ARTICLE

Fluid inclusion study of the Wunugetu Cu–Mo deposit, InnerMongolia, China

Nuo Li & Yan-Jing Chen & Thomas Ulrich & Yong Lai

Received: 23 July 2010 /Accepted: 22 August 2011 /Published online: 27 September 2011# Springer-Verlag 2011

Abstract Hydrothermal alteration and mineralization atthe Wunugetu porphyry Cu–Mo deposit, China, includefour stages, i.e., the early stage characterized by quartz,K-feldspar and minor mineralization, followed by amolybdenum mineralization stage associated with potas-sic alteration, copper mineralization associated withsericitization, and the last Pb–Zn mineralization stageassociated with carbonation. Hydrothermal quartz con-tains three types of fluid inclusions, namely aqueous(W-type), daughter mineral-bearing (S-type) and CO2-rich (C-type) inclusion, with the latter two types absent inthe late stage. Fluid inclusions in the early stage displayhomogenization temperatures above 510°C, with salinitiesup to 75.8 wt.% NaCl equivalent. The presence of S-typeinclusions containing anhydrite and hematite daughterminerals and C-type inclusions indicates an oxidizing,CO2-bearing environment. Fluid inclusions in the Mo- andCu-mineralization stages yield homogenization temper-atures of 342–508°C and 241–336°C, and salinities of8.6–49.4 and 6.3–35.7 wt.% NaCl equivalent, respectively.The presence of chalcopyrite instead of hematite andanhydrite daughter minerals in S-type inclusions indicates a

decreasing of oxygen fugacity. In the late stage, fluidinclusions yield homogenization temperatures of 115–234°Cand salinities lower than 12.4 wt.% NaCl equivalent. It isconcluded that the early stage fluids were CO2 bearing,magmatic in origin, and characterized by high temperature,high salinity, and high oxygen fugacity. Phase separationoccurred during the Mo- and Cu-mineralization stages,resulting in CO2 release, oxygen fugacity decrease and rapidprecipitation of sulfides. The late-stage fluids were meteoricin origin and characterized by low temperature, low salinity,and CO2 poor.

Keywords Fluid inclusion .Wunugetu porphyry Cu–Modeposit . Great Hinggan Range . China

Introduction

The Great Hinggan Range hosts a number of porphyry,skarn, and epithermal ore deposits and occurrencesrelated to Mesozoic magmatism (Zhao and Zhang1997; Qi et al. 2005; Chen et al. 2007). It is consideredas one of the 16 most promising exploration areas inChina (Chen et al. 2009b). The area is also well known forits widespread Mesozoic igneous rocks and is called theGreat Hinggan Mesozoic Igneous Province (Sengör andNatal'in 1996; Fig. 1).

The Wunugetu porphyry Cu–Mo deposit, discovered in1978, is located 22 km south of the Manchuri City, InnerMongolia, China (Fig. 1). It is the second largest Cu–Mosystem in the Great Hinggan Range, with a Cu metalreserve of 127 Mt grading 0.46% and Mo metal reserve of42 Mt grading 0.05% (Qin et al. 1999). In order tocharacterize the mineralization in the Great Hinggan Range(Chen et al. 2009b), several geological and geochemical

Editorial handling: F. Barra

N. Li :Y.-J. Chen (*) :Y. LaiKey Laboratory of Orogen and Crust Evolution,Peking University,Beijing 100871, Chinae-mail: yjchen@pku.edu.cn

Y.-J. Chene-mail: gigyjchen@126.com

T. UlrichDepartment of Earth Sciences, Aarhus University,8000 Aarhus, Denmark

Miner Deposita (2012) 47:467–482DOI 10.1007/s00126-011-0384-1

studies on the Wunugetu deposit have been carried out andpublished in Chinese (Wang and Qin 1988; Ye and Wang1989; Yang 1991; Qin et al. 1993, 1998, 1999; Wang et al.1993; Zhang 2006; Wang et al. 2007; Yin 2007; Chen2010). However, the characteristics and compositionalevolution of the ore fluids have not been well constrained.

In this paper, we summarize new geological data on therelationship between intrusion and mineralization, andconstrain the physical and chemical evolution of thehydrothermal system that formed the Wunugetu porphyryCu–Mo deposit on the basis of fluid inclusion micro-thermometry and compositional identification using laserRaman spectroscopy and scanning electron microscopy.

Geologic setting

The Wunugetu deposit is located in the Argun massif to thewest of the Derbugan fault (Figs. 1 and 2). The Argunmassif is characterized by widespread Jurassic-Early Cre-taceous volcanic rocks, Mesozoic granitoids, and a paucityof deformed and metamorphosed pre-Mesozoic terrains.The pre-Mesozoic terrains vary from gneisses to very low-grade metamorphosed volcanic rocks and sedimentarysequences of Early Precambrian to Paleozoic age. Theseterrains are interpreted to represent a complex pre-Mesozoic

tectonic evolution that involves Paleozoic subduction-related accretion, Early Mesozoic collision, and LateMesozoic-Cenozoic post-collision tectonics associated withsubduction of the Pacific plate (Chen et al. 2007). ThePrecambrian basement of the Argun massif compriseslower amphibolite-facies gneisses of the Xinghuadukougroup and upper greenschist-facies schists of the Jiagedagroup (Wu et al. 2010).

The Mesozoic volcanic rocks are widespread in this area,and include basalts, basaltic andesites, andesites, trachytes,rhyolites, volcanoclastic sequences and tuffs. Based on thelithological associations and lava flow sequence, theMesozoic volcanic rocks were divided into three formations(Wang et al. 2006; Fig. 2): (1) the Tamulan Formationcomposed mainly of basalts and basaltic andesitic rocks,with 39Ar/40Ar ages clustering at 160–163 Ma and 140–147 Ma; (2) the Shangkuli Formation, comprising mainlybasalt andesite, trachyte, and rhyolite lavas, and minor tuffand tuffaceous sandstone intercalation. 39Ar/40Ar isotopeages range between 120 and 125 Ma; and (3) the YiliekedeFormation composed mainly of basalt and andesitebasalt, with 39Ar/40Ar ages of 113–116 Ma. The volcanicrocks are unconformably overlain by the CretaceousDamoguaihe Formation, which is mainly composed ofsandstones intercalated with coal beds, tuffaceous units,and mudstones.

Fig. 1 Geological map of NEChina, showing distribution ofMesozoic igneous rocks in theGreat Hinggan Range

468 Miner Deposita (2012) 47:467–482

The NE-trending Derbugan fault is the major tectonicfeature in the studied area, which is recognized to dip intothe upper mantle (Wu et al. 2002). Its subsidiary NW-trending and NWW-trending structures control the occur-rence of volcanic edifices and epithermal deposits (Zhu etal. 2001; Qi et al. 2005). These subsidiary faults evolvedfrom compression to extension during the Late Jurassic orCretaceous (Li 1994).

The Wunugetu deposit is located northwest of theDerbugan fault (Fig. 2) and is hosted within theWunugetu Igneous Complex, a breccia pipe-like body ofapproximately 1.6 by 0.9 km at surface (Fig. 3). Thecomplex is composed of intermediate to felsic volcanic-subvolcanic rocks formed mainly by two magmaticevents. The early event formed rhyolite breccias andignimbrite followed by a quartz monzonite porphyry whilethe late event formed dacite breccias followed by dioriteand syenite dikes (Fig. 3).

In the center of the porphyry system, the WNW-trendingF7 fault normally offsets the volcanic pipe by approximately600–700 m, setting a north and south ore district (Zhang2006). In the northern part, the quartz monzonite porphyry

stock intruded the biotite granite batholith, covering an areaof about 0.42 km2. Five Cu orebodies and two Moorebodies, mainly of pod-like or banded or tabular shape,host about 80% of total Cu and Mo reserves. In the southerndistrict, small quartz monzonite porphyries host 28 Cu and11 Mo orebodies. Individual orebodies are mainly elongatedfor hundreds of meters, with widths of tens to hundreds ofmeters and ranging in depth from 300 to 650 m.

Magmatic rocks

Biotite granite

The host rock for the Wunugetu porphyry Cu–Mo system,the biotite granite batholith, underwent structural deforma-tion (Fig. 3). The biotite granite is medium to coarsegrained and is uniform in mineralogical composition.Quartz and plagioclase, in roughly equal amounts, comprise45% to 50% of the biotite granite and microcline constitutes40% to 45% by volume. Biotite and accessory mineralssuch as apatite, zircon, magnetite, and ilmenite make up the

Fig. 2 Regional geology of theWunugetu district showingmajor tectonic units, thevolcanic-sedimentary sequence,and location of the WunugetuCu–Mo deposit (modified afterZhang 2006)

Miner Deposita (2012) 47:467–482 469

remaining 10% to 15%. Within the biotite granite, relicts ofthe Lower Cambrian Argun Formation can be observed(Fig. 3). Based on major, trace elements and REEgeochemical features, Wang and Qin (1988) concluded thatthe magma was derived from the upper crust by partialmelting. Previous geochronological studies reported K–Arages of 176.9 to 201.6 Ma and a Rb–Sr isochron age of212 Ma (Qin et al. 1998). Single zircon SIMS U–Pbanalysis by Chen (2010) revealed a more precise age of200±2 Ma (n=16, MSWD=0.09) (Table 1).

Quartz monzonite porphyry and rhyolite breccia

The quartz monzonite porphyries and the rhyolite breccia pipeare the most conspicuous intrusive rocks in the WunugetuIgneous Complex, with the largest quartz monzonite porphyryoccurring in the northern half of the deposit (Fig. 3).

The rhyolite breccia is proposed to be a shallower phase ofthe largest quartz monzonite porphyry because no clearboundary can be identified between these two units. Mineral

shards such as quartz, plagioclase, K-feldspar, and biotite,with diameters of 1 to 2 mm, are cemented by tuff or melt.Feldspars in rhyolite breccia are intensively altered to sericite,hydromuscovite, and illite. Chen (2010) constrained itsformation age to 187±11 Ma (n=11, MSWD=0.09) bysingle-grain zircon LA-ICP-MS U–Pb analysis (Table 1).

The quartz monzonite porphyries contain approximately25% phenocrysts of plagioclase, quartz and some orthoclasein a microcrystalline matrix of quartz and plagioclase. Majorelement studies (Chen 2010) show that these porphyries havehigh contents of SiO2 (69.20–71.70%), Al2O3 (14.65–16.05%), and Na2O (4.26–4.98%) and low contents ofCaO (0.92–1.58%), MgO (0.10–0.57%), and FeOT (0.84–1.58%), indicating a calc-alkaline I-type granite. REE andtrace elements data for the porphyry are characterized byinconspicuous Eu anomalies, LILE enrichment and HFSEdepletion, especially for a significantly negative Nb-Ta andSr-Yb anomaly. The rocks also exhibit positive εNd(t) values(+0.3 to +1.0) and relatively high initial 87Sr/86Sr values(0.7052–0.7069). Wang and Qin (1988) and Chen (2010)

Fig. 3 Geological map of theWunugetu porphyry Cu–Modeposit (a) and schematic illus-tration of a NW-trending crosssection (b; A-A′ in (a)) showingmain lithologies, metal zonation,and hydrothermal alteration pat-terns (modified after no. 706Geological Exploration Team,Heilongjiang Nonferrous MetalsExploration Bureau, unpub-lished data). Abbreviations: QKQuartz-K-feldspar zone, QSQuartz-Sericite zone, IH Illite-Hydromuscovite zone

470 Miner Deposita (2012) 47:467–482

Tab

le1

Sum

maryof

magmatic

rocksin

theWun

ugetudepo

sit

Rock

Geometry

andmainfeatures

Com

positio

nAlteratio

nRelationto

mineralization

Mineral/m

ethod/Age*

Biotitegranite

batholith

NE-trending,

covering

anarea

ofabout

110km

2in

theWun

ugetuarea;intruded

bylatermagmatic

rocksincluding

rhyo

litebreccia,

adam

ellitepo

rphy

ry,

dacite

breccia,

anddiorite/rhyolite

dykes

Quartz(25%

),microcline(45%

),plagioclase(25%

),andbiotite

(7%),with

accessorymineralsof

apatite,zircon,

magnetite,

andilm

enite;medium

tocoarse

grained

IntenseK-feldsparandbiotite

alteratio

n,sericitizationand

silicification,

weakanhy

drite

alteratio

nandov

erprintedby

hydrom

uscovite

andillite

alteratio

n

Hostrock

Whole

rock

andbiotite/

K–A

r/176.9–

201.6Maa;

who

lerock/Rb–Sr/21

2Maa;

zircon/U–P

b/20

0±2Mab

Rhyolite

breccia

Breccia

pipe;intrudeinto

thebiotite

granite,andin

turn

intruded

bydiorite/rhyolite

dykes

5–10

%mineral

fragments(1–2

mm)comprised

ofquartz,plagioclase,

andminor

K-feldspar,biotite;

cementedby

tuffor

melt

Intensesericitization,

hydrom

uscovite,andillite

alteratio

n

Hostrock

Zircon/U–P

b/18

7±11

Mab

Adamallitepo

rphy

rySmallpo

rphy

rylocatedin

thevo

lcanic

cond

uit,with

anarea

ofabout0.42

km2;

modifiedby

laterfaultsandmagmatic

rockssuch

asdacite

breccia,

dacite,and

rhyo

litedy

kes

25%

phenocrystsof

plagioclase,

quartz

andminor

orthoclase

ina

microcrystalline

matrixof

quartz,and

plagioclase,

porphyry

texture

IntenseK-feldsparandbiotite

alteratio

n,silicification,

and

weakanhydrite

alteratio

n

Causativ

eintrusion

ofmineralization

Zircon/U–P

b/18

8.3±0.6Maa,

zircon/U–P

b/17

9±2Mab;

who

lerock/Rb–Sr/18

3.9±

1.0Maa,who

lerock/Rb–Sr/

179.0±1.9Mab;andwho

lerock/Ar–Ar/179.0±1.9Mab

Dacite

breccia

1.26-km

2du

mbb

ell-shaped

brecciaun

it;cover,intrud

edinto,and/or

incontact

with

adam

ellitepo

rphy

ryby

faults;

intruded

bydiorite/syenite

dykes

Mineral

fragments(0.2–40mm)

comprised

mainlyof

plagioclase,

orthoclase

andqu

artz,plus

lithic

fragmentsof

biotite

granite,dacite

ignimbrite,adam

ellite,

andores;

cementedby

tuffor

melt

Weakhy

drom

uscovite,illite

andcarbon

atealteratio

nPost-mineralization

Rhyolite/dacite

dyke

Occuringalon

gtheNE-trend

ingor

circular

faultsystem

s,andintrudes

into

thebiotite

granite,adam

ellitepo

rphy

ry,

rhyo

litebreccia,

andCu–Moorebod

ies,

butno

neinto

thedacite

breccia

Plagioclase

andquartz

phenocrysts

(0.3–0.5

mm)in

cryptocrystalline

matrixof

feldspar

andqu

artz

Weakhy

drom

uscovite,illite,

andcarbon

atealteratio

nPost-mineralization

Diorite/syenite

dyke

Occurring

alongtheNE-trendingfaults,

andintrudes

therhyo

litebrecciaand

dacite

breccia

Plagioclase

andho

rnblende

phenocrysts(0.2–0.4

mm)in

cryptocrystalline

matrixof

feldspar

andho

rnblende

Weakhy

drom

uscovite,illite,

andcarbon

atealteratio

nPost-mineralization

aQin

etal.(199

9)bChen(201

0)

Miner Deposita (2012) 47:467–482 471

interpreted these quartz monzonite porphyries to originatefrom remelting of thickened lower crust. For their intrusiveages, Qin et al. (1998) got a U–Pb age of 188.3±0.6 Maby single-grain zircon evaporation method and a whole-rock Rb–Sr isochron age of 183.9±1.0 Ma. Recently,Chen (2010) obtained three more precise and consistentages of ~179 Ma, i.e., SIMS U–Pb zircon age of 179±2 Ma (n=16, MSWD=0.16), an 39Ar/40Ar plateau age of179.0±1.9 Ma for the matrix, and a whole-rock Rb–Sr ageof 179.0±1.9 Ma (n=7, MSWD=1.2), which represent theformation age of the quartz monzonite porphyry (Table 1).These quartz monzonite porphyries are hydrothermallyaltered and mineralized, and show the characteristics ofore-causative intrusive rocks (Fig. 3).

Dacite breccia and rhyolite dike

A 1.26-km2 dumbbell-shaped dacite breccia unit occurs inthe southeastern part of the district (Fig. 3). The mineralcontent is mainly plagioclase, orthoclase and quartz, pluslithic shards of biotite granite, dacite ignimbrite, quartzmonzonite, and ores. These shards generally range from 0.2to 40 mm in diameter and are cemented by tuff or meltwhich suffered from weak carbonate, illite, or hydro-muscovite alterations. The breccia unit covered, intruded,and is in contact with quartz monzonite porphyries alongfaults (i.e., F5 and F7; Fig. 3), indicating that the formationof dacite breccia postdated the quartz monzonite porphyriesand Cu–Mo mineralization.

Intermediate and acidic dikes

Numerous dacitic to rhyolitic dikes occur along the NE-trending or circular fault systems and intrude into the biotitegranite, quartz monzonite porphyry, rhyolite breccia, andCu–Mo orebodies but none into the dacite breccia (Fig. 3).This indicates that the dacite or rhyolite dikes are possiblycoeval with the dacite breccia. In contrast, the diorite orsyenite dikes must postdate the dacite breccia because theyclearly intruded into the dacite breccia. Therefore, thesedikes are believed to have formed after the Cu–Momineralization.

Alteration and mineralization

Hydrothermal alteration at the Wunugetu deposit is highlyvariable, with several alteration minerals occurring indifferent generations and settings, or overlapping alterationstages (Qin et al. 1993), which indicates a complex andlong history of fluid activity. Alteration is typically zonedfrom an inner quartz-K-feldspar zone assemblage (QKzone) outward to quartz-sericite halo (QS zone), with later

illite-hydromuscovite-carbonate overprinting the formerassemblages (Fig. 3).

Quartz-K-feldspar zone

A quartz-K-feldspar veinlet infilling and alteration stage iswidespread throughout the central part of the Wunugetusystem, which mainly affects the biotite granite and quartzmonzonite porphyry. K-feldspar, biotite, quartz, sericite andsome anhydrite, plus late-stage hydromuscovite, illite andcarbonate, define an alteration zone of about 2 km long and0.8 km wide (Fig. 3).

K-feldspar accounts for 5% to 10% of alterationminerals inthe QK zone, and is distinguished by the presence of pale pinkto creamK-feldspar. In the biotite granite, the alteration occursas irregular replacement of the igneous matrix, and in moreintensely altered samples, it also has replaced the phenocrysts(Fig. 4a) and destroyed the original texture of the rock. In thequartz monzonite porphyry, it mainly occurs as variousveins, which are proximal to Mo mineralization.

Secondary quartz accounts for 10% to 15% of totalalteration minerals in the QK zone, with the highest up to60% to 75%. It usually occurs as various quartz-dominatedor quartz-only veins and as anhedral grains. In theinnermost concentric zone, barren quartz veins with minormolybdenite and thin K-feldspar alteration haloes constitutethe “barren quartz core.” Also abundant in this zone arenumerous centimeter-sized, discontinuous, irregular aggre-gates, and pods of quartz.

Locally, biotite (Fig. 4b, c) occurs as micro-scale crystalsadjacent to quartz-K-feldspar veins, with a volume occu-pation of about 1% to 2%.

Quartz-Sericite zone

Upward and outward from, but also overlapping the QKzone, is a hydrothermal alteration zone containing quartz(6% to 20%), sericite (5% to 35%), hydromuscovite (6% to30%), and minor illite and carbonate. This zone is referredto as “quartz-sericite zone,” which mainly occurs in biotitegranite, rhyolite breccia and quartz monzonite porphyry. Allthe original mafic minerals and most feldspar have beenconverted to sericite or hydromuscovite, resulting in a dullbrownish color of the rock.

Quartz-sericite-sulfide veins are characteristically notstraight and have wide alteration envelopes. They aremainly associated with Cu mineralization (Fig. 4f, g) andminor Mo mineralization (Fig. 4d, e).

Illite-hydromuscovite zone

Overprinting the QK and QS zones, illite (2% to 10%),hydromuscovite (15% to 25%, Fig. 4h), sericite (1% to

472 Miner Deposita (2012) 47:467–482

10%) plus minor carbonate (Fig. 4i) define the “illite-hydromuscovite zone” (IH zone). This alteration occurs inthe biotite granite and rhyolite breccia. Original textures ofthese rocks are partly or completely replaced by alepidoblastic texture. Quartz veins appear monomineralicin hand specimen, commonly without visible alterationhaloes. In contrast to the contorted veins of the QS zone,these veins are parallel, and accompanied by minor Cu, Pb,and Zn mineralizations.

Mineralization

The Wunugetu deposit has a pronounced mineralizationzoning that comprises, outward from the quartz monzoniteporphyry, Mo, Mo–Cu, Cu–Pb–Zn, and Pb–Zn dominatedzones. Mo mineralization mainly occurs in the endo- andexo-contact of the quartz monzonite porphyry with quartzand K-feldspar. It is either disseminated in the altered rockor occurs as quartz-molybdenite veins. These molybdenite

veins have been observed to cut veins of quartz-K-feldspar-cubic pyrite, but in turn they are cut by chalcopyrite-bearing veins, suggesting that molybdenite is earlier thanchalcopyrite, but later than the formation of euhedral pyrite.

Chalcopyrite is the dominant copper mineral and, alongwith minor bornite, chalcocite, tennantite, and tetrahedrite,appears to be paragenetically later than molybdenite. TheCu-bearing minerals are associated with quartz-sericitealteration. The sulfides occur in quartz-sulfide veins, withadditional late covellite in cracks cutting earlier formedminerals. The ores with disseminated veinlets generallydisplay moderate copper grade of 0.2% to 0.6% Cu, withthe highest up to 2.08%. In the illite-hydromuscovite zone,minor chalcopyrite plus galena and sphalerite are present asinfilling of earlier fractures.

Uneconomic Pb and Zn mineralization is observed in theillite-hydromuscovite zone. Sphalerite and galena occur asunevenly distributed anhedral crystals, with diameters ofabout 0.01–3.0 mm. Chalcopyrite is occasionally distributed

Fig. 4 Alteration and mineralization photomicrographs of theWunugetu Cu–Mo deposit. a Plagioclase is replaced by K-feldspar,which in turn, is replaced by sericite; b, c the coexistence of radialmolybdenite and biotite in quartz-K-feldspar zone; d, e molybdeniteaggregates in the quartz-sericite zone; f, g copper mineralization in thequartz-sericite zone; chalcopyrite appears to be paragenetically later

than pyrite but earlier than sphalerite; h tiny hydromuscoviteaggregate in the late stage; i late-stage comb quartz-carbonate veinwith minor pyrite in the inner part. Abbreviations: Bi biotite, Cccarbonate, Cp chalcopyrite, Kf K-feldspar, Mo molybdenite, Plplagioclase, Py pyrite, Sp sphalerite

Miner Deposita (2012) 47:467–482 473

in sphalerite due to unmixing of the higher temperature solidsolution while some pyrite occurs as 1 to 3 mm wide veins. Itis common that sphalerite, galena, and minor chalcopyriteselectively replace earlier pyrite and chalcopyrite alongfractures.

Paragenesis

Based on field observation, as well as petrographic andtextural relationships, a four-stage paragenesis is proposed.

1. Early stage: quartz+K-feldspar±anhydrite±sulfides(pyrite-molybdenite)±magnetite

This earliest stage is characterized by modificationof preexisting minerals by the way of deformation andbrecciation. Precipitation of quartz, K-feldspar, anhy-drite, and magnetite has commenced in the QK zoneduring the early stage. Sulfides in this stage, includingboth molybdenite and pyrite, are limited.

2. Mo mineralization stage: quartz+K-feldspar+molybde-nite±chalcopyrite±pyrite

The quartz-molybdenite veins, quartz-molybdenite-chalcopyrite veins, and disseminated molybdenitedefine the main episode of Mo mineralization in theWunugetu system, and are associated mainly withquartz-K-feldspar alteration.

3. Cu-mineralization stage: quartz+sericite+chalcopyrite+tennantite

Rapid precipitation of fine-grained Cu mineralscharacterizes the Cu-mineralization stage. In this stage,molybdenite decreases, whereas Cu-bearing sulfides,such as chalcopyrite, tennantite, bornite, tetrahedrite,and chalcocite, increase significantly. These sulfidesconstitute variable quartz-sulfides veins in the QS zone.

4. Late stage: quartz+illite+hydromuscovite+carbonate(+sulfide)

Representative minerals in the late stage include illite,hydromuscovite, carbonate, and some sphalerite andgalena. Additionally, comb quartz-carbonate veins thatcut earlier veins occur in this stage. In these veins, quartzcrystals usually grow from parallel walls towards thecenter, with later infilling of calcite crystals±sulfides(Fig. 4i). It is assumed that the formation of calcite isslightly later than quartz, although they are probablydeposited by the same fluid system.

Fluid inclusion study

Samples and methods

Samples for the fluid inclusion (FI) study include ore-bearing or barren quartz veins from various alteration types.

Microthermometry was carried out on a Linkam THMSG600and THMSG1500 Heating–Freezing Systems attached to aLeitz microscope at the Institute of Geology and Geophysics,Chinese Academy of Sciences (IGGCAS). Thermocoupleswere calibrated at −56.6°C, 0.0°C, and +374.1°C usingsynthetic FIs supplied by FLUID INC. The precision oftemperature measurements on cooling runs is about ±0.2°Cwhile on heating runs, it is about ±2°C. Ice-melting temper-atures were observed at a heating rate of less than 0.1°C/min,and homogenization temperatures at a rate of ≤1°C/min.Homogenization of halite-bearing FIs was obtained on onlyone assemblage per sample chip to avoid stretching of FIs dueto repeated heating. Heating cycles of about 5°C were used todetermine the homogenization temperature of bubble andhalite in halite-bearing FIs. Heating cycles also constrainedthe melting temperature of clathrate to within ±0.2°C in mostCO2-bearing FIs.

Salinities of aqueous FIs were estimated using the dataof Bodnar (1993) for the NaCl–H2O system. Salinities ofhalite daughter mineral-bearing FIs were estimated usingthe data and methodology of Bodnar and Vityk (1994). ForFIs that homogenize by halite dissolution, this method mayunderestimate salinity by up to 3 wt.% NaCl equivalent(Bodnar and Vityk 1994). Salinities of CO2-rich FIs werecalculated using the equations of Collins (1979).

Compositions of individual FI in quartz, including gas,liquid, and daughter mineral phases, were analyzed usingthe RM-2000 laser Raman microspectrometer at IGGCAS.The inductive radiation at 514 nm is provided by an ionizedargon laser (Spectra Physics) with a beam size of 1 μm.Daughter minerals in opened FIs were identified by LEO-1450VP scanning electron microscope (SEM) with anattached INCA-ENERGY X-ray spectrometer (EDX) atIGGCAS. SEM-EDS analyses were acquired on carbon-coated broken quartz fragments (about 10×1×3 mm) atbeam currents between 0.05 and 5 nA and electronacceleration potentials of 5 to 20 kV. Opened FIs wereidentified on broken quartz fragments with secondaryelectron imaging, and element compositions of daughterminerals were identified by SEM-EDS.

Fluid inclusion assemblage

Due to the superposition of multistage hydrothermal events,FIs of different compositions and trapped at different timesoccur juxtaposed within a single vein or even within asingle crystal. Such superposition complicates the interpre-tation of fluid origin and evolution by obscuring temporalrelationships between FIs, minerals and alteration minerals(cf. Rusk and Reed 2002; Redmond et al. 2004; Seedorffand Einaudi 2004; Seedorff et al. 2005; Rusk et al. 2008).

Goldstein and Reynolds (1994) defined a single fluidinclusion assemblage as “the most finely discriminated,

474 Miner Deposita (2012) 47:467–482

petrographically associated, group of inclusions.” A groupof inclusions is trapped synchronously and thereforerepresent a true fluid inclusion assemblage if the inclusionswere trapped along the same primary growth zone of hostcrystal or along the same healed fracture. However, in mostporphyry systems, it is difficult to identify FIs in veinquartz that adhere to the above criteria. In the Wunugetudeposit, FIs occurring along primary growth zones areextremely rare due to the scarcity of quartz crystals witheuhedral growth zones. FIs generally occur in scatteredgroups and clusters, some with unambiguous evidence forcontemporaneous trapping. In this study, most FIs measuredoccur in clusters or groups and show similar vapor/liquidratios in a single grain or in several nearby grains of quartz.If these FIs exhibit similar heating and freezing behavior,we infer that they were trapped from similar fluids undersimilar conditions and share a common origin.

Fluid inclusion types

Fluid inclusion types are identified based on their compo-sitions and phases (L-V-S) at room temperature (21°C),phase transitions observed during heating and cooling, andlaser Raman spectroscopy. Three compositional types,designated as W-, S-, and C-types, are identified in thisstudy and are described below.

W-type (aqueous) TheW-type FIs are the most abundant typein various mineralized zones. They contain two visible phasesat room temperature, liquid and vapor, and are divided intotwo subtypes according to their liquid/vapor ratio, namelyvapor- and liquid-rich W-type inclusions, respectively. Thevapor-rich W-type FIs contain liquid plus 60 to 85 vol.%vapor at room temperature, or are rarely present as monophasevapor inclusions (Fig. 5a). These inclusions typically havenegative crystal or ellipse shape and are normally >15 μm indiameters but rarely up to 40 μm. They may occur in clustersor coexist with daughter mineral-bearing FIs (S-type, seebelow) in the inner portions of quartz grains. Liquid-richW-type FIs occur commonly in all veins, with spherical,ellipse or irregular shapes (Fig. 5b). In these FIs, thevapor phase comprises 3 to 10 or 30 to 45 vol.%, and theirdiameters range from <10 to 35 μm. The majority of W-typeFIs show initial ice-melting temperature of ≥23°C, whichapproximates the eutectic melting temperatures for the systemNaCl–KCl–H2O (−22.9°C, Sterner et al. 1988) and NaCl–H2O (−21.2°C, Hall et al. 1988). Laser Raman spectroscopyreveals that a few W-type FIs contain traces of CO2 thoughno visible phase transition of CO2 were recognizable duringheating–cooling runs.

S-type (solid or daughter mineral bearing) The S-type FIsconsist of one or more daughter minerals, aqueous solution,

and a vapor bubble. They have an irregular to negativecrystal shape and are normally 6 μm to about 45 μm indiameter. The most common daughter mineral, apart fromthe halite crystal, is opaque and triangular, identified bySEM/EDS and laser Raman spectroscopy as Cu–Fe sulfide,most likely chalcopyrite (Fig. 5c–e). Transparent daughterminerals are mainly cubic halite (Fig. 5d, f). Red hexagonalhematite (Fig. 5d), round sylvite, and tabular gypsumdaughter minerals can also be observed. S-type FIs withup to four daughter minerals are identified at the Wunugetudeposit (Fig. 5d).

C-type (carbonic or CO2 bearing) The C-type FIs are rareand consist of two (liquid H2O+CO2-rich supercriticalfluid) or three phases (liquid H2O+liquid CO2+vaporCO2) at room temperature (Fig. 5e). In both two- andthree-phase FIs, the vapor bubbles are the carbonic phaseranging from 5 to 30 vol.% and 65 to 80 vol.%,respectively. These FIs are generally 5–10 μm in diameterwith a subhedral to round shape. Such FIs are restricted toearly stage crystals where they are closely associated withthe vapor-rich W-type FIs (Fig. 5e).

Not all of the described types of FIs are present in eachvein, and their abundances are variable in minerals ofdifferent stages. In early stage veins, the vapor-rich W-typeFIs are the predominant type, followed by S-, liquid-rich W-and C-types. Compared with the early stage veins, the Mo-and Cu-mineralization stage veins contain more liquid-richW-type FIs, companied by vapor-rich W-type and S-type FIs.In the late-stage veins, only the liquid-rich W-type FIs can beobserved.

Microthermometric characteristics

Microthermometric results of 142 quartz-hosting FIs ofdifferent stages are presented in Table 2, Figs. 6 and 7.Homogenization temperatures (Th) of FIs in hydrothermalquartz crystals cluster in four groups of >510°C, 342°C to508°C, 241°C to 336°C and 115°C to 234°C,corresponding to the four-stage mineralization process,respectively (Table 2).

In the early stage quartz, 85% to 90% of FIs arevapor-rich W-type, followed by S-type, and rare liquid-rich W-type and C-type. Microthermometric data for thevapor-rich W-type FIs are difficult to get due to thesmall amount of liquid and decrepitation before homog-enization. Limited data show that they have final ice-melting temperatures between −5.1°C and −7.6°C,corresponding to salinities of 8.0 to 11.2 wt.% NaClequivalent. Their homogenization temperatures are usuallyhigher than 510°C. Liquid-rich W-type FIs are rare in thisstage, with final ice-melting temperatures of −6.6°C to–5.9°C

Miner Deposita (2012) 47:467–482 475

and homogenization temperatures of 511°C to 598°C. Duringheating, vapor bubbles in S-type FIs disappear before halitecrystals dissolve (mainly around 571°C to 612°C, withcorresponding salinities of 69.8 to 75.8 wt.% NaCl equiva-lent), whereas some inclusions decrepitate before halitedissolution at temperatures above 600°C. Opaque daughterminerals do not dissolve, only change their position within theinclusion. The coexistence of anhydrite and hematite daughterminerals in S-type FIs, together with the presence ofmagnetiteand anhydrite in ores, implies that the early stage fluid wasoxidizing, which is characteristic of large to giant porphyryCu–Au systems (Zhao et al. 2002; Liang et al. 2009). Toemphasize, the C-type FIs are restricted to the early stageminerals. Such FIs are rare and their sizes are too small(generally <8 μm in diameter) to carry microthermometricmeasurement. One of them yielded clathrate-melting tem-

perature of 6.9°C and carbonic-phase homogenizationtemperature of 21.5°C, but unfortunately, it decrepitated at520°C before total homogenization.

FIs in quartz of the Mo-mineralization stage include 75%vapor-rich W-type, 15% S-type and 10% liquid-rich W-type.The vapor-rich W-type FIs yielded final ice-melting temper-atures from −15.6°C to −5.5°C, indicating salinities from 8.6to 19.1 wt.% NaCl equivalent. They homogenized to thevapor phase at temperatures of 342°C to 508°C. Theliquid-rich W-type FIs showed final ice-melting temper-atures of −8.0°C to −4.8°C, indicating salinities of 7.6to 11.7 wt.% NaCl equivalent, and homogenized to theliquid phase at temperatures of 357°C to 448°C.Daughter minerals in S-type FIs were identified ashalite and chalcopyrite but neither hematite nor anhy-drite daughter minerals were observed, suggesting that

Fig. 5 Typical fluid inclusionsin the Wunugetu Cu–Modeposit. a Vapor-rich W-typefluid inclusions; b liquid-rich W-type fluid inclusions; c chalco-pyrite daughter mineral-bearingS-type fluid inclusion; d S-typefluid inclusion, withhalite, hematite, and chalcopy-rite daughter minerals; e coex-isting C-type fluid inclusion andvapor-rich W-type fluid inclu-sion; f coexisting daughtermineral-bearing inclusions,vapor-rich aqueous inclusions,and liquid-rich aqueous inclu-sions, indicating evidence offluid boiling. Abbreviations:LH2O liquid H2O, VH2O vaporH2O, LCO2 liquid CO2, VCO2

vapor CO2, Cp chalcopyrite, Hhalite, Hem hematite

476 Miner Deposita (2012) 47:467–482

the fluids became less oxidizing compared with theearly stage. Halite daughter minerals dissolved eitherbefore or after the disappearance of the vapor bubbleduring heating, indicating that the fluid system washeterogeneously saturated or oversaturated. The halitedissolution temperatures range from 343°C to 415°C,corresponding to salinities of 41.7 to 49.4 wt.% NaClequivalent.

FIs in quartz of the Cu-mineralization stage are predomi-nated by liquid-rich W-type, followed by S-type and vapor-richW-type. The vapor-richW-type FIs yield homogenizationtemperatures of 301°C to 317°C, and final ice-meltingtemperatures of −6.0°C to −4.2°C that indicate salinities of6.7 to 9.2 wt.% NaCl equivalent. The liquid-rich W-type FIsyielded homogenization temperatures from 241°C to 336°C,final ice-melting temperatures from −6.8°C to −3.9°C, and

Table 2 Microthermometric data of fluid inclusions of the Wunugetu Cu–Mo deposit

Stage Inclusion type Number of measurements Tm, ice (°C) Tm, clath (°C) Tm;CO2 (°C) Tm, s (°C) Th (°C) Salinity (% NaCl)

Early stage V 20 −7.6–−5.1 513–624 8.0–11.2

L 3 511–598 9.1–10.0

S 4 571–612 571–612 69.8–75.8

C 1 6.9 21.5 >520 5.9

Mo stage V 43 −15.6–−5.5 342–508 8.6–19.1

L 18 357–448 7.6–11.7

S 11 343–415 343–439 41.7–49.4

Cu stage V 3 301–317 6.7–9.2

L 27 −6.8–−3.9 241–336 6.3–10.2

S 5 229–268 249–282 33.4–35.7

Late stage L 7 −8.6–−2.0 115–234 3.4–12.4

V vapor-rich aqueous inclusion, L liquid-rich aqueous inclusions, S daughter mineral-bearing inclusuion, C carbon dioxide inclusion, Tm, ice lastice-melting temperature, T m, clath melting temperature of clathrate, Tm;CO2 homogenization temperature of CO2 liquid and vapor, Tm, s meltingtemperature of daughter minerals, Th final homogenization temperature

Fig. 6 Histograms of homogenization temperatures measured for FIsfrom different stages

Fig. 7 Plot of homogenization temperatures and salinity of individualFIs (assemblages are encircled)

Miner Deposita (2012) 47:467–482 477

salinities from 6.3 to 10.2 wt.% NaCl equivalent. In S-typeFIs, the vapor bubbles disappeared at temperatures of 249°Cto 282°C, halite crystals dissolved at temperatures of 229°C to268°C, corresponding to salinities of 33.4 to 35.7 wt.% NaClequivalent, which are lower than those of the Mo-mineralization stage.

Only the liquid-rich W-type FIs were observed in late-stage quartz. They are characterized by low homogeniza-tion temperature (115°C to 234°C), low salinity (3.4 to12.4 wt.% NaCl equivalent) and are CO2 poor. This showsthat the fluids became dilute after the Mo and Cumineralization.

Fluid composition

Laser Raman microspectroscopy analyses of individual FIs(Fig. 8) indicate that H2O dominates the liquid phase(Fig. 8a), while CO2 can only be identified in vapor bubbles(Fig. 8b). Sometimes in the Raman spectra for the liquidphase of W-type FIs, the peak of 1,066–1,071 cm−1 wasobserved, suggesting the existence of minor CO3

2−. The289 cm−1 peak (Fig. 8c) shows that the black opaque daughterminerals in S-type FIs are chalcopyrite. The red opaquedaughter minerals are believed to be hematite (Fig. 8d). Noother gases have been detected from the C-type FIs besidesCO2 and H2O.

SEM/EDS system was used to define the daughterminerals in opened S-type FIs. Hematite was verified tobe a common daughter mineral (Fig. 9b, b′). The daughtermineral with triangle or irregular shape (Fig. 9a, a′) yieldeda spectrum containing peaks of Fe, Cu, and S and wasinterpreted to be chalcopyrite. This supports the results

obtained from petrographic studies and laser Ramanspectroscopy measurements.

Discussion

The CO2-rich fluid system

Coexisting vapor-rich aqueous inclusions and daughtermineral-bearing inclusions are often indicative of porphyrysystems (e.g., Alumbrera: Ulrich et al. 2001; Endeavour:Lickfold et al. 2003), but CO2-bearing inclusions in thesesystems have only recently been described in severalporphyry systems, such as the Wunugetu Cu–Mo deposit(this study), the Bingham Cu deposit, Utah (Redmond et al.2004); the Butte Cu–Mo deposit, Montana (Rusk et al. 2008);the Questa Mo deposit, New Mexico, USA (Klemm et al.2008); the El Teniente Cu–Mo deposit (Klemm et al. 2007)and the Los Pelambres and Chuquicamata Cu deposits(Rusk et al. 2007), Chile; the Malala Mo deposit, Indonesia(Van Leeuwen et al. 1994); the Henderson and Climax Modeposits, Colorado, and the Copper Creek and Mineral ParkCu–Mo systems, Arizona (Rusk et al. 2007); and theporphyry-skarn Mo systems (Li et al. 2009; Yang et al.2009a, b, c) and the Qiyugou gold deposit (Chen et al.2009a; Fan et al. 2011) in the Qinling orogenic belt, China.

The emplacement depth is a factor controlling thecontent of CO2 in magmatic fluids. The CO2-rich porphyrysystems are generally deeper than the inferred depth of 1 to5 km for most porphyry systems. For instances, theemplacement depth of the Butte deposit is constrained to6 to 9 km (Rusk et al. 2008); and the estimated formation

Fig. 8 Laser Raman spectra offluid inclusions. a H2O in liquidphase of liquid-rich W-typeinclusion; b CO2 in vapor phaseof vapor-rich W-type inclusion;c chalcopyrite daughter mineralin S-type inclusion; d hematitedaughter mineral in S-typeinclusion. The host mineralquartz can be present in Ramanspectra because of the small sizeof daughter minerals. Abbrevia-tions: Cp chalcopyrite, Hemhematite, Q quartz

478 Miner Deposita (2012) 47:467–482

depth of porphyry deposits in the East Qinling Mo belt,including Yuchiling, Jinduicheng, Nannihu, and Shangfang-gou, is up to 8 km (Li et al. 2009; Yang et al. 2009a, b, c).Baker (2002) and Lang and Baker (2001) reported similarchange in FIs with depth in intrusion-related gold deposits.Deposits formed at depth of >5 km generally containabundant low-salinity, CO2-rich aqueous FIs which arepossibly postdated by moderate- to high-salinity brines;whereas deposits formed at shallow settings (<5 km) mainlycontain high-temperature, immiscible brine and low-salinity vapor, with little or no CO2. Experimentalstudies have shown that CO2 occurs in molecular formin felsic melts, and its solubility decreases with decreasingpressure and increasing temperature (Lowenstern 2000,2001). Thus, CO2 is more abundant in deeply seatedmagmas than in shallow-seated magmas. The low solubil-ity of CO2, approximately ten times less soluble in felsicmelts than in water (Fogel and Rutherford 1990), willresult in earlier exsolution of volatiles from CO2-richmagmas at much higher pressures than those predicted formagmas which contain only water or little CO2.

The origin of magmas is another important factorcontrolling the content of CO2 in magmatic fluids. Low-enstern (2000, 2001) suggested that magmas with high CO2

contents generally contain a significant amount of crustal

contamination, such as those associated with intrusion-related gold deposit; and that the CO2 concentration inrhyolites and dacites is possibly augmented by partialmelting and assimilation of crustal materials, includinggraywackes, calcareous sandstones and many hydrother-mally altered rocks. Chen and Li (2009) recently discoveredthat the intracontinental intrusion-related hypothermalsystems (including the usually named porphyry, skarn,breccia pipe, vein, and IOCG types), such as the EastQinling porphyry Mo belt (Chen and Li 2009) andporphyry Mo deposits in Dabie Shan (Chen and Wang2011), are CO2-rich, contrasting to the well-documentedCO2-poor porphyry systems developed in volcanic arcs.They attributed the diverse fluid features to contrastingorigins or sources of magmas, i.e., the ratios of CO2/H2O,together with K/Na and F/Cl, are high in continental crust,but low in oceanic crust.

Fluid mixing and boiling

According to Audétat and Günther (1999), post-entrapmentmodification is unambiguously identified if S-type FIscoexisting with vapor-rich W-type FIs on apparent boilingtrails homogenize through halite dissolution. At Wunugetu,the salinities and homogenization temperatures in the early

Fig. 9 SEM photos and corresponding EDS spectra of daughterminerals in S-type fluid inclusions. a and a′ chalcopyrite (Cp); b and b′hematite (Hem) daughter mineral. The peak of host rock quartz can be

present due to the small size of daughter minerals. The coated carboncan also be seen in the spectra

Miner Deposita (2012) 47:467–482 479

stage do not vary systematically with inclusion size andshape. The analyzed FIs generally have negative crystalshapes (Fig. 5a, b), which show no evidence of post-entrapment disturbance. Therefore, post-entrapment modi-fication appears implausible. Assuming the S-type FIs canbe approximated by the H2O–NaCl system, phase equilibriaconstraints require that FIs homogenizing by halite disso-lution were trapped in the liquid-stable, vapor-absent fieldat pressures above the liquid–vapor phase boundary, andthey could not stably coexist with a low-density fluid phaseat the time of trapping (Bodnar 1994; Cline and Bodnar1994). Thus, heterogeneous trapping is likely occurringduring the early stages, based on variable filling ratios ofW-type FIs and the homogenization behavior of S-type FIs,which homogenize by halite dissolution.

In the Mo- and Cu-mineralization stages, there areabundant S-type inclusions that homogenize to the liquidphase. These FIs are observed to coexist with low-densityvapor-rich W-type FIs which homogenized to the vaporphase, and share similar homogenization temperatures,implying phase separation or boiling of the fluid system.Additionally, the δD and δ18O data of the ore-formingfluids are −120‰ and +6.3‰ for the Mo-mineralizationstage, −113‰ and +3.3‰ for the Cu-mineralization stage,and −121‰ and +1.3‰ for the late stage, respectively (Ye andWang 1989), supporting fluid mixing by meteoric waterinput.

Fluid evolution and fluid–rock interaction

Based on petrographic relationships and microthermometryresults of fluid inclusions presented above we envisage afluid evolution at Wunugetu that consisted of an initialH2O–NaCl–CO2 fluid system, evolving from over 510°Cduring the early stage, to 342°C to 508°C in the Momineralization, 241°C to 336°C in Cu mineralization, andto lower than 240°C in the late stage. The salinitiesdecrease from 75.8 wt.% NaCl equivalent in the earlystage, to <12.4 wt.% NaCl equivalent in the late stage.C-type FIs can only be observed in early stage quartzbut not in subsequent stages, indicating that the CO2

content in the fluid decreases gradually due to fluidmixing and/or boiling.

Observations of hematite- and/or anhydrite-bearing S-typeFIs in the early stage veins that contain magnetite andanhydrite, but rare sulfides, indicate that the early stage fluidswere highly oxidized. In contrast, sulfide-bearing quartzveins that are associated with the Mo and Cu mineral-ization contain S-type inclusions that lack hematite andanhydrite daughter phases as well as C-type FIs, whichindicates that the fluids became more reduced and showa decrease in CO2 content. Combined with the H–Oisotope data reported by Ye and Wang (1989), it can be

concluded that the fluids have evolved from magmatic tometeoric in origin.

In the early stage, the original magmatic fluids, whichare marked by high temperature, high oxygen-fugacity, CO2

and alkali rich, carried Cu and Mo and potentially alsomobilized and extracted these metals from wallrocks duringupward migration and fluid–rock interaction, forming thealteration assemblage of K-feldspar, biotite, quartz, andtrace anhydrite. The alteration during the early stage ischaracterized by “alkali metasomatism” (Hu et al. 2002).Due to the high oxygen-fugacity and CO2 content, thesulfur activity in the fluids is constrained, and thusdeposition of sulfides in this stage is limited. Such highsalinity, high oxygen fugacity fluids favor the formation oftectosilicates, phyllosilicate, and some oxides, whichmainly occur inboard intrusion and/or in endo-contact zone.

A series of physico-chemical changes of the system arecaused by early fluid–rock interaction: (1) the consumptionof alkali cations and OH− relatively enhance the activity ofH+; (2) formation of quartz and K-feldspar decrease theSiO2 content and the viscosity of the fluids, but enhance thepenetrability of the fluids; (3) formation of magnetite andanhydrite at high temperature, together with the escape ofCO2, resulted in a decrease in oxygen-fugacity of the fluids(Heinrich 2005; Liang et al. 2009), which facilitates thetransition from Mo6+ to Mo4+ and from SO4

2− to S2−; and (4)increase in H+ activity promotes CO2 escape from the fluidsdue to 2H+ + CO3

2−→H2O+CO2 ↑. These changes undoubt-edly cause “acidic metasomatism” (Hu et al. 2002) or “acidicleaching” (Heinrich 2005), which is characterized by fluidphase separation, CO2 release and precipitation of sulfidesincluding molybdenite and chalcopyrite.

The fluid boiling/phase separation could hydrofractureoverlying and surrounding wallrocks, and accelerate influxand circulation of meteoric water. Along with meteoricwater input, the deep-sourced fluids become negligible, andthe temperature and metal and CO2 contents in the fluidsystem are reduced, whereas oxidizability and acidity areenhanced. Hence, no S- or C-type FIs can be observed inthe late-stage quartz. The late-stage fluid flow is character-ized by acidic leaching, in the form of quartz, sericite,hydromuscovite, illite, kaolinite, and carbonate, and con-tributes little to mineralization.

Conclusions

The Wunugetu Cu–Mo deposit is a large porphyry systemassociated with a quartz monzonite porphyry. The fluidsresponsible for Cu–Mo mineralization are magma-derivedfluids characterized by high temperature, high salinity, highCO2 content, and high oxygen fugacity. Such parentalfluids can potentially scavenge Cu and Mo from the

480 Miner Deposita (2012) 47:467–482

wallrock and transport them to the hydrothermal systemabove. In addition to cooling, fluid mixing, boiling/phaseseparation and wallrock reactions also played an importantrole in Mo and Cu mineralization. Fluid inclusion eviden-ces and vein-cutting relationships indicate that Mo miner-alization occurred at high temperature associated withpotassic alteration, whereas Cu mineralization occurredlater and was associated with sericitic alteration. Alongwith continued input of meteoric fluid into the hydrother-mal system, heat, energy, and metals waned, forming thealteration association of illite, hydromuscovite, and carbon-ate which overprinted much of the deposit but contributelittle to mineralization.

Acknowledgments The research was financially supported by theNational Basic Research Program (no. 2006CB4035008) and theNational Nature Science Foundation of China (nos. 40730421 and40425006). We are grateful to Professors HR Fan, LJ Wang, QY Wei,and P Ni for their enthusiasm and valuable science input. Constructivesuggestions, pertinent comments, and careful corrections by twoanonymous reviewers and Professors Fernando Barra and PatrickWilliams greatly improved the quality of the manuscript.

References

Audétat A, Günther D (1999) Mobility and H2O loss from fluidinclusions in natural quartz crystals. Contrib Miner Petrol 137:1–14

Baker T (2002) Emplacement depth and carbon dioxide-rich fluidinclusions in intrusion-related gold deposits. Econ Geol 97:1111–1117

Bodnar RJ (1993) Revised equation and table for determining thefreezing point depression of H2O-NaCl solutions. GeochimCosmochim Acta 57:683–684

Bodnar RJ (1994) Synthetic fluid inclusions: XII: the system H2O–NaCl. Experimental determination of the halite liquidus andisochors for a 40 wt.% NaCl solution. Geochem CosmochimActa 58:1053–1063

Bodnar RJ, Vityk MO (1994) Interpretation of microthermometricdata for H2O–NaCl fluid inclusions. In: DeVivo B, Frezzotti ML(eds) Fluid inclusions in minerals: Methods and applications.Virginia Polytechnic Institute and State University, Blacksburg,VA, pp 117–130

Chen ZG (2010) Mesozoic tectonic-magmatic mineralization ofDerbugan metallogenic belt in NE China, and its geodynamicsetting. Ph.D thesis, Graduate School of the Chinese Academy ofSciences, Beijing, China, pp 1–194 (in Chinese with Englishabstract)

Chen YJ, Li N (2009) Nature of ore-fluids of intracontinentalintrusion-related hypothermal deposits and its difference fromthose in island arcs. Acta Petrologica Sinica 25:2477–2508, inChinese with English abstract

Chen YJ, Wang Y (2011) Fluid inclusion features of the Tangjiaping Modeposit in Dabie Shan, Henan Province: implications for the natureof porphyry systems of post-collisional tectonic settings. Interna-tional Geology Review, doi: 10.1080/00206811003783422

Chen YJ, Chen HY, Zaw K, Pirajno F, Zhang ZJ (2007) Geodynamicsettings and tectonic model of skarn gold deposits in China: anoverview. Ore Geol Rev 31:139–169

Chen YJ, Pirajno F, Li N, Guo DS, Lai Y (2009a) Isotope systematicsand fluid inclusion studies of the Qiyugou breccia pipe-hostedgold deposit, Qinling Orogen, Henan Province, China: implica-tions for ore genesis. Ore Geol Rev 35:245–261

Chen YJ, Zhai MG, Jiang SY (2009b) Significant achievements andopen issues in study of orogenesis and metallogenesis surround-ing the North China continent. Acta Petrologica Sinica 25:2695–2726, in Chinese with English abstract

Cline JS, Bodnar RJ (1994) Direct evolution of brine from acrystallizing silicic melt at the Questa, New Mexico, molybde-num deposit. Econ Geol 89:1780–1802

Collins LF (1979) Gas hydrates in CO2-bearing fluid inclusions andthe use of freezing data for estimation of salinity. Econ Geol74:1435–1444

Fan HR, HU FF, Wilde SA, Yang KF, Jin CW (2011) The Qiyugougold-bearing breccia pipes, Xiong’ershan region, central China:fluid inclusion and stable-isotope evidence for an origin frommagmatic fluids. Int Geol Rev 53:25–45

Fogel RA, Rutherford MJ (1990) The solubility of carbon dioxide inrhyolitic melts: a quantitative FTIR study. Am Miner 75:1311–1326

Goldstein RH, Reynolds TJ (1994) Systematics of fluid inclusions indiagenetic materials. Society for Sedimentary Geology ShortCourse 31:199

Hall DL, Sterner SM, Bondar RJ (1988) Freezing point depression ofNaCl–KCl–H2O solutions. Econ Geol 83:197–202

Heinrich CA (2005) The physical and chemical evolution of low-salinity magmatic fluids at the porphyry to epithermal transition:a thermodynamic study. Miner Deposita 39:864–889

Hu SX, Zhao YY, Sun JG, Ling HF, Ye Y, Lu B, Ji HZ, Xu B, Liu HY,Fang CQ (2002) Fluids and their sources for gold mineralizationin the north China platform. Journal of Nanjing University(Natural Sciences) 38:381–391, in Chinese with English abstract

Klemm LM, Pettke T, Heinrich CA, Campos E (2007) Hydrothermalevolution of the El Teniente deposit, Chile: porphyry Cu–Mo oredeposition from low-salinity magmatic fluids. Econ Geol102:1021–1045

Klemm LM, Pettke T, Heinrich CA (2008) Fluid and source magmaevolution of the Questa porphyry Mo deposit, New Mexico,USA. Miner Deposita 43:533–552

Lang JR, Baker T (2001) Intrusion-related gold systems: the presentlevel of understanding. Miner Deposita 36:477–489

Li WS (1994) Deposits related with the Manzhouli-Xin Baerhu YouqiMesozoic activizing belt. In: Rui ZY, Shi LD, Fang RH (eds)Geology of nonferrous metallic deposits in the northern marginof the North China landmass and its adjacent area. GeologicalPublishing House, Beijing, pp 270–295, in Chinese with Englishabstract

Li N, Chen YJ, Ni ZY, Hu HZ (2009) Characteristics of ore-formingfluids of the Yuchiling porphyry Mo deposit, Songxian County,Henan Province, and its geological significance. Acta PetrologicaSinica 25:2509–2522, in Chinese with English abstract

Liang HY, Sun WD, Su WC, Zartman RE (2009) Porphyry copper-goldmineralization at Yulong, China, promoted by decreasing redoxpotential during magnetite alteration. Econ Geol 104:587–596

Lickfold V, Cook DR, Smith SG, Ulrich TD (2003) Endeavor copper-gold porphyry deposits, Northparkes, New South Wales: intru-sive history and fluid evolution. Econ Geol 98:1607–1636

Lowenstern JB (2000) A review of the contrasting behavior of twomagmatic volatiles: chlorine and carbon dioxide. J GeochemExplor 69–70:287–290

Lowenstern JB (2001) Carbon dioxide in magmas and implications forhydrothermal systems. Miner Deposita 36:490–502

Qi JP, Chen YJ, Pirajno F (2005) Geological characteristics andtectonic setting of the epithermal deposits in the northeast China.J Miner Petrol 25:47–59, in Chinese with English abstract

Miner Deposita (2012) 47:467–482 481

Qin KZ, Wang ZT, Wang LJ, Bao YH, Li YM (1993) Studies onhydrothermal convection, alteration superimposition and ore-forming processes of the Wunugetushan porphyry coppermolybdenum deposit, Inner Mongolia. Geological Explorationfor Non-Ferrous Metals 2:136–143, in Chinese with Englishabstract

Qin KZ, Tanaka R, Li WS, Ishihara S (1998) The discovery of Indo-Sinian granites in Manzhouli area: evidence from Rb–Srisochron. Acta Petrologica et Mineralogica 17:235–240, inChinese with English abstract

Qin KZ, Li HM, Li WS, Ishihara S (1999) Intrusion and mineraliza-tion ages of the Wunugetushan porphyry Cu–Mo deposit, InnerMongolia, Northwestern China. Geol Rev 45:180–185, inChinese with English abstract

Redmond B, Einandi MT, Tnan EE, Landtwing MR, Heinrich CA(2004) Copper deposition by fluid cooling in intrusion-centeredsystems: new insights from the Bingham porphyry ore deposit,Utah. Geology 32:217–220

Rusk BG, Reed MH (2002) Scanning electron microscope-cathodoluminescence of quartz reveals complex growth historiesin veins from the Butte porphyry copper deposit, Montana.Geology 30:727–730

Rusk BG, Hofstra AH, Emsbo P, Hunt AG, Landis GP, Rye RO(2007) Origin and composition of fluids that form porphyrycopper (Mo–Au) deposits. GSA Meeting Abstracts with Pro-grams 39:608

Rusk BG, Reed MH, Dilles JH (2008) Fluid inclusion evidence formagmatic-hydrothermal fluid evolution in the porphyry copper–molybdenum deposit at Butte, Montana. Econ Geol 103:307–334

Seedorff E, Einaudi MT (2004) Henderson porphyry molybdenumsystem, Colorado: II Decoupling of introduction and depositionof metals during geochemical evolution of hydrothermal fluids.Econ Geol 99:39–72

Seedorff E, Dilles JH, Proffett JM, Einaudi MT, Zurcher L, StavastWJA, John DA, Barton MD (2005) Porphyry deposits: character-istics and origin of hypogene features. In: Skinner BJ (ed)Economic Geology—100th Anniversary Volume. Society ofEconomic Geologists, Littleton, pp 251–298

Sengör AMC, Natal'in BA (1996) Paleotectonics of Asia: fragments ofsynthesis. In: Yin A, Harrison TM (eds) The Tectonic Evolutionof Asia. Cambridge University Press, Cambridge, pp 486–640

Sterner SM, Hall DL, Bodnar RJ (1988) Synthetic fluid inclusions:solubility relations in the system NaCl–KCl–H2O under vapor-saturated conditions. Geochim Cosmochim Acta 52:989–1005

Ulrich T, Gunther D, Heinrich CA (2001) The evolution of a porphyryCu–Au deposit, based on LA-ICP-MS analysis of fluid inclusions:Bajo de la Alumbrera, Argentina. Econ Geol 97:1889–1920

Van Leeuwen TM, Taylor R, Coote A, Longstaffe FJ (1994) Porphyrymolybdenum mineralization in a continental collision setting atMalala, northwest Sulaweisi, Indonesia. J Geochem Explor50:279–315

Wang ZT, Qin KZ (1988) Geological-geochemical characteristic andmetallogenic material sources of the Wunugetushan lower crustporphyry copper–molybdenum deposit. Mineral Deposits 7:3–15,in Chinese with English abstract

Wang ZT, Qin KZ, Li WS, Pan LJ (1993) Metallogenic evolution,metallogenic model and exploration of the Manzhouli-Xinbarag

metallogenic province, Inner Mongolia. Miner Depos 12:212–220, in Chinese with English abstract

Wang F, Zhou XH, Zhang LC, Ying JF, Zhang YT, Wu FY, Zhu RX(2006) Late Mesozoic volcanism in the Great Xing’an Rang (NEChina): timing and implications for the dynamic setting of NEAsia. Earth Planet Sci Lett 251:179–198

Wang RQ, Song LY, Cao SW, Jia JB (2007) Geochemical character-istics of the Wunugetushan porphyry Cu–Mo deposit and itsevaluation indicators. Miner Resour Geol 21:515–519, inChinese with English abstract

Wu G, Quan H, Zhang JF, Zhu HC (2002) Structural interpretation bygravity, magnetic force and remote sensing on the north ofHeishangou in Derbugan metallogenic province. Geol Resour11:53–59, in Chinese with English abstract

Wu G, Chen YJ, Zhao ZH, Zhang Z, Li ZT (2010) Timing andtectonic evolution of the basement of the Argun massif innorthern Great Hinggan Range. Gondwana Res (in press)

Yang JH (1991) A study on stable isotope of Erguna-Hulunmetallogenic province, Inner Mongolia. Geol Explor Met 3:50–56, in Chinese

Yang Y, Zhang J, Yang YF, Shi YX (2009a) Characteristics of fluidinclusions and its geological implications of the ShangfanggouMo deposit in Luanchuan county, Henan province. ActaPetrologica Sinica 25:2563–2574, in Chinese with Englishabstract

Yang YF, Li N, Ni ZY (2009b) Fluid inclusion study of theJinduicheng porphyry Mo deposit, Hua county, Shaanxi prov-ince. Acta Petrologica Sinica 25:2983–2993, in Chinese withEnglish abstract

Yang YF, Li N, Yang Y (2009c) Fluid inclusion study of the Nannihuporphyry Mo–W deposit, Luanchuan county, Henan Province.Acta Petrologica Sinica 25:2550–2562, in Chinese with Englishabstract

Ye X, Wang LJ (1989) A study on fluid inclusion and metallo-genesis of a porphyry Cu–Mo deposit, Urugetu Hill, InnerMongolia, China. Sci Geol Sin 33:84–92, in Chinese withEnglish abstract

Yin YC (2007) Ore controlling factors of subvolcanic porphyry typecopper-molybdenum deposit in Wunugetushan of Inner Mongo-lia, and its ore prospecting orientation. Miner Resour Geol21:298–303, in Chinese with English abstract

Zhang HX (2006) Geological characteristics and metallogenic modelof the Wunugetushan Cu–Mo deposit, Inner Mongolia. Masterthesis, Jilin University, Jilin, pp 1–72 (in Chinese with Englishabstract)

Zhao YM, Zhang DQ (1997) Metallogeny and prospective evaluationof copper-polymetallic deposits in the Da Hinggan Mountainsand its adjacent regions. Seismological Press, Beijing, pp 83–106, in Chinese with English abstract

Zhao ZH, Xiong XL, Wang Q, Bao ZW, Zhang YQ, Xie YW, Ren SK(2002) Alkali-rich magmatism and related large-superlarge Cu–Audeposits of China. Science in China Series D 32:1–10, in Chinesewith English abstract

Zhu Q, Wu G, Zhang JF, Shao J, Zhu HC (2001) Progress of thestudies on Derbugan metallogenic province and explorationtechniques. Chin Geol 28:19–27, in Chinese with Englishabstract

482 Miner Deposita (2012) 47:467–482