Geochemistry of the Permian Kalatongke Mafic Intrusions, Northern Xinjiang, Northwest China: Implications for the Genesis of Magmatic Ni-Cu Sulfide Deposits

ZHAOCHONG ZHANG,† State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, 100083, P. R. China

JINGWEN MAO, FENGMEI CHAI, SHENGHAO YAN, BAILIN CHEN, MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037, P. R. China

AND FRANCO PIRAJNO Geological Survey of Western Australia, 100 Plain Street, East Perth WA 6004, Australia School of Earth and Geographical Sciences, The University of Western Australia, Crawley 6009, Australia

Abstract The Kalatongke Cu-Ni sulfide deposit in northern Xinjiang, northwest China, is located on the southern side of the regional Irtysh fault zone, which is the boundary between the early Paleozoic Altai orogenic belt to the north and the late Paleozoic Junggar terrane to the south. In the Kalatongke region there are 11 mafic intrusions which were emplaced in Lower Carboniferous strata. Economic Ni-Cu sulfide ores are found within three of these intrusions, which are well differentiated, and compositionally zoned. Four rock types are recognized which, from top to base of the three mineralized intrusions, include biotite diorite, biotite-hornblende norite, biotite-hornblende-olivine norite, and biotite hornblende-dolerite. The biotite-hornblende olivine norites and biotite-hornblende norites are the most favorable host rocks for Ni-Cu mineralization. The initial 87 86 ( Sr/ Sr)t (t = 280 Ma) ratios of the intrusions vary from 0.70375 to 0.70504, and εNd(t) from 6.3 to 8.2, im- plying that the magmas originated from depleted asthenospheric mantle. However, the strong enrichment of lithophile elements such as K, Rb, Th, U, and LREE, the negative Nb and Ta anomalies, and the high δ18O values of whole rocks (5.4–10.6‰) suggest significant crustal contamination. These patterns are present in almost all samples from the intrusions, indicating that the contamination took place before the magma was emplaced at its present level in the crust. Crustal contamination is interpreted to have driven the magma to S-saturation and brought orthopyroxene onto the liquidus. Convection, or perhaps flow differentiation of the crystal-bearing magma during ascent, caused the dense sulfide melt with entrained olivine and orthopyroxene crystals to become concentrated in the center of the intrusions, whereas the fractionated magmas formed other, less mafic intrusions, which intrude the nearby strata. Introduction ppb) and 3.4 t of Pd (0.20 ppb). A mine was subsequently de- IN MANY DEPOSITS, crustal contamination has been identified veloped in 1985 and started production in 1989. In 2005, a as having a major role in triggering S saturation in the mafic new Ni-Cu orebody consisting of massive sulfide ores with magmas (Brugmann et al., 1993; Naldrett, 2004; Lightfoot about 200,000 t of Cu and Ni (avg grades of 4.09 and 3.73 wt and Keays, 2005; Wang and Zhou, 2006), although some de- %, respectively) was discovered at the boundary between Y2 posits (e.g., Jinchuan and Nebo-Babel in Western Australia) and Y1. The Kalatongke deposit is now the second largest Ni- are thought to have originated as continuous magma chono- Cu deposit in China, after Jinchuan (Lehmann et al., 2007). liths with multiple and related magma pulses (Seat et al., The ore-bearing intrusions contain a large amount of or- 2007; Tang et al., 2007). The main issues are the following: thopyroxene, probably suggesting that the parental magmas what were the contaminants (e.g., pyrite-rich chert at Kam- were siliceous high Mg basalts (SHMB) that were formed by balda, anhydrite at Noril’sk, and S-rich metasediments at crustal contamination of komatiites (Arndt and Jenner, 1986; Voisey’s Bay), and at what stage in the evolution of the mag- Barley, 1986; Cattell, 1987; Skulski et al., 1988; Barnes, 1989; mas did the contamination take place? Sun et al. 1989; Skulski and Percival, 1996). This feature pro- The Kalatongke copper-nickel sulfide deposit is located in vides us with an opportunity to evaluate the role of crustal Fuyun County, about 380 km north of Urumqi, the capital of contamination in the generation of the Kalatongke intrusion Xinjiang, northwest China. It was discovered in 1978 by the and ore formation. No. 4 Party of the Xinjiang Bureau of Geology and Mineral Although the Kalatongke intrusions and hosted ore de- Resources. The exploration program for the No. 1 and No. 2 posits have been previously studied, most publications are in mafic intrusions (named Y1 and Y2, respectively) established Chinese (e.g., Wang and Zhao, 1991; Wang et al., 1992; Zhang a reserve of 419,000 tons (t) of Cu (avg grade of 2.46 wt %), et al., 2003). In this paper, we present the results of an addi- 240,000 t of Ni (avg grade of 1.42 wt %), 8,355 t of Co (avg tional field and petrologic-geochemical study of the intrusions grade of 0.049 wt %), as well as 2.5 t of Pt (avg grade of 0.15 that host the Kalatongke deposit. On the basis of our obser- vations and results we propose a new model for the formation † Corresponding author: e-mail, [email protected] of the deposit that involves flow differentiation.

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Geologic Setting movement. The intersections of northwest-striking faults with The Kalatongke region is located in the East Junggar ter- west-northwest–striking faults were favorable sites for the rane, which is bounded by the Siberian craton, the Kaza- emplacement of mafic complexes. khstan block, and the Tianshan orogenic belt in the central The Kalatongke area is underlain by Devonian to Carbonif- portion of Central Asian orogenic belt (Fig. 1a, b). The Irtysh erous volcanic and sedimentary rocks. The Devonian succes- fault is a boundary between the early Paleozoic Altai orogenic sion consists of marine sedimentary clastic rocks intercalated belt to the north and the Late Paleozoic Junggar terrane to with carbonates and tuffaceous rocks and overlain by inter- the south (Fig. 1c; Coleman, 1989; Huang et al., 1990; Xiao et mediate-mafic flows and pyroclastic rocks intercalated with chert (Beitashan Formation). These are followed by interme- al., 1990). The Junggar terrane is traditionally divided into the diate-mafic volcanic rocks and minor interbedded sedimen- East and West Junggar terranes and the Junggar basin. The tary rocks (Yundukala Formation). The Carboniferous is rep- Junggar basin contains thick continental deposits and is resented by the Heishantou and Nanmingshui Formations, bounded to the south by a south-dipping foreland thrust which comprise a succession of intermediate-mafic and felsic zone, which is composed mainly of an east-west–trending vol- volcanic and pyroclastic rocks, chert, sedimentary and volcanic arc complex. The East Junggar terrane comprises sev- canic breccias, carbonate and tuffaceous beds. These rocks eral northwest-trending, highly deformed metasedimentary were metamorphosed to lower greenschist facies during the and ophiolite assemblages which were accreted to the south- Triassic. ern margin of the Siberian plate along the Irtysh fault. The West Junggar terrane was accreted to the Kazakhstan block to The Kalatongke Intrusions and the west. Associated Cu-Ni Mineralization The East Junggar terrane comprises several accretionary Eleven northwest-trending mafic intrusions are present in complexes that were generated by subduction-accretion the 1.7 km2 Kalatongke region (Fig. 2a). All intrude the sedi- processes in Paleozoic times (Coleman, 1989; Feng et al., mentary and volcanic rocks of the Lower Carboniferous Nan- 1989). Two highly deformed and dismembered belts of ophi- mingshui Formation. The three largest intrusions (Y1, Y2, olites, the Wulunguhe and Kalamaili ophiolites, occur in the and Y3) are well differentiated, zoned, and strongly mineral- East Junggar terrane; the Wulunguhe ophiolite was dated to ized, but mostly not exposed. In contrast, Y4, Y5, Y6, Y7, Y8, 481 ± 5 and 489 ± 4 Ma by Jian et al. (2003) using SHRIMP Y9, Y10, and Y11 intrusions are weakly differentiated and U-Pb zircon methods, whereas the Kalamaili ophiolite was contain only uneconomic copper mineralization. Rb-Sr and determined to be 373 ± 10 Ma (Tang et al., 2007). These Sm-Nd isochron ages of the Y1, Y2, and Y3 intrusions, yield ophiolites reflect the formation of oceanic crust in the early to ages of 285 ± 16.7, 297 ± 23, 301 ± 28, 290 ± 33.5, and 297.7 middle Paleozoic. Subduction of the oceanic lithosphere be- ± 11 Ma, respectively (Wang and Zhao, 1991; Li et al., 1998). neath the Altai orogen and the Kazakhstan block is mani- Moreover, recent U-Pb dating of zircons from the Y1 intru- fested by the presence of thick marine volcanic rocks interca- sion yielded an age of 287 ± 3 Ma (Han et al., 2004), and Re- lated with sedimentary rocks of Devonian to Carboniferous Os dating of chalcopyrite and pyrrhotite in the ores from Y2 ages. This was followed by accretion and imbrication of arc gives an age of 285 ± 17 Ma (Zhang et al., 2008a). series and back-arc basins toward the Kazakhstan block, as The Y1 intrusion exhibits an irregular lensoid shape that is the three blocks (Tarim, Kazakhstan, and Siberian craton) 695 m long and 39 to 289 m wide with an outcrop area of converged. Final closure of the Paleo-Asian ocean with colli- about 0.1 km2. Its long axis strikes northwest, and dips at 60° sion between the Kazakhstan and Siberian plates occurred by to 85° to the northeast. In cross section, the Y1 intrusion the Late Carboniferous. During the Permian, the tectonic forms an inclined, funnel-shaped body, which becomes more regime was predominantly collisional, although Allen et al. dike-like at depth (Fig. 2b). Four principal rock types are rec- (1993) proposed a Late Permian transtensional phase. The ognized in the Y1 intrusion. From top to base, they are bi- basement was intruded by large volumes of magma in the otite-rich diorite (~5 vol %), biotite-hornblende norite (~38 middle and late Paleozoic (Fig. 1c), building extensive ig- vol %), biotite- hornblende-olivine norite (~30 vol %) and bi- neous complexes, including Ni-Cu ore-bearing mafic rocks otite-hornblende–dolerite (~27 vol %). The intrusion is more and postcollisional granitoids that added to the crustal growth mafic and olivine-rich at the base and more felsic toward the of Eurasia (Sengör et al., 1993; Han et al., 1997; Dobretsov top. In general, the more mafic rocks contain economic Ni- and Vladimirov, 2001). Cu ores, whereas the more felsic rocks are only weakly min- Regionally, the mafic intrusions are distributed discontinu- eralized (Figs. 2b, 3).The boundaries between these different ously astride both sides of the Irtysh fault, forming a belt rock types are transitional. Partially assimilated enclaves of about 200-km long and 10- to 20-km wide (Fig. 1c; Wang and country rocks (Nanmingshui Formation) are commonly ob- Zhao, 1991; Wang et al., 1992). All of the intrusions are within served. about 10 km of the Irtysh fault. The Ni-Cu ores-bearing Kala- The Y2 intrusion is located 400 m to the southeast of Y1. Y2 tongke mafic intrusions are located near the center of the belt is a lens-shaped body, more than 1,400 m long and 30 to 200 (Fig.1c). m wide. Its long axis strikes 300° and dips at 70° to 80° to the The Kalatongke region is characterized by a series of north- northeast. From the top to the base, the intrusion consists of west- and west-northwest–trending folds (Fig. 2a) and four biotite-rich diorite (~30 vol %), biotite-hornblende norite groups of faults, trending northwest, west-northwest, east- (~50 vol %), and biotite-hornblende-olivine norite (~20 vol west, and northeast, respectively. The northwest-striking %). The boundaries between these rock types are gradational. faults are large scale and experienced multiple stages of Two orebodies are recognized in the Y2 intrusion. One is

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Quaternary Permian volcanic rocks Carboniferous pyroclastic rocks Devonian volcanic rocks Cambrian-Ordovician sandstone and limestone Proterozoic schist

Permian granite

Mafic intrusion

Carboniferous granite

Ophiolite

Regional fault

FIG. 1. (a) Relationship of study area with the central Asian orogenic belt (modified from Jahn et al., 2000); (b) Simplified geologic map of the Junggar terrane in northern Xinjiang (modified from Chen and Jahn, 2004); (c) Regional geologic map of the southeastern Altai orogenic belt and northeastern Junggar terrane, northern Xinjiang.

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(m) A Zk36 Zk35 Zk17 Zk34 Zk157 Zk13 Zk37 B b

Zk11 Zk19 Zk27 Zk35 Zk43 Zk51 Zk59 Zk63 Zk71 Zk79 Zk87 Zk95 Zk103 (m) C D (m) E F c d

Carboniferous Outcrops of Mafic intrusion Granite porphyry slate and tuff mafic intrusion projected at the surface

Diabase dike Biotite diorite Hornblende norite Olivine norite

Sparsely Hornblende dolerite Densely disseminated ore disseminated ore Massive ore

Massive ore with extremely high Cu Fault Drill hole Anticline and syncline

Location of fig. 2b Location of fig. 2c

FIG. 2. (a) Simplified geologic map of the Kalatongke district. The stars represent the localities of the drill holes from which the samples were collected; (b) cross section of the funnel-shaped Y1 intrusion and position of disseminated and massive sulfides; (c) cross section of the Y2 intrusion showing lithological zoning and position of ore zone; (d) cross section of the Y3 intrusion and hosted orebody (after Wang and Zhao, 1991).

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FIG. 3. Column of no. ZK 168-32 drill core showing the variations of rock types, minerals and Cu, Ni and Co contents in the rocks (modified from Wang and Zhao, 1991). Abbreviations: BD = biotite diorite, BHGD = biotite-hornblende gabbro- dolerite, BHN = biotite-hornblende norite, BHON = biotite-hornblende-olivine norite.

1,000 m long and 100 m thick. It is hosted by biotite-horn- between these rock types are gradational. A stratiform ore- blende-olivine norite in the eastern part of the Y2 intrusion body of disseminated sulfides, ~1,050 m long and 20 m thick and is composed of disseminated ores. The other body occurs (Fig. 2d), occurs at the bottom of the intrusion. The main in biotite-hornblende norite and biotite-hornblende-olivine characteristics of the four rock types are illustrated in Fig. 3 norite in the western portion of the intrusion and consists of and summarized in Table 1, and the three main rock types of disseminated and massive ores (Fig. 2c). the Y1, Y2, and Y3 intrusions are described below. The Y3 intrusion is located to the southeast of Y1 and Y2. It Biotite-hornblende diorite forms in the upper part of the has a rod-like shape, and is 1,320 m long and 200 to 420 m intrusions, usually less than 90 m beneath the surface. This wide. From top to bottom, it consists of biotite-rich diorite gray-green to gray rock is fine to medium grained (2–5 mm (~60 vol %), biotite-hornblende-dolerite (~20–30 vol %), and grain size). It consists mainly of andesine-oligoclase (~60–70 biotite-hornblende norite (~10–20 vol %). The boundaries vol %), hornblende (~10–15 vol %) and secondary biotite

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(~2–10 vol %), and accessory quartz, apatite, magnetite, zircon, and sphene. The rock has a granular texture characterized by interlocking of randomly oriented hornblende and

Significant plagioclase (Fig. 4a). In addition to saussuritization, alteration minerals include carbonate, sericite, and kaolinite. Biotite-hornblende dolerite forms the base and a marginal phase at the base of the intrusions. This green-black to gray- black rock is fine to medium grained (0.2–1 mm grain size). It usually has a poikilitic texture with cumulus olivine and intercumulus feldspar (Fig. 4b). Labradorite (~30–50 vol %) and bronzite (~10–30 vol %) are the dominant minerals. Other minerals include augite (~5–10 vol %), olivine (~5–25 vol %), biotite (~3–7 vol %) and hornblende (5–10 vol %). Accessory minerals are apatite, magnetite, and ilmenite. In general, this rock contains minor sulfide minerals (pyrite and pyrrhotite). Biotite-hornblende norite occupies the middle to upper parts of the intrusions. In vertical section, this unit is funnel- shaped, becoming narrower with depth. The rock is dark gray to dark green in color, and fine to coarse grained. It has a poikilitc texture (Fig. 4c) and consists of labradorite (~30–50 vol %), bronzite (~20–30 vol %), brown hornblende (~3–15 vol %), biotite (~2–10 vol %), quartz (<5 vol %) and augite (<5 vol %). Accessory minerals are apatite, magnetite, and sphene. Alteration phases include talc, chlorite, and actinolite. The biotite-hornblende norite contains sparsely disseminated pyrrhotite, chalcopyrite, pentlandite, and minor pyrite. Biotite-hornblende-olivine norite is developed in the middle to lower parts of the intrusions. The rock is dark gray to gray black, and medium to fine grained, with a poikilitic or cumulate texture (Fig. 4d). In this rock labradorite (15–40 vol

Minerals %), bronzite (10–30 vol %), and olivine (10–40 vol %) are the main minerals, with minor brown hornblende (5–20 vol %), biotite (5–15 vol %), and augite (<3 vol %). The chemical compositions of the main minerals are listed in Table 2. Ac- cessory minerals include apatite, magnetite, and ilmenite. Pyrrhotite, chalcopyrite, pentlandite, and minor pyrite and cubanite are sparsely to densely disseminated throughout. A large proportion (~60% in volume) of the Y1 intrusion is mineralized. Economic ores (Cu >0.2 wt % or Ni >0.2 wt %: Wang and Zhao, 1991) are hosted in biotite-hornblende

1. Main Characteristics of the Four Rock Types in the Kalatongke Intrusions 1. Main Characteristics of the Four Rock Types norite and biotite-hornblende-olivine norite at depths of 550

andesine-oligoclase pyroxene, K-feldspar ilmenite, zircon, sphene to 1,000 m below the surface (Fig. 2b). The orebodies are ABLE

T both irregular and lens-shaped in vertical section and pocket- like in shape in horizontal section, steeply dipping to the northeast. The orebodies consist of massive sulfide ores surrounded by disseminated sulfide ores. The boundary between disseminated ores and massive ores is sharp, whereas that between disseminated ores and barren country rocks is unclear and often only defined by grades. In the disseminated ores, the Cu and Ni grades increase downward. In the upper parts of the weakly disseminated ores, some droplets of sulfide minerals are observed enclosed in orthopyroxene. Location in Proportion The mineralization in Y1 has a clear concentric zoning pattern, from high-grade massive ore in the center to zones of progressively more disseminated sulfides further outward (Fig. 2a). Locally, brecciated ore zones are present in areas of high-grade disseminated ore. Accordingly, the Cu and Ni contents decrease outward from the massive ores. Gold, Ag, Pt, Pd, Sc, and Te are enriched in the high-grade Cu-Ni ores. Ex- cept for some massive sulfides and moderately disseminated Rock typeBiotite dioriteBiotite-hornblende the intrusionnorite Upper Middle- (volume)Biotite-hornblende olivine norite Middle- 5 38 MajorBiotite-hornblende gabbro-dolerite Side and upper lower 29.6 bottom 27.4 Labradorite, Hornblende, Secondary Labradorite, Hornblende, biotite, Biotite, quartz, Labradorite, Apatite, magnetite, Hornblende, biotite, bronzite Accessory bronzite, olivine Apatite, magnetite, Apatite, magnetite, augite Bronzite, olivine, chlorite, Talc, quartz Sericite, uralite phlogopite, Talc, Poikilitic, gabbro Apatite, magnetite, Ophitic and augite, quartz Subhedral grained Altered Strong None Uralite, chlorite hornblende, biotite Strong Diabasic, gabbro, ilmenite, sphene ilmenite, zircon, sphene Texture ilmenite, zircon Weak serpentine, uralite cumulate sericite, actinolite and cumulate sulfides ophitic

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FIG. 4. Photomicrographs of thin sections from the Kalatongke intrusions under polarized light. (a) Granular texture characterized by interlocking of randomly oriented hornblende, biotite and plagioclase in hornblende diorite (cross-polarized light). (b) Cumulus olivine, orthopyroxene and minor clinopyroxene with intercumulus plagioclase in biotite-hornblende dolerite (cross-polarized light); (c) Poikilitic small clinopyroxene grains surrounded by large orthopyroxene grain in biotite- hornblende norite (plane-polarized light); (d) Cumulus olivine, orthopyroxene and minor clinopyroxene with intercumulus hornblende and plagioclase in biotite-hornblende olivine norite (cross-polarized light). Bi = biotite, Cpx = clinopyroxene, Hb = hornblende, Mt = magnetite, Ol = olivine, Opx = orthopyroxene, Pl = plagioclase. ore, most ores contain <1 ppm of Pt + Pd (Table 3). For the the methods of Norrish and Chappell (1977). Major elements most part, Pt and Pd concentrations correlate roughly with were measured on Siemens 303AS and 3080E spectrometers the amount of sulfide minerals. However, some Cu-Ni-poor and trace elements on VG PQ-2 Turbo and PQ-2S instru- ores have relatively high Pt and Pd contents, particularly ments. Ferric and ferrous iron measurements were deter- those with the high Se/S ratios (Table 3). mined by wet chemical method (titration). The trace element abundances were determined by inductively coupled plasma- Sampling and Analytical Methods mass spectrometry (ICP-MS) following Dulski (1994). The Twenty-eight samples were collected systematically from precision of the analyses was generally ~1 percent for major two recently drilled boreholes in Y1 and Y2 (Fig. 2). Each oxides, ~0.5 percent for SiO2, and 3 to 7 percent for trace el- sample comprises about 15 to 25 cm of core. Pieces of weath- ements. Accuracy of these methods was monitored by re- ered surfaces and altered zones were removed and washed peated analyses of standard BHVO-1. carefully in distilled water, then ground in an agate mill. The isotope ratios of Nd and Sr were measured at the Chi- Bulk-rock major and trace element compositions were de- nese Academy of Sciences following Harmer et al. (1986). termined for the powders at the Chinese Academy of Geo- 87Sr/86Sr and 143Nd/144Nd ratios were determined for whole- logical Sciences (Beijing). Major element determinations rock samples on a VG 354 mass spectrometer, and isotopic ra- were performed by X-ray fluorescence spectroscopy using tios were normalized to 145Nd144Nd = 0.7219 and 86Sr/88Sr =

0361-0128/98/000/000-00 $6.00 191 192 ZHANG ET AL. NiO Total End member 3 O 2 OCr 2 OK 2 FeO MnO MgO CaO Na 3 O 2 2. Analyses of Representative Olivine, Clinopyroxene, Orthopyroxene, Plagioclase, Hornblende, and Biotite Al ABLE T 2 TiO 2 SiO 1 Mineral Y104-3 OlOlOlY104-4 OlOlOlOl 38.08ZK157-03 37.93Ol 38.60Ol 0.01ZK157-09 n.d. 39.01Cpx n.d. 38.94Cpx 0.02 38.88Cpx 0.01 38.87 0.02Z2-2 0.03 0.02Cpx 21.57 0.02 39.47Cpx 22.85 0.01 0.03 39.14Cpx 21.19 0.01 0.32Z2-21 52.02 n.d. 0.01Cpx 19.71 0.33 50.97 0.02 n.d.Cpx 20.64 0.34 52.70 39.56Cpx 0.70 20.29 0.03 38.18 0.29Z2-32 20.36 1.10 52.78 39.72 0.02 0.31Cpx 0.79 50.83 0.06Cpx 2.86 19.04 0.30 51.95 40.62 0.06 0.28Y104-3 3.21 0.37 20.24 39.36 0.09Opx 2.55 0.61 51.13 0.02 39.48 7.62 0.29Opx 0.47 52.21 0.10 39.70 0.01 8.25Opx 1.73 0.30 52.25 0.05 0.02 7.53Opx 4.11 0.94 n.d. 41.11 0.04 0.19Opx 2.78 0.70 51.89 0.01 0.02 0.01 39.96 0.18 6.10Y104-4 0.04 53.13 0.03 n.d. 0.18 6.15Opx 3.95 n.d. 16.06 0.06 0.01 5.60Opx 3.66 0.49 54.13 n.d. n.d. 0.01 15.69 0.03 0.16z2-8 0.29 0.46 54.21 n.d. 16.64 n.d. 19.62 0.13 9.10Opx 54.13 n.d. n.d. 0.16 19.59 0.12 9.04Opx 2.85 0.28 53.80 n.d. n.d. 15.14 0.12 0.02 12.50 18.73Z2-21 3.73 0.26 54.18 0.02 15.18 0.14 0.46 99.79 0.25Opx 0.42 16.06 n.d. n.d. 0.56 23.04 99.51 0.19 7.89 1.48Opx 0.36 54.59 n.d. 0.01 0.07 0.60 10.54 100.12 0.47 22.39 1.39Y104-3 0.13 54.57 0.12 76.6 23.4 17.38 n.d. 22.20 1.60Pl 74.9 25.1 18.28 n.d. 12.53 0.10 n.d. 0.40 99.83 0.28 1.64Pl 77.0 23.0 0.31 56.82 n.d. 9.93 0.08 0.35 12.72 0.03 99.51 0.25 11.13 1.22Y104-6 0.37 54.88 13.12 0.23 0.05 11.18 99.13Pl 78.6 21.4 15.81 0.26 12.97 0.07 n.d. 0.03 23.84 99.37 17.55 1.66Pl 0.03 55.45 77.3 22.7 0.26 0.10 13.40 0.07 n.d. 1.28 2.09Pl 0.24 55.33 0.29 77.6 22.4 100.08 n.d. n.d. 1.25 19.82 29.51Pl 77.7 22.3 10.90 0.31 13.19 n.d. 0.11 0.01 29.31 99.82 0.70Y104-4 0.14 0.30 12.55 0.03 0.35 0.01 29.02 52.56 1.79Pl 79.4 20.6 0.09 99.57 0.30 0.47 0.01 1.58 29.24 52.63Pl 1.02 99.59 77.9 22.1 0.34 15.23 n.d. 0.01 1.59 29.36 99.72 1.05Pl 0.24 12.24 0.11 0.01 40.8 1.22 0.05 52.67 1.57 0.17 0.01 0.01 0.04 40.8 1.42 0.04 28.94 57.58 0.28 99.73 0.49 39.1 12.49 0.02 0.07 0.98 28.84 63.89 99.67 30.01 0.30 13.62 0.01 46.6 0.08 0.07 56.17 99.43 29.61 0.01 n.d. 0.53 45.6 0.04 47.0 1.09 0.07 23.74 0.56 48.5 0.28 n.d. 46.2 0.01 0.05 1.40 0.01 28.96 55.54 95.62 0.31 29.75 0.63 n.d. 45.3 12.4 0.10 53.56 96.98 0.47 25.89 n.d. n.d. 13.4 43.1 0.04 0.04 1.77 29.15 53.71 n.d. 99.57 12.3 23.42 26.2 43.7 0.02 n.d. 0.04 1.41 0.07 22.05 n.d. 0.63 26.86 25.5 45.7 100.03 0.05 0.06 0.01 0.52 n.d. 50.2 0.02 98.52 0.12 0.05 1.46 0.06 9.7 0.38 27.36 57.0 0.01 n.d. n.d. 0.03 5.14 9.9 n.d. 41.2 0.66 0.05 28.96 58.2 0.07 8.9 n.d. 99.88 n.d. 24.9 29.03 29.1 0.08 0.06 0.05 0.02 99.82 0.08 0.33 16.7 n.d. 0.57 0.03 11.73 0.04 45.8 99.99 n.d. 0.45 0.06 16.1 11.82 3.0 56.1 99.88 0.31 0.05 20.6 0.04 n.d. 0.02 3.0 0.08 n.d. 99.67 n.d. 0.06 4.45 0.07 11.75 12.8 2.3 n.d. 0.06 4.62 100.22 78.3 18.9 2.7 0.01 7.88 0.03 0.05 78.0 100.13 3.10 1.9 n.d. 0.04 0.17 0.04 4.25 77.9 9.23 0.01 0.10 2.1 18.7 99.05 77.9 0.01 6.74 0.02 19.0 2.7 10.38 8.55 99.95 78.1 n.d. 0.25 11.96 19.8 5.97 78.0 11.60 100.13 3.8 19.4 0.33 78.2 5.49 0.40 2.7 20.0 99.10 4.76 0.49 19.9 4.91 2.8 70.7 11.0 19.1 0.09 78.6 0.08 0.05 78.3 25.5 66.0 18.6 99.33 99.33 18.8 22.9 62.2 99.46 61.8 99.07 99.93 36.7 63.0 37.6 99.54 42.0 18.4 99.27 35.4 1.1 48.3 99.85 0.6 99.70 55.9 54.6 78.8 61.4 1.6 48.6 60.1 2.1 44.9 2.8 38.1 3.1 39.6 0.6 0.5 0.3

0361-0128/98/000/000-00 $6.00 192 GEOCHEMISTRY OF THE PERMIAN KALATONGKE MAFIC INTRUSIONS, CHINA 193 NiO Total End member 3 clase; analyses were made with Cameca CAMEBAX electron O 2 2 glass analyzed as an unknown at the Institute of Mineral Re- OCr 2 OK 2 (Cont.) 2. ABLE T FeO MnO MgO CaO Na = 3) are compared with recommended (rec) values (Wilson, 1997) = 3) are compared with recommended (rec) values (Wilson, 3 n O 2 Al 2 TiO 2 SiO 1 All oxide values are in wt percent Notes: n.d. = not detected Abbreviations: Bi = biotite, Cpx clinopyroxene, Hb hornblende, Ol olivine, Opx orthopyroxene, Pl plagioclase En, and Fs for both orthopyroxene clinopyroxene, An, Ab, Or plagio End members represent Fo and Fa for olivine, Wo, 1 Mineral ZK157-01 PlPlZ2-8 PlPlPlZ2-21 Pl 53.43Pl 52.67Y104-3 Hb 0.06 56.62Hb 0.05 56.51Z2-12 59.40Hb 28.86 0.04Hb 29.06 0.03 52.90Hb 0.03 56.73Z2-2 0.46 26.90Hb 0.48 27.37 42.29 0.02Hb 25.34 42.1 0.06Z2-8 0.02 0.42Hb 0.01 0.22 29.11 4.02 44.98Hb 0.31 26.51 44.4 4.44Z2-21 0.10 0.01 56.55 11.07Hb 0.06 n.d. 0.31 2.14Hb n.d. 0.71 11.28 42.93 10.80 2.64Y104-3 0.05 0.01 41.37 12.04 9.45Bi 0.02 0.06 6.58Bi 0.02 9.61 0.01 2.15 42.71 4.58 9.4 8.94Bi 0.61 2.85 41.91 4.48 0.04 10.71Zk157-01 0.06 9.53 11.09Bi 0.03 0.01 6.77 3.91 0.69 44.43 11.51 14.98 12.23 5.83Bi 4.6 0.21 44.08 12.00 0.09 0.04Zk157-13 5.58 11.42 10 8.40Bi 0.1 7.30 11.02 4.09 0.04 0.01 0.65 38.94Bi 14.75 11.1 3.66 4.35 0.26 39.15 0.50Bi 0 38.46 6.13 14.59 0.64Z2-8 0.02 9.44 12.74 0.21 10.74 0.62 1.78Bi 10.27 11.35 9.65 0.24 2.14 37.31Bi 10.87 3.67 0.60 36.87 14.53Z2-21 21.92 0.16 9.6 14.37 0.19 0.04 3.04 20.33 10.48Bi 0.05 14.09 4.95 37.62Bi 13.51 2.94 11.04 13.91 14.29 6.15 99.00 37.68 2.63Bi 9.51 0.24 1.04 1.4 0.01 0 10.34 99.06 38.62Bi 0.14 13.12 11.91 5.41Z2-32 11.5 11.45 13.52 1.00 57.6 2.25 14.29 5.05 38.18 0.18Bi 0.02 99.46 62.5 0.23 13.13 0.01 15.23 3.92 38.99 0.74 13.52 99.79 0.05 15.69 0.16 2.3 10.49 38.0 13.01 0.94 99.81 2.52 20.57 47.6 5.11 38.33 0.01 14.43 10.77 19.87 36.2 13.15 0.09 13.32 3.43 99.01 38.1 50.7 17.37 14.76 96.53 0.09 12.72microprobes and used Smithsonian mineral standards oxides for calibration; average measured (meas) values standard BCR- 38.77 35.8 1.79 13.5 99.22 1.15 n.d. 12.52 1.02 4.4 48.3 12.62 4.72sources, Chinese Academy of Geological Sciences ( 41.17 2.62 n.d. 14.85 13.13 96.94 63.0 1.3 0.13 10.99 46.1 n.d. 13.48 3.49 0.07 45.0 4.04 97.45 38.16 60.1 0.85 13.93 13.26 2.18 1.88 0.1 12.86 0.86 1.07 n.d. 4.1 15.79 1.75 35.5 96.96 2.42 13.07 97.52 0 15.85 1.04 3.1 13.11 51.1 13.06 4.63 0.1 4.0 12.73 0.87 7.58 16.72 0.08 0 7.73 0.74 13.18 96.73 96.84 1.03 1.5 11.97 0.01 8.94 13.23 0.11 11.57 15.49 3.8 0.57 17.78 0.06 0.01 0.01 9.2 97.06 0.1 0.06 13.76 96.74 n.d. 0.63 0.58 15.73 0.04 0.01 9.11 0 0.32 17.27 17.8 97.8 0 0.12 8.99 8.99 0 20.3 97.23 0.55 0.06 8.98 0 0.77 15.96 94.71 0 0.04 0.04 95.09 0 9.13 0.52 94.95 0.07 8.87 0 0.44 0.63 0 9.12 95.49 0.13 95.54 0.04 9.25 0.21 9.11 94.05 95.40 0.16 9.51 94.51 0.07 9.85 0.04 0.06 96.00 95.95 0.01 95.01 94.97 95.53 96.37 95.93

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TABLE 3. PGE and Other Trace Elements of Various Ore Types

Au Ag Os Ru Rh Pt Pd Se/S Ore type Cu (%) Ni (%) S (%) Se (%) (ppm) (ppm) (ppb) (ppb) (ppb) (ppm) (ppm) Cu/Ni (×10–4)

1 (6) 20.53 1.95 34.00 103.5 11.352 123.25 3.7 4.3 1.027 1.363 10.54 3.04 2(30) 4.71 3.90 31.42 51 0.252 17.865 6.3 7.2 5.3 0.223 0.195 1.21 1.62 3(27) 1.77 1.33 12.88 23.3 0.189 10.881 1.9 3.3 3.4 0.099 0.099 1.34 1.81 4(59) 1.25 0.65 5.89 11 0.269 11.025 1.6 3.5 3.9 0.096 0.115 1.92 1.87 5(3) 3.19 1.15 10.88 63 2.81 103.80 2.9 5 2.26 0.46 2.77 5.79 6(3) 1.50 0.86 9.94 51 0.14 6.99 7.1 3.8 5.3 0.12 0.14 1.74 5.13 7(60) 0.56 0.40 3.59 6.8 0.097 4.003 1.5 4.2 5 0.037 0.067 1.41 1.89 8(15) 0.49 0.21 1.94 4 0.091 4.80 0.2 0.7 1.3 0.025 0.044 2.38 2.06

Notes: 1 = massive ore with highest Cu and high Ni grade grades, 2 = massive ore with high Cu and Ni grades, 3 = densely disseminated ore with high Cu and Ni grades, 4 = moderately disseminated ore with high Cu and low Ni grades, 5 = veinlet-like ore with high Cu and Ni grades, 6 = brecciated ore with high Cu and low Ni grades, 7 = weakly disseminated ore with low Cu and Ni grades, 8 = very weakly disseminated ore with low Cu and Ni grades; numbers in parentheses represent the calculated numbers of each ore type; data were calculated from Wang and Zhao (1991)

0.1194. Repeated analyses of NIST and LaJolla Nd yielded However, the Y1 intrusion exhibits decreasing (La/Yb)n ra- averages of 0.710245 ± 0.000018 (2σ, n = 6) and 0.511870 ± tios, whereas the Y2 intrusion display the inverse variation 0.000018 (2σ, n = 6), respectively. Total chemical blanks were trend. <200 pg for Sr and <100 pg for Nd. Pb isotope ratios were de- Both the Y1 and Y2 intrusions display similar chondrite- termined on whole-rock samples on a VG MM30 mass spec- normalized rare earth element (REE) patterns with strong trometer using an optical pyrometer to monitor filament tem- light REE (LREE) enrichment and moderate heavy REE perature in order to ensure constant fractionation effects. (HREE) enrichment relative to chondrite (Fig. 7). The Oxygen measurements were performed on whole rock LREE enrichment is in the range of 23 to 58 times chondrite using the bromine pentafluoride method of Vennemann and for La. LREE are strongly fractionated from the HREE, Smith (1990). Laser fluorination of mineral separates and gas which are 4 to 8 times the chondritic values in the case of Yb purification followed the procedure described by Harris et al. and Lu. The analyzed samples show both weak negative Eu (2000). The analyses were compared with those of an internal anomalies and slightly positive Eu anomalies (Fig. 7). Com- 18 standard, calibrated relative to NBS-28 (δ OSMOW = 9.6‰), pared with other Ni-Cu sulfide deposits in China (Tang and and no data correction was needed. Almost all analyses were Ren, 1988; Tang and Barnes, 1998), the Kalatongke intrusion duplicated with analytical precision of ±0.2‰ or better, and have relatively enriched in REE and have high LREE/HREE two results for whole-rock samples from Y1 and Y2 were ratios. checked by determining the O isotope compositions of Strong incompatible element enrichment, especially in clinopyroxene. terms of large ion lithophile elements (LILE) is evident in the primitive-mantle normalized plots (Fig. 8). All rocks from the Analytical Results Y1 and Y2 intrusions display similar patterns, characterized by Representative major elements and trace elements analy- significantly negative Nb, Ta, and Ti anomalies. ses, as well as Sr, Nd, and O isotope analyses of the rock types The Y1 and Y2 intrusions have similar Sr and Nd isotope 87 86 from the Y1 and Y2 intrusions are presented in Tables 4 and compositions. The age-corrected ( Sr/ Sr)t (t = 285 Ma) ra- 143 144 5. tios range from 0.70375 to 0.70504, and ( Nd/ Nd)t ratios SiO2 abundances range from 41 to 55 wt percent, and Al2O3 vary from 0.51259 to 0.51268, with εNd(t) of +6.3 to +8.2 concentrations vary from 8 to 17.5 wt percent. The TiO2 con- (Table 5 and Fig. 9a). All Paleozoic igneous rocks in the Jung- tents are quite low (generally < 1 wt %), which is similar to gar terrane, including both extrusive and intrusive rocks, 87 86 those observed in the host rocks of other Ni-Cu sulfide de- mafic-ultramafic, and felsic rocks, have low ( Sr/ Sr)t ratios posits in China (e.g., Huangshan in Xinjiang: Zhou et al., (<0.706) and positive εNd(t) values (5–8) (Wu et al., 2000; 2004; Jinchuan, Gansu province: Lehmann et al., 2007; Hong et al., 2003; Chen and Arakawa, 2005; Zhang et al., Baimazhai, in Yunnan province: Wang and Zhou, 2006). Mg# 2008b). In general, the Sr and Nd isotope ratios of the Y1 and values, defined as atomic Mg/(Mg + Fe), vary from 0.51 to Y2 intrusions are similar to those observed in the Huangshan 0.74, and most values are lower than 0.67. High Mg# values Ni-Cu sulfide deposit, eastern Tianshan, Xinjiang (Zhou et al., 87 86 may be linked to the accumulation of olivine. 2004), but εNd(t) values are much higher and ( Sr/ Sr)t ratios Some regular variations of major and trace elements with lower than many other Ni-Cu sulfide deposits (e.g., the No- depth can be observed both in the Y1 and Y2 intrusions. In ril’sk deposit: Fig. 9b, Arndt et al., 2003; the Jinchuan deposit: the Y1 intrusion, SiO2, CaO, and FeO abundances initially in- Zhang et al., 2004; Baimazhai deposit: Wang and Zhou, 2006). 18 crease with depth and then decrease downward. TiO2 and The δ O values of the rocks from the two intrusions fall Al2O3 remain constant downward (Fig. 5). In contrast, in the into a wide range, from 5.4 to 11.0 per mil. Except for one 18 Y2 intrusion, SiO2 and CaO roughly decrease, and CaO in- sample (Z2-4), all samples have δ O values less than 7 per creases, whereas TiO2 and Al2O3 remain approximately con- mil, and. the majority of the data are within 6 and 7. In addi- stant with depth (Fig. 6). As a whole, both the Y1 and Y2 in- tion, the δ18O appears to correlate positively with (87Sr/86Sr)t trusions exhibit increasing Cr, Ni and Co contents with depth. values (Fig. 10).

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FIG. 5. Major and trace element variations of the Y1 intrusion with depth. See text for detailed interpretation.

FIG. 6. Major and trace element variations of the Y2 intrusion with depth. See text for detailed interpretation.

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TABLE 4. Whole-Rock Major and Trace Analyses of the Y1 and Y2 Intrusions

Sample no. 157-12 157-13 157-18 157-06 Y104-2 157-03 Y104-3 Y104-4 157-02 Y104-6 157-09 157-01 Z2-2 Z2-4 Intrusion Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y2 Y2 Rock PD N NB NG N ON ON ON ON N DL DL PD PD Depth (m) 15 44 84 95 106 115 132 151 165 335 346 356 144.5 275.5

SiO2 47.23 51.84 48.43 48.2 46.25 42.85 39.24 42.54 42.96 38.80 41.01 44.63 44.87 52.82 TiO2 0.89 0.79 0.66 1.10 0.91 0.79 0.69 0.80 0.81 1.10 1.09 1.14 0.72 0.67 Al2O3 11.29 9.74 17.51 11.34 10.29 7.94 7.23 8.10 9.5 10.35 11.57 12.99 12.14 13.5 Fe2O3 6.31 2.27 1.25 5.79 5.33 3.71 4.32 5.88 4.66 9.87 6.57 1.65 1.32 1.24 FeO 2.82 9.65 9.5 8.64 8.66 13.86 15.36 10.98 11.28 11.01 11.89 11.64 10.85 6.68 MnO 0.11 0.19 0.15 0.21 0.17 0.22 0.22 0.21 0.2 0.17 0.16 0.17 0.19 0.16 MgO 6.75 12.45 6.16 9.12 13.93 18.7 21.04 20.37 16.75 13.60 11.5 12.69 11.48 5.41 CaO 8.9 4.03 7.81 5.12 3.93 3.3 3.49 3.47 3.79 4.70 5.07 5.76 8.82 6.63 Na2O 1.92 2.09 3.63 2.28 2.53 1.37 1.16 1.38 1.54 1.20 2.13 1.94 1.26 3.31 K2O 0.78 1.59 0.83 1.42 0.34 1.22 0.78 1.22 1.67 1.05 1.03 1.38 1.44 1.33 P2O5 0.42 0.37 0.26 0.47 0.51 0.42 0.38 0.44 0.39 0.37 0.37 0.35 0.16 0.27 CO2 5.36 0.66 0.57 0.48 0.65 0.75 0.47 0.56 0.84 0.91 0.57 1.2 1.92 3.98 + H2O 7 2.82 2.58 3.47 3.84 3.94 2.22 2.30 4.58 3.66 4.3 4.18 4.36 4.02 Mg# 0.62 0.69 0.54 0.57 0.68 0.69 0.69 0.72 0.69 0.58 0.57 0.66 0.66 0.59 La 19.50 17.90 12.90 22.00 16.91 15.40 12.18 15.08 14.80 10.23 12.10 12.40 8.52 17.10 Ce 42.90 38.40 29.00 49.20 39.21 35.20 27.63 33.66 32.90 25.22 29.10 29.90 19.20 35.80 Pr 5.37 4.71 3.74 6.39 4.98 4.59 3.46 4.17 4.22 3.42 3.99 4.02 2.54 4.38 Nd 20.40 17.80 14.90 24.90 20.94 18.00 14.57 17.07 16.30 15.33 16.50 16.20 11.00 16.50 Sm 4.32 3.85 3.61 5.53 4.27 3.90 2.96 3.44 3.47 3.51 4.07 3.93 2.84 3.56 Eu 1.28 1.08 1.40 1.40 1.28 1.14 0.86 0.96 1.10 1.13 1.33 1.32 0.99 1.02 Gd 3.71 3.28 3.24 4.55 3.73 3.24 2.63 2.95 2.98 3.24 3.70 3.58 2.82 3.14 Tb 0.57 0.53 0.53 0.76 0.53 0.53 0.37 0.43 0.48 0.51 0.64 0.61 0.46 0.54 Dy 3.30 3.05 2.85 4.28 3.13 2.95 2.13 2.50 2.74 3.13 3.81 3.60 2.68 3.20 Ho 0.61 0.55 0.52 0.79 0.60 0.51 0.42 0.47 0.47 0.62 0.69 0.68 0.48 0.61 Er 1.63 1.53 1.43 2.15 1.76 1.44 1.19 1.40 1.33 1.77 1.86 1.90 1.34 1.75 Tm 0.24 0.22 0.20 0.30 0.24 0.20 0.16 0.19 0.18 0.25 0.27 0.26 0.19 0.25 Yb 1.51 1.47 1.25 1.93 1.60 1.27 1.05 1.26 1.22 1.61 1.75 1.72 1.21 1.68 Lu 0.23 0.23 0.19 0.31 0.24 0.20 0.17 0.19 0.18 0.24 0.25 0.27 0.18 0.28 V 128 122 192 123 101 141 164 124 110 120 111 119 201 156 Cr 739 1228 93.2 1142 2663 1096 464 566 604 200 Co 46.8 81.6 71.4 145 101 123 164 124 125 120 170 87.3 81.9 30.3 Ni 503 997 778 2162 2271 1087 3842 2326 1745 4347 3602 941 826 73 Cu 756 1616 1872 4144 5875 592 5977 2637 1786 7565 1966 1735 2420 65 Zn 95.9 131 64 154 137 141 164 145 111 113 94.2 81.5 81.2 72.9 Rb 23.1 37.4 13.8 32 4.05 22.2 13.7 20.5 33.2 16.9 17.3 33.3 38.1 26.9 Sr 411 405 851 399 333 313 330 346 478 395 505 463 293 336 Zr 130 131 82.3 152 138 110 90.4 112 119 126 141 141 58.2 121 Nb 9.51 8.58 5.84 12.8 9.06 8.82 6.10 6.72 7.91 5.80 6.87 7.37 3.88 7.11 Ba 271 444 331 417 183 350 210 318 413 227 299 275 367 339 Hf 3.06 2.98 2 3.76 3.10 2.6 1.85 2.39 2.6 2.70 3.19 3.08 1.65 2.91 Ta 0.64 0.49 0.37 1.71 0.44 0.7 0.28 0.36 0.47 0.36 0.44 0.53 0.32 0.49 Pb 15 13.3 19.9 54 27.7 11.8 29.8 14.9 12.6 75.3 19 11.4 17.1 4.22 Th 1.89 1.75 1.03 2.34 1.73 1.16 0.76 0.98 0.99 0.64 0.86 0.89 1.34 2.47 U 1.44 0.45 0.33 0.8 0.47 0.39 0.21 0.26 0.31 0.19 0.25 0.26 0.48 0.7 Y 15.9 15 13.9 20.6 16.3 14.1 11.1 12.8 13.4 16.7 18 17.8 12.7 16.4 Sc 20 19 25.1 19.6 138 11.9 90.4 112 12.9 126 15.3 16.1 40.2 22.4

Discussion O isotope data in this study reflect those of the original magmatic rocks. Alteration effects The Kalatongke intrusions were altered during postmag- The nature of the primary magma matic greenschist facies metamorphism as exhibited by their In the Kalatongke intrusions, fine-grained dolerites are high loss on ignition, although Al, Ca, Mg, K, Rb, Ba, Sr, and considered to be the chilled margins of the intrusions. How- other trace elements have not been highly modified (Fig. 8). ever, they display significantly variable compositions (Table The similar δ18O values of clinopyroxene and whole rock 4), and locally contain some digested xenoliths of the country (Table 5) suggest that the O isotope compositions also have rocks, and therefore, the dolerites probably cannot represent not changed due to alteration effects. In addition, high field primary magma. strength elements (HFSE) such as Th, Zr, Hf, Nb, Ta, Ti, Y Although it is difficult to determine the exact nature of the and REE, especially their interelement ratios, and Sm-Nd primary magma because of crustal contamination (cf. Leh- isotopes have remained unchanged. We suggest that the mann et al., 2007), we attempted to use the method of Chai εNd(t) values and the reported values of HFSE as well as the and Naldrett (1992) to estimate the nature of the primary

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TABLE 4. (Cont.)

Sample no. Z2-6 Z2-8 Z2-10 Z2-12 Z2-14 Z2-15 Z2-17 Z2-20 Z2-21 Z2-25 Z2-28 Z2-31 Z2-32 Z2-34 Intrusion Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 Y2 PD NG GN GN GN N N N N G N N N N Depth (m) 286.2 326.4 362 403 444 457 502 562.4 585 619 625.7 643 652 683

SiO2 51.74 54.79 52.31 53.29 51.55 53.18 52.85 53.61 52.57 51.17 51.36 51.98 45.85 44.07 TiO2 0.63 0.6 0.5 0.59 0.58 0.54 0.57 0.53 0.59 0.94 0.65 0.61 0.68 0.73 Al2O3 10.06 12.12 14.6 9.60 8.94 8.34 8.24 8.5 8.64 15.46 8.96 9.84 8.52 10.4 Fe2O3 1.35 1.78 1.91 3.09 1.17 3.35 3.20 1.51 3.03 2.05 3.02 2.32 11.44 6.61 FeO 9.65 7.29 6.25 6.99 11.23 7.15 7.19 9.14 7.71 5.26 7.92 9.21 7.99 11.08 MnO 0.19 0.17 0.15 0.21 0.21 0.23 0.25 0.22 0.23 0.26 0.24 0.22 0.22 0.21 MgO 11.07 8.2 9.48 15.35 14.48 16.60 16.68 16.52 16.43 2.63 15.55 12.89 10.23 10.1 CaO 4.75 6.04 4.64 3.74 3.18 3.18 3.30 3.53 3.66 11.86 4.04 3.76 4.45 3.45 Na2O 2.06 2.67 3.3 2.18 1.8 1.46 1.61 1.92 1.67 2.88 1.55 2.4 1.50 1.99 K2O 1.51 2.22 2.31 1.69 1.4 1.60 1.33 1.46 1.58 1.83 1.48 1.86 1.06 1.04 P2O5 0.31 0.29 0.18 0.29 0.25 0.24 0.29 0.22 0.26 0.38 0.27 0.24 0.28 0.38 CO2 1.42 1.38 0.66 0.47 0.3 0.30 0.30 0.75 0.74 2.49 1.18 0.93 0.12 0.22 + H2O 3.66 2.76 3.04 2.65 3.14 3.04 3.28 1.82 2.02 2.12 3.10 3.12 3.78 3.76 Mg# 0.68 0.65 0.71 0.76 0.71 0.77 0.77 0.76 0.76 0.43 0.75 0.70 0.53 0.55 La 18.6 18.3 14 14.7 16.5 12.1 13.4 13.2 13.2 20.6 14.2 16.2 13.9 21.6 Ce 39.1 38.4 28.6 32.6 34.3 25.6 28.7 27.9 28.2 42.3 30.3 33.3 29.9 44.1 Pr 4.75 4.7 3.43 4.00 4.12 3.01 3.42 3.42 3.33 5.17 3.63 3.96 3.64 5.2 Nd 17.6 17.5 12.5 16.5 15.2 12.1 13.6 12.7 13.4 21.9 14.4 14.2 14.8 18.3 Sm 3.71 3.83 2.62 3.37 3.22 2.37 2.73 2.77 2.66 4.68 2.86 3 3.07 3.59 Eu 1.09 1.15 0.9 0.91 0.92 0.64 0.69 0.79 0.75 1.57 0.78 0.86 0.82 1.11 Gd 3.23 3.28 2.38 2.99 2.73 2.12 2.43 2.32 2.43 4.42 2.62 2.51 2.73 2.93 Tb 0.49 0.54 0.37 0.44 0.44 0.32 0.35 0.38 0.35 0.67 0.38 0.4 0.40 0.45 Dy 2.92 3.02 2.06 2.60 2.48 1.92 2.05 2.21 2.08 4.12 2.27 2.48 2.43 2.39 Ho 0.55 0.57 0.38 0.51 0.45 0.38 0.42 0.4 0.42 0.83 0.46 0.43 0.47 0.43 Er 1.52 1.55 1.09 1.55 1.27 1.15 1.27 1.16 1.27 2.53 1.34 1.25 1.42 1.22 Tm 0.2 0.23 0.16 0.22 0.18 0.16 0.18 0.17 0.18 0.35 0.19 0.18 0.20 0.17 Yb 1.34 1.45 1.01 1.42 1.25 1.11 1.19 1.2 1.25 2.45 1.30 1.29 1.33 1.12 Lu 0.21 0.23 0.15 0.22 0.2 0.17 0.19 0.19 0.19 0.37 0.20 0.2 0.21 0.17 V 123 134 119 102 112 104 107 104 108 109 114 107 104 100 Cr 822 428 533 1181 1314 41.2 1257 1168 Co 83.6 48 46.5 49.1 172 53.7 52.6 55.7 52.3 30.5 52.3 59.2 157 268 Ni 729 146 209 286 971 422 407 371 359 293 447 665 5549 3026 Cu 4589 178 191 141 6394 316 226 322 362 818 608 851 3187 17480 Zn 96.3 70.1 76.1 111 117 116 129 94.6 109 75.5 118 95.5 107 140 Rb 38.8 38.4 42.1 37.6 34.9 34.9 29.0 29.6 38.4 38.1 38.5 44.2 19.7 24.2 Sr 381 442 665 352 336 289 306 329 297 671 299 409 202 301 Zr 108 124 93.5 106 108 105 105 92 100 151 107 117 115 98.1 Nb 7.79 7.46 5.86 9.49 7.41 8.42 5.75 6 6.72 13.0 7.21 8.28 8.73 8.82 Ba 442 553 744 322 428 322 297 379 291 427 306 506 322 494 Hf 2.69 2.96 2.17 2.38 2.55 2.17 2.28 2.12 2.18 3.71 2.42 2.73 2.66 2.76 Ta 0.52 0.52 0.48 0.33 0.49 0.29 0.31 0.35 0.31 0.44 0.38 0.5 0.36 0.61 Pb 23.4 6.51 6.07 6.59 26.5 7.49 8.08 7.65 10.4 11.8 22.4 9.69 8.73 76.8 Th 2.34 2.4 1.79 1.62 2.3 1.49 1.58 1.43 1.53 2.72 1.55 2.79 1.73 2.56 U 0.51 0.56 0.44 0.40 0.53 0.39 0.40 0.37 0.42 0.81 0.41 0.54 0.46 0.56 Y 14.2 15.1 10.4 14.1 12.6 10.2 11.3 11 11.6 23.5 12.3 12.1 13.2 11.4 Sc 21.9 24.2 18.8 24.4 21.1 24.0 24.5 16.1 24.0 16.1 22.2 18.7 18.8 9.99

Major element oxide values are in wt percent; trace element data are in ppm; Mg# = atomic Mg/(Mg+Fe); Abbreviations: PD = pyroxene diorite, N = norite, NG = noritic gabbro, ON = olivine norite, DL = dolerite, GN = gabbroic norite magma of the Kalatongke intrusions. The results are shown in near the line. This sample, which is a chilled margin of the Y1 Figure 11. Line OA represents the FeO/MgO ratio of a liquid intrusion, is interpreted to be close to parental melt composi- in equilibrium with olivine (Fo = 80), the most Mg-rich tion, whereas the majority of other samples represent mixtures olivines in the Kalatongke intrusion. The Mg-Fe distribution of cumulus olivine and intercumulus liquids. Analysis of sam- coefficient (KD= (FeO/ MgO)olivine/(FeO/MgO)liquid) of 0.3 ple 157-09 suggests the primary magma may have contained from Roeder and Emslie (1970) was used in the calculations. 11.5 wt percent MgO (corresponding to high Mg basalt), We assume the ratio of FeO/FeOtotal to be 0.9, which is rea- slightly lower than that of the Jinchuan intrusion (Chai and sonable for an oxidation state close to the QFM buffer. The Naldrett, 1992) and therefore it is not picritic magma. Chai average FeO value of the samples was corrected for Fe2O3 in (2006) also concluded that the primary magmas are high Mg the trapped liquid portion using the assumed FeO/FeOtotal basaltic magmas rather than picritic magmas, based on PGE ratio. The majority of the Kalatongke data plot below the ratios. However, additional sampling is required to confirm equilibrium line, and only one sample (dolerite, 157-09) falls that the primary magmas are not ultramafic.

0361-0128/98/000/000-00 $6.00 197 198 ZHANG ET AL. O 18 δ DM (t) (Ma) (‰) ε t Nd/ T Nd) 144 143 ( ) -6 σ 10 × ( 0 Samples/chondrite Nd/ 2 Nd) 144 143

FIG. 7. Chondrite-normalized rare earth element patterns of the Y1 and Nd Sm/ ( Y2 intrusions in the Kalatongke mine (normalized values are from Sun and 143 147 McDonough, 1989). All rocks have similar REE patterns characterized by LREE enrichment relative to HREE. Sm Nd (ppm) (ppm) t Sr) 86 Sr/ 87 )( -6 σ 10 5. Sr, Nd, and O Isotope Data of the Y1 Y2 Intrusions 5. Sr, × ( 0 ABLE T Sr) 86 Sr/ 87 Sr ( 87 Rb/ 87 O (‰) value of clinopyroxene grains separated from the sample; 285 Ma is used for age correction Sr and Nd isotopes 18 δ Samples/primitive mantle

FIG. 8. Incompatible element patterns normalized to primitive mantle (Sun and McDonough, 1989) for the Y1 and Y2 intrusions in the Kalatongke mine. All rocks display significantly negative Nb, Ta, and Ti anomalies and are enriched in more highly incompatible elements relative to moderately in- The data in parentheses represent the compatible ones. Sample Rb SrSample Rb 2 Z2-4Z2-6Z2-10Z2-12Z2-20 Y2Z2-21 Y2 Y2157-12 Y2157-13 26.91 Y2157-03 40.38 35.29 Y2Y104-3 328.2 Y1 31.26157-09 381.0 Y1 31.67 763.0 Y1 34.25 0.237 332.8 20.27 Y1 0.307 329.0 0.134 33.47 0.705454 Y1 281.1 0.2717 23.76 0.705133 420.7 0.704514 0.278 11.31 0.704899 404.0 20 0.3524 15.20 299.0 19 0.139 0.704877 16 0.705076 248.3 12 0.240 0.704496 0.705602523.3 0.230 0.703895 18 0.703974 0.704979 2.84 13 0.1317 0.703802 0.704801 3.07 180.0840 0.704184 2.10 0.703752 3.358 17 0.703653 0.704171 14.21 18 0.705039 2.24 15.54 11 1.888 10.97 16.356 0.704011 0.1209 18 3.78 0.703872 0.1193 0.1242 0.703652 11.38 0.1158 3.40 13.126 0.512845 0.703832 3.89 0.512814 0.51282 2.796 19.25 0.08701 0.512878 0.1191 12 16.723.34 0.512821 30 0.118718.05 13.8 0.512905 10 9 0.512615 0.1230 12 14.54 0.512854 0.512588 0.1278 11 0.512658 0.1226 0.512887 6.80.512584 0.1389 0.512656 0.512927 15 6.3 0.512837 0.512679 7.7 10 6.2 0.512948 7.6 10 0.512629 513 12 8.1 0.512654 554 435 9 10.6(11.0) 0.512653 7.1 575 0.512604 405 7.6 407 0.512684 7.5 6.6 6.6 6.0 487 5.9 8.2 454 7 5.4 409 536 5.9 427 6.8 6.1(5.9) 5.7 6.3 no. Intrusion (ppm) (ppm)

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Y1 Y2 Baimazhai Limahe

(t) Huangshan

Nd Noril’sk ε Jinchuan (t) Nd ε

87 86 87 86 ( Sr/ Sr)t ( Sr/ Sr)t

87 86 FIG. 9. ( Sr/ Sr)t versus εNd(t) diagrams showing (a) the Sr and Nd isotope compositions of the Y1 and Y2 intrusions in the Kalatongke intrusions and (b) comparison with other Ni-Cu ore-bearing intrusions. All data have been adjusted to estimated 270 Ma positions on the light of the data sources. Data sources: Huangshan (Zhou et al., 2004), Baimazhai (Wang and Zhou, 2006), Limahe (Tao et al., 2008; Li et al., 2008), Jinchuan (Zhang et al., 2004), Noril’sk (Arndt et al., 2003).

Crustal contamination and intrusive rocks and mafic-ultramafic and felsic rocks, ε The Kalatongke intrusions contain abundant orthopyrox- have positive Nd(t) values (5 to 8: Wu et al., 2000; Hong et al., ene, suggesting the magma from which the orthopyroxene 2003; Chen and Arakawa, 2005; Zhang et al., 2008b). In con- crystallized was also Si rich. Such Si- and Mg-rich magmas trast, oxygen isotope data is a useful tool to identify crustal likely formed from mantle-derived magmas by crustal conta- contamination (e.g., Kyser et al., 1986; Harmon et al., 1986- δ18 mination of a high Mg magma as invoked for siliceous high 1987; Mattey et al., 1994). Our O values range from 5.4 to Mg basalts (Arndt and Jenner, 1986; Barley, 1986; Cattell, 11.0 per mil, much higher than typical MORB (Ito et al., 1987; Skulski et al., 1988; Barnes, 1989; Sun et al., 1989; Skul- 1987) and oceanic island basalts (Kyser et al., 1982). More δ18 ski and Percival, 1996). The xenoliths of the country rocks are than half the analyzed samples lie outside the O range of supportive of such crustal contamination together with the mantle, suggesting crustal contamination. negative Nb, Ta, and Ti anomalies (Fig. 8). Other isotopic The extent of crustal contamination of the magmas that data, especially that of Nd isotope, are less conclusive because formed the Kalatongke intrusions can be estimated in two all igneous rocks in the Junggar terrane, including extrusive ways by incompatible element ratios and Sr-O isotope data. For incompatible ratios, we choose (Th/Yb)N and (Ta/Th)N (subscript N represents primitive mantle normalization: Fig. O(‰) 18 δ FeO (wt%)

87 86 ( Sr/ Sr)t

87 86 18 FIG. 10. ( Sr/ Sr)t versus δ O diagram. The curve represents simple mixing modeling results. The 87Sr/86Sr ratios and Sr contents for the pre- MgO (wt%) sumed Kalatongke parental magma are 0.702 and 50 ppm, respectively, and 0.706 and 350 ppm (Taylor and McLennan, 1995) for average continental FIG. 11. MgO versus FeO diagram for olivine and bulk rocks showing the crust. Because the granitic rocks in the Junggar terrane have low 87Sr/86Sr ra- relationship between olivine and melt compositions. The line indicates liquid tios (~0.706), we consider this value as the average Sr isotope composition of compositions in equilibrium with olivine of Mg# (Fo = 80), assuming the the crust in the area. ratio of FeO/FeOtotal to be 0.9. See the text for detailed interpretation.

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12). The former is a sensitive indicator of crustal contamina- high-degree partial melting of an unusually hot mantle source tion, whereas the latter is a good indicator of the extent of Ta (i.e., a plume: Campbell and Griffiths, 1990; Pirajno, 2000; anomaly. Compared with N-MORB and E-MORB, the Kala- Lehmann et al., 2007; Zhou et al., 2007), whereas other re- tongke rocks have lower (Ta/Th)p and higher (Th/Yb)p ratios. searchers have argued that they were derived from subconti- From Figure 12, the modeling indicates that the extent of nental lithosphere (e.g., Li et al., 2005). Two lines of evidence crustal contamination of the Kalatongke rocks ranges from 2 suggest that the Kalatongke intrusions cannot be considered to 20 percent, with the rocks from the Y2 intrusions more the expression of a mantle plume. contaminated than those from the Y1 intrusions (i.e., 9–20% versus 2–9%). For Sr and O isotope compositions, we con- 1. Magmatism related to mantle plumes is characterized sider MORB-like mantle and average Sr and O isotope com- by great volumes of mantle-derived magmas and high erup- positions of the continental upper crust as two end members. tion rates, but the Kalatongke intrusions and other nearly From Figure 10, we also conclude that the Kalatongke rocks contemporaneous mafic intrusions in the Junggar terrane are can be explained by mantle-derived parental magma contam- small (most are <2 km2). Many large Permian granitic plutons inated by 10 to 24 percent crustal material. (>100 km2) exposed in the Junggar terrane (Zhou et al., 2006) Except for two samples from the two intrusions with no- reflect significant erosion. Therefore, the small exposure of 18 87 86 tably high δ O and ( Sr/ Sr)t ratios, the isotopic and REE the mafic intrusions is likely indicative of a small volume of and trace element patterns indicate that the assimilation took mafic magmas. place before the magma was emplaced at its present level in 2. Although we cannot preclude the possibility that the 18 87 86 the crust. The two samples with high δ O and ( Sr/ Sr)t ra- magmas that formed the Kalatongke intrusions could be the tios might have been contaminated in situ because they sit at fractionated end members of more magnesian magmas that the high part of the intrusions. are poorly exposed, as pointed out above, the PGE character- As stated above, all rocks from the Kalatongke intrusions istics (Pd/Ir and Ni/Cu) suggest that the parental magma was contain variable amounts of hornblende and biotite, reflecting not ultramafic but a magnesian basalt (Chai, 2006). the high volatile contents in the parental magmas. The associa- 87 86 tion between magmatic Ni-Cu ores and volatile-rich mafic Low ( Sr/ Sr)t ratios and high εNd(t) values of the two in- magmas is relatively rare, but similar cases have been recog- trusions in the Kalatongke deposit suggest a source in the nized in the Cu-Ni ore-bearing intrusions in the eastern Tian- convecting mantle or in lithospheric mantle (cf. Wu et al., shan, e.g., Huangshan and Baishiquan intrusions (Chai, 2006). 2000; Hong et al., 2003). However, mantle metasomatism 18 87 86 Interestingly, these intrusions also have relatively high δ O val- could lead to elevated ( Sr/ Sr)t and low εNd(t) values. The ues (>6‰, Chai, 2006). Therefore, we propose that the feature high εNd(t) values (6.2–8.2) of the Kalatongke rocks suggest of volatile-rich mafic magmas in the Kalatongke intrusions that the lithospheric mantle is an unlikely source of mag- could be a consequence of crustal contamination, although we mas, but an isotopically depleted asthenospheric source is cannot preclude the possibility that this is a primary character- possible. The Sr-Nd isotope diagram shows that this source istic of magmas sourced from metasomatized lithosphere. material would have been crustally contaminated as dis- cussed above. In addition, the Zr/Nb ratios (11–22), and Sources Zr/Y ratios (4.6–10.3) similar to MORBs (Pearce and Norry, Many authors have proposed that the primary magmas 1979) further support a MORB-like source (Sato et al., that fed Ni-Cu-(PGE)–bearing intrusions formed through 2007). The presence of negative Nb-Ta and Ti anomalies in the primitive mantle normalized trace element patterns could indicate the involvement of sediments or fluids (aqueous N-MORB fluids or partial or bulk melts of subducted sediments or even the subducted crust itself: e.g., Hergt et al., 1989; Hawkesworth et al., 1997; Elliott et al., 1997; Elburg et al., E-MORB 2002). Previous studies have shown that fluids generated by N dehydration of hydrothermally altered subducted oceanic 1% crust have low 87Sr/86Sr (~0.7035), whereas subducted sediments have high 87Sr/86Sr ratios (>0.708: Hawkesworth et (Ta/Th) 5% al., 1997; Turner et al., 1997; Woodhead et al., 1998). The 10% 87 86 Continental upper crust rocks from the Y1 and Y2 intrusions have low ( Sr/ Sr)t ratios (0.70375–0.70504), suggesting that sediments were not 20% 30% 40% involved in the mantle source. Although the Kalatongke intrusions formed in a within-plate extensional setting rather than a subduction setting, a subduction event occurred dur- (Th/Yb)N ing the Devonian in the Junngar terrane which could have metasomatized the mantle (Zhang et al., 2008b). We pro- FIG. 12. (Th/Yb)N versus (Ta/Yb)N diagram for the Kalatong rocks. The pose that the parental magmas that fed the Kalatongke in- curve represents the simple mixing modeling results. E-MORB is considered to be the presumed Kalatongke parental magma, and average continental trusions were derived from a metasomatized asthenospheric crust (Taylor and McLennan, 1995) is used to represent the end member of mantle source modified by aqueous fluids during previous crust. subduction processes.

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Constraints on ore genesis to disseminated ore could be interpreted by flow differentia- One of the most important mechanism to trigger for S-sat- tion in a dynamic magma conduit, apparently a common phe- uration and formation of the immiscible sulfide melts is nomenon in igneous systems (Ross, 1986). However, Barrière crustal contamination. This process decreases the solubility of (1976), on the basis of experimental evidence, suggested that sulfide in the silicate liquid, if siliceous rocks are assimilated, flow differentiation (e.g., Bagnold effect) is not an efficient or increases the sulfur content of the silicate liquid, if sulfur- process for inward differentiation in intrusions larger than rich rocks are added. The rocks surrounding the Kalatongke 100 m in diameter. Therefore, the only other possibilities to deposit are very poor in sulfur, and the δ34S values of 65 sul- explain differentiation in the Kalatongke intrusion are gravity and convection, both of which can operate after emplacement fide samples (chalcopyrite, pyrite, and pyrrhotite) separated of the intrusion (Barrière, 1976). The funnel-shaped Kala- from the Kalatongke ores range from –0.34 to +1.84 per mil tongke intrusions have been previously interpreted as being with a peak value of +0.48 per mil (Wang and Zhao, 1991), of an Alaska type (Xiao et al., 2004; Pirajno et al., 2008). Here consistent with typical mantle value of 0 ± 2 per mil, indicat- we suggest that these intrusions can be interpreted as a con- ing no contribution of crustal S. Assimilation of siliceous duit through which both silicate melt and sulfide liquid rocks, however, is likely because some high Mg rocks also passed, and fractionated magmas formed Y4 to Y11, which in- have high SiO2 contents (more than 52 wt %). Crustal conta- truded the nearby strata. mination of basaltic magmas would lower both the contents of FeO and temperature and thus lower the S capacity of the Conclusions magma, resulting in sulfide over saturation (Wendlandt, The primary magma that fed the Kalatongke intrusions that 1982). In addition, contamination would cause an increase in host Cu-Ni sulfide deposits were derived from metasoma- fO , which might also lead to the separation of an immiscible 2 tized asthenospheric mantle modified by aqueous fluids dur- sulfide liquid (Haughton et al., 1974; Buchanan and Nolan, ing previous subduction. The magmas experienced significant 1979). Although some studies indicate that this process may crustal contamination, varying from 2 to 20 percent, but Y2 be unlikely (Mavrogenes and O’Neill, 1999), we propose that appears to be more heavily crustally contaminated than Y1. crustal contamination was a key factor leading to sulfide over The crustal contamination led to an increase of Si and a de- saturation and formation of the immiscible sulfide melts for crease of Fe in the magmas coupled with increasing oxygen the Kalatongke deposit (cf. Naldrett, 2004). fugacity, which caused S oversaturation in the magmas and Most of the world’s large intrusive Ni-Cu sulfide deposits the formation of immiscible sulfide liquids. A clear circular occur in relatively small, sill- and dikelike bodies (e.g. No- zoning pattern, from high-grade massive ore in the center ril’sk, Pechenga, Voisey’s Bay, Jinchuan, Kabanga) interpreted outward to more sparsely disseminated ores, implies that the to represent magma conduits (Naldrett, 2004; Barnes and ore formed by convection or flow differentiation in a dynamic Lightfoot, 2005). Like other Ni-Cu ore-hosting intrusions in magma conduit. the world, the total volume of all intrusions in the Kalatongke As crustal contamination is an important indicator for the area is quite small and 60 percent of the Y1 intrusion and 30 formation of Ni-Cu sulfide deposits, it is necessary to under- percent of the Y2 intrusion are mineralized. Such high sulfide stand valuable geochemical signatures of crustal contamina- contents in the intrusions are far greater than the magma tion. In the Junggar terrane, almost all igneous rocks formed could dissolve (Li and Ripley, 2005). The excess sulfides in from Paleozoic to Cenozoic times have positive εNd(t) values the Kalatongke intrusions must have been derived from a (Hong et al., 2003). Therefore, Nd isotope data are not sensi- much larger volume of magma than the intrusion itself. The tive to crustal contamination. Instead, Sr and O isotope data, geochemical variations with the depth (Figs. 5, 6) and field especially O isotopes, appear to be more useful to determine observation have suggested that both the Y1 and Y2 intrusions the crustal contamination, and enrichment of LREEs and were generated in a single magma event in a magma chamber LILEs could be complementary criteria. If this is correct, rather than by multiple magma replenishment. Hence, it is there are important implications for the exploration of the de- unlikely that the Kalatongke intrusions formed by repetitive posits similar to Kalatongke in the region because only Kala- replenishment of fresh magma into a large magma chamber. tongke intrusions host Ni-Cu ores among tens of mafic intru- An alternative possibility is that excess sulfides were provided sions in the region. by flow of magma through the system, progressively enrich- ing the sulfides in a dynamic conduit. Acknowledgments The Kalatongke orebodies have a circular zoning pattern We thank the management of the Kalatongke Cu-Ni from the high-grade massive ore in the center outward to mine for logistical support during field work at the Kala- disseminated ore, and there is a distinct boundary between tongke deposit. Dr. J. Li is acknowledged for constructive massive ore and disseminated ore. It is conceivable that the guidance in tectonic framework extended to the first author massive ore was emplaced after the disseminated ores, but (Z.C.Z.). Constructive reviews and suggestions by two we interpret these relationships to indicate that sulfide melt anonymous reviewers helped to improve the revised ver- is mobile during the late stages of magma evolution and de- sion. The editorial suggestions of Drs. Mark Hannington posited in sharp contact with other rocks. Although tectonic and Larry Meinert helped to improve the revised version. squeezing might be invoked to introduce the sulfides, the Financial support was provided by NSFC grants (4077 Kalatongke intrusions formed in an extensional setting 2045, 40572047), the 305 Project of the Ministry of Sci- rather than a compressional setting. We consider that the ences and Technology (No. 2001BA609A-07-02), 111 Pro- zoning pattern of massive sulfide ore in the center outward ject (B07011) and PCSIRT. Franco Pirajno publishes with

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