Geochronological, Petrological, and Geochemical Studies of ... · 2014). Outside China, only a few magmatic Ni-Cu sulfide deposits have been reported to occur in convergent tectonic

Geochronological, Petrological, and Geochemical Studies of the Daxueshan Magmatic Ni-Cu Sulfide Deposit in the Tethyan Orogenic Belt, Southwest China

Qingfei Wang,1 Jun Deng,1,† Gongjian Li,1 Jinyu Liu,1 Chusi Li,2 and Edward M. Ripley2

1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China2Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, Indiana 47405, USA

AbstractThe Daxueshan deposit is the first magmatic Ni-Cu sulfide deposit that has been discovered in the eastern part of the Tethyan orogenic belt, which stretches from southwest China to Turkey. Although the size of the deposit is small, containing ~0.52 million tonnes of sulfide ore with grades of 0.67 wt % Ni and 0.46 wt % Cu, it provides a unique opportunity to learn more about nickel metallogeny in arcs. The host intrusion of this deposit is com-posed of gabbro, harzburgite, and lherzolite. Sulfide mineralization occurs as disseminated and massive sulfides (pyrrhotite, pentlandite, and chalcopyrite) in the basal zone of the ultramafic rocks. Sensitive high-resolution ion microprobe U-Pb dating of zircon crystals from the gabbro yields a crystallization age of 300.5 ± 1.6 Ma. The εHf(t) values of these zircon crystals are from −2 to −11. The forsterite contents of olivine from sulfide-bearing (>0.3 wt % S) and sulfide-barren (<0.3 wt % S) ultramafic rocks are from 80 to 83 mol % and from 76 to 80 mol %, respectively. Coexisting pyroxenes are bronzite and augite. The Al/Ti ratios of augite from the Daxueshan intrusion and global arc cumulates are similar. Coeval arc basalts in the area are characterized by light rare earth element (REE) enrichments relative to heavy REEs, pronounced negative Nb-Ta anomalies, elevated initial 87Sr/86Sr ratios from 0.7065 to 0.7071, and slightly negative εNd(t) values from −0.8 to −0.3. The Daxueshan mafic-ultramafic rocks have higher initial 87Sr/86Sr ratios from 0.7116 to 0.7139, lower εNd(t) values from −5.7 and −7.1, and higher degrees of light REE enrichments. These differences can be explained by higher degrees of crustal contamination (up to 20% more) for the mafic-ultramafic intrusive rocks than the coeval basalts. The δ34S and γOs values of sulfide separates from the deposit are from −2.6 to 1.2‰ and from 28 to 482, respectively. The former are similar to the typical mantle value (0 ± 2‰), whereas the latter are significantly different from the primitive mantle value, indicating contamination with organic matter-bearing (and hence Os-rich) sedimen-tary rocks. Olivine chemistry and Sr-Nd-Hf-Os isotope data indicate that fractional crystallization and crustal contamination played a role in triggering sulfide saturation in the Daxueshan magma, although their relative significance is unclear. Like most arc-type magmatic sulfide deposits worldwide, the platinum group element (PGE) tenors of the Daxueshan deposit are extremely low, indicating a severe PGE depletion of the parental magma due to previous sulfide segregation at depth, including the lower part of the arc crust, to form sulfide-bearing, Cu-PGE–rich cumulates. This finding supports the notion that the formation of sulfide-bearing cumu-lates in the lower part of the arc crust may be a critical step in continent building or the genesis of porphyry ore deposits because new magma or volatiles may cannibalize sulfides from the previous cumulates in the pathway.

IntroductionMagmatic Ni-Cu and Pt-Pd ore deposits are associated with mafic-ultramafic rocks in a variety of tectonic settings, but available data show that intraplate settings are far more important than suprasubduction zone or convergent margin environments globally (Naldrett, 2011; Mudd and Jowitt, 2014). Outside China, only a few magmatic Ni-Cu sulfide deposits have been reported to occur in convergent tectonic settings. The most important ones are the Aguablanca Ni-Cu sulfide deposit in southwest Spain (Tornos et al., 2006) and the Giant Mascot Ni-Cu sulfide deposit in the Canadian Cor-dillera of British Columbia, Canada (Manor et al., 2016). In China, however, convergent plate tectonic settings are almost as important as intraplate environments for magmatic Ni-Cu sulfide deposits (Fig. 1). Available data show that the total Ni reserves plus production from Chinese magmatic sulfide deposits that occur in intraplate and convergent plate mar-gin settings are almost equal (Li et al., 2018). More than 90% of the total reserve plus production of Ni from the intraplate magmatic sulfide deposits in China is accounted for by one

deposit, the Jinchuan deposit (Li and Ripley, 2011). The recently discovered Xiarihamu deposit in the Kunlun orogenic belt (C. Li et al., 2015b; Song et al., 2016), the largest known subduction-related magmatic Ni-Cu deposit worldwide, accounts for more than one-quarter of the total Ni reserve plus production from those occurring in convergent tectonic settings in China. The rest of this class is mainly accounted for by those that formed 15 to 20 m.y. after the end of subduction in the Central Asian orogenic belt in northern China (e.g., Xie et al., 2012; Song et al., 2013; Y.F. Deng et al., 2014, 2015; Xue et al., 2016).

A new global nickel exploration frontier has emerged after the recent discovery of the Daxueshan magmatic Ni-Cu sulfide deposit in the eastern part of the giant trans-Asian Tethyan orogenic belt that stretches from southwest China to Turkey (Fig. 1). To date, this is the only magmatic sulfide deposit discovered in this vast orogenic belt, and the geology of this deposit has never been reported in the Western litera-ture. In this paper, we report geochronological, mineralogi-cal, petrological, and geochemical data including Sr, Nd, Hf, Os, and S isotopes for the Daxueshan magmatic Ni-Cu sulfide deposit and use them to elucidate the genetic controls on ore genesis and discuss the exploration implications.

©2018 Society of Economic Geologists, Inc.Economic Geology, v. 113, no. 6, pp. 1307–1332

ISSN 0361-0128; doi: 10.5382/econgeo.2018.4593; 26 p. 1307

† Corresponding author: e-mail, [email protected]

Submitted: January 26, 2018Accepted: August 5, 2018

Downloaded from https://pubs.geoscienceworld.org/segweb/economicgeology/article-pdf/113/6/1307/4530356/1307-1332.pdfby China University of Geosciences Beijing useron 12 December 2018

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1308 WANG ET AL.

Geologic BackgroundThe Daxueshan magmatic sulfide deposit is located in the Baoshan district, which is the northern part of the Sibumasu block that extends from the Yunnan Province of China to Thailand (Fig. 2A). The Sibumasu block is a microcontinental fragment thought to have been derived from the Gondwana supercontinent after its breakup in the Paleozoic (e.g., Met-calfe, 2013; J. Deng et al., 2014a). The Baoshan region of the Sibumasu Gondwana-derived microcontinent has commonly been referred to as the Baoshan block in the literature (Fig. 2A, B). In this region, the Baoshan block is separated from the Indochina block by the Cenozoic Chongshan shear zone to the east, and from the Tengchong block by the Cenozoic Gaoligongshan shear zone to the west (J. Deng et al., 2014b). Farther to the south, the Paleozoic tectonic suture between the Baoshan block and the Indochina block, notably the Changning-Menglian ophiolite belt, is well preserved (Fig. 2A). The ophiolites in this belt are composed of harzburgi-tes, pyroxenites, gabbros, dolerites, basalts, and marine cherts containing Middle Devonian to Middle Triassic radiolaria fossils (Feng et al., 2001). The U-Pb ages of magmatic zir-con crystals from the gabbros of the ophiolite complexes vary between 349 and 331 Ma (Duan et al., 2006). The oceanic

closure time is established to be Early Triassic in light of the high-pressure metamorphism (253–~248 Ma, 40Ar-39Ar age from the phengites in quartz schist and glaucophane in blueschist; Bi, 2014) and the subsequent emplacement of the S-type batholith along this belt (J. Deng et al., 2014a).

Rocks that are exposed within the Baoshan block are mainly late Neoproterozoic to Cambrian low-grade metamorphosed siliciclastic and carbonate rocks, Paleozoic to Mesozoic car-bonates and clastic rocks, Carboniferous to Permian volca-nic rocks (301–~282 Ma), and 502 to ~448, ~260, and 85 to ~60 Ma granitoids (Burchfiel and Chen, 2012; Yu et al., 2014; Liao et al., 2015). The Carboniferous-Permian volcanic rocks in the Baoshan block are mainly basalts and basaltic andesites. They overlie the Carboniferous Dingjiazhai Formation that is mainly composed of glaciomarine diamictites at the base and marine clastic sedimentary rocks at the top (Fig. 2D; Wang et al., 2002). Conodont fossils within this formation indicate a deposition age between Gzhelian (304–~299 Ma) and mid-dle Artinskian (287 Ma; Ueno, 2003). The conodont fossils associated with the limestones, which are interbedded with the volcanic rocks, indicate a deposition age between middle-late Artinskian (287~284 Ma) and Kungurian (284~272 Ma) (Wang et al., 2004).

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Fig. 1. The distribution of major magmatic sulfide deposits in China (after Yao et al., 2018) and the location of the newly discovered Daxueshan Ni-Cu deposit.


DAXUESHAN MAGMATIC Ni-Cu SULFIDE DEPOSIT, TETHYAN OROGENIC BELT, SW CHINA 1309

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Fig. 2. (A) Schematic map showing major continental blocks and tectonic suture zones in the region from Yunnan, China, to Thailand (modified from Sone and Metcalfe, 2008; G.J. Li et al., 2015). (B) Simplified geologic map of the Baoshan district, the northern part of the Sibumasu block (modified from Burchfiel and Chen, 2012; J. Deng et al., 2014a). (C) Occurrence of numerous Paleozoic mafic-ultramafic intrusions in the Daxueshan-Wama area (modified from Bureau of Geology and Mineral Resources of Yunnan Province, 1983). (D) Lithostratigraphic column of Carboniferous to Permian in the Baoshan district (Jin, 2002). The widely distributed basaltic rocks are coeval with the Daxueshan mafic-ultramafic intrusion that hosts the magmatic sulfide deposit (the red star).


1310 WANG ET AL.

The U-Pb ages of magmatic zircon crystals from the doler-ite dikes that intrude the Carboniferous strata in the Laoying, Banqiao, and Caojian areas in northern Baoshan (Fig. 2B) vary from 282 to 314 Ma (Liao et al., 2015, and reference therein). These dolerite dikes are considered to be coeval with the asso-ciated basalts in the region because they have similar mantle-normalized incompatible trace element patterns and the same positions in the reconstructed chronostratigraphy (Liao et al., 2015, and reference therein). Available U-Pb ages of zircon for several dikes that occur in a small area show a large age span up to ~20 m.y., and there is a lack of age progression in any particular direction (Fig. 2B). Such temporal and spatial distributions are consistent with subduction-related rather than plume-related magmatism. Another line of supporting evidence for the subduction model is that the late Carbonifer-ous to Early Permian mafic volcanic rocks are dominated by the calc-alkaline series and show pronounced negative Nb-Ta anomalies but only minor to negligible crustal contamination, indicated by whole-rock Sr-Nd isotopes (Liao et al., 2015, and reference therein).

Deposit Geology and Sample DescriptionsThe Daxueshan magmatic sulfide deposit contains ~0.52 mil-lion tonnes of sulfide ore with an average grade of 0.67 wt % Ni and 0.46 wt % Cu. It is hosted by one of many small mafic-ultramafic intrusions in the surrounding area of the Xiamai Village (Fig. 2C). The host intrusion of the Daxueshan deposit is exposed in a small area covering ~0.4 km in width and ~0.8 km in length (Fig. 3A). The country rocks include the Lower Devonian mudstone, siltstone, silty shale, and lime-stone (Fig. 3B-F). The Daxueshan mafic-ultramafic intrusion consists of a gabbroic unit to the west and an ultramafic unit to the east (Fig. 3A). The nature of the contact between these two units is unknown, mainly due to thick vegetation and the lack of drilling across the contact. The ultramafic unit dips

at 10° to 40° to the north (Fig. 3B-F). This unit is composed of harzburgite and lherzolite. Sulfide mineralization is mainly associated with the harzburgite layers within this unit (Fig. 3B-F).

Most samples used in this study were collected from the west-ern wall of an open pit (Fig. 4A) where harzburgite and lherzo-lite occur as alternating layers with thicknesses varying between 5 and 10 m. Additional samples were collected from an ore pile near the open pit. A large in situ gabbro sample for zircon U-Pb age determination was collected from a nearby creek. We also collected several Carboniferous basalt samples from the nearby Wama area (Fig. 2B) for geochemical comparison.

The lherzolite at Daxueshan contains 50 to 60% olivine, 15 to 20% orthopyroxene, and 10 to 15% clinopyroxene, with minor phlogopite and spinel (Fig. 5A). Orthopyroxene and clinopyroxene mainly occur in the interstitial spaces between olivine crystals. Spinel is mainly enclosed in olivine. Harz-burgite is composed of 55 to 60% olivine, 15 to 20% orthopy-roxene, and 1 to 5% clinopyroxene, with minor amounts of phlogopite and spinel (Fig. 5B). In sulfide-bearing harzburgite samples, rounded sulfide inclusions are present within some olivine crystals (Fig. 5C). Gabbro is composed of 40 to 50% clinopyroxene and 50 to 60% plagioclase, with minor amounts of interstitial hornblende, biotite, and Fe-Ti oxides (Fig. 5D). The basalt samples from the Wama area are characterized by an aphanitic texture, showing randomly orientated, fine-grained plagioclase, pyroxene, and Fe-Ti oxides in the matrix of devitrified and altered glass (Fig. 5E).

Sulfide mineralization in the Daxueshan intrusion occurs predominantly as disseminated sulfides, most closely associ-ated with harzburgite (Fig. 5F). In the disseminated sulfide ores, the sulfide assemblages occur in the interstitial spaces between olivine and pyroxene (Fig. 5G). Massive sulfide ores are rare (Fig. 5H) and occur in the fractures, being composed of pyrrhotite, pentlandite, and chalcopyrite.

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Fig. 3. (A) Plan view and (B-F) cross sections of the Daxueshan sulfide-bearing mafic-ultramafic intrusion (based on Guan, 2010).



Analytical MethodsZircon crystals separated from a large gabbro sample (DXS-60) were mounted in epoxy resin discs and polished. Cath-odoluminescence and backscattered electron images were used to select grains or areas free of microfractures, inherited core and overgrowths, and lack of secular compositional zon-ing for U-Pb age determination and Hf isotope analysis by in situ methods. Zircon U-Pb age determination was undertaken using a sensitive high-resolution ion microprobe (SHRIMP-II) in the Beijing Center of the National Science and Tech-nology Infrastructures of China. The analytical conditions and operation procedures are similar to those described in Williams et al. (1998). A primary O2– ion beam with 4.5- to 6.5-nA beam current, 10-kV accelerating voltage, and 20-μm beam size was used. TEM standard zircon crystals (206Pb/238U = 0.0668, age = 416.8 ± 0.24 Ma, recommended by Black et al., 2003) were interspersed between every three analyses to determine the elemental discrimination and to correct the iso-topic fractionation, which occurred during sputter ionization.

Data reduction and plotting were carried out using the Isoplot software of Ludwig (2003).

Zircon Hf isotopes were determined using a Neptune Plus multicollector-inductively coupled plasma-mass spectrom-eter (MC-ICP-MS, Thermo Fisher Scientific Instrument) in combination with a Geolas 2005 excimer ArF laser ablation system in the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, China. The instrument operating conditions and ana-lytical procedures are the same as those described in Hu et al. (2012). Off-line data reduction was carried out using the ICPMSDataCal software of Liu et al. (2008).

The chemical compositions of rock-forming minerals were determined by wavelength-dispersive X-ray analysis using a CAMECA SX50 electron microprobe at Indiana University. The analytical conditions were 15-kV accelerating voltage, 20-nA beam current, 1-μm beam size, and 20-s peak-counting time. Nickel and Ca in olivine were analyzed using a beam current of 100 nA and a peak-counting time of 50 s. The detection limits for Ni and Ca under these conditions are 100 and 50 ppm, respectively.

Whole-rock chemical compositions were analyzed in the Ministry of Education’s Key Laboratory of Western Mineral Resources and Geological Engineering at Chang’an Uni-versity, Xi’an, China. Major element concentrations were measured on fused glass disks of powdered samples using a wavelength X-ray fluorescence spectrometer (XRF-1800). Trace element contents were determined using an Agilent 7700E ICP-MS on solutions obtained from samples that were dissolved in high-pressure Teflon bombs using an HF + HNO3 mixture for 48 h at ~190°C. Sulfur abundances in the sulfide-mineralized rocks were determined using a Vario EL2 elemental analyzer at the Institute of Geology and Min-eral Resources, Xi’an, China. The Ni, Cu, and Co concentra-tions were determined by ICP-atomic emission spectroscopy (AES) in the SGS Mineral Laboratory, Tianjin, China. The concentrations of platinum group elements (PGEs) in these samples (DXS-33 to -39 and BS-1 to -10) were determined by a combination of NiS-bead preconcentration and Te coprecip-itation, followed by ICP-MS analysis in the National Research Center for Geo-Analysis, Beijing, China. The PGE contents of samples from DXS-40 to -56 were determined in the State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, using the method of Qi et al. (2011).

Whole-rock Rb-Sr and Sm-Nd isotopes were determined using a Thermo-Finnigan TRITON thermal ionization mass spectrometer and a Micromass Isoprobe MC-ICP-MS, respectively, at the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences. Sample preparation, ana-lytical procedures, and data reduction are the same as those described in Li et al. (2004). Instrumental mass fractionations were corrected by normalizing the measured 87Sr/86Sr and 143Nd/144Nd to 0.1194 and 0.7219, respectively.

Whole-rock Re-Os isotopes were determined using a Thermo-Finnigan TRITON thermal ionization mass spec-trometer at the Guangzhou Institute of Geochemistry, Chi-nese Academy of Sciences. About 2 g of sample powder (spiked with 190Os and 185Re), 2.5 ml of concentrated HCl, and 7.5 ml of concentrated HNO3 were frozen in a Carius

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Fig. 4. (A) Photo of open pit and (B-E) spatial variations of olivine forsterite Ni contents and whole-rock Ni-Cu-S contents across the western wall of the open pit. WR = whole rocks.


1312 WANG ET AL.

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Fig. 5. Microphotographs of rock and ore samples from the Daxueshan magmatic sulfide deposit and the Wama basalt: (A) lherzolite, (B) harzburgite, (C) sulfide inclusion in olivine in harzburgite, (D) gabbro, and (E) basalt. Representative sulfide-mineralized samples: (F) photograph of hand specimen of the disseminated sulfide, (G) microphotograph of patchy sulfide, and (H) microphotograph of massive sulfide. Mineral abbreviations: Ccp = chalcopyrite, Cpx = clinopyroxene, Ol = olivine, Opx = orthopyroxene, Pl = plagioclase, Pn = pentlandite, Po = pyrrhotite.



tube, and then sealed and heated to 240°C for 24 to 48 h. Upon opening the Carius tube, carbon tetrachloride was added and Os was extracted from the aqueous phase. Osmium was finally purified by microdistillation. Rhenium was sepa-rated and purified by anion exchange using AG1X8 resin (100–200 mesh). Osmium was loaded onto a preheated Pt filament. Isotope abundances in OsO3

− were measured using a TRITON mass spectrometer. Instrumental mass fractionation of Os was corrected by normalizing the measured 192Os/188Os ratio to 3.08271 (Luck and Allègre, 1983).

Sulfides in the mineralized samples were separated from the samples by microdrilling. The sulfide separates were then analyzed for S isotopes using a Finnigan Delta V stable isotope ratio mass spectrometer at Indiana University, following the analytical procedures described in Studley et al. (2002). The results are reported in standard delta notation, δ34S = [(34S/

32S)sample/(34S/32S) standard) − 1], and given as ‰ values on the Vienna-Canyon Diablo Troilite (V-CDT) scale via multiplica-tion by 1,000. Sulfide standards used were IAEA-S1, IAEA-S2, and IAEA-S3, with values of −0.3, 21.7, and −31.3‰, respectively, on the SO2 scale. Analytical uncertainty was less than ±0.05‰, and sample reproducibility was within ±0.2‰.

Analytical Results

Zircon U-Pb age and Hf isotopes

U-Th-Pb data for zircon from the gabbro of the Daxueshan mafic-ultramafic intrusion are listed in Table 1. The cathodo-luminescence images of the selected zircon crystals and the concordia U-Pb isotope plot are illustrated in Figure 6A and B, respectively. As shown in Figure 6B, the results from 16 selected grains yield a concordia U-Pb isotope age of 300.5 ±

Table 1. U-Th-Pb Data for Zircon from Gabbro (DXS-60) of the Daxueshan Mafic-Ultramafic Intrusion

U Th Pb 207Pb/206Pb 206Pb/238UGrain no. (ppm) (ppm) (ppm) Th/U 207Pb/206Pb 1σ 206Pb/238U 1σ (Ma) 1σ (Ma) 1σ

1 248 2,214 11 9 0.0500 10 0.0477 2 193 237 300 7 2 227 3,339 9 15 0.0503 8 0.0471 2 207 185 297 7 3 1,063 10,290 44 10 0.0519 1 0.0481 2 283 30 303 6 4 1,088 4,239 44 4 0.0511 2 0.0468 2 245 41 295 6 5 1,692 9,304 70 5 0.0519 1 0.0483 2 283 24 304 6 6 351 2,269 14 6 0.0502 4 0.0467 2 204 95 294 6 7 2,485 16,628 102 7 0.0519 1 0.0476 2 281 26 300 6 8 1,905 4,223 80 2 0.0520 1 0.0485 2 286 23 305 6 9 314 4,142 13 13 0.0510 2 0.0465 2 240 57 293 710 1,833 4,825 73 3 0.0520 1 0.0466 2 287 28 293 611 2,651 6,629 112 3 0.0505 4 0.0487 2 219 86 306 612 3,223 6,052 137 2 0.0530 1 0.0493 2 327 25 310 613 3,303 10,525 142 3 0.0529 2 0.0491 2 324 50 309 614 2,383 8,874 101 4 0.0523 8 0.0481 2 297 190 303 715 3,434 9,020 141 3 0.0509 7 0.0469 2 236 155 295 716 2,528 5,935 107 2 0.0537 2 0.0488 2 357 40 307 7

20

6Pb

/ 23

8U

207Pb / 235U

Gabbro

0.042

0.044

0.046

0.048

0.050

0.052

0.22 0.26 0.30 0.34 0.38 0.42

280

300

320

270

290

310

330

Concordia Age=300.5±1.6 MaMSWD=1.7 (2σ, n=16)

Probability=0.20

B

294.6±6.1

302.7±6.4

300.6±7.1

296.6±6.9

293.3±6.7299.7±6.3 305.2±6.4

294.5±6.4304.3±6.3

293.4±6.3 306.5±6.5295.4±7.2 307.1±6.8

303.0±6.7308.8±6.5310.3±6.5

100 μm U-Pb age spot (25 μm)

304.3±6.3 206Pb/238U age (Ma)

A

Fig. 6. (A) Cathodoluminescence images of the dated zircon crystals from the Daxueshan gabbro (DXS-60). (B) Concordia plot for the dated zircon crystals.


1314 WANG ET AL.

1.6 Ma, which is within the range of the dated dolerite dikes in the region (Fig. 2B). Lu-Hf-Yb data for the selected zircon crystals from the gabbro of the Daxueshan mafic-ultramafic rocks are listed in Table A1. The calculated εHf (t) values of the selected zircon crystals vary from −11 to −2 (Fig. 7).

Mineral compositions

The average compositions of olivine, Cr spinel, pyroxenes, and plagioclase from the Daxueshan mafic-ultramafic intru-sion are listed in Table A2. The spatial variations of olivine compositions are illustrated in Figure 4B and C. On average, the forsterite and Ni contents of olivine in the sulfide-bearing harzburgite layers are significantly higher than those of oliv-ine found in associated sulfide-barren (no visible sulfide or containing <0.3 wt % S) lherzolite layers. The former con-tain olivine with 79 to 81 mol % forsterite and 850 to 1,300 ppm Ni, whereas the latter contain olivine with 77 to 79 mol % forsterite and 460 to 650 ppm Ni. With the exception of one sample, the forsterite content of olivine in the lowermost lherzolite layer decreases toward the basal contact with sedi-mentary rocks (Fig. 4B). The forsterite and Ni contents of olivine in two sulfide-barren harzburgite samples are within the ranges of olivine in all of the sulfide-barren lherzolite samples, with one exception: DXS-45 (forsterite = 80 mol %, Ni content = 400 ppm; Fig. 8). Olivine crystals in the sulfide-bearing samples are characterized by variable Ni contents, consistent with variable extent of Fe-Ni exchange between olivine and trapped sulfide liquid at the sample scale (Fig. 8).

Cr spinel inclusions enclosed in olivine in the Daxueshan harzburgite and lherzolite contain 14.7 to 19.5 wt % Al2O3, 39.5 to 42.9 wt % Cr2O3, and 6.2 to 8.1 wt % MgO, with Mg# [100 × Mg/(Mg + Fe2+), molar] varying from 30 to 38 and Cr# [100 × Cr/(Cr + Al), molar] varying from 58 to 66 (Table A2). The anorthose contents of plagioclase in Daxueshan lherzolite and gabbro are 64 to 83 mol % and 66 to 74 mol %, respec-tively (Table A2). Orthopyroxene crystals in the Daxueshan ultramafic rocks are all bronzite (Fig. 9A). Their Mg numbers

-40

-30

-20

-10

0

10

20

0 1000 1500500

Depleted Mantle

Chondrite

Cru

stal

con

tam

inati

on

10%

30%

Zircon U-Pb age (Ma)

ε H

f (t)

Baoshan detrital zircons

Gabbro from Daxueshan

Fig. 7. Hf isotopes of the dated zircon crystals with a concordia age of 300.5 ± 1.6 Ma from the Daxueshan gabbro. The detrital zircon data for the Baoshan block are from D.P. Li et al. (2015).

0

400

800

1200

1600

2000

2400

7677787980818283

Oliv

ine

Ni c

onte

nt (

ppm

)

Sulfide-bearing harzburgite

Olivine Fo content (mole %)

Sulfide-barren harzburgiteSulfide-barren lherzolite

Fig. 8. Comparison of olivine forsterite and Ni contents between sulfide-bearing and sulfide-barren ultramafic rocks in the Daxueshan intrusion.

0

2

4

6

8

10

12

14

16

0 2 31

Mid-Atlantic ridge magmatic cumulates

Duke Island Complex

Trend of arccumulates

Emei

shan

LIP

Alas

ka C

ompl

ex

Trend of rift

cumulates

Alkaline

Peralkaline

Al z in

Cpx

TiO2 (wt%) in Cpx

B

augite

bronzite hypersthene

hedenbergitediopside

LherzoliteCpx in

Opx in

HarzburgiteGabbro

LherzoliteHarzburgite

En

Wo

Fs

20

40

20 40 60 80

A

Fig. 9. (A) Classification of pyroxenes in the Daxueshan mafic-ultramafic intrusion. (B) Compositional comparison of clinopyroxene (Cpx) in the ultra-mafic intrusive rocks that occur in different settings: arc cumulates (Xie et al., 2012; C. Li et al., 2015b), Duke Island Complex and Alaska Complex (Thakurta et al., 2008), rift setting (Barnes and Kunilov, 2000), Emeishan large igneous province (LIP; Tao et al., 2008; Bai et al., 2012; Tang et al., 2013; Wang et al., 2014), and Mid-Atlantic Ridge (Loucks, 1990). En = enstatite, Fs = ferrosilite, Wo = wollastonite.



are between 81 and 84 (Table A2). Clinopyroxene crystals in the Daxueshan mafic-ultramafic intrusion are all augite (Fig. 9A). The enstatite contents of augite crystals in the gabbro are 48 to 49 mol % (Table A2). The enstatite contents of augite crystals in the ultramafic rocks are clearly higher, varying from 50 to 57 mol %. The Al/Ti ratios of the augite crystals in the Daxueshan mafic-ultramafic intrusion are significantly differ-ent from those in rift or plume-related cumulates but similar to those in arc cumulates elsewhere in the world (Fig. 9B).

Whole-rock major and trace elements

The concentrations of major and trace elements in the Dax-ueshan mafic-ultramafic intrusion, siltstones, and the Carbon-iferous basalts in the nearby Wama area are listed in Table A3. A comparison of major element compositions between the intrusive and volcanic rocks is illustrated in Figure 10. In this diagram, the whole-rock compositions are normalized to 100% on a loss on ignition-free basis, and sulfide-bearing sam-ples are excluded. It shows that the gabbros and basalts have similar major element compositions. In contrast, the ultra-mafic rocks have significantly higher MgO and FeO coupled with lower SiO2, which is consistent with the effect of abun-dant cumulus olivine in the ultramafic rocks.

The mantle-normalized immobile incompatible trace ele-ment patterns for the Daxueshan mafic-ultramafic intrusion and nearby basalts are illustrated in Figure 11A. The trace element abundances and patterns of the basalts and gabbros are similar, and they are comparable with those of continental

arc basalts (C. Li et al., 2015a) but significantly different from those of ocean-island basalts (C. Li et al., 2015a), notably for Nb and Ta. The incompatible trace element abundances in the Daxueshan ultramafic rocks, especially the harzburgites, are much lower than those in the associated gabbros and basalts, consistent with the presence of abundant cumulus minerals in these rocks. Like the associated gabbros and basalts, the Daxueshan ultramafic rocks are also characterized by pro-nounced negative Nb-Ta anomalies, similar to arc-related mafic-ultramafic intrusions—for example, Lengshuiqing (Yao et al., 2018), Qingmingshan (Zhou et al., 2017), Xiarihamu (C. Li et al., 2015b), and Heishan (Xie et al., 2014) in China, and Aguablanca (Tornos et al., 2006) in Spain (Fig. 11A). In the plot of Th/Yb vs. Nb/Yb (Fig. 11B), the Wama basalt plots within the field of continental arc basalts, and all of the sam-ples from the Daxueshan mafic-ultramafic intrusion plot on a mixing line between the Wama basalt and the Lower Devo-nian siltstones near the Daxueshan intrusion.

Sr-Nd-Os-S isotopes

Sr-Nd isotopes of the Daxueshan mafic-ultramafic intrusion, Lower Devonian siltstones, and the Wama basalts are listed in Table 2. A comparison between the intrusive rocks and basalts is illustrated in Figure 12. The Daxueshan mafic-ultramafic intrusive rocks have εNd (t = 300 Ma) values from −7.1 to −5.7 and initial 87Sr/86Sr ratios from 0.7116 to 0.7143. The Wama basalts have higher εNd (t = 300 Ma) from −0.8 to −0.3 and lower initial 87Sr/86Sr ratios from 0.7065 to 0.7071. The isotopic

0

5

10

15

20

0 10 20 30 40 50

Opx

Cpx

Ol

Pl

CaO

(wt%

)

MgO (wt%)

D0

5

10

15

20

25

Opx

Cpx

Ol

Fo=76.4

Fo=82.5

Pl

FeOT (w

t%)

B

0

5

10

15

20

25

30

0 10 20 30 40 50

CpxOl

Pl

Opx

Al 2

O3 (

wt%

)

MgO (wt%)

C35

40

45

50

55

60 A

Opx

Ol

PlCpx

SiO

2 (w

t%)

Wama basalts

HarzburgiteLherzolite

Gabbro

Fig. 10. Compositional comparison between the Wama basalts, the Daxueshan mafic-ultramafic intrusive rocks, and the major rock-forming minerals. Cpx = clinopyroxene, Fo = forsterite, Ol = olivine, Opx = orthopyroxene, Pl = plagioclase.


1316 WANG ET AL.

compositions of the Wama basalts are not significantly different from those of the primitive mantle. They plot only slightly off to the right of the oceanic mantle array (Fig. 12). The Daxue-shan mafic-ultramafic intrusive rocks plot on the mixing line between the Wama basalts and Lower Devonian siltstones.

Re-Os isotopes of the mafic-ultramafic intrusion and the Wama basalt are listed in Table 3. The γOs values (t = 300 Ma) are 28 to 67 for two gabbro samples and 58 to 482 for seven lherzolite samples, which are all significantly higher than the primitive mantle value. Sulfur isotopes of the Daxueshan magmatic sulfide deposit are listed in Table 4. The sulfide-mineralized lherzolite sample (DXS-04) is characterized by a negative δ34S value (−2.62‰). The six sulfide-mineralized harzburgite samples all have positive δ34S values from 0.16‰ to 1.20‰, which are not significantly different from mid-oce-anic-ridge basalt (MORB) values (−1.57–+0.60‰, Labidi et al., 2013).

Chalcophile elements

The concentrations of chalcophile elements in the Daxueshan magmatic sulfide deposit and associated basalts are listed in Table 5. The listed Ni concentrations have been corrected for contribution from olivine. The correction was made using the average Ni contents of olivine in the samples and the abun-dances of olivine in the samples estimated from thin section observation. The chalcophile metals show positive correla-tions with S contents in whole rocks (Fig. 13).

Using the equation of Barnes and Lightfoot (2005), where it is assumed that pyrrhotite, chalcopyrite, and pentlandite with Ni/Fe = 1 are the original magmatic sulfide assemblage, we have estimated the Ni, Cu, and PGE tenors (recalculated to 100% sulfides) in the sulfide-bearing samples (>0.3 wt % S) from the Daxueshan magmatic sulfide deposit. The mantle-normalized patterns of the metal tenors in the bulk sulfide ores of this deposit are illustrated in Figure 14A. Like other arc-type magmatic sulfide deposits in China, such as Xiari-hamu (Song et al., 2016), Lengshuiqing (Yao et al., 2018), Qin-gmingshan (Zhou et al., 2017), and Heishan (Xie et al., 2014), the Daxueshan deposit is also characterized by depletions in PGEs relative to Ni and Cu, and fractionation between Ir and

Baoshan granites

DXS intrusion

CAB

MORB

Th/Y

b

Nb/Yb

30%

OIB

0.1 1001010.01

0.1

1

10BLower Devonian

Siltstone

LherzoliteHarzburgiteGabbroWama basalts

Sam

ple/

Prim

itive

man

tle

1

10

100

Th Nb Ta La Ce Nd Zr Hf Sm Gd Y Yb Lu

A Arc-related (ultra)mafic intrusion

Heishan

AguablancaQingmingshan

LengshuiqingXiarihamu

OIB

CAB

Fig. 11. (A) Mantle-normalized trace element patterns of the Daxueshan mafic-ultramafic intrusive rocks (the normaliza-tion values are from Sun and McDonough, 1989). The data for Lengshuiqing, Qingmingshan, Heishan, Xiarihamu, and Aguablanca are from Yao et al. (2018), Zhou et al. (2017), Xie et al. (2014), C. Li et al. (2015b), and Tornos et al. (2006), respectively. (B) Comparison of whole-rock Nb/Yb and Th/Yb between the Wama basalt, the Daxueshan mafic-ultramafic intrusive rocks, and the Baoshan crustal rocks. The average values of oceanic island basalts (OIB), continental arc basalts (CAB), and mid-ocean-ridge basalts (MORB) for comparison are from C. Li et al. (2015a).

Oceanic m

antle

Baoshan crust

(87Sr/86Sr)i

-10

-5

0

5

0.7 0.71 0.72 0.73

ε N

d (t

)

-15

10%

30%

20%

Crustal contamination

Xiarihamu

Lower Devonian Siltstone

Wama basalts

HarzburgiteLherzolite

Gabbro

Baoshan granites

Lower crust

Fig. 12. Plot of whole-rock 87Sr/86Sr vs. εNd(t) for the Daxueshan mafic-ultra-mafic intrusive rocks and the Wama basalts. The mantle array is from Zindler and Hart (1986). Data for the Xiarihamu deposit are from Zhang et al. (2017). The elemental and isotopic compositions of the crustal end member are based on the results from Rudnick and Gao (2003) and the Lower Devonian siltstones in this study, respectively. Parameters for mantle-derived magma: Sr = 90 ppm and Nd = 7.3 ppm (Sun and McDonough, 1989), 87Sr/86Sr = 0.7065 and εNd(t) = 0.29 (the Wama arc-like basalt). Lower crust: 87Sr/86Sr = 0.7096, εNd(t) = −20.6 (Rudnick and Gao, 2003). The Baoshan crust is repre-sented by the S-type granites (Chen et al., 2007; Wang et al., 2015).



Tabl

e 2.

Sr-

Nd

Isot

opes

of t

he D

axue

shan

Mafi

c-U

ltram

afic

Intr

usio

n, S

iltst

ones

, and

the

Wam

a B

asal

ts

Rb

Sr

Sm

Nd

Sam

ple

no.

Roc

k ty

pe

(p

pm)

87

Rb/

86Sr

87

Sr/86

Sr

(87 S

r/86

Sr) i

(ppm

)

147 S

m/14

4 Nd

143 N

d/14

4 Nd

ε Nd

DX

S-02

L

herz

olite

32

.95

136.

35

0.69

732

0.71

6161

0.

7131

841

2.58

10

.46

0.14

8988

56

0.51

2205

26

–6.6

2D

XS-

03

Lhe

rzol

ite

28.6

3 10

7.66

0.

7674

6 0.

7160

26

0.71

2749

1 2.

32

9.50

5 0.

1475

0427

0.

5122

1003

–6

.47

DX

S-04

L

herz

olite

22

.06

115.

12

0.55

313

0.71

5936

0.

7135

749

1.98

7.

941

0.15

0963

37

0.51

2199

62

–6.8

DX

S-06

L

herz

olite

28

.91

113.

34

0.73

606

0.71

6173

0.

7130

31

2.12

8.

832

0.14

5060

27

0.51

2199

55

–6.5

8D

XS-

07

Lhe

rzol

ite

23.6

6 89

.468

0.

7630

8 0.

7162

46

0.71

2988

1 2.

03

8.40

4 0.

1458

3767

0.

5122

0598

–6

.48

DX

S-09

L

herz

olite

23

.09

99.3

82

0.67

044

0.71

5882

0.

7130

2 1.

98

8.00

5 0.

1497

0961

0.

5122

0062

–6

.74

DX

S-11

L

herz

olite

22

.49

129.

35

0.50

18

0.71

5738

0.

7135

954

1.79

7.

294

0.14

8356

79

0.51

2193

96

–6.8

1D

XS-

13

Lhe

rzol

ite

27.3

3 10

9.47

0.

7205

9 0.

7169

35

0.71

3858

8 2.

12

8.69

6 0.

1476

7413

0.

5121

9542

–6

.76

DX

S-15

L

herz

olite

27

.82

143.

11

0.56

109

0.71

6104

0.

7137

088

1.93

7.

978

0.14

6688

45

0.51

2196

32

–6.7

DX

S-17

L

herz

olite

25

.13

101.

93

0.71

146

0.71

6367

0.

7133

296

2.29

9.

351

0.14

8014

82

0.51

2194

46

–6.7

9D

XS-

18

Lhe

rzol

ite

33.4

8 92

.65

1.04

289

0.71

6888

0.

7124

357

2.22

8.

948

0.15

0186

5 0.

5122

0577

–6

.65

DX

S-19

L

herz

olite

22

.06

97.5

82

0.65

243

0.71

6465

0.

7136

797

1.82

7.

622

0.14

4518

81

0.51

2175

3 –7

.03

DX

S-22

L

herz

olite

15

.3

44.6

0.

9900

4 0.

7158

19

0.71

1592

5 1.

57

6.41

1 0.

1483

4815

0.

5122

19

–6.3

3D

XS-

24

Lhe

rzol

ite

20.2

70

.9

0.82

225

0.71

5467

0.

7119

572

2.15

9.

169

0.14

1863

89

0.51

2218

–6

.1D

XS-

30

Har

zbur

gite

22

.18

41.5

63

1.54

031

0.71

9164

0.

7125

883

2.04

8.

433

0.14

6238

36

0.51

2202

35

–6.5

7D

XS-

32

Har

zbur

gite

24

.4

55.5

57

1.26

733

0.71

7969

0.

7125

586

2.04

8.

19

0.15

0405

96

0.51

2183

89

–7.0

9D

XS-

57

Gab

bro

46.9

30

0.29

0.

4507

1 0.

7162

3 0.

7143

058

3.41

13

.49

0.15

2996

8 0.

5122

5733

–5

.76

DX

S-58

G

abbr

o 39

.82

292.

7 0.

3926

4 0.

7158

19

0.71

4142

9 3.

4 13

.46

0.15

3027

6 0.

5122

565

–5.7

7D

XS-

59

Gab

bro

35.2

9 23

9.55

0.

4251

3 0.

7152

7 0.

7134

547

3.38

13

.74

0.14

8647

01

0.51

2242

18

–5.8

8D

XS-

60

Gab

bro

43.6

1 25

9.77

0.

4844

6 0.

7160

74

0.71

4005

3 3.

33

13.2

3 0.

1520

2334

0.

5122

5818

–5

.7D

XS-

61

Gab

bro

54.9

29

4.8

0.53

72

0.71

6 0.

7137

3.

5 14

0.

1521

0.

5122

5 –5

.8D

XS-

62

Gab

bro

43.5

30

1.3

0.41

65

0.71

77

0.71

59

2.8

11.1

0.

1552

0.

5122

8 –5

.5D

XS-

63

Silts

tone

15

7.2

164.

43

2.75

994

0.73

6576

0.

7247

936

8.61

44

.69

0.11

6533

69

0.51

1765

–1

4D

XS-

64

Silts

tone

17

6.9

113.

16

4.51

125

0.74

5478

0.

7262

191

7.87

44

.13

0.10

7894

6 0.

5117

64

–13.

7W

ama

WM

-01

Bas

alt

28.6

9 30

7.23

0.

2695

0.

7076

1 0.

7065

3.

04

12.2

7 0.

15

0.51

2531

–0

.3W

M-0

2 B

asal

t 17

.68

278.

84

0.18

3 0.

7078

61

0.70

71

3.48

12

.51

0.16

81

0.51

2569

–0

.3W

M-0

3 B

asal

t 16

.14

189.

85

0.24

53

0.70

7775

0.

7067

3.

78

15.1

3 0.

1511

0.

5125

06

–0.8

Not

e: I

nitia

l iso

tope

rat

ios

and

ε Nd

wer

e ca

lcul

ated

usi

ng th

e fo

rmat

ion

age

of 3

00 M

a


1318 WANG ET AL.

Ru (IPGEs) and Rh, Pt, and Pd (PPGEs)—i.e., depletions in IPGEs relative to PPGEs (Fig. 14A).

A comparison of mantle-normalized chalcophile element patterns between the Daxueshan magmatic sulfide deposit and the associated Wama basalts is illustrated Figure 14B. The PGE patterns of the deposit and associated basalts are remarkably similar, although the basalts do not show PGE depletions relative to Cu and Ni (Fig. 14B) as the deposit does (Fig. 14A). Like other known PGE-undepleted arc basalts worldwide (Woodland et al., 2002; Park et al., 2012, 2013), the Wama basalts are characterized by fractionated PGE pat-terns, showing IPGE depletions relative to PPGEs (Fig. 14B).

Discussion

Oxidation state

We have used the method of Barnes et al. (2013) to estimate the oxidation state of the Daxueshan magmatic sulfide deposit. This method is based on the relationship between KDolivine-

sulfide [(XNiS/XFeS) sulfide liquid/(XNiS/XFeS) olivine, molar], Ni content in the sulfide liquid, and the oxidation state, which was ini-tially described by Brenan (2003). The analytical results for four sulfide-bearing lherzolite samples from the Daxueshan deposit (DXS-39, DXS-44, DXS-54, DXS-56) yield values between quartz-fayalite-magnetite (QFM) +0.2 and QFM +1.2 (i.e., log fO2 1.2 units higher than the value of the QFM buffer; Fig. 15), which are similar to the estimated oxidation states for other arc-hosted magmatic sulfide deposits in China such as Xiarihamu (C. Li et al., 2015b), Lengshuiqing (Yao et al., 2018), and Heishan (Xie et al., 2014). It is important to note that the estimated oxidation states of these deposits are

within the range of modern arc basalts estimated from melt Fe3+/Fe2+ (Kelley and Cottrell, 2012). In addition, Jugo et al. (2005) have determined experimentally that this fO2 range is consistent with sulfide stability in basaltic magma (the transi-tion from sulfide to sulfate dominance occurs between QFM and QFM +2).

Controls on PGE tenors

The main controls of PGE variation in a magmatic sulfide deposit are (1) initial contents of PGEs in the parental magma, (2) R-factor (magma/sulfide mass ratio, Campbell and Nal-drett, 1979) during sulfide segregation, and (3) fractional crystallization of monosulfide solid solution (MSS). Consid-ering that disseminated ores are commonly less affected by the MSS fractional crystallization (Naldrett et al., 1994), they were selected for the evaluation of the first two controls on the Daxueshan magmatic Ni-Cu sulfide deposit. We start with checking if the chalcophile element contents in any of the associated Wama basalts can be used to represent the initial contents of these metals in the parental magma for the Dax-ueshan deposit using Cu/Pd (Fig. 16A). It is well known that the partition coefficient between immiscible sulfide liquid and magma for Pd (105–106, Mungall and Brenan, 2014) is two to three orders of magnitude higher than that for Cu (~1,000, Ripley et al., 2002). Because of such a difference, an immis-cible sulfide liquid always has a lower Cu/Pd ratio than that of the parental magma (Barnes and Ripley, 2016). As shown in Figure 16A, the Cu/Pd ratios of the Daxueshan sulfide ores are one to two orders of magnitude higher than that of the basalts, which rules out any of the analyzed basalts as the parental magma for the deposit as far as chalcophile elements are concerned. Using the equation of Campbell and Naldrett (1979) and sulfide/magma DPd = 105 and DCu = 103, mass balance calculation indicates that a previous event of sulfide segregation with an R-factor = 3,000 from a melt (magma-1)containing 3.5 ppb Pd and 110 ppm Cu (values that are within the ranges of the Wama basalts) could produce a second-stage magma (magma-2) that contains 0.102 ppb Pd and 79 ppm Cu. Such a magma would be consistent with the parental magma from which the Daxueshan magmatic sulfide deposit was formed (Fig. 16A). The variations of Pd and Cu tenors in the bulk sulfide ores of the deposit are consistent with the results of the second-stage sulfide segregation with R-factors

Table 3. Re-Os Isotopes of the Daxueshan Mafic-Ultramafic Intrusion and the Wama Basalt

Re OsSample no. Rock type (ppb) Re/Os 187Re/188Os 2σ 187Os/188Os 2σ (187Os/188Os)i γOs(t)

DXS-02 Lherzolite 0.217 0.0119 18.2 95.0 3.4 0.75250355 0.0017 0.2767 120.36DXS-06 Lherzolite 0.069 0.0356 1.9 9.5 1.4 0.23584474 0.0009 0.1884 49.99DXS-07 Lherzolite 0.177 0.0242 7.3 36.4 1.5 0.38181325 0.0019 0.1994 58.76DXS-09 Lherzolite 0.168 0.0174 9.7 48.6 1.6 0.46818723 0.0019 0.2245 78.76DXS-15 Lherzolite 0.074 0.0113 6.5 32.6 2.3 0.40803501 0.0059 0.2446 94.74DXS-17 Lherzolite 0.192 0.0135 14.2 72.5 2.0 0.60211201 0.0019 0.2390 90.34DXS-19 Lherzolite 0.711 0.0338 21.1 117.2 1.6 1.31778646 0.0092 0.7307 481.85DXS-57 Gabbro 0.079 0.0075 10.5 52.9 2.1 0.47641867 0.0010 0.2116 68.49DXS-58 Gabbro 0.100 0.0036 27.4 144.8 2.9 0.88647242 0.0028 0.1612 28.32DXS-61 Gabbro 0.064 0.004 16.0 79.2 3.3 0.7811 0.0025 0.384 205.8WM-04 Basalt 0.10521 0.0429 2.5 12.0 0.2 0.2217 0.0002 0.1618 28.86

Note: Initial isotopic ratios and γOs were calculated using the formation age of 300 Ma

Table 4. S Isotopes of the Daxueshan Magmatic Ni-Cu Sulfide Deposit

Sample no. Host rock Mineralization δ34S, ‰

DXS-04 Lherzolite Disseminated sulfides –2.62DXS-30 Harzburgite Disseminated sulfides 0.52DXS-33 Harzburgite Disseminated sulfides 1.24DXS-35 Harzburgite Disseminated sulfides 0.45DXS-36 Harzburgite Disseminated sulfides 0.16DXS-37 Harzburgite Disseminated sulfides 0.72DXS-39 Harzburgite Disseminated sulfides 0.24



varying between 500 and 2,500 (Fig. 16A). It is important to note that the two-stage modeling using PGE data (Pd, Ir, and Rh) alone, without Cu, yields similar results (Fig. 16B, C). In the above calculation, we use sulfide/magma DPGE = 105, which is similar to experimental results (Mungall and Brenan, 2014), and assume that magma-1 contains 0.25 ppb Ir and 0.3 ppb Rh, which are within the ranges of the Wama basalts (Table 5). Accordingly, the estimated contents of Ir and Rh in magma-2 are 0.0073 and 0.0083 ppb, respectively. It is clear from the modeling results that the parental magma for the Daxueshan magmatic sulfide deposit underwent previous sul-fide segregation at depth, including the lower part of the arc crust to form sulfide-bearing, Cu-PGE–rich cumulates. This finding supports the notion that the formation of sulfide-bear-ing cumulates in the lower part of the arc crust may be a criti-cal step in continent building (Lee et al., 2012) or the genesis of porphyry ore deposits because new magma or volatiles may cannibalize sulfides from the previous cumulates in the path-way (Wilkinson, 2013).

Crustal contamination, source mantle characteristics, and magma genesis

The Daxueshan intrusion, the host of the magmatic deposit, has lower εNd and higher initial 87Sr/86Sr ratios than the coeval

Wama basalt. Using whole-rock Sr-Nd isotopes (Fig. 12), mix-ing calculations indicate that the parental magma of the Dax-ueshan magmatic sulfide deposit underwent ~25 wt % more crustal contamination than the basalts. Back calculation indi-cates that the εHf value of the parental magma for the Daxue-shan deposit is ~5 (Fig. 7), implying a moderately Lu depleted mantle source. As shown in Figure 12, the εNd value for the primary magma is ~2, implying that the source mantle was also slightly depleted in Sm. This moderately Sm-Lu depleted mantle source is not unique to the Daxueshan magmatic sul-fide deposit; the subduction-related Xiarihamu magmatic sulfide deposit has a similar signature (Fig. 12, Zhang et al., 2017).

It is important to know whether the observed negative Nb-Ta anomalies in the Daxueshan mafic-ultramafic intru-sive rocks and associated basalts are entirely due to crustal contamination. The Sr-Nd isotopes indicate that the extent of crustal contamination in the Wama basalts is <3 wt % (Fig. 12). The mantle-normalized Th/Nb ratios of these basalts are 3.13 to 3.67, which are much higher than the expected ratios of 1.38 for 3 wt % crustal contamination, and thus imply that crustal contamination is not the main cause of the observed negative Nb-Ta anomalies. On the other hand, these samples plot within the field of global continental arc basalts in the

Table 5. Chalcophile Element Compositions of the Daxueshan Magmatic Sulfide Deposit and the Associated Wama Basalts

Harzburgite S (wt %) Cu (wt %) Ni (wt %) Ir (ppb) Ru (ppb) Rh (ppb) Pt (ppb) Pd (ppb)

DXS-33 2.97 0.32 0.38 0.34 0.62 0.40 5.36 5.51DXS-34 2.04 0.29 0.35 0.32 0.60 0.34 4.28 5.14DXS-37 2.17 0.34 0.39 0.40 1.13 0.49 5.36 5.97DXS-38 1.99 0.28 0.35 0.25 0.40 0.38 3.27 4.56DXS-39 1.79 0.22 0.28 0.24 0.42 0.31 3.56 3.66DXS-40 3.23 0.34 0.36 0.96 0.59 0.73 10.83 16.98DXS-43 0.59 0.09 0.13 0.19 0.27 0.41 1.23 2.53DXS-44 1.1 0.10 0.16 0.22 0.28 0.48 2.12 2.51DXS-46 3.01 0.32 0.38 0.62 0.72 0.83 4.46 7.60DXS-48 0.88 0.12 0.14 0.18 0.36 0.29 3.73 2.18DXS-49 1.91 0.16 0.22 0.28 0.39 0.39 4.66 3.36DXS-50 0.97 0.13 0.19 0.28 0.53 0.46 2.06 2.95DXS-52 2.88 0.31 0.33 0.44 0.56 0.94 3.88 6.75DXS-53 2.43 0.30 0.34 0.51 0.40 0.45 3.90 6.44DXS-54 1.23 0.13 0.18 0.29 0.37 0.42 1.86 2.94DXS-55 2.27 0.26 0.33 0.44 0.46 0.48 5.12 5.12DXS-56 2.05 0.21 0.25 0.53 0.39 0.62 6.21 4.00

Basalt Cu (ppm) Ni (ppm) Ir (ppb) Ru (ppb) Rh (ppb) Pt (ppb) Pd (ppb)

BS-1 63 87 0.44 0.49 0.37 5.52 8.27BS-2 113 88 0.12 0.17 0.23 6.78 3.18BS-3 74 134 0.21 0.32 0.15 3.09 1.84BS-4 83 132 0.24 0.35 0.17 3.82 2.30BS-5 145 43 0.06 0.11 0.36 6.60 5.22BS-6 125 131 0.13 0.59 0.35 6.84 6.21BS-7 155 82 0.07 0.37 0.36 7.98 5.59BS-8 98 80 0.13 0.13 0.28 6.20 4.15BS-9 96 87 0.13 0.33 0.39 7.77 7.71

GBW standard, obtained 0.05 0.10 0.10 1.60 2.30GBW standard, recommended 0.04 0.08 0.11 1.67 2.12Detection limits 0.02 0.02 0.02 0.02 0.02

Estimated initial concentrationsMagma-1 110 0.25 0.30 3.50Magma-2 79 0.0073 0.0083 0.102


1320 WANG ET AL.

Th/Yb vs. Nb/Yb diagram (Fig. 11B), consistent with magma generated by flux melting in subduction zones. About 25 wt % of crustal contamination of the Wama basalt can explain the observed trace element variations in the Daxueshan mafic-ultramafic intrusive rocks (Fig. 11B), consistent with the Sr-Nd isotopes of these rocks (Fig. 12).

Ore genesis and exploration implications

How a mantle-derived magma becomes saturated with immis-cible sulfide liquid is one of the most important questions

pertaining to the formation of a magmatic sulfide deposit. Addition of external S and fractional crystallization are two common causes (see summary in Ripley and Li, 2013). The forsterite contents of olivine and Ni/Cu ratios of bulk sul-fides in the Daxueshan magmatic sulfide deposit (forsterite of olivine ~81 mol %, Ni/Cu of bulk sulfides ~1) are signifi-cantly lower than those in the Xiarihamu magmatic sulfide deposit (forsterite of olivine ~89 mol %, Ni/Cu of bulk sul-fide ~6: Zhang et al., 2017), which indicates a more fraction-ated parental magma for the Daxueshan deposit than for the

0.01

0.1

1Cu

(wt.

%)

Sulfide-bearing harzburgite

Sulfide-barren harzburgite

A

0.01

0.1

1

10

Ir (p

pb)

C

0.01

0.1

1

10

Ru (p

pb)

D

0.01

0.1

1

10

S (wt.%)

Rh (p

pb)

E

0.1

1

10

100

0.1 1.0 10

Pd (p

pb)

S (wt.%)

F

0.1 1.0 10

0.1

1

10

20

Pt (p

pb)

B

Fig. 13. Whole-rock S vs. chalcophile element concentrations in the Daxueshan magmatic sulfide deposit and associated sulfide-poor mafic-ultramafic intrusive rocks.



Xiarihamu deposit. Using the KDOlivine-Magma [(XFeO/XMgO) olivine/(XFeO/XMgO) magma, molar] of 0.3 (Roeder and Emslie, 1970), our calculation indicates that a decrease of 8 mol % in olivine forsterite content corresponds to ~20 wt % of olivine frac-tional crystallization. It is clear that the parental magma of the Daxueshan deposit underwent moderate fractional crys-tallization, but whether this process played a major or minor role in triggering sulfide saturation in the Daxueshan magma remains to be determined.

Sulfur isotopes of the Daxueshan deposit (δ34S of −2.6–+1.2‰) are inconclusive with respect to the role of external sulfur in sulfide mineralization. However, Re-Os isotopes of the deposit (γOs of 28–482) indicate that selective crustal contamination involving organic matter-bearing or sulfide-bearing sedimentary rocks possibly took place, because Os is a chalcophile element commonly hosted in organic matter or sulfides in the crust. On the other hand, Sr-Nd-Hf isotopes of the host intrusion (Figs. 7, 12) and abundant orthopyroxene in the intrusion indicate significant assimilation of siliceous crustal materials. The assimilation of siliceous country rocks can also be responsible for driving a basaltic magma to sulfide saturation (Ripley and Li, 2013).

Primitive arc magmas may be highly oxidized (e.g., Evans et al., 2012) and, thus, magnetite fractionation (Jenner et al., 2010) or reduction (Tomkins et al., 2012) may have been an important process to induce sulfide saturation in the magma from which the Daxueshan deposit formed. It is impossible to evaluate the role of magnetite fractionation in the forma-tion of the Daxueshan deposit. Contamination with graphitic crustal rocks has been demonstrated to drive sulfide satura-tion of oxidized arc basalt in Japan (Tomkins et al., 2012) and would be consistent with Os isotope values. However, the carbonaceous mudstone in the region basically overlies the orebody-hosting intrusion and, thus, crustal rocks are unlikely to be the contaminant. Moreover, we have not found graphite in the sulfide-bearing samples from the Daxueshan deposit and, hence, direct support for the involvement of this process during the formation of the deposit is lacking.

Considering the different lines of evidence described above, we conclude that both fractional crystallization and crustal contamination played a role in triggering sulfide saturation in the Daxueshan magmatic system, although the relative signifi-cance of these two competing processes remains uncertain. We also cannot completely rule out the involvement of exter-nal sulfide and graphite.

Ni Ir Ru Rh Pt Pd Cu

Sam

ple/

Prim

itiv

e m

antl

e

10

102

103

104

10-1

100

10-2

AXiarihamuHeishanLengshuiqingQingmingshan

Daxueshan

Pual Ridge lavasArc picrites

Basalts in BaoshanDaxueshan

Ni Ir Ru Rh Pt Pd Cu

Sam

ple/

Prim

itiv

e m

antl

e

10

102

103

104

10-1

100

10-2

B

Fig. 14. Mantle-normalized chalcophile element patterns for (A) the Daxueshan magmatic sulfide deposit, in comparison with the arc-type Xiarihamu magmatic sulfide deposit (Song et al., 2016), Lengshuiqing (Yao et al., 2018), Qingmingshan (Zhou et al., 2017), and Heishan (Xie et al., 2014); the primitive mantle values are from Palme and O’Neill (2014); and (B) the coeval basalts in the Baoshan block, arc picrites (Woodland et al., 2002; Park et al., 2012), and Pual Ridge lava (Park et al., 2013).

30

25

2020

10

5

15

0 5 10 15 20 25 30

QFM-2

QFM-1

QFM

QFM+1

K DO

l-Su

l =(X N

iS/X

FeS)su

lfid

e li

qu

id/(

X NiO

/XFe

O)o

livi

ne

Ni tenor (wt.%)

Xiarihamu JinchuanVoisey’s Bay

Daxueshan

Heishan

Lengshuiqing

Fig. 15. The oxidation state of the Daxueshan magmatic sulfide deposit (cal-culated with mineralized samples: DXS-39, DXS-44, DXS-54, DXS-56). The basis of the plot and the results for the Jinchuan and Voisey’s Bay deposits are from Barnes et al. (2013). The results for the Xiarihamu deposit are from C. Li et al. (2015b), for the Heishan deposit from Xie et al. (2014), and for the Lengshuiqing deposit from Yao et al. (2018).


1322 WANG ET AL.

104

103

103

103

105

106

0.01 0.1 1.0 10 100

Cu/P

d

Pd

10

100

1 10 100

Pd

Ir

10

100

1 10 100

Pd

Rh

R5000

Magma-13.5 ppb Pd110 ppm Cu

Magma-20.102 ppb Pd79 ppm Cu

Magma-20.102 ppb Pd0.0073 ppb Ir

Magma-20.102 ppb Pd0.0087 ppb Rh

R4000R3000

R2000

R2500

R500

R500

R500

R1000

R2000

R1500

R2500

R1000R1500 R2000

R2500

Sulfide liquid-2

Sulfide liquid-2

Sulfide liquid-2

R2000

R1000

R1500

A

B

C

Basalt

Sulfide ore

Stage-1 sulfide

segregation

Stage-2 sulfidesegregation

Fig. 16. Modeling of two-stage sulfide segregation from magma for the Daxueshan magmatic sulfide deposit using the equa-tion of Campbell and Naldrett (1979) and sulfide/magma DCu = 103 and DPGE = 105, which are similar to the experimental values (Ripley et al., 2002; Mungall and Brenan, 2014).



The temporal-spatial association of the ~300 Ma Daxue-shan magmatic sulfide deposit with arc basalts, which is estab-lished for the first time by this study, bears some significant exploration implications. As shown in Figure 2C, many mafic-ultramafic intrusions (0.2–1.2 km2) are exposed surrounding the Daxueshan deposit. The best exploration targets for this type of deposit in the area are those that contain olivine-rich rocks and are contemporaneous with the Daxueshan deposit. As shown in Figure 2B, many areas in the Baoshan block are covered by Carboniferous-Permian arc basalts, so the first step of nickel exploration is to look for exposed, coeval mafic-ultramafic intrusions in these areas. The Early Permian mafic intrusions in southern Tibet, northwest of the Baoshan block (Zhu et al., 2010; Zhang and Zhang, 2017), should be included in a regional Ni exploration program.

ConclusionsOur new zircon U-Pb age of ~300 Ma for the host intrusion of the Daxueshan magmatic sulfide deposit firmly establishes a temporal association of this deposit and arc basaltic magma-tism in the Baoshan block. Mineral chemistry indicates that the Daxueshan mafic-ultramafic rocks formed from a fraction-ated arc basalt. Sr-Nd-Hf isotope data indicate that the paren-tal magma of the Daxueshan intrusion underwent higher degrees of crustal contamination than the coeval arc basalts in the nearby Wama area. Os isotope data indicate that organic matter or sulfides are present in the contaminants. Both frac-tional crystallization and crustal contamination appear to have played a role in causing sulfide saturation in the Daxueshan magma, but their relative importance is not clear. The age and lithochemistry of the Daxueshan magmatic sulfide deposit can be used to guide Ni exploration in the Baoshan region.

Like most magmatic sulfide deposits in convergent tectonic settings, the parental magma of the Daxueshan deposit is severely depleted in PGEs, possibly due to previous sulfide segregation at depth, including the lower part of the arc crust, to form sulfide-bearing, Cu-PGE–rich cumulates, which sup-ports the notion that the formation of sulfide-bearing cumu-lates in the lower part of the arc crust may be a critical step in continent building (Lee et al., 2012) or the genesis of por-phyry ore deposits because new magma or volatiles may can-nibalize sulfides from the previous cumulates in the pathway (Wilkinson, 2013).

AcknowledgmentsThis research was jointly supported by the National Key Basic Research Development Program (973 Program; 2015CB452606), the National Key Research and Develop-ment Project of China (2016YFC0600307), and the project from China Geological Survey (Grant no. DD20160346). We thank Prof. Andrew Tomkins and an anonymous reviewer for their constructive reviews, and associate editor Simon Jowitt for editorial input.

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1326 WANG ET AL.

Table A1. Hf-Lu-Yb Data for Zircon from Gabbro of the Daxueshan Mafic-Ultramafic Intrusion

Sample no. Hf (ppm) Lu (ppm) Yb (ppm) 176Hf/177Hf 1σ 176Lu/177Hf 1σ 176Yb/177Hf 1σ εHf(t)

1 9119.938 129 1001.7 0.2824929 0.000015 0.00175665 0.000013 0.06679204 0.000434 –3.63 2 9255.111 211 1482.2 0.2824817 0.000015 0.0028555 0.000088 0.09848072 0.003227 –4.24 3 10584.61 199 1448.8 0.282476 0.000021 0.0022998 0.000073 0.08151284 0.003153 –4.33 4 10007.24 147 1222.1 0.2824807 0.000013 0.00185962 0.000044 0.07590918 0.001332 –4.08 5 8472.15 111 911.74 0.2825461 0.000046 0.00177544 0.000090 0.06982831 0.002575 –1.75 6 9750.564 158 1133.8 0.2825151 0.000013 0.0019921 0.000009 0.06987722 0.000851 –2.89 7 10629.96 151 1203 0.2825016 0.000017 0.00176717 0.000047 0.06924357 0.00116 –3.32 8 10549.33 217 1576.6 0.2824832 0.000015 0.0024667 0.000090 0.08785131 0.003613 –4.11 9 8021.131 333 2305.5 0.2823978 0.000023 0.00515496 0.000014 0.17596333 0.000709 –7.6710 7960.146 463 3119.4 0.2823155 0.000024 0.00733044 0.000141 0.24353816 0.004371 –1111 6899.299 300 2076.6 0.282356 0.000019 0.0052829 0.000087 0.1797778 0.003158 -9.17

Note: Method of calculating εHf(t) is from Li et al. (2004); λ = 1.867 × 10–11 year–1 (Steiger and Jager, 1997)


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99

0.76

40

.6

52.6

6

.8D

XS-

32

Har

zbur

gite

1

51.3

0.

7 2.

5 6.

03

17.9

5 18

.64

98.7

1.

90

0.11

0.

13

0.99

0.

74

39.7

53

.3

7.0

DX

S-43

G

abbr

o 4

51.1

0.

5 2.

0 8.

02

16.5

1 19

.53

98.7

1.

91

0.09

0.

19

0.92

0.

78

41.3

48

.5

10.2

Ort

hopy

roxe

neD

XS-

32

Har

zbur

gite

2

54.0

0.

4 1.

1 11

.57

29.4

8 1.

96

99.4

1.

93

0.05

0.

35

1.57

0.

08

3.9

81

.8

14.3

DX

S-03

L

herz

olite

6

54.5

0.

2 1.

5 10

.76

29.8

3 2.

27

99.8

1.

94

0.06

0.

32

1.58

0.

09

4.5

81

.8

13.7

DX

S-19

L

herz

olite

2

53.8

0.

4 1.

5 11

.50

29.3

8 2.

18

99.7

1.

92

0.06

0.

34

1.56

0.

08

4.3

81

.5

14.2

Sam

ple

no.

Roc

k ty

pe

n Ti

O2

Al 2O

3 C

r 2O

3 F

eO

Fe 2

O3

MgO

To

tal

Ti4+

A

l3+

Cr3

+ F

e2+

Fe3

+ M

g2+

Tota

l

Cr

spin

elD

XS-

03

Lhe

rzol

ite

2 0.

8 19

.2

40.5

24

.76

7.73

7.

53

100.

6 0.

17

5.96

8.

27

5.27

1.

43

2.90

24

DX

S-07

L

herz

olite

3

1.6

16.9

41

.7

24.8

4 6.

60

7.35

9

9.0

0.32

5.

39

8.73

5.

42

1.25

2.

90

24D

XS-

09

Lhe

rzol

ite

6 1.

2 18

.0

41.5

24

.40

6.34

7.

57

99.

0 0.

25

5.69

8.

62

5.28

1.

20

2.97

24

DX

S-13

L

herz

olite

3

1.4

17.4

41

.0

25.4

7 6.

67

6.84

9

8.7

0.28

5.

55

8.63

5.

58

1.27

2.

70

24D

XS-

15

Lhe

rzol

ite

4 1.

2 18

.4

41.0

25

.21

6.40

7.

15

99.

4 0.

24

5.81

8.

50

5.45

1.

20

2.79

24

DX

S-17

L

herz

olite

4

1.6

15.7

40

.8

25.5

7 8.

64

6.75

9

9.1

0.33

5.

06

8.63

5.

64

1.66

2.

69

24D

XS-

32

Har

zbur

gite

7

1.5

16.5

41

.7

25.3

5 7.

01

6.77

9

8.8

0.32

5.

22

8.79

5.

60

1.35

2.

72

24

Not

es: n

= n

umbe

r of

ana

lyse

s; o

xide

s in

wt %

; min

eral

s in

mol

%M

iner

al a

bbre

viat

ions

: Ab

= al

bite

, An

= an

orth

ose,

En

= en

stat

ite, F

o =

fors

teri

te, F

s =

ferr

osili

te, O

r =

orth

ocla

se, W

o =

wol

last

onite


1328 WANG ET AL.

Table A3. The Concentrations of Major Elements (wt %) and Trace Elements (ppm) in the Daxueshan Mafic-Ultramafic Intrusion, Siltstones, and the Wama Basalts

Sample no. DXS-01 DXS-02 DXS-03 DXS-04 DXS-05 DXS-06 DXS-07 DXS-08 DXS-09 DXS-10 DXS-11 DXS-12 Sample no. DXS-13 DXS-14 DXS-15 DXS-16 DXS-17 DXS-18 DXS-19 DXS-20 DXS-21 DXS-22 DXS-23 DXS-24

Rock type Lherzolite Rock type Lherzolite

SiO2 44.8 45.23 44.94 42.84 42.54 44.03 42.73 41.51 42.46 41.76 44.76 42.36 42.71 42.13 43.83 43.83 44.12 42.91 43.17 43.32 42.88 43.83 44.12 46.21TiO2 0.76 0.68 0.63 0.53 0.5 0.55 0.54 0.62 0.53 0.49 0.5 0.55 0.56 0.57 0.53 0.52 0.62 0.64 0.51 0.54 0.45 0.46 0.6 0.6Al2O3 8.78 8.94 8.5 7.25 6.86 8.9 6.78 7.38 6.98 6.28 8.14 7.71 7.71 8.7 8.09 7.8 7.76 7.37 7.88 7.96 6.87 6.92 8.24 9.23Fe2O3T 12.52 12.89 13.43 14.33 14.47 13.82 14.46 13.69 14.29 15.27 14.01 13.72 14.25 13.82 13.88 14.38 13.54 13.69 14.43 14.14 14.79 14.22 13.2 13.68MnO 0.18 0.16 0.17 0.17 0.17 0.17 0.17 0.16 0.17 0.17 0.17 0.17 0.19 0.17 0.17 0.17 0.16 0.16 0.16 0.17 0.17 0.18 0.17 0.17MgO 20.96 20.27 20.52 24.72 24.97 21.94 25.35 22.45 25.01 25.42 23.68 22.08 22.03 20.69 22.86 23.46 22.27 22.27 23.74 23.5 27.02 27.42 24.39 21.57CaO 4.66 5.35 4.76 4.4 4.03 5.5 4.2 5.64 4.36 4.02 5.01 4.6 4.21 4.38 5.18 4.72 4.75 4.87 4.66 4.67 4.23 4.25 2.84 5.69Na2O 0.28 0.67 0.65 0.44 0.49 0.97 0.52 0.01 0.55 0.47 0.66 0.49 0.22 0.28 0.7 0.51 0.69 0.61 0.71 0.71 0.44 0.49 0.13 0.94K2O 0.29 0.67 0.58 0.41 0.48 0.58 0.47 0.08 0.51 0.41 0.41 0.5 0.44 0.58 0.5 0.56 0.48 0.75 0.46 0.43 0.53 0.49 0.48 0.49P2O5 0.08 0.07 0.07 0.06 0.05 0.06 0.06 0.07 0.06 0.05 0.05 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.06 0.07 0.06 0.06 0.07 0.07LOI 6.97 4.26 5.16 4.64 4.84 2.40 3.96 8.39 3.93 4.75 2.75 7.52 6.62 6.87 3.13 4.47 4.01 5.54 2.63 3.16 3.59 2.76 6.68 2.39 Total 100.28 99.19 99.41 99.79 99.40 98.92 99.24 100.00 98.85 99.09 100.14 99.76 99.00 98.25 98.93 100.48 98.47 98.88 98.41 98.67 99.82 99.83 99.85 99.80 Mg# 77 76 75 78 78 76 78 77 78 77 77 76 76 75 77 77 77 76 77 77 79 79 79 76 Th 3.74 3.33 2.89 2.33 2.40 2.78 2.73 3.21 2.56 2.25 2.35 2.85 2.91 2.89 2.57 2.58 3.10 2.89 2.44 2.60 3.75 2.76 3.32 3.62 Nb 4.36 3.79 3.38 2.86 2.74 3.20 3.15 3.62 2.92 2.63 2.72 3.26 3.39 3.35 3.00 2.88 3.58 3.41 2.95 3.11 3.44 3.18 4.20 4.22 Ta 0.36 0.33 0.28 0.24 0.24 0.26 0.26 0.29 0.24 0.22 0.24 0.27 0.27 0.28 0.23 0.23 0.27 0.27 0.23 0.24 0.29 0.26 0.41 0.39 La 11.44 9.78 8.58 7.61 7.10 8.09 7.74 6.66 7.50 6.66 6.87 8.17 8.05 8.72 7.54 7.24 8.68 8.23 7.13 7.47 6.86 6.48 8.62 8.89 Ce 23.52 20.70 18.25 15.67 14.83 17.08 16.53 14.91 15.68 13.93 14.41 17.12 16.85 17.80 15.75 15.22 18.37 17.33 14.86 15.42 13.49 12.96 17.53 17.94 Nd 12.19 10.46 9.51 7.94 7.67 8.83 8.40 8.00 8.01 7.09 7.29 8.58 8.70 9.07 7.98 7.73 9.35 8.95 7.62 7.94 6.90 6.41 8.82 9.17 Zr 68 61 53 44 45 52 51 60 49 43 45 53 54 55 50 48 58 58 48 52 33 35 38 55 Hf 2.01 1.81 1.57 1.29 1.31 1.49 1.50 1.69 1.39 1.23 1.28 1.55 1.55 1.56 1.40 1.36 1.62 1.63 1.33 1.45 0.87 0.90 1.00 1.51 Sm 2.91 2.58 2.32 1.98 1.85 2.12 2.03 1.99 1.98 1.75 1.79 2.09 2.12 2.18 1.93 1.81 2.29 2.22 1.82 1.86 1.69 1.57 2.21 2.15 Gd 2.97 2.61 2.41 1.94 1.85 2.13 2.09 2.04 1.99 1.71 1.80 2.10 2.10 2.17 1.98 1.93 2.31 2.23 1.86 1.91 1.74 1.68 2.22 2.36 Y 15.95 14.04 12.79 10.58 10.41 11.78 11.42 11.21 10.95 9.70 10.21 11.71 11.70 12.08 11.06 10.71 12.82 12.26 10.18 10.68 Yb 1.67 1.53 1.36 1.15 1.14 1.28 1.20 1.27 1.16 1.03 1.10 1.24 1.22 1.30 1.18 1.12 1.35 1.30 1.06 1.11 Lu 0.25 0.23 0.21 0.18 0.17 0.19 0.19 0.20 0.18 0.16 0.17 0.19 0.19 0.20 0.18 0.17 0.21 0.20 0.16 0.17 0.19 0.19 0.24 0.26


Rock type Harzburgite Rock type Harzburgite

SiO2 43.51 44.71 39.32 40.65 39.74 41.17 42.87 42.24 39.62 35.88 38.55 39.72 36.77 37.21 38.12 38.11 38.86 37.36 40.53 43.39 38.55 40.64 42.59 35.67TiO2 0.54 0.69 0.53 0.58 0.57 0.56 0.54 0.57 0.32 0.3 0.35 0.44 0.32 0.34 0.34 0.36 0.35 0.34 0.34 0.52 0.38 0.52 0.49 0.3Al2O3 7.87 9.29 6.49 6.83 6.27 6.39 6.91 7.21 5.99 5.78 6.37 5.25 5.58 4.54 4.86 4.77 4.93 6.3 6 7.43 4.71 6.5 6.53 5.7Fe2O3T 15.9 12.38 18.54 16.54 17.8 15.44 14.72 14.51 20.66 23.68 20.93 19.63 21.35 19.92 18.8 19.32 18.47 22.39 20.27 14.56 16.54 16.31 15.18 22.33MnO 0.17 0.17 0.16 0.13 0.16 0.19 0.16 0.16 0.06 0.13 0.14 0.14 0.17 0.14 0.15 0.15 0.15 0.12 0.06 0.17 0.13 0.16 0.17 0.16MgO 23.41 20.98 25.41 25.28 25.19 24.73 23.75 24.27 22.91 22.22 22.51 24.5 23.69 26.11 26.5 25.77 26.3 22.72 23.47 23.31 27.1 23.68 25.86 22.74CaO 4.86 4.1 0.17 0.16 0.18 2.32 3.7 3.32 0.15 0.16 0.16 0.18 0.2 2.6 2.99 2.72 3.11 0.3 0.14 4.44 2.43 3.02 4.11 0.18Na2O 0.49 0.32 0.01 0.01 0.01 0.12 0.3 0.31 0.01 0.01 0.01 0.01 0.01 0.14 0.18 0.15 0.22 <0.01 <0.01 0.4 0.06 0.21 0.63 <0.01K2O 0.55 0.35 0.15 0.12 0.15 0.28 0.38 0.44 0.03 0.06 0.05 0.07 0.08 0.18 0.22 0.22 0.21 0.11 0.04 0.42 0.17 0.36 0.46 0.07P2O5 0.06 0.07 0.05 0.06 0.06 0.06 0.06 0.07 0.04 0.04 0.06 0.05 0.05 0.04 0.04 0.04 0.04 0.05 0.04 0.06 0.04 0.06 0.05 0.06LOI 3.75 7.67 7.35 9.82 10.40 9.06 6.02 6.35 9.96 10.18 9.81 9.26 11.00 8.28 7.58 7.77 6.76 10.20 9.02 4.55 8.39 6.63 3.47 10.79 Total 100 101 98 100 101 100 99 99 100 98 99 99 99 99 100 99 99 100 100 99 98 98 100 98 Mg# 75 77 73 75 74 76 76 77 69 65 68 71 69 72 74 73 74 67 70 76 77 74 77 67 Th 3.07 3.37 2.19 2.43 2.55 2.60 2.63 2.72 1.89 1.94 2.69 2.02 1.92 1.25 1.30 3.32 2.19 2.55 1.54 2.65 3.12 2.47 2.12 2.60 Nb 3.91 3.88 2.68 3.08 3.03 2.97 3.09 3.21 1.33 1.14 1.44 2.35 1.36 1.66 1.69 1.70 1.32 2.88 2.04 3.03 3.49 1.44 2.09 3.18 Ta 0.32 0.57 0.28 0.27 0.28 0.25 0.25 0.26 0.16 0.15 0.21 0.21 0.19 0.14 0.14 0.22 0.16 0.26 0.17 0.23 0.29 0.19 0.19 0.20 La 7.77 10.24 5.63 5.34 6.72 7.95 7.71 7.67 2.64 3.67 4.02 4.29 4.43 4.03 3.96 4.53 3.00 5.70 3.69 6.57 6.46 4.34 4.42 5.48 Ce 15.45 21.45 12.94 12.27 15.47 16.72 16.21 16.24 5.91 8.14 8.32 9.57 9.18 8.28 8.35 9.35 6.80 14.01 8.27 13.77 14.61 9.22 9.45 11.59 Nd 7.77 11.22 7.09 6.67 8.17 8.43 8.15 8.19 3.27 4.55 5.15 5.22 5.29 4.33 4.37 4.66 3.58 6.11 4.76 6.82 6.88 4.83 5.08 5.87 Zr 37 60 43 48 47 49 50 53 36 37 51 38 37 26 26 61 37 42 30 43 50 40 38 48 Hf 0.99 1.83 1.27 1.41 1.43 1.41 1.42 1.48 1.18 1.23 1.54 1.10 1.10 0.73 0.76 1.75 1.08 1.33 0.71 1.43 1.54 0.97 0.83 1.20 Sm 1.95 2.67 1.78 1.64 1.99 2.04 1.97 2.04 0.91 1.22 1.55 1.31 1.48 1.07 1.09 1.29 0.84 1.50 0.87 1.72 1.88 1.23 1.19 1.45 Gd 2.00 2.74 1.77 1.68 1.96 2.01 1.99 2.08 0.96 1.42 1.91 1.33 1.51 1.08 1.14 1.63 0.87 2.09 1.24 1.85 2.00 1.33 1.48 1.57 Y 14.26 9.57 9.29 10.59 11.09 11.26 11.38 6.62 9.73 12.82 7.42 8.88 6.20 6.40 12.05 8.11 11.71 7.89 11.64 12.15 10.59 9.64 11.12 Yb 1.54 1.08 1.14 1.18 1.20 1.17 1.19 0.84 0.99 1.27 0.82 0.93 0.67 0.69 1.21 0.83 1.09 0.73 1.17 1.38 1.09 0.79 1.09 Lu 0.23 0.24 0.17 0.18 0.19 0.18 0.18 0.18 0.13 0.15 0.19 0.12 0.14 0.10 0.10 0.19 0.15 0.14 0.13 0.17 0.21 0.15 0.11 0.14



Table A3. The Concentrations of Major Elements (wt %) and Trace Elements (ppm) in the Daxueshan Mafic-Ultramafic Intrusion, Siltstones, and the Wama Basalts


Rock type Lherzolite Rock type Lherzolite

SiO2 44.8 45.23 44.94 42.84 42.54 44.03 42.73 41.51 42.46 41.76 44.76 42.36 42.71 42.13 43.83 43.83 44.12 42.91 43.17 43.32 42.88 43.83 44.12 46.21TiO2 0.76 0.68 0.63 0.53 0.5 0.55 0.54 0.62 0.53 0.49 0.5 0.55 0.56 0.57 0.53 0.52 0.62 0.64 0.51 0.54 0.45 0.46 0.6 0.6Al2O3 8.78 8.94 8.5 7.25 6.86 8.9 6.78 7.38 6.98 6.28 8.14 7.71 7.71 8.7 8.09 7.8 7.76 7.37 7.88 7.96 6.87 6.92 8.24 9.23Fe2O3T 12.52 12.89 13.43 14.33 14.47 13.82 14.46 13.69 14.29 15.27 14.01 13.72 14.25 13.82 13.88 14.38 13.54 13.69 14.43 14.14 14.79 14.22 13.2 13.68MnO 0.18 0.16 0.17 0.17 0.17 0.17 0.17 0.16 0.17 0.17 0.17 0.17 0.19 0.17 0.17 0.17 0.16 0.16 0.16 0.17 0.17 0.18 0.17 0.17MgO 20.96 20.27 20.52 24.72 24.97 21.94 25.35 22.45 25.01 25.42 23.68 22.08 22.03 20.69 22.86 23.46 22.27 22.27 23.74 23.5 27.02 27.42 24.39 21.57CaO 4.66 5.35 4.76 4.4 4.03 5.5 4.2 5.64 4.36 4.02 5.01 4.6 4.21 4.38 5.18 4.72 4.75 4.87 4.66 4.67 4.23 4.25 2.84 5.69Na2O 0.28 0.67 0.65 0.44 0.49 0.97 0.52 0.01 0.55 0.47 0.66 0.49 0.22 0.28 0.7 0.51 0.69 0.61 0.71 0.71 0.44 0.49 0.13 0.94K2O 0.29 0.67 0.58 0.41 0.48 0.58 0.47 0.08 0.51 0.41 0.41 0.5 0.44 0.58 0.5 0.56 0.48 0.75 0.46 0.43 0.53 0.49 0.48 0.49P2O5 0.08 0.07 0.07 0.06 0.05 0.06 0.06 0.07 0.06 0.05 0.05 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.06 0.07 0.06 0.06 0.07 0.07LOI 6.97 4.26 5.16 4.64 4.84 2.40 3.96 8.39 3.93 4.75 2.75 7.52 6.62 6.87 3.13 4.47 4.01 5.54 2.63 3.16 3.59 2.76 6.68 2.39 Total 100.28 99.19 99.41 99.79 99.40 98.92 99.24 100.00 98.85 99.09 100.14 99.76 99.00 98.25 98.93 100.48 98.47 98.88 98.41 98.67 99.82 99.83 99.85 99.80 Mg# 77 76 75 78 78 76 78 77 78 77 77 76 76 75 77 77 77 76 77 77 79 79 79 76 Th 3.74 3.33 2.89 2.33 2.40 2.78 2.73 3.21 2.56 2.25 2.35 2.85 2.91 2.89 2.57 2.58 3.10 2.89 2.44 2.60 3.75 2.76 3.32 3.62 Nb 4.36 3.79 3.38 2.86 2.74 3.20 3.15 3.62 2.92 2.63 2.72 3.26 3.39 3.35 3.00 2.88 3.58 3.41 2.95 3.11 3.44 3.18 4.20 4.22 Ta 0.36 0.33 0.28 0.24 0.24 0.26 0.26 0.29 0.24 0.22 0.24 0.27 0.27 0.28 0.23 0.23 0.27 0.27 0.23 0.24 0.29 0.26 0.41 0.39 La 11.44 9.78 8.58 7.61 7.10 8.09 7.74 6.66 7.50 6.66 6.87 8.17 8.05 8.72 7.54 7.24 8.68 8.23 7.13 7.47 6.86 6.48 8.62 8.89 Ce 23.52 20.70 18.25 15.67 14.83 17.08 16.53 14.91 15.68 13.93 14.41 17.12 16.85 17.80 15.75 15.22 18.37 17.33 14.86 15.42 13.49 12.96 17.53 17.94 Nd 12.19 10.46 9.51 7.94 7.67 8.83 8.40 8.00 8.01 7.09 7.29 8.58 8.70 9.07 7.98 7.73 9.35 8.95 7.62 7.94 6.90 6.41 8.82 9.17 Zr 68 61 53 44 45 52 51 60 49 43 45 53 54 55 50 48 58 58 48 52 33 35 38 55 Hf 2.01 1.81 1.57 1.29 1.31 1.49 1.50 1.69 1.39 1.23 1.28 1.55 1.55 1.56 1.40 1.36 1.62 1.63 1.33 1.45 0.87 0.90 1.00 1.51 Sm 2.91 2.58 2.32 1.98 1.85 2.12 2.03 1.99 1.98 1.75 1.79 2.09 2.12 2.18 1.93 1.81 2.29 2.22 1.82 1.86 1.69 1.57 2.21 2.15 Gd 2.97 2.61 2.41 1.94 1.85 2.13 2.09 2.04 1.99 1.71 1.80 2.10 2.10 2.17 1.98 1.93 2.31 2.23 1.86 1.91 1.74 1.68 2.22 2.36 Y 15.95 14.04 12.79 10.58 10.41 11.78 11.42 11.21 10.95 9.70 10.21 11.71 11.70 12.08 11.06 10.71 12.82 12.26 10.18 10.68 Yb 1.67 1.53 1.36 1.15 1.14 1.28 1.20 1.27 1.16 1.03 1.10 1.24 1.22 1.30 1.18 1.12 1.35 1.30 1.06 1.11 Lu 0.25 0.23 0.21 0.18 0.17 0.19 0.19 0.20 0.18 0.16 0.17 0.19 0.19 0.20 0.18 0.17 0.21 0.20 0.16 0.17 0.19 0.19 0.24 0.26


Rock type Harzburgite Rock type Harzburgite

SiO2 43.51 44.71 39.32 40.65 39.74 41.17 42.87 42.24 39.62 35.88 38.55 39.72 36.77 37.21 38.12 38.11 38.86 37.36 40.53 43.39 38.55 40.64 42.59 35.67TiO2 0.54 0.69 0.53 0.58 0.57 0.56 0.54 0.57 0.32 0.3 0.35 0.44 0.32 0.34 0.34 0.36 0.35 0.34 0.34 0.52 0.38 0.52 0.49 0.3Al2O3 7.87 9.29 6.49 6.83 6.27 6.39 6.91 7.21 5.99 5.78 6.37 5.25 5.58 4.54 4.86 4.77 4.93 6.3 6 7.43 4.71 6.5 6.53 5.7Fe2O3T 15.9 12.38 18.54 16.54 17.8 15.44 14.72 14.51 20.66 23.68 20.93 19.63 21.35 19.92 18.8 19.32 18.47 22.39 20.27 14.56 16.54 16.31 15.18 22.33MnO 0.17 0.17 0.16 0.13 0.16 0.19 0.16 0.16 0.06 0.13 0.14 0.14 0.17 0.14 0.15 0.15 0.15 0.12 0.06 0.17 0.13 0.16 0.17 0.16MgO 23.41 20.98 25.41 25.28 25.19 24.73 23.75 24.27 22.91 22.22 22.51 24.5 23.69 26.11 26.5 25.77 26.3 22.72 23.47 23.31 27.1 23.68 25.86 22.74CaO 4.86 4.1 0.17 0.16 0.18 2.32 3.7 3.32 0.15 0.16 0.16 0.18 0.2 2.6 2.99 2.72 3.11 0.3 0.14 4.44 2.43 3.02 4.11 0.18Na2O 0.49 0.32 0.01 0.01 0.01 0.12 0.3 0.31 0.01 0.01 0.01 0.01 0.01 0.14 0.18 0.15 0.22 <0.01 <0.01 0.4 0.06 0.21 0.63 <0.01K2O 0.55 0.35 0.15 0.12 0.15 0.28 0.38 0.44 0.03 0.06 0.05 0.07 0.08 0.18 0.22 0.22 0.21 0.11 0.04 0.42 0.17 0.36 0.46 0.07P2O5 0.06 0.07 0.05 0.06 0.06 0.06 0.06 0.07 0.04 0.04 0.06 0.05 0.05 0.04 0.04 0.04 0.04 0.05 0.04 0.06 0.04 0.06 0.05 0.06LOI 3.75 7.67 7.35 9.82 10.40 9.06 6.02 6.35 9.96 10.18 9.81 9.26 11.00 8.28 7.58 7.77 6.76 10.20 9.02 4.55 8.39 6.63 3.47 10.79 Total 100 101 98 100 101 100 99 99 100 98 99 99 99 99 100 99 99 100 100 99 98 98 100 98 Mg# 75 77 73 75 74 76 76 77 69 65 68 71 69 72 74 73 74 67 70 76 77 74 77 67 Th 3.07 3.37 2.19 2.43 2.55 2.60 2.63 2.72 1.89 1.94 2.69 2.02 1.92 1.25 1.30 3.32 2.19 2.55 1.54 2.65 3.12 2.47 2.12 2.60 Nb 3.91 3.88 2.68 3.08 3.03 2.97 3.09 3.21 1.33 1.14 1.44 2.35 1.36 1.66 1.69 1.70 1.32 2.88 2.04 3.03 3.49 1.44 2.09 3.18 Ta 0.32 0.57 0.28 0.27 0.28 0.25 0.25 0.26 0.16 0.15 0.21 0.21 0.19 0.14 0.14 0.22 0.16 0.26 0.17 0.23 0.29 0.19 0.19 0.20 La 7.77 10.24 5.63 5.34 6.72 7.95 7.71 7.67 2.64 3.67 4.02 4.29 4.43 4.03 3.96 4.53 3.00 5.70 3.69 6.57 6.46 4.34 4.42 5.48 Ce 15.45 21.45 12.94 12.27 15.47 16.72 16.21 16.24 5.91 8.14 8.32 9.57 9.18 8.28 8.35 9.35 6.80 14.01 8.27 13.77 14.61 9.22 9.45 11.59 Nd 7.77 11.22 7.09 6.67 8.17 8.43 8.15 8.19 3.27 4.55 5.15 5.22 5.29 4.33 4.37 4.66 3.58 6.11 4.76 6.82 6.88 4.83 5.08 5.87 Zr 37 60 43 48 47 49 50 53 36 37 51 38 37 26 26 61 37 42 30 43 50 40 38 48 Hf 0.99 1.83 1.27 1.41 1.43 1.41 1.42 1.48 1.18 1.23 1.54 1.10 1.10 0.73 0.76 1.75 1.08 1.33 0.71 1.43 1.54 0.97 0.83 1.20 Sm 1.95 2.67 1.78 1.64 1.99 2.04 1.97 2.04 0.91 1.22 1.55 1.31 1.48 1.07 1.09 1.29 0.84 1.50 0.87 1.72 1.88 1.23 1.19 1.45 Gd 2.00 2.74 1.77 1.68 1.96 2.01 1.99 2.08 0.96 1.42 1.91 1.33 1.51 1.08 1.14 1.63 0.87 2.09 1.24 1.85 2.00 1.33 1.48 1.57 Y 14.26 9.57 9.29 10.59 11.09 11.26 11.38 6.62 9.73 12.82 7.42 8.88 6.20 6.40 12.05 8.11 11.71 7.89 11.64 12.15 10.59 9.64 11.12 Yb 1.54 1.08 1.14 1.18 1.20 1.17 1.19 0.84 0.99 1.27 0.82 0.93 0.67 0.69 1.21 0.83 1.09 0.73 1.17 1.38 1.09 0.79 1.09 Lu 0.23 0.24 0.17 0.18 0.19 0.18 0.18 0.18 0.13 0.15 0.19 0.12 0.14 0.10 0.10 0.19 0.15 0.14 0.13 0.17 0.21 0.15 0.11 0.14

Table A3. (Cont.)

SiO2

TiO2

Al2O3

Fe2O3T

MnOMgOCaONa2OK2OP2O5

LOITotalMg#ThNbTaLaCeNdZrHfSmGdYYbLu

SiO2

TiO2

Al2O3

Fe2O3T


LOITotalMg#

ThNbTaLaCeNdZrHfSmGdYYbLu


1330 WANG ET AL.

Sample no. DXS-49 DXS-50 DXS-51 DXS-52 DXS-53 DXS-54 DXS-55 DXS-56 DXS-57 DXS-58 DXS-59 DXS-60 Sample no. DXS-61 DXS-62 DXS-63 DXS-64 WM-01 WM-02 WM-03

Rock type Harzburgite Gabbro Rock type Gabbro Siltstone Basalt

SiO2 37.3 39.19 39.79 38.75 37.6 36.67 38.11 39.23 50.22 51.13 50.8 51.03 50.34 50.17 62.50 63.63 47.83 47.98 48.15TiO2 0.41 0.61 0.42 0.46 0.37 0.35 0.35 0.44 0.92 0.99 0.99 0.91 0.9 0.77 0.84 0.88 1.19 1.36 1.4Al2O3 5.52 6.74 5.82 5.79 5.35 5.04 5.22 5.89 15.49 15.76 15.37 15.43 15.95 15.8 16.46 16.96 15.1 14.75 14.51Fe2O3T 21.44 18.37 17.76 19.13 19.68 20.51 20.25 17.33 9.49 9.92 10.04 9.72 9.38 8.27 6.98 5.70 10.47 11.59 11.67MnO 0.14 0.14 0.14 0.16 0.16 0.13 0.12 0.17 0.15 0.15 0.16 0.16 0.15 0.14 0.11 0.08 0.17 0.16 0.17MgO 22.88 23.27 24.02 24.64 25.43 23.83 23.86 23.81 7.93 8.14 7.84 8.15 7.66 7.58 2.35 2.99 8.32 6.91 7.28CaO 0.22 1 0.9 0.58 0.2 0.63 0.8 1.79 9.19 9.35 9.31 9.28 9.13 10.23 1.12 0.28 8.41 9.96 10.13Na2O 1.24 1.15 0.25 <0.01 0.08 <0.01 <0.01 0.17 2.15 2.16 2.23 2.16 2.19 2.08 2.31 1.63 3.22 2.96 2.6K2O 0.17 0.19 0.39 0.27 0.14 0.27 0.28 0.38 1.06 0.95 0.87 1.01 1.19 1.11 3.07 3.60 0.94 0.65 0.55P2O5 0.06 0.06 0.05 0.05 0.04 0.04 0.04 0.05 0.1 0.1 0.11 0.1 0.1 0.08 0.10 0.08 0.13 0.13 0.15LOI 9.71 9.19 9.73 9.53 10.56 10.85 10.48 9.01 1.62 0.97 1.41 1.47 1.70 2.90 3.85 3.61 3.61 2.79 2.43Total 99 100 99 99 100 98 100 98 98 100 99 99 99 99 100 99 99 99 99 Mg# 68 72 73 72 72 70 70 73 63 62 61 63 62 65 64 57 58 Th 2.11 2.21 1.72 1.58 1.67 2.33 1.71 1.67 3.95 3.94 3.97 3.79 4.07 3.05 22.09 21.90 2.99 2.85 4.2Nb 2.19 2.62 1.78 1.76 1.68 2.25 1.97 1.83 5.52 5.61 5.59 5.37 5.76 4.38 17.50 18.32 8.02 6.54 9.61Ta 0.16 0.19 0.14 0.11 0.15 0.18 0.17 0.12 0.41 0.42 0.41 0.40 0.43 0.33 1.56 1.62 0.51 0.42 0.62La 5.23 5.80 4.01 3.43 3.70 4.90 3.87 3.89 12.04 12.13 12.37 11.83 12.76 9.56 53.60 52.50 10.27 9.29 12.72Ce 11.30 12.64 8.96 7.43 8.09 11.24 8.37 8.15 25.46 25.71 25.69 24.74 26.80 20.37 104.00 101.00 22.13 20.91 27.78Nd 6.00 7.24 4.99 4.00 4.29 5.54 4.40 4.07 13.49 13.46 13.74 13.23 14.01 11.06 44.69 44.13 12.27 12.51 15.13Zr 35 37 26 28 28 36 28 28 86 87 86 83 88 67 218 224 87 97 113Hf 1.02 1.23 0.72 0.73 0.80 1.15 0.71 0.66 2.38 2.40 2.40 2.32 2.47 1.92 5.90 6.04 2.46 2.79 3.18Sm 1.48 1.53 1.08 0.74 1.07 1.46 1.05 0.92 3.41 3.40 3.38 3.33 3.52 2.84 8.61 7.87 3.04 3.48 3.78Gd 1.37 1.76 1.41 1.02 1.27 1.55 1.25 1.26 3.48 3.48 3.56 3.44 3.65 3.00 7.40 6.54 3.92 4.44 4.84Y 9.45 10.34 8.39 7.20 7.53 9.84 7.63 7.97 20.37 20.71 21.31 20.45 21.16 17.43 31.75 26.96 26.99 33.73 35.13Yb 0.82 0.97 0.87 0.66 0.69 1.12 0.76 0.73 2.07 2.11 2.14 2.10 2.21 1.78 3.15 2.91 2.25 2.92 2.97Lu 0.12 0.18 0.10 0.11 0.10 0.11 0.12 0.10 0.33 0.33 0.34 0.33 0.33 0.28 0.50 0.47 0.34 0.45 0.46

Notes: LOI = loss on ignition, Mg# = [100Mg2+/(Mg2+ + Fe2+), molar]; total iron reported as Fe2O3T; oxides in wt %, trace elements in ppm

Table A3. (Cont.)



Sample no. DXS-49 DXS-50 DXS-51 DXS-52 DXS-53 DXS-54 DXS-55 DXS-56 DXS-57 DXS-58 DXS-59 DXS-60 Sample no. DXS-61 DXS-62 DXS-63 DXS-64 WM-01 WM-02 WM-03

Rock type Harzburgite Gabbro Rock type Gabbro Siltstone Basalt

SiO2 37.3 39.19 39.79 38.75 37.6 36.67 38.11 39.23 50.22 51.13 50.8 51.03 50.34 50.17 62.50 63.63 47.83 47.98 48.15TiO2 0.41 0.61 0.42 0.46 0.37 0.35 0.35 0.44 0.92 0.99 0.99 0.91 0.9 0.77 0.84 0.88 1.19 1.36 1.4Al2O3 5.52 6.74 5.82 5.79 5.35 5.04 5.22 5.89 15.49 15.76 15.37 15.43 15.95 15.8 16.46 16.96 15.1 14.75 14.51Fe2O3T 21.44 18.37 17.76 19.13 19.68 20.51 20.25 17.33 9.49 9.92 10.04 9.72 9.38 8.27 6.98 5.70 10.47 11.59 11.67MnO 0.14 0.14 0.14 0.16 0.16 0.13 0.12 0.17 0.15 0.15 0.16 0.16 0.15 0.14 0.11 0.08 0.17 0.16 0.17MgO 22.88 23.27 24.02 24.64 25.43 23.83 23.86 23.81 7.93 8.14 7.84 8.15 7.66 7.58 2.35 2.99 8.32 6.91 7.28CaO 0.22 1 0.9 0.58 0.2 0.63 0.8 1.79 9.19 9.35 9.31 9.28 9.13 10.23 1.12 0.28 8.41 9.96 10.13Na2O 1.24 1.15 0.25 <0.01 0.08 <0.01 <0.01 0.17 2.15 2.16 2.23 2.16 2.19 2.08 2.31 1.63 3.22 2.96 2.6K2O 0.17 0.19 0.39 0.27 0.14 0.27 0.28 0.38 1.06 0.95 0.87 1.01 1.19 1.11 3.07 3.60 0.94 0.65 0.55P2O5 0.06 0.06 0.05 0.05 0.04 0.04 0.04 0.05 0.1 0.1 0.11 0.1 0.1 0.08 0.10 0.08 0.13 0.13 0.15LOI 9.71 9.19 9.73 9.53 10.56 10.85 10.48 9.01 1.62 0.97 1.41 1.47 1.70 2.90 3.85 3.61 3.61 2.79 2.43Total 99 100 99 99 100 98 100 98 98 100 99 99 99 99 100 99 99 99 99 Mg# 68 72 73 72 72 70 70 73 63 62 61 63 62 65 64 57 58 Th 2.11 2.21 1.72 1.58 1.67 2.33 1.71 1.67 3.95 3.94 3.97 3.79 4.07 3.05 22.09 21.90 2.99 2.85 4.2Nb 2.19 2.62 1.78 1.76 1.68 2.25 1.97 1.83 5.52 5.61 5.59 5.37 5.76 4.38 17.50 18.32 8.02 6.54 9.61Ta 0.16 0.19 0.14 0.11 0.15 0.18 0.17 0.12 0.41 0.42 0.41 0.40 0.43 0.33 1.56 1.62 0.51 0.42 0.62La 5.23 5.80 4.01 3.43 3.70 4.90 3.87 3.89 12.04 12.13 12.37 11.83 12.76 9.56 53.60 52.50 10.27 9.29 12.72Ce 11.30 12.64 8.96 7.43 8.09 11.24 8.37 8.15 25.46 25.71 25.69 24.74 26.80 20.37 104.00 101.00 22.13 20.91 27.78Nd 6.00 7.24 4.99 4.00 4.29 5.54 4.40 4.07 13.49 13.46 13.74 13.23 14.01 11.06 44.69 44.13 12.27 12.51 15.13Zr 35 37 26 28 28 36 28 28 86 87 86 83 88 67 218 224 87 97 113Hf 1.02 1.23 0.72 0.73 0.80 1.15 0.71 0.66 2.38 2.40 2.40 2.32 2.47 1.92 5.90 6.04 2.46 2.79 3.18Sm 1.48 1.53 1.08 0.74 1.07 1.46 1.05 0.92 3.41 3.40 3.38 3.33 3.52 2.84 8.61 7.87 3.04 3.48 3.78Gd 1.37 1.76 1.41 1.02 1.27 1.55 1.25 1.26 3.48 3.48 3.56 3.44 3.65 3.00 7.40 6.54 3.92 4.44 4.84Y 9.45 10.34 8.39 7.20 7.53 9.84 7.63 7.97 20.37 20.71 21.31 20.45 21.16 17.43 31.75 26.96 26.99 33.73 35.13Yb 0.82 0.97 0.87 0.66 0.69 1.12 0.76 0.73 2.07 2.11 2.14 2.10 2.21 1.78 3.15 2.91 2.25 2.92 2.97Lu 0.12 0.18 0.10 0.11 0.10 0.11 0.12 0.10 0.33 0.33 0.34 0.33 0.33 0.28 0.50 0.47 0.34 0.45 0.46

Notes: LOI = loss on ignition, Mg# = [100Mg2+/(Mg2+ + Fe2+), molar]; total iron reported as Fe2O3T; oxides in wt %, trace elements in ppm

SiO2

TiO2

Al2O3

Fe2O3T


LOITotalMg#

ThNbTaLaCeNdZrHfSmGdYYbLu

Table A3. (Cont.)


1332 WANG ET AL.

Qingfei Wang is a professor at China University of Geosciences (Beijing). He received a B.Sc. degree in 2000 from China University of Geosciences (Wuhan) and a Ph.D. degree in 2005 from China University of Geosciences (Beijing). He was a vis-iting scholar at Indiana University Bloomington, USA, in 2012. His current research focus is regional metallogeny in convergent tectonic settings, such as the Tethyan orogenic belts in Yunnan and Tibet, western China. The ultimate goal of his research is to develop geologic or genetic models that can be used for mineral explora-tion at both regional and deposit scales.


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Geochronological, Petrological, and Geochemical Studies of ... · 2014). Outside China, only a few magmatic Ni-Cu sulfide deposits have been reported to occur in convergent tectonic