotope geochemistry: the Santa Catarina Fluorite District, SouthernBrazil. Chemical Geology 223, 227–248.

Sánchez, V., Vindel, E., Martín-Crespo, T., Corbella, M., Cardellach, E., Banks, D., 2009.Source and composition of fluids associated with fluorite deposits of Asturias(N Spain). Geofluids 9, 338–355.

Sánchez, V., Cardellach, E., Corbella, M., Vindel, E., Martín-Crespo, T., Boyce, A.J., 2010.Variability in fluid sources in the fluorite deposits from Asturias (N Spain): furtherevidences from REE, radiogenic (Sr, Sm, Nd) and stable (S, C, O) isotope data. OreGeology Reviews 37, 87–100.

Sasmaz, A., Yavuz, F., 2007. REE geochemistry and fluid-inclusion studies of fluorite de-posits from the Yaylagozu area (Yildizeli–Sivas) in Central Turkey. Neues Jahrbuchfür Mineralogie 183, 215–226.

Sasmaz, A., Önal, A., Sagiroglu, A., Önal, M., Akgul, B., 2005a. Origin and nature of themineralizing fluids of thrust zone fluorites in Celikhan (Adiyaman, Eastern Turkey):a geochemical approach. Geochemical Journal 39, 131–139.

Sasmaz, A., Yavuz, F., Sagiroglu, A., Akgul, B., 2005b. Geochemical patterns of theAkdagmadeni (Yozgat, Central Turkey) fluorite deposits and implications. Journalof Asian Earth Sciences 24, 469–479.

Schwinn, G., Markl, G., 2005. REE systematics in hydrothermal fluorite. Chemical Geol-ogy 216, 225–248.

Sheikholeslami, M.R. (Compiler), 2005. Mahallat Quadrangle Map 1:100,000. Geologi-cal Survey of Iran.

Shepherd, T.J., Rankin, A.H., Alderton, A.H., 1985. A Practical Guide to Fluid InclusionStudies. Blackie, Glasgow. 239 pp.

Sisson, V.B., Hollister, L.S., 1990. A fluid-inclusion study of metamorphosed politic andcarbonate rocks, south-central Maine. American Mineralogist 75, 59–70.

Sterner, S.M., Hall, D.L., Bodnar, R.J., 1988. Synthetic fluid inclusions. V. Solubility rela-tions in the system NaCl–KCl–H2O under vapor-saturated conditions. Geochimicaet Cosmochimica Acta 52, 989–1006.

Strong, D.F., Fryer, B.J., Kerrich, R., 1984. Genesis of the St. Lawrence fluorspar depositsas indicated by fluid inclusion, rare earth element, and isotopic data. EconomicGeology 78, 1142–1158.

Thiéry, R., Van den Kerkhof, A.M., Dubessy, J., 1994. VX properties of CH4–CO2 and CO2–N2 fluid inclusions: modelling for Tb31 °C and Pb400 bars. European Journal ofMineralogy 6, 753–771.

USGS, 2001. Fluorspar. U.S. Geological Survey Minerals Yearbook-2000.Williams-Jones, A.E., Samson, I.M., Olivo, G.R., 2000. The genesis of hydrothermal

fluorite-REE deposits in the Gallinas Mountains, New Mexico. Economic Geology95, 327–342.

Wood, S.A., 1990a. The aqueous geochemistry of the rare earth elements and yttrium.Review of available low temperature data for inorganic complexes and the inor-ganic REE speciation of natural waters. Chemical Geology 82, 159–186.

Wood, S.A., 1990b. The aqueous geochemistry of the rare earth elements and yttrium.Theoretical predictions of speciations in hydrothermal solutions to 350 °C at satu-ration water vapor pressure. Chemical Geology 88, 99–125.

Xiang, S., Jun, D., Ligiang, Y., Qingfei, W., Zirong, Y., Qingjie, G., Changming, W., 2010.REE and Sr–Nd isotope geochemistry for Yixian fluorite deposit, Western LiaoningProvince, China, and its geological implications. Journal of Earth Science 21,227–235.