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Research paper

Mesozoic accretion of juvenile sub-continental lithospheric mantle beneath SouthChina and its implications: Geochemical and Re–Os isotopic results from Ningyuanmantle xenoliths

Chuan-Zhou Liu ⁎, Zhi-Chao Liu, Fu-Yuan Wu, Zhu-Yin ChuState Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China

a b s t r a c ta r t i c l e i n f o

Article history:Received 26 January 2011Received in revised form 10 October 2011Accepted 11 October 2011Available online 20 October 2011

Editor: L. Reisberg

Keywords:Mantle xenolithsRe–Os isotopesHighly siderophile elementsSouth ChinaMesozoic magmatismMantle accretion

The mechanism for the widespread Mesozoic magmatism in South China has been ascribed to either thepaleo-Pacific plate subduction or intra-continental lithospheric extension. Mantle xenoliths entrained inthe Jurassic Ningyuan alkaline basalts from southern Hunan Province, including twelve lherzolites and oneharzburgite, have been studied to constrain the composition and age of the Mesozoic sub-continental litho-spheric mantle. The lherzolites contain 2.06–4.09 wt.% Al2O3 and 2.03–3.91 wt.% CaO, which are higher thanthe abundances of these species in the harbzurgite (1.72 wt.% and 1.17 wt.%, respectively). The Cr# of spinelvaries from 0.07 to 0.24. Orthopyroxene contains 3.61–4.96 wt.% Al2O3 and 0.51–0.8 wt.% CaO, whereas clin-opyroxene contains 4.78–7.32 wt.% Al2O3 and 1.04–2.01 wt.% Na2O. Both whole rock and mineral composi-tions suggest that the Ningyuan mantle xenoliths have been subjected to low degrees of partial melting.Modeling of Y and Yb contents of clinopyroxene indicates that the lherzolites have been subjected to 3–5%degrees of partial melting, while the harzburgite has experienced about 12% melting. Clinopyroxene inmost Ningyuan mantle xenoliths shows variable depletion in incompatible elements, suggesting that theyhave been weakly enriched after melting. Clinopyroxene in one sample (TYS01-3) displays strong enrich-ment in incompatible elements, reflecting the local occurrence of melt metasomatism. Equilibrium tempera-tures estimated by two-pyroxene geothermometry vary from 994 to 1081 °C, indicating that the Mesozoicmantle lithosphere has a hot geotherm. All lherzolites display consistent highly siderophile element (HSE)patterns and have suprachondritic Ru/Ir and Pd/Ir ratios. The harzburgite shows remarkable depletion inPt, Pd and Re. The lherzolites have 187Os/188Os ratios of 0.12116–0.12929, which are higher than that ofthe harzburgite (0.11681). A correlation between 187Os/188Os and Al2O3 exists among the Ningyuan mantlexenoliths, which if interpreted as an isochron analog yields a model age of ~2.2 Ga. This age is older thanthe Re depletion age (TRD) of the harzburgite (~1.8 Ga), which represents a minimum age of melt depletion.The old ages either support the existence of ancient lithosphere relics beneath the Ningyuan region or reflectthe accretion of ancient mantle materials from the asthenosphere during the Mesozoic. Although the tectonicimplication of the old ages is ambiguous, compositions of the Ningyuan mantle xenoliths suggest that ancientmantle lithosphere beneath South China has been thinned and replaced by hotter, younger mantle during theMesozoic, which has led to extensive lithospheric extension and abundant magmatism.

© 2011 Elsevier B.V. All rights reserved.

1. Introduction

A remarkable geological feature of the South China Block (SCB) isthe widespread Mesozoic magmatism, in which granites and ryho-lites predominate volumetrically over basalts (Zhou et al., 2006).The tectonic regime responsible for the Mesozoic magmatism inSouth China has been an issue of long-term debate. Current viewson the Mesozoic petrogenesis can be grouped into two general cate-gories. One suggests that the early Mesozoic tectonic setting of

South China was an Andean-type active continental margin relatedto the subduction of the paleo-Pacific plate (Holloway, 1982; Faureet al., 1996; Zhou and Li, 2000). The other emphasizes the intraconti-nental lithospheric extension, which was accompanied by astheno-spheric upwelling (Gilder et al., 1996; Fan et al., 2003; Li et al.,2003; Wang et al., 2003; Li et al., 2004; Wang et al., 2004). A betterunderstanding of the composition and age of the lithospheric mantlebeneath South China during the Mesozoic could provide effectiveconstraints on these different models.

Furthermore, the composition and age of the Mesozoic lithosphericmantle are of key importance for constraining the timing of the litho-spheric transformation beneath South China. Compositions of garnetlherzolite entrained in the Paleozoic Dahongshan lamproites indicate

Chemical Geology 291 (2012) 186–198

⁎ Corresponding author. Tel.: +86 10 82998547; fax: +86 10 62010846.E-mail address: [email protected] (C.-Z. Liu).

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that the lithospheric mantle had a thickness larger than 110 km and apaleogeotherm distinctly colder than the oceanic geotherm (Zhang etal., 2001). This is in stark contrast to the Cenozoic lithosphere inferredfrom the Cenozoic basalts and their entrained mantle xenoliths(Fig. 1). The Cenozoicmantle xenoliths commonly have fertile composi-tions and high equilibrium temperatures, suggesting a hot geotherm(Fan and Hopper, 1989; Qi et al., 1995; Xu et al., 2000; Xu et al., 2002;Yu et al., 2003; Zheng et al., 2004; Yu et al., 2006; Huang and Xu,2010). Previous studies have suggested that the old (i.e., Archean andProterozoic) mantle that existed beneath the SCB has been largely orcompletely removed and replaced by younger, hotter and more fertilemantle (Xu et al., 2000; Xu et al., 2002). However, it remains unclearwhen the mantle thinning and replacement processes occurred inSouth China.

In contrast to the widespread distribution of the Cenozoic basalts,the Mesozoic basaltic rocks outcrop sporadically in the interior of theSCB (Zhao et al., 1998; Wang et al., 2003; Li et al., 2004; Wang et al.,2004; Wang et al., 2005; Xie et al., 2005; Xu and Xie, 2005; Jiang et al.,2009). The Jurassic alkaline basalts in both Ningyuan (170–173 Ma)and Daoxian (147–152 Ma) from southern Hunan Province containabundant lower crustal andmantle xenoliths, including gabbros, pyrox-enites, lherzolites and harzburgites (Guo et al., 1997;Wang et al., 1997;

Guo et al., 1999; Kong et al., 2000; Zheng et al., 2004; Dai et al., 2008;Zhang et al., 2008; Xia et al., 2010). In this study, we present the com-prehensive geochemical compositions of Ningyuan mantle xenolithsto discuss the accretion of juvenile mantle during the Mesozoic andthe implications for the widespread Mesozoic magmatism in SouthChina.

2. Geological setting and petrography

2.1. Geological setting

The South China Block (SCB) has been commonly divided into twomajor blocks, with the Yangtze block to the northwest and the Cathaysiablock to the southeast (Fig. 1). The Yangtze block consists of an Archeanto Paleoproterozoic basement (Chen and Jahn, 1998; Zheng et al.,2006), including occurrences of 2.90–2.95 Ga tonalite–trondhjemite–granodiorite (TTG) gneiss (Qiu et al., 2000). The basement of the Cathay-sia block exhibits Paleoproterozoic to Mesoproterozoic ages and possiblyNeoarchean ages (Li et al., 1989; Yu et al., 2007). These two tectonic unitswere amalgamated along the Jiangshan–Shaoxing fault at 820–970 Ma(Li, 1999; Zhao and Cawood, 1999; Wu et al., 2006). Subsequently, theSCB has experienced a breakup event at ca. 820 Ma, possibly caused by

North China Craton

South China Block

Yangtze

Cathaysia

SongpaGanzeBlock

Daoxian

Ningyuan

Pal

eo-P

acif

ic

105oE

36oN

32oN

28oN

24oN

20oN

110oE 115oE 120oE

0 200 400

Km

1000 Km

Qinling-Dabie Orogenic Belt

Tan

-Lu

Fau

lt

Penghu

Niutoushan

Leizhou

Penglai

Nushan

Panshishan

Qilin

Mingxi

XilongXinchang

Guanzhou

Dahongshan

Zhenyuan

JS-PYFZ

SHZ

Triassic granitoids

Jurassic granitoids

Cretaceous granitoids

Cretaceous basalts

Jurassic basalts

Paleozoic lamproites

Mesozoic mantle xenoliths

Cenozoic mantle xenoliths

Jianghan Basin

Fig. 1. Sketch map showing the distribution of the Mesozoic magmatism in South China Block (modified after Chen et al., 2008), in which the Paleozoic lamproites, Mesozoic andCenozoic mantle xenoliths are also shown. JS-PYHZ: Jiangshan–Shaoxing and Pingxiang–Yushan fault zone; SHZ: Shi–Hang zone. GPS location of the Ningyuan mantle xenoliths:25°43′01.8″ N, 112°01′51.6″ E.

187C.-Z. Liu et al. / Chemical Geology 291 (2012) 186–198


a mantle plume (Wang et al., 2007a). Afterwards, it was affected by theCaledonian event during the Late Ordovician–Silurian and, subsequently,the Indosinian event during the Late Permian–Triassic (Wang et al.,2007b). During Jurassic–Cretaceous times, the SCB has been reworkedby several tectonic and magmatic events, as represented by granitic in-trusions, acidic and intermediate volcanism, ductile and brittle normaland strike-slip faulting, extensional doming and syntectonic terrigeneoussedimentation (Faure et al., 1996; Lin et al., 2000;Wang et al., 2001). TheMesozoic tectonic and magmatic events have been related to either thesubduction of the paleo-Pacific oceanic plate beneath the Chinese conti-nent (Zhou and Li, 2000; Xie et al., 2005; Xu and Xie, 2005; Zhou et al.,2006; Jiang et al., 2009), or the intracontinental rifting (Fan et al., 2003;Li et al., 2003; Wang et al., 2003; Li et al., 2004; Wang et al., 2004;Wang et al., 2005).

Mesozoic magmatic rocks are widely distributed in the SCB, and canbe roughly divided into two periods. The Early Mesozoic intrusionsoccur mainly in the interior of the SCB, whereas the Late Mesozoic gran-itoids and volcanic rocks are confinedmostly to coastal areas (Zhou et al.,2006). In particular, the Jurassic volcanic rocks outcrop along an east–west trending array in the interior of the Cathaysia block (Zhou et al.,2006; Xu, 2008), amongwhich both Ningyuan (170–173 Ma) and Daox-ian (147–152 Ma) basalts contain various crustal and mantle xenoliths(Guo et al., 1997; Wang et al., 1997; Guo et al., 1999; Kong et al., 2000;Zheng et al., 2004; Dai et al., 2008; Zhang et al., 2008). During the Ceno-zoic, the continental margin of South China was characterized by an ex-tensional tectonic environment (Ru and Piggot, 1986). Upwelling ofasthenosphere as a response to the extension produced large volumesof intraplate basalts, which are widespread in the coastal areas (Chunget al., 1997; Zhu et al., 2004). The Cenozoic basalts in several localitiescontain abundant mantle xenoliths (Fig. 1), and garnet peridotites havebeen reported in Xinchang, Xilong, and Mingxi (see reviews in Huangand Xu, 2010).

2.2. Petrography

Twelve lherzolites and one harzburgite were selected for study. Theyhave sizes of ca. 6 cm across and show porphyroclastic textures with lit-tle deformation. Secondary minerals (e.g., amphibole and phlogopite)were not observed in any xenolith. All Ningyuan mantle xenoliths havebeen subjected to variable degrees of alteration. Olivine displays meshtextures and is commonly crosscut by serpentine veins (Fig. 2a). Spinelgenerally shows a ‘holly-leaf’ shape (Fig. 2b), and occasionally a roundshape interstitial among the silicate minerals (Fig. 2c). Orthopyroxeneporphyrocrysts with sizes of ~1 mm–2 cm are commonly anhydral,and are surrounded by small olivines (Fig. 2c, d). Clinopyroxene por-phyrocrysts (~300 μm–5 mm) are generally smaller than those of ortho-pyroxene (Fig. 2e). Exsolution lamellae are well developed in bothclinopyroxene and orthopyroxene (Fig. 2d, e). The harzburgite (TYS07)is characterized by low content of clinopyroxene (b5%). The clinopyrox-ene is of small size and displays a poikilitic texture around orthopyrox-ene (Fig. 2f). Sulfides, which are either included in silicates or in theinterstitial silicatematrix, have been observed in someNingyuanmantlexenoliths.

3. Analytical methods

Whole rock major elements were determined at Northwest Uni-versity and other analyses were performed at the Institute of Geologyand Geophysics, Chinese Academy of Sciences (IGGCAS).

3.1. Major and trace elements

Whole-rock major element compositions were determined by theX-ray fluorescence technique (XRF), which has been described inRudnick et al. (2004). Precisions are 1–3% for elements present inconcentrations higher than 1%, and about 5% for elements with

concentrations less than 1%. Mineral major elements were measuredon a JEOL JXA-8100 electron probe using an accelerating potential of15 kV and a sample current of 10 nA.

Trace elements in clinopyroxene were analyzed in situ by laser ab-lation inductively coupled plasma mass spectrometry (LA-ICP-MS).The detailed description of the method has been given in Liu et al.(2010). The LA-ICP-MS system consists of a Lambda Physik LPX 120Ipulsed ArF excimer laser coupled to an Agilent 7500 ICP-MS. Isotopeswere measured in a peak-hopping mode. A spot size of 80 μm and arepetition rate of 8 Hz were used for analysis. Counting times were25 s for background and 75 s for the analysis of clinopyroxene andstandards. The data were reduced by the GLITTER 4.0 program. Iso-tope 43Ca was used as an internal standard and NIST 610 glass as anexternal calibration standard. Reference values of NIST 610 are select-ed from Pearce et al. (1997).

3.2. Highly siderophile elements (HSEs) and Re–Os isotopes

Both HSEs and Re–Os isotopes were measured by the isotope dilu-tion method following the procedure described by Chu et al. (2009).About 2 g sample powder, together with Re–Os (187Re and 190Os)and HSE (99Ru, 105Pd, 191Ir and 194Pt) isotope tracers, was mixedwith reverse aqua regia (i.e., 3 ml 12N HCl and 6 ml 16N HNO3) anddigested in a Carius Tube at 240 °C for ~48–72 h. Osmium wasextracted from the aqua regia solution by solvent extraction intoCCl4 and further purified by micro-distillation. Afterwards, Ru, Pd,Re, Ir and Pt were sequentially separated from the solution by anionexchange resin (AG-1 ×8, 100–200 mesh).

Osmium isotopes were determined using negative thermal ioniza-tion mass-spectrometry (N-TIMS) technique (Creaser et al., 1991;Volkening et al., 1991) and conducted on a GV Isoprobe-T instrumentin static mode using Faraday cups. To increase the ionization efficien-cy, Ba(OH)2 solution was used as the ion emitter. The measured Osisotopes were corrected for mass fractionation using the 192Os/188Osratio of 3.0827. The Nier oxygen isotope composition (17O/16O=0.0003708 and 18O/16O=0.002045) has been used for oxidecorrection. The in-run precisions were better than 0.2% (2δ; δ = rela-tive standard deviation) for all the samples. The Johnson–Mattheystandard of UMD was measured as an external standard and gave187Os/188Os ratios of 0.11378±2. The concentrations of other HSEswere measured on a Thermal-Electron Neptune MC-ICPMS in peak-jumping mode or static mode, according to their measured signal in-tensities. In-run precisions for 185Re/187Re, 191Ir/193Ir, 99Ru/101Ru,194Pt/196Pt and 105Pd/106Pd were 0.1–0.3% (2δ). The total proceduralOs blank was 3–5 pg with a 187Os/188Os ratio of ca. 0.15, which wasnegligible for all samples in this study. Total procedural blanks wereabout 3 pg for Re, 7 pg for Ir, 7 pg for Ru, 4 pg for Pt and 4 pg for Pd.The blank corrections were negligible (b1%) for Ir, Ru, Pt and Pd,but up to 3% for Re.

4. Results

4.1. Whole-rock chemistry

Whole-rock major element compositions of Ningyuan mantle xeno-liths are shown in Table 1. The Ningyuan mantle xenoliths have variablevalues of loss on ignition (LOI; 3.94–5.89 wt.%). On the basis ofwater-freecontents, the lherzolites contain 32.75–37.56 wt.% MgO, 8.61–10.22 wt.%Fe2O3, 0.05–0.12 wt.% Na2O and 0.02–0.16 wt.% TiO2. Compared to thelherzolites, the harzburgite (TYS07) has distinct lower Al2O3 (1.73 wt.%), CaO (1.18 wt.%) but higher MgO (38.21 wt.%) contents. Most sampleshave MgO contents substantially lower than that of the primitive mantle(McDonough and Sun, 1995), whichmight reflect magnesium loss by al-teration (Snow and Dick, 1995). The Ningyuan mantle xenoliths contain2.07–4.12 wt.% Al2O3 and 2.04–3.93 wt.% CaO, giving CaO/Al2O3 ratios

188 C.-Z. Liu et al. / Chemical Geology 291 (2012) 186–198


of~0.68–1.2. The bulk-rock MgO contents show negative correlationswith Al2O3, CaO, Na2O and TiO2 contents (Fig. 3a–d).

4.2. Mineral compositions

Major element compositions of olivine, spinel, orthopyroxene andclinopyroxene are given in Table 2. Trace element compositions ofclinopyroxene are listed in Table 3.

4.2.1. Major elementsOlivine from the Ningyuan mantle xenoliths has fosterite contents

[Fo=100×Mg/(Mg+Fe)] of 88.3–90.8 and contains 0.35–0.39 wt.%NiO. The Fo contents do not correlate with the NiO contents. Spinelhave Mg# [=Mg/(Mg+Fe)] of 0.76–0.79 and Cr# [=Cr/(Cr+Al)] of

0.07–0.24 (Fig. 4a). It contains 0.29–0.39 wt.% NiO and 0.04–0.12 wt.%TiO2. Orthopyroxene from the Ningyuan mantle xenoliths has Mg# of0.89–0.91, which shows reverse correlations with both TiO2 and Al2O3

contents (Fig. 4b). Orthopyroxene contains 3.61–4.96 wt.% Al2O3 and0.51–0.8 wt.% CaO. Clinopyroxene with Mg# of 0.90–0.92 contains4.78–7.32 wt.% Al2O3, 18.74–21.23 wt.% CaO, 1.04–2.01 wt.% Na2O and0.12–0.59 wt.% TiO2. Clinopyroxene in the harzburgite (TYS07) haslower contents of Al2O3 and TiO2 but higher Cr2O3 contents than thosein the lherzolites. The Mg# of clinopyroxene show reverse correlationswith both Al2O3 (Fig. 4c) and TiO2 contents (Fig. 4d). Sample TYS01-3plots away from the correlation to remarkably low contents of TiO2

and Na2O. The spinel Cr# displays reverse relationships with the Na2Ocontents of the clinopyroxene (Fig. 4a). The Na2O contents of clinopyr-oxene in our samples are comparable to those reported for Daoxian

Ol

Ol

Ol

Ol

Ol

eOl

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c

f

b

Ol

Ol

Ol

dOlOl

Ol

Opx

CpxOpx

Cpx

Sp

Sp

Sp

Sp

Ol

Sp

Opx

Opx

Cpx

Ol

Fig. 2.Microscopic photographs of Ningyuan mantle xenoliths. (a) Olivine porphyroclasts cut by serpentine veins. (b) Spinel interstitial between clinopyroxene and orthopyroxene.(c) Round spinel inclusion in the orthopyroxene porphyroclast. (d) Anhedral orthopyroxene with clinopyroxene exsolution lamellae surrounded by small olivines. (e) Subhedralclinopyroxene porphyroclast surrounded by serpentinized olivine. (f) Poikilitic clinopyroxene around the orthopyroxene porphyrocryst. Ol: olivine; Opx: orthopyroxene; Cpx: clin-opyroxene; Sp: spinel.



mantle xenoliths by Zheng et al. (2004), but distinctly higher than thoseof Ningyuan mantle xenoliths obtained by Xia et al. (2010).

4.2.2. Trace elementsClinopyroxene from all lherzolites but TYS01-3 displays flat pat-

terns from heavy rare earth elements (HREE) to middle rare earth el-ements (MREE), but shows variable depletion in light rare earthelements (LREE; Fig. 5a). Their (La/Yb)n (n: chondrite-normalized;Anders and Grevesse, 1989) ratios vary from 0.07 to 0.41. In contrast,clinopyroxene in sample TYS01-3 shows remarkable enrichment inboth LREE and MREE, with a (La/Yb)n ratio of 3.67. Clinopyroxene inthe harzburgite TYS07 displays a relatively flat REE pattern, with aslightly depletion in LREE. Its HREE contents are distinctly lowerthan those of the lherzolites (Fig. 5a).

Clinopyroxene in sample TYS01-3 shows an enriched pattern intrace elements (Fig. 5b), especially the large ion lithophile elements(LILE: Ba, Th and U). It also shows remarkable negative anomalies inSr and the high strength field elements (HFSE: Zr, Hf, Nb, Ta and Ti).Clinopyroxene from other lherzolites and the harzburgite show de-pleted trace element patterns and negative Nb, Ta and Ti anomalies.However, they do not display negative Zr, Hf and Sr anomalies.

4.3. Equilibrium temperatures

Mineral chemistry indicates that equilibriumhas been achieved in allNingyuanmantle xenoliths, and thus the temperatures can be calculatedusing various geothermometers (Wood and Banno, 1973; Wells, 1977;Bertrand and Mercier, 1985; Brey and Kohler, 1990; Witt-Eickschenand Seck, 1991), which are listed in Table 4.When a single thermometer

Table 1Whole rock major elementsof Ningyuan mantle xenoliths (in wt.%).

SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI Total Mg# CaO/Al2O3

TYS01-3 43.90 0.02 2.06 9.19 0.11 37.41 2.03 0.05 0.01 0.01 4.81 99.60 0.89 0.99TYS02-2 44.07 0.09 3.10 8.81 0.11 36.03 3.30 0.08 0.01 0.02 3.94 99.56 0.89 1.06TYS02-3 43.96 0.10 3.26 8.81 0.11 34.89 3.91 0.09 0.02 0.02 4.29 99.46 0.89 1.20TYS03-2 45.38 0.07 2.80 8.87 0.11 35.31 2.78 0.07 0.02 0.02 4.26 99.69 0.89 0.99TYS03-8 44.16 0.13 3.10 10.17 0.13 35.02 2.45 0.08 0.03 0.03 4.19 99.49 0.87 0.79TYS03-16 44.48 0.11 3.33 9.18 0.11 34.27 3.30 0.09 0.04 0.03 5.01 99.95 0.88 0.99TYS03-16-R 44.45 0.10 3.33 9.15 0.11 34.19 3.29 0.09 0.03 0.03 4.86 99.63 0.88 0.99TYS03-19 44.70 0.11 4.01 8.70 0.11 33.61 3.40 0.10 0.01 0.02 4.34 99.11 0.89 0.85TYS03-23 44.22 0.12 3.60 9.84 0.12 32.72 3.82 0.11 0.04 0.03 5.28 99.90 0.87 1.06TYS04-4 44.66 0.07 3.45 8.58 0.10 34.82 2.89 0.07 0.01 0.02 4.81 99.48 0.89 0.84TYS05-2 43.77 0.14 3.00 8.58 0.11 34.38 3.49 0.08 0.09 0.06 5.89 99.59 0.89 1.16TYS05-2-R 43.65 0.14 2.96 8.56 0.11 34.39 3.48 0.08 0.09 0.06 5.89 99.41 0.89 1.18TYS06 44.70 0.11 3.72 9.00 0.11 33.22 3.45 0.11 0.01 0.02 4.79 99.24 0.88 0.93TYS07 45.42 0.02 1.72 8.69 0.10 38.01 1.17 0.03 0.01 0.02 4.28 99.47 0.90 0.68TYS08 44.70 0.16 4.09 9.03 0.12 33.51 3.19 0.12 0.07 0.04 4.17 99.20 0.88 0.78TYS08-R 44.80 0.16 4.08 9.01 0.12 33.60 3.21 0.12 0.07 0.04 4.13 99.34 0.88 0.79

Mg#=Mg/(Mg+Fe); Fe2O3: total iron.R: replicate analysis.

0

1

2

3

4

5

32 33 34 35 36 37 38 39

Lherzolite

Harzburgite

0

1

2

3

4

5

32 33 34 35 36 37 38 39

0.00

0.04

0.08

0.12

0.16

32 33 34 35 36 37 38 39 0.00

0.05

0.10

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32 33 34 35 36 37 38 39

MgO (in wt.%)

Al 2

O3

(in w

t %)

TiO

2 (in

wt %

)

Na 2

O (

in w

t %)

MgO (in wt.%)

MgO (in wt.%) MgO (in wt.%)

CaO

(in

wt %

)

a b

c d

Fig. 3. Diagrams of bulk-rock MgO versus bulk contents of Al2O3 (a), CaO (b), Na2O (c) and TiO2 (d).



is employed, equilibrium temperatures of Ningyuan mantle xenolithsshow an overall uniform trend, although temperatures obtained by dif-ferent thermometers for a given sample are variable. Applying thetwo-pyroxene geothermometer of Brey and Kohler (Brey and Kohler,1990), temperatures of Ningyuan mantle xenoliths are calculated tovary from 994 to 1081 °C. Similar high temperatures (948–1135 °C)have been previously reported for Daoxian mantle xenoliths using thesame geothermometer (Zheng et al., 2004). Garnet is absent in bothNingyuan andDaoxianmantle xenoliths, whichmakes it difficult to pre-cisely estimate the pressures. Nevertheless, it is reasonable to conclude

that they were derived from depths shallower than the spinel-garnettransition (e.g., b65 km).

4.4. HSEs and Re–Os isotopes

The Ningyuan mantle xenoliths contain 2.09–4.27 ppb Os, 2.1–3.64 ppb Ir, 3.9–7.69 ppb Ru, 3.77–7.29 ppb Pt, 1.88–5.94 ppb Pdand 0.08–0.28 ppb Re (Table 5). The lherzolites display consistentHSE patterns (Fig. 6), similar to those of fertile abyssal peridotites(Liu et al., 2009) and those inferred for the primitive upper mantle

Table 2Mineral major elements of Ningyuan mantle xenoliths (in wt.%).

Sample TYS01-3 TYS02-2 TYS02-3 TYS03-2 TYS03-8 TYS03-16 TYS03-19 TYS03-23 TYS04-4 TYS05-2 TYS06 TYS07 TYS08

OlivineSiO2 40.52 40.92 40.63 40.47 40.43 41.00 40.43 41.02 40.70 41.23 40.65 41.02 40.96TiO2 0.02 0.02 0.01 0.01 0.00 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01Al2O3 0.02 0.03 0.02 0.02 0.01 0.00 0.01 0.01 0.02 0.00 0.01 0.01 0.01Cr2O3 0.02 0.01 0.02 0.02 0.02 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01FeO 11.11 10.35 10.31 9.56 10.63 9.97 10.29 10.34 10.39 9.07 10.51 8.97 10.45MnO 0.17 0.13 0.13 0.12 0.15 0.13 0.13 0.13 0.13 0.13 0.15 0.12 0.14MgO 47.15 47.51 48.23 48.64 49.16 48.85 48.25 48.83 48.40 49.49 48.27 49.39 48.28CaO 0.07 0.07 0.07 0.07 0.09 0.04 0.07 0.05 0.06 0.03 0.07 0.08 0.06Na2O 0.01 0.03 0.03 0.02 0.02 0.02 0.03 0.03 0.00 0.01 0.02 0.02 0.01K2O 0.00 0.01 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.01 0.01 0.00 0.00NiO 0.35 0.35 0.38 0.38 0.35 0.38 0.37 0.39 0.37 0.37 0.37 0.37 0.35Total 99.43 99.42 99.82 99.31 100.85 100.42 99.59 100.81 100.08 100.37 100.07 100.00 100.28Fo 88 89 89 90 89 90 89 89 89 91 89 91 89

SpinelSiO2 0.02 0.04 0.03 0.04 0.27 0.02 0.04 0.03 0.03 0.01 0.02 0.02 0.03TiO2 0.06 0.11 0.09 0.11 0.12 0.06 0.08 0.08 0.07 0.06 0.04 0.06 0.07Al2O3 59.58 57.86 57.69 53.47 58.95 57.24 59.47 58.34 58.05 54.29 58.98 46.43 58.76Cr2O3 7.18 9.72 9.51 14.27 9.14 9.83 8.63 9.14 9.52 14.01 8.75 22.19 8.82FeO 11.26 10.40 10.31 10.70 10.61 10.71 9.99 10.38 10.97 10.84 10.09 11.17 10.19MnO 0.09 0.10 0.08 0.13 0.08 0.07 0.06 0.07 0.08 0.09 0.10 0.11 0.10MgO 20.79 21.00 20.89 20.64 20.87 21.35 20.99 21.21 20.70 20.16 21.02 19.45 21.09CaO 0.01 0.01 0.01 0.00 0.02 0.01 0.00 0.01 0.01 0.00 0.01 0.00 0.01Na2O 0.01 0.01 0.00 0.01 0.03 0.01 0.00 0.02 0.02 0.02 0.01 0.01 0.02K2O 0.00 0.01 0.00 0.00 0.01 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.01NiO 0.37 0.39 0.37 0.34 0.36 0.38 0.37 0.36 0.36 0.34 0.36 0.29 0.37Total 99.37 99.64 98.99 99.71 100.45 99.69 99.64 99.65 99.82 99.81 99.40 99.74 99.47Mg# 0.77 0.78 0.78 0.77 0.78 0.78 0.79 0.78 0.77 0.77 0.79 0.76 0.79Cr# 0.07 0.10 0.10 0.15 0.09 0.10 0.09 0.10 0.10 0.15 0.09 0.24 0.09

OthopyroxeneSiO2 54.97 55.40 54.00 55.50 53.91 55.48 54.92 55.33 55.66 56.45 55.35 55.94 55.50TiO2 0.07 0.11 0.12 0.10 0.14 0.11 0.11 0.13 0.10 0.08 0.13 0.04 0.12Al2O3 4.49 4.50 4.96 4.02 4.80 4.17 4.51 4.68 4.00 3.61 4.64 3.68 4.43Cr2O3 0.25 0.35 0.42 0.44 0.37 0.33 0.33 0.34 0.30 0.36 0.34 0.66 0.32FeO 7.03 6.53 6.59 6.12 6.68 6.45 6.46 6.61 6.57 5.97 6.67 5.73 6.63MnO 0.15 0.13 0.15 0.14 0.14 0.13 0.15 0.14 0.13 0.13 0.14 0.12 0.14MgO 31.66 31.67 31.67 32.94 32.46 32.92 32.40 32.54 32.70 33.64 32.42 33.07 32.44CaO 0.67 0.65 0.76 0.63 0.80 0.59 0.60 0.61 0.62 0.51 0.68 0.74 0.64Na2O 0.05 0.13 0.20 0.12 0.14 0.11 0.11 0.10 0.11 0.06 0.10 0.08 0.09K2O 0.00 0.00 0.01 0.01 0.01 0.01 0.00 0.01 0.01 0.01 0.01 0.00 0.00NiO 0.08 0.10 0.09 0.09 0.08 0.08 0.09 0.08 0.09 0.08 0.08 0.10 0.07Total 99.43 99.58 98.97 100.10 99.52 100.39 99.69 100.57 100.28 100.90 100.57 100.16 100.40Mg# 0.89 0.90 0.90 0.91 0.90 0.90 0.90 0.90 0.90 0.91 0.90 0.91 0.90

ClinopyroxeneSiO2 51.79 51.97 51.88 52.65 51.26 52.77 52.39 52.70 52.00 53.22 52.49 53.67 52.45TiO2 0.31 0.52 0.52 0.44 0.58 0.48 0.55 0.59 0.57 0.38 0.58 0.12 0.57Al2O3 6.42 7.32 7.07 6.60 7.06 6.52 7.10 7.30 7.10 5.83 6.97 4.78 7.16Cr2O3 0.61 0.87 0.83 1.14 0.77 0.79 0.72 0.85 0.82 0.99 0.78 1.29 0.81FeO 3.01 2.82 2.81 2.64 3.08 2.70 2.84 2.89 2.84 2.47 2.86 2.43 2.90MnO 0.10 0.10 0.08 0.09 0.09 0.09 0.08 0.09 0.07 0.07 0.08 0.08 0.10MgO 14.83 14.41 14.45 15.00 15.34 14.93 14.68 14.61 14.55 15.35 14.65 15.98 14.59CaO 21.23 19.53 19.46 19.02 19.24 19.26 19.43 18.82 19.47 20.43 18.91 20.37 18.84Na2O 1.04 1.93 1.86 1.76 1.68 1.81 1.83 2.01 1.83 1.60 1.81 1.24 1.86K2O 0.00 0.00 0.00 0.01 0.00 0.01 0.00 0.00 0.01 0.00 0.01 0.00 0.00NiO 0.04 0.04 0.04 0.04 0.06 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04Total 99.39 99.49 99.00 99.38 99.16 99.39 99.66 99.90 99.30 100.38 99.16 100.00 99.33Mg# 0.90 0.90 0.90 0.91 0.90 0.91 0.90 0.90 0.90 0.92 0.90 0.92 0.90



Table 3Trace element compositions of clinopyroxene of Ningyuan mantle xenoliths (in ppm).

TYS01-3 TYS02-2 TYS02-3 TYS03-2 TYS03-8 TYS03-16 TYS03-19 TYS03-23 TYS04-4 TYS05-2 TYS06 TYS07 TYS08

Li 4.20 1.76 1.80 1.42 2.61 1.94 2.56 1.69 2.78 1.71 2.01 1.63 2.10Sc 56 53 53 53 54 57 57 55 56 60 51 58 53Ti 2659 2854 2860 2327 3083 2543 2837 3229 3189 1952 3076 601 3013V 268 267 272 236 283 257 277 258 277 253 260 214 259Cr 3368 5406 5445 6618 5264 4865 4677 5224 5413 6373 5099 7896 4819Co 28 22 21 21 26 18 22 19 21 20 20 21 20Ni 369 343 352 317 407 289 359 300 332 347 311 371 316Zn 18.7 10.2 10.1 10.3 13.3 7.7 11.4 8.6 9.7 8.2 9.7 9.7 9.8Ga 5.7 5.0 4.8 3.7 5.8 4.0 4.5 4.5 5.0 3.5 5.0 2.6 4.5Sr 100 42 40 55 45 29 46 55 56 54 54 19 50Y 16.3 15.4 14.9 13.6 16.5 15.7 15.1 16.0 15.1 12.3 16.1 5.3 15.9Zr 30.3 20.3 19.4 26.3 25.0 15.2 21.6 27.4 27.3 14.3 24.5 7.6 24.9Nb 1.424 0.036 0.023 0.102 0.083 0.017 0.053 0.046 0.046 0.186 0.040 0.078 0.034Ba 2.036 0.074 0.079 0.077 0.078 0.099 0.074 0.020 0.028 0.352 0.157 0.158 0.334La 7.889 0.364 0.317 0.809 0.442 0.173 0.394 0.620 0.618 0.653 0.580 0.238 0.548Ce 29.289 2.229 2.151 3.048 2.718 1.297 2.195 2.969 3.110 2.853 3.126 0.878 2.729Pr 5.100 0.516 0.486 0.578 0.582 0.339 0.463 0.585 0.583 0.555 0.608 0.158 0.563Nd 27.878 3.423 3.294 3.619 3.798 2.466 3.086 3.931 3.767 3.264 4.008 1.067 3.674Sm 6.488 1.525 1.432 1.413 1.535 1.283 1.368 1.649 1.464 1.098 1.663 0.415 1.540Eu 1.763 0.667 0.645 0.615 0.749 0.591 0.603 0.689 0.709 0.503 0.735 0.184 0.691Gd 4.750 1.835 1.718 1.616 1.784 1.808 1.644 1.810 1.770 1.383 1.773 0.597 2.050Tb 0.623 0.408 0.391 0.372 0.436 0.389 0.384 0.428 0.384 0.307 0.425 0.119 0.408Dy 3.411 2.731 2.703 2.483 2.984 2.690 2.739 2.791 2.724 2.174 2.895 0.909 2.859Ho 0.650 0.613 0.584 0.533 0.664 0.612 0.592 0.616 0.601 0.478 0.629 0.202 0.635Er 1.612 1.705 1.637 1.445 1.771 1.665 1.634 1.722 1.627 1.373 1.744 0.573 1.709Tm 0.226 0.239 0.232 0.197 0.262 0.243 0.238 0.238 0.232 0.180 0.253 0.087 0.236Yb 1.489 1.676 1.635 1.351 1.783 1.714 1.666 1.726 1.680 1.265 1.728 0.633 1.678Lu 0.204 0.223 0.221 0.185 0.247 0.227 0.221 0.230 0.226 0.176 0.239 0.090 0.233Hf 0.996 0.714 0.690 0.822 0.860 0.605 0.757 0.890 0.848 0.354 0.805 0.223 0.804Ta 0.077 0.002 0.003 0.013 0.003 0.002 0.002 0.004 0.004 0.011 0.003 0.004 0.003Pb 0.636 0.029 0.037 0.031 0.047 0.057 0.023 0.049 0.162 0.300 0.018 0.019 0.030Th 0.330 0.003 0.003 0.008 0.007 0.018 0.004 0.003 0.005 0.015 0.004 0.004 0.004U 0.203 0.003 0.003 0.003 0.005 0.004 0.004 0.003 0.002 0.007 0.003 0.003 0.005

3

4

5

6

7

8

9

0.88 0.89 0.90 0.91 0.92 0.93 0.94

Cpx Mg#

Spinel Cr#

Cpx Mg#

Cpx

Al 2

O3

(in w

t.%)

Cpx

TiO

2 (in

wt.%

)

Cpx

Na 2

O (

in w

t.%)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.88 0.89 0.90 0.91 0.92 0.93 0.94

0.0

0.5

1.0

1.5

2.0

2.5

0 0.05 0.10 0.15 0.20 0.25 0.30 0.35

TYS01-3

TYS01-3

TYS01-3

This study

Zheng et al. (2004)Xia et al. (2010)

2.5

3.0

3.5

4.0

4.5

5.0

5.5

0.88 0.89 0.90 0.91 0.92 0.93

Opx Mg#

Opx

Al 2

O3

(in w

t.%)

a b

c d

Fig. 4.Mineral compositions of the Ningyuan mantle xenoliths. (a) Spinel Cr# vs. Cpx Na2O content; (b) Opx Mg# vs. Al2O3 content; (c) Cpx Mg# vs. Al2O3 content; (d) Cpx Mg# vs.TiO2 content. Literature data of Daoxian (Zheng et al., 2004; Xia et al., 2010) and Ningyuan (Zheng et al., 2004; Xia et al., 2010) are also shown for comparison. Symbols are same asin Fig. 3.



(Becker et al., 2006). Most Ningyuan mantle xenoliths have high HSEcontents, suggesting that sulfides in these samples have not beensignificantly lost during late-stage processes. They have chondriticOs/Ir and Pt/Ir ratios, but suprachondritic Ru/Ir and Pd/Ir ratios.Most lherzolites have subchondritic to roughly chondritic Re/Ir

ratios, whereas three lherzolites (TYS02-3, TYS03-8 and TYS03-19)display suprachondritic Re/Ir ratios. The harzburgite (TYS07) showsa relative flat pattern from Os to Ru, but strong depletion in Pt, Pdand Re.

The 187Re/188Os and 187Os/188Os ratios of the Ningyuan lherzolitexenoliths vary from 0.18 to 0.51 and from 0.12116 to 0.12929, respec-tively (Table 5). Among the Ningyuanmantle xenoliths, the harzburgitehas the lowest 187Re/188Os of 0.1 and the most unradiogenic 187Os/188Os ratio of 0.11681. The 187Os/188Os ratios of Ningyuanmantle xeno-liths show positive correlations with both 187Re/188Os ratios and bulk-rock Al2O3 contents (Fig. 7a, b). Both TYS02-3 and TYS03-8 havemodel ages (TMA) calculated relative to the primitive upper mantle(PUM; Meisel et al., 2001) older than the Earth's age, whereas TYS03-19 gives a future model age. The TMA ages of other samples vary from~1.58 to ~3.24 Ga. The Re-depletion age (TRD) relative to the PUM is cal-culated assuming a Re/Os ratio of zero in the sample. Therefore, the TRDrepresent minimum ages and provide few age constraints on lherzo-lites, in which substantial amounts of Re are still left after melt extrac-tion. The lherzolites have TRD ages varying from ~0.25 to ~1.25 Ga,which are, unsurprisingly, younger than that of the harzburgite(~1.82 Ga). It should be noted that the harzburgite is unusually fertile,and probably contains some Re after melt extraction. Therefore, its TRDage (~1.82 Ga) may be much younger than the true extraction age.

5. Discussion

5.1. Melt depletion and enrichment processes

The Mesozoic mantle xenoliths entrained in both Daoxian andNingyuan basalts are mainly composed of fertile lherzolites, with afew harzburgites and dunites (Wang et al., 1997; Zheng et al., 2004;Zhang et al., 2008; Xia et al., 2010). All Ningyuan lherzolites reportedin the present study have fertile bulk-rock compositions, i.e., highAl2O3 and CaO contents, whereas the harzburgite has only a slightlyrefractory composition. The fertile nature of these rocks is alsoshown by the mineral compositions. Olivines in the Ningyuan mantlexenoliths have low Fo contents (88–91), which are distinctly lowerthan those of refractory Archean and Proterozoic cratonic mantle xe-noliths (Boyd, 1989; Griffin et al., 1998). Both clinopyroxene andorthopyroxene have high Al2O3 contents. Furthermore, clinopyroxenecontains high Na2O contents. All these geochemical characteristicssupport the suggestion that the Ningyuan mantle xenoliths havebeen subjected to only low degrees of partial melting.

Degrees of partial melting experienced by mantle peridotites canbe constrained by spinel composition. Spinel becomes Cr-rich withprogressive melt extraction, resulting in a positive relationship be-tween degree of fractional partial melting (F) and spinel Cr# (Dickand Bullen, 1984; Hellebrand et al., 2001). Hellebrand et al. (2001)formulated a function, F=10ln(Cr#)+24, suitable for Cr# of 0.1–0.6, to calculate the degree of partial melting suffered by residualperidotites from the depleted MORB mantle (DMM) source. Degreesof partial melting are estimated by this method to be ~1–5% formost Ningyuan lherzolites, and ~10% for the harzburgite (Fig. 8a).This substantiates the hypothesis that the Ningyuan mantle xenolithshave experienced low to moderate degrees of melt extraction. De-grees of partial melting of three Ningyuan lherzolites cannot beinferred by this function because of their low Cr# (i.e., b0.1). A possi-ble explanation is that their compositions are more fertile than the in-ferred compositions of the DMM. In other words, little melt has beenextracted from these three samples.

Degrees of partial melting experienced bymantle peridotites can alsobe inferred from some trace elements (e.g., Y and Yb) in clinopyroxene(Norman, 1998; Xu et al., 2000). Comparison of Y and Yb contents in clin-opyroxene and the modeled melting trend suggest that the Ningyuanlherzolites represent residues after ~3–6% fractional melting of the prim-itive mantle, whereas the harzburgite has experienced ~13% degrees of

0.1

1

10

100

La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

TYS01-3

TYS07

Cpx

/Cho

ndrit

e

TYS01-3

TYS07

Cpx

/Cho

ndrit

e

0.001

0.01

0.1

1

10

100

Th U Ba

NbTa

LaCe

SrNd

ZrHf

SmEu

TiGd

TbDy

YHo

ErTm

YbLu

Lherzolite

Harzburgite

a

b

Fig. 5. Diagrams of REE (a) and trace elements (b) of clinopyroxene of Ningyuan man-tle xenoliths. The chondritic normalization values are from Anders and Grevesse(1989).

Table 4Equilibrium temperatures of Ningyuan mantle xenoliths (°C).

Sample TBKOpx

TBK Opx/Cpx

TBM Opx/Cpx

TBMCpx

TESOpx

TWB Opx/Cpx

TWellsOpx/Cpx

TYS01-3

961 957 1021 1185 957 1033 943

TYS02-2

952 1008 1084 1288 1017 1053 960

TYS02-3

991 1015 1103 1286 1002 1056 965

TYS03-2

943 1081 1242 1308 976 1104 1013

TYS03-8

1000 1068 1199 1298 929 1092 1008

TYS03-16

931 1053 1192 1298 933 1081 990

TYS03-19

933 1038 1146 1293 957 1069 977

TYS03-23

938 1071 1201 1320 966 1084 997

TYS04-4

939 1024 1117 1288 928 1060 967

TYS05-2

900 994 1118 1252 938 1062 959

TYS06 961 1074 1216 1310 970 1090 1005TYS07 980 1048 1223 1249 1062 1109 1014TYS08 947 1076 1212 1314 960 1089 1003

TBK: Brey and Kohler (1990); TBM: Bertrand and Mercier (1985); TES: Witt-Eickschenand Seck (1991); TWB: Wood and Banno (1973); Twells: Wells (1977).



fractional melting (Fig. 8b). It should be noted that degrees of partialmelting estimated using clinopyroxene trace elements are slightly higherthan the values obtained using spinel Cr#. The difference probably lies inthe different compositions of mantle sources assumed in the twomethods, i.e., the DMM is more depleted than the primitive mantle.

Therefore, bothwhole rock andmineral compositions of theNingyuanmantle xenoliths suggest that the Mesozoic lithospheric mantle beneathsouthernHunanProvince hadbeen subjected to very low tomoderate de-grees of partial melting. On the other hand, the Mesozoic mantle litho-sphere has experienced limited or negligible enrichment after melting,because clinopyroxenes in most Ningyuan mantle xenoliths show vari-ably depleted REE patterns (Fig. 5a). Nevertheless, clinopyroxene in alherzolite (TYS01-3) shows strong enrichment in both LREE and LILE(Fig. 5a, b),which indicates themantle lithospheremight have been local-ly metasomatized.

5.2. Age of the Mesozoic lithospheric mantle beneath southern HunanProvince

There are multiple methods that can be used to determine ages ofperidotites using the Re–Os isotope system. As for most chronome-ters, the most robust ages are derived from isochrons. A positive cor-relation on a Re–Os isochron diagram is found for the Ningyuanmantle xenoliths (Fig. 7a), which if interpreted chronologicallywould yield a rough age of 1571±370 Ma. However, true Re–Os iso-chrons have been rarely reported for mantle peridotites. This may, onone hand, reflect the fact that mantle peridotites represent residuesafter variable degrees of partial melting of a mantle precursorwhose 187Os/188Os ratio was not perfectly uniform at the time ofmelting. On the other hand, it is also plausible that the mantle perido-tites were not genetically related. More possible reasons include the

mobility of Re, which can be fluid-mobile under oxidizing conditions(Xiong andWood, 1999; Becker, 2000), and addition of Re during latemagmatic processes, i.e., metasomatism and refertilization (Büchl etal., 2002; Becker et al., 2006; van Acken et al., 2008).

Other immobile elements, such as aluminum and heavy rare earthelements (HREE; Yb or Lu), are sometimes plotted against 187Os/188Os to determine model ages of peridotites that are assumed toshare a common origin throughmelt extraction (Reisberg and Lorand,1995; Peslier et al., 2000a; Peslier et al., 2000b). These elements havebulk partition coefficients similar to that of Re during melting of man-tle peridotites, and thus, can be used as proxies for the extent of meltextraction. More importantly, these elements are more resistant thanRe to disturbance by secondary processes (e.g., metasomatism andrefertilization). The most commonly employed element in this regard

Table 5HSE and Re–Os isotope compositions of Ningyuan mantle xenoliths.

Os Ir Ru Pt Pd Re 187Re/188Os 187Os/188Os 2δ (187Os/188Os)i TMA(Ga) TRD(Ga)

TYS01-3 4.27 3.64 7.69 6.49 5.17 0.16 0.18 0.12116 0.0002 0.12064 2.05 1.26TYS02-2 3.88 3.58 7.15 7.06 5.83 0.28 0.35 0.12551 0.0007 0.12451 3.28 0.72TYS02-3 3.63 3.08 6.45 6.40 5.81 0.28 0.38 0.12573 0.0002 0.12466 4.63 0.70TYS03-2 2.56 3.14 5.89 5.99 4.11 0.15 0.29 0.12372 0.0009 0.12291 2.50 0.94TYS03-8 3.40 2.92 5.61 5.96 4.48 0.28 0.40 0.12424 0.0001 0.12311 10.43 0.91TYS03-16 3.24 2.96 5.51 6.53 4.99 0.22 0.32 0.12565 0.0001 0.12473 2.34 0.69TYS03-19 2.63 2.29 3.95 7.29 7.40 0.28 0.51 0.12929 0.0006 0.12783 −0.21 0.25TYS03-23 2.09 2.10 3.93 4.77 5.70 0.16 0.36 0.12720 0.0002 0.12619 2.14 0.48TYS04-4 3.67 3.28 6.82 7.16 5.94 0.22 0.29 0.12490 0.0001 0.12406 2.13 0.78TYS05-2 3.50 3.15 6.61 5.63 5.05 0.18 0.24 0.12160 0.0001 0.12092 2.59 1.22TYS06 2.34 2.55 5.04 5.86 4.63 0.17 0.35 0.12775 0.0001 0.12675 1.58 0.40TYS07 3.76 3.06 6.25 3.77 1.88 0.08 0.10 0.11681 0.0001 0.11653 2.32 1.82TYS08 2.89 2.76 5.22 5.82 4.53 0.22 0.37 0.12650 0.0001 0.12545 3.24 0.58

HSE concentrations are in ppb. Both TMA and TRD are calculated relative to the primitive upper mantle (PUM), using λ of 1.666×10−11, (187Re/188Os) PUM of 0.42 and (187Os/188Os)PUM of 0.1296.

0.0001

0.001

0.01

0.1

Os Ir Ru Pt Pd Re

Sam

ple/

CI c

hond

rite

TYS07

Harzburgite

Lherzolite

Fig. 6. HSE patterns of Ningyuan mantle xenoliths. HSE concentrations were normal-ized to CI chondrite values (Horan et al., 2003).

This study

Zhang et al. (2008)

Lherzolite

Harzburgite

0.110

0.115

0.120

0.125

0.130

0.135

0.110

0.115

0.120

0.125

0.130

0.135

0.0 0.1 0.2 0.3 0.4 0.5 0.6

187 O

s/18

8 Os

187 O

s/18

8 Os

187Re/188Os

Abyssal peridotites

TYS07

TYS03-19

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

0.0

0.5

1.0

1.5

2.0

TRD

Al2O3 (in wt.%)

(Ga)

187Os/188Os

Al2O3=0.7 wt.%=0.1138

PUM

PUM

Y =0.111+ 0.004X

t=1571± 370Ma(187Os/188Os)i=0.1151±0.0020

5 10 15 (N)

a

b

Fig. 7. Diagrams of 187Os/188Os versus 187Re/188Os (a) and bulk Al2O3 contents (b). The187Os/188Os of abyssal peridotites is from Brandon et al. (2000), Harvey et al. (2006)and Liu et al. (2008). The PUM data are from Meisel et al. (2001). The literature dataof Ningyuan mantle xenoliths are also shown (Zhang et al., 2008).



is aluminum (Reisberg and Lorand, 1995), leading some authors tocoin the term “alumina-chron”. A good correlation can be found forthe Ningyuan mantle xenoliths on the 187Os/188Os vs. Al2O3 diagram(Fig. 7b). The alumina-chron gives an initial 187Os/188Os ratio of0.111, assuming a zero Al2O3 content, which corresponds to an ageof Late Archean (~2.6 Ga) relative to the primitive upper mantle(PUM; Meisel et al., 2001). However, it has been argued that about0.7 wt.% Al2O3 still remains in mantle residues after Re is completelyconsumed during melting (Handler and Bennett, 1999). Extrapolationof the alumina-chron of the Ningyuan xenoliths to 0.7 wt.% Al2O3

yields an 187Os/188Os ratio of ~0.1138, giving a model age of~2.2 Ga. It should be noted that the alumina-chron age is older thanthe Re-depletion age (TRD) of the most refractory sample (TYS07;~1.8 Ga). The latter ignores the in-growth of 187Os due to Re in thesample, and thus represents a minimum estimate of the true melt de-pletion age (Walker et al., 1989).

The whole-rock Re–Os isotopes thus suggest that the Ningyuanmantle xenoliths might have experienced a melt extraction eventduring the Paleoproterozoic (~1.8–2.2 Ga). It is generally assumedthat melt extraction occurred during creation of the subcontinentallithospheric mantle. If this assumption is accepted, the Mesozoic sub-continental lithospheric mantle beneath southern Hunan Provincewas probably formed during the Paleoproterozoic. In this case, themelting process produced residues with Re/Os ratios that varied sys-tematically with the degree of fertility of the peridotites (Reisbergand Lorand, 1995). Ancient mantle, coexisting with juvenile mantle,has been found in previous studies of Cenozoic mantle xenolithsfrom the coastal areas of South China (Xu et al., 2000; Xu et al.,2002; Zheng et al., 2004).

However, interpretation of Os isotope ages of mantle xenoliths hasto consider the Os isotope heterogeneity of the convecting uppermantle (Rudnick and Walker, 2009). There is growing evidence thatOs isotopic heterogeneities caused by ancient melting can be pre-served for over a billion year in the asthenosphere (Brandon et al.,2000; Harvey et al., 2006; Liu et al., 2008). For example, some abyssalperidotites from Gakkel ridge, Arctic Ocean, have Os model ages up to2 Ga (Liu et al., 2008). In particular, a positive 187Os/188Os–Al2O3 cor-relation was also found for abyssal peridotites from the same dredgesite on Gakkel ridge, Arctic Ocean (Liu et al., 2008). Such a correlationhas been explained as a mixture of different mantle domains in theasthenosphere, in which the refractory mantle domains preserve an-cient melting ages during convecting stirring processes (Liu et al.,2008). If such ancient depleted materials were accreted to the litho-spheric mantle, the apparent model ages would be unrelated to thetime of lithospheric formation (Reisberg et al., 2005).

While the tectonic interpretation of the ancient Os ages is ambigu-ous, for the following reasons our preferred model is that the Ningyuanmantle xenoliths were more likely derived from a juvenile lithosphericmantle rather than representing a Paleoproterozoic lithosphere relic.First, the Mesozoic mantle xenoliths entrained in both Ningyuan andDaoxian basalts consist dominantly of fertile lherzolites, with minorharzburgites (Wang et al., 1997; Zheng et al., 2004; Zhang et al., 2008;Xia et al., 2010). Their compositions are significantly distinct from theProterozoic mantle xenoliths, but follow the oceanic trend (see Fig. 13in Zheng et al., 2004). The studied lherzolites have slightly variable187Os/188Os ratios of 0.12116–0.12929, which plot within the range ofthe abyssal peridotites (Fig. 7b). Secondly, previous studies haveshown that both Ningyuan and Daoxianmantle xenoliths have depletedNd isotope compositions (Guo et al., 1999; Chen et al., 2004; Zhang et al.,2008). Zhang et al. (2008) have reported that the Ningyuan mantle xe-noliths have depleted 143Nd/144Nd ratios of 0.513188–0.513341 andεNd of +11–+13.5. Thirdly, if the peridotites represented a Paleoproter-ozoic lithosphere relic they should have been metasomatized by slab-released fluids/melts during the subduction of the paleo-Pacific plate,whichwas initiated as early as themid-Permian (Li and Li, 2007). Howev-er, no hydrous phases have been reported in the Ningyuan mantle xeno-liths (Wang et al., 1997; Zheng et al., 2004; Zhang et al., 2008; Xia et al.,2010). Clinopyroxene trace element compositions of samples in thisstudy indicate that the lithospheric mantle has been only weaklymetasomatized.

5.3. The Mesozoic mantle replacement in the South China Block

Generally, the sub-contintental lithospheric mantle (SCLM) is bothtemporally and mechanically coupled with the overlying crust (Pearson,1999; Carlson et al., 2005). The Yangtze block consists of an Archean toPaleoproterozoic basement (Chen and Jahn, 1998; Zheng et al., 2006),whereas the basement of the Cathaysia block exhibits Paleoproterozoicto Mesoproterozoic ages and possibly Neoarchean ages (Li et al., 1989;Yu et al., 2007). This implies the existence of ancient lithospheric mantlebeneath the South China Block. Compositions of the garnet lherzolite xe-nolith entrained in the Paleozoic Dahongshan lamproites suggest that thesubcontinental lithospheric mantle (SCLM) beneath the SCB during thePaleozoic had a cold geotherm and a thickness larger than 110 km atthat time (Zhang et al., 2001). In contrast, equilibrium temperatures ofthe Ningyuanmantle xenoliths indicate a hot geotherm for the Mesozoiclithosphere beneath the Ningyuan region. On the other hand, absence ofgarnet in the Ningyuanmantle xenoliths points to a thin (b80 km)man-tle lithosphere during the Mesozoic. Furthermore, the Jurassic basalts insouthern Hunnan Province show OIB-like geochemical compositions(Guo et al., 1998; Fan et al., 2003; Jiang et al., 2009), reflecting that theyoriginated from depths shallower than 65–80 km (McKenzie and Bickle,1988). A similar conclusion has also been reached for the Cenozoic tholei-itic basalts in the Jianghan Basin (Peng et al., 2006). If the Ningyuanman-tle xenoliths represent a relic of ancient mantle, the ancient SLCM

0.1

1

10

0 1 2 3 4 5 6

25%

20%

15%

10%

5%3%

1%

Yn, Cpx

Yb n,

Cpx

Fractional melting trend

Fractional melting trend

+

+

+

+ + + + + + + + + + +

0.10.1 0.2 0.3 0.4 0.50

1

10

100

Yb n

, Cpx

+

DMM

++1%

5%10%

15%

Sp Cr# [Cr/(Cr+Al)]

Abyssal peridotites

+

Lherzolite

Harzburgite

TYS07

TYS07

b

a

Fig. 8. Diagrams of (Yb)n of clinopyroxene vs. Sp Cr# (a) and Yn of clinopyroxene (b).(a) The degrees of partial melting are estimated to be 1–5% for most lherzolites and10% for the harzburgite. Spinel in three Ningyuan lherzolites has Cr# even lowerthan the inferred values of the depleted MORB mantle (DMM). The fractional meltingtrend and the abyssal peridotite data are from Liu et al. (2008). (b) Low to moderate(3–13%) degrees of partial melting are estimated by the method of Norman (1998).The starting compositions for Y and Yb are 4.67 and 0.488 ppm, and DY

Cpx/melt=0.42and DYb

Cpx/melt=0.40. n: primitive mantle normalized (McDonough and Sun, 1995).



beneath the SCBmust have been significantly thinned and replaced by ju-venile asthenospheric mantle. Heat from the asthenosphere would haveproduced a hot geotherm for the lithosphere relic. On the other hand, itis also possible that the ancient SCLM has been completely removedand replaced by asthenospheric mantle. Therefore, juvenile mantle hasbeen accreted from the asthenosphere beneath the Ningyuan region, nomatter how we interpret the Re–Os isotopes of the Ningyuan mantlexenoliths.

In addition to the modification of the geotherm, the compositionof the lithospheric mantle was also transformed as a result of accre-tion of juvenile mantle during the Mesozoic. The Paleozoic (ca.480~500 Ma) lamproites emplaced at Dahongshan in Hubei Provinceand Zhengyuan in Guizhou Province show enriched Sr–Nd isotopiccharacteristics, with εNd of −3 to −12 (Liu et al., 1993; Fang et al.,2002), which suggests that they were derived from an enriched lith-ospheric mantle. In contrast, the Mesozoic mantle xenoliths have de-pleted Nd isotope compositions (Guo et al., 1999; Chen et al., 2004;Zhang et al., 2008). Furthermore, compositions of the Cenozoic tholei-itic basalts in the Jianghan Basin indicate that they originated from ajuvenile and depleted asthenospheric mantle (Peng et al., 2006).

Mantle thinning and accretion would lead to lithospheric exten-sion in the South China Block. Therefore, the age of SCLM thinningand accretion can be constrained through by considering evidencefor lithospheric extension. The following geological observations sup-port the suggestion that the South China Block was in an extensionalsetting during the Mesozoic. First, rift basins and faulted depressionbasins were widely distributed in South China during the Mesozoic(Gilder et al., 1991; Zhou et al., 2006). Sedimentary settings inSouth China changed from stable shallow-sea facies during the Paleo-zoic to lake facies during the Mesozoic (Li and Li, 2007; Shu et al.,2009). Secondly, both alkaline and tholeiitic basalts were eruptedduring the Jurassic in an east–west trending array in the interior ofthe Cathaysia block (Fan et al., 2003; Wang et al., 2003; Xie et al.,2005; Zhou et al., 2006; Chen et al., 2008; Xu, 2008). Furthermore,emplacement of gabbros, A-type granites and syenitic rocks alsopoints to an extensional setting in South China during the Mesozoic(Li et al., 2003; Li et al., 2004; Zhu et al., 2006; Li and Li, 2007). Thepyoxenite and gabbro xenoliths entrained in the Daoxian basaltsshow depleted isotopic compositions (i.e., εNd of 0–+8), whichhave been explained as cumulates of asthenosphere-derived magmasunder extensional settings (Guo et al., 1997; Dai et al., 2008). Zirconsfrom the gabbroic xenoliths give U–Pb ages of ~225 Ma (Fan et al.,2003; Dai et al., 2008). This suggests that lithosphere extension andthus mantle accretion in South China commenced as early as theLate Triassic (Fan et al., 2003).

We suggest that the lithospheric thinning and accretion in SouthChina was probably caused by mantle delamination according to the fol-lowing scenario. The lithospheric mantle beneath the SCB was metaso-matized by the fluids/melts released from the subducted paleo-Pacificplate. Melt metasomatism reduced the viscosity of the lithospheric man-tle through formation of hydrous minerals (Pollack, 1986), thus favoringmantle delamination. Delamination led to the upwelling of the hot as-thenosphere. Decompressional melting of the asthenosphere gave riseto not only the mafic volcanic rocks but also underplating of basalticmagmas (Guo et al., 1997; Guo et al., 1998; Guo et al., 1999; Li et al.,2003; Wang et al., 2003; Li et al., 2004; Wang et al., 2005). Underplatingof high temperature basaltic magmas led to the anatexis of the crustalrocks, which produced the A-type granites, syenitic rocks and the wide-spread granitoids during the Jurassic in South China (Li et al., 2003; Li etal., 2004; Zhou et al., 2006; Li and Li, 2007).

6. Conclusion

Both whole rock and mineral compositions of mantle xenolithsentrained in the Mesozoic Ningyuan basalts suggest that they havebeen subjected to low degrees of partial melting, after which they

have been only weakly metasomatized. The estimated temperaturesindicate that the Mesozoic lithosphere beneath southern Hunan Prov-ince has a hot geotherm. Absence of garnet in the Ningyuan mantlexenoliths implies a thin lithosphere (b80 km) during the Mesozoic.The Os isotopic composition of the harzburgite gives a TRD age of~1.8 Ga, which is slightly younger than the alumina-chron age ofthe Ningyuan mantle xenoliths (~2.2 Ga). Although the tectonic im-plication of the old ages is ambiguous, the Ningyuan mantle xenolithsprovide further evidence of thinning of ancient lithospheric mantleand accretion of juvenile mantle beneath South China during the Me-sozoic. Mantle thinning and accretion was probably caused by mantledelamination, which led to lithospheric extension. Upwelling of hotasthenosphere in response to the lithospheric extension not onlygave rise to the mafic rocks but may also have led to the extensivegranitic magmatism in South China during the Jurassic.

Acknowledgments

This study was financially supported by grants from KnowledgeInnovation Project of the Chinese Academy of Sciences (KZCX1-YW-15-5), National Natural Science Foundation of China (grant no.40873024) and the State Key Laboratory of Lithospheric Evolution,IGGCAS (grant no. 10801130). We are grateful to Q. Mao and Y.G.Ma from IGGCAS for help with electron microprobe analysis. Wethank Laurie Reisberg for editorial handling and constructive sugges-tions. Comments from two anonymous reviewers significantly im-proved the quality of the paper.

References

Anders, E., Grevesse, N., 1989. Abundances of the elements—meteoritic and solar. Geo-chimica et Cosmochimica Acta 53 (1), 197–214.

Becker, H., 2000. Re–Os fractionation in eclogites and blueschists and the implicationsfor recycling of oceanic crust into the mantle. Earth and Planetary Science Letters177, 287–300.

Becker, H., et al., 2006. Highly siderophile element composition of the Earth's primitiveupper mantle: constraints from new data on peridotite massifs and xenoliths. Geo-chimica et Cosmochimica Acta 70 (17), 4528–4550.

Bertrand, P., Mercier, J.C.C., 1985. The mutual solubility of coexisting ortho-pyroxeneand clinopyroxene-toward an absolute geothermometer for the natural system.Earth and Planetary Science Letters 76 (1–2), 109–122.

Boyd, F.R., 1989. Compositional distinction between oceanic and cratonic lithosphere.Earth and Planetary Science Letters 96, 15–26.

Brandon, A.D., Snow, J.E., Walker, R.J., Morgan, J.W., Mock, T.D., 2000. 190Pt–186Os and187Re–187Os systematics of abyssal peridotites. Earth and Planetary Science Letters177 (3–4), 319–335.

Brey, G.P., Kohler, T., 1990. Geothermobarometry in four-phase lherzolites II. New ther-mobarometers, and practical assessment of existing thermobarometers. Journal ofPetrology 31, 1353–1378.

Büchl, A., Brügmann, G., Batamova, V.G., Münker, C., Hofmann, A.W., 2002. Melt perco-lation monitored by Os isotopes and HSE abundances: a case study from the man-tle section of the Troodos Ophiolite. Earth and Planetary Science Letters 204,385–402.

Carlson, R.W., Pearson, D.G., James, D.E., 2005. Physical, chemical, and chronologicalcharacteristics of continental mantle. Reviews of Geophysics 43 (1), RG1001.doi:10.1029/2004rg000156.

Chen, J.F., Jahn, B.M., 1998. Crustal evolution of southeastern China: Nd and Sr isotopicevidence. Tectonophysics 284, 101–133.

Chen, B.H., Jia, B.H., Liu, Y.R., Peng, X.J., He, C.P., 2004. Sm–Nd isochron age of spinel-lherzolite xenoliths from Mesozoic volcanic rocks in the South Hunan and its geo-logical significance. Geological Review 50 (2), 180–183 (in Chinese with Englishabstract).

Chen, C.H., Lee, C.Y., Shinjo, R., 2008. Was there Jurassic paleo-Pacific subduction inSouth China?: constraints from 40Ar/39Ar dating, elemental and Sr–Nd–Pb isotopicgeochemistry of the Mesozoic basalts. Lithos 106, 83–92.

Chu, Z.Y., et al., 2009. Temporal evolution of the lithospheric mantle beneath the east-ern North China Craton. Journal of Petrology 50, 1857–1898.

Chung, S.L., Cheng, H., Jahn, B.M., O'Reilly, S.Y., Zhu, B.Q., 1997. Major and trace ele-ment, and Sr–Nd isotope constraints on the origin of Paleogene volcanism inSouth China prior to the South China Sea opening. Lithos 40, 203–220.

Creaser, R.A., Papanastassiou, D.A., Wasserburg, G.J., 1991. Negative thermal ion massspectrometry of osmium, rhenium, and iridium. Geochimica et CosmochimicaActa 55, 397–401.

Dai, B.Z., Jiang, S.Y., Jiang, Y.H., Zhao, K.D., Liu, D.Y., 2008. Geochronology, geochemistryand Hf–Sr–Nd isotopic compositions of Huziyan mafic xenoliths, southern HunanProvince, South China: petrogenesis and implications for lower crust evolution.Lithos 102, 65–87.



Dick, H.J.B., Bullen, T., 1984. Chromian spinel as a petrogenetic indicator in abyssal andalpine-type peridotites and spatially associated lavas. Contributions to Mineralogyand Petrology 86 (1), 54–76.

Fan, Q.C., Hopper, P.R., 1989. The mineral chemistry of ultramafic xenoliths of easternChina: implications for upper mantle composition and the paleogeotherms. Journalof Petrology 30, 1117–1158.

Fan, W.M., Wang, Y.J., Guo, F., Peng, T.P., 2003. Mesozoic mafic magmatism in Hunan–Jiangxi provinces and the lithosphereic extension. Earth Science Frontiers 10,159–169 (in Chinese with English abstract).

Fang, W.X., et al., 2002. On emplacement ages of lamproites in Zhengyuan County, Gui-zhou Province, China. Chinese Science Bulletin 47 (10), 874–880.

Faure, M., Sun, Y., Shu, L.S., Monié, P., Charvet, J., 1996. Extensional tectonics within asubduction-type orogen: the case study of the Wugongshan dome (Jiangxi Prov-ince, SE China). Tectonophysics 263, 77–108.

Gilder, S.A., Keller, G.R., Luo, M., Goodell, P.C., 1991. Eastern Asia and the Western Pa-cific timing and spatial distribution of rifting in China. Tectonophysics 197,225–243.

Gilder, S.A., et al., 1996. Isotopic and paleomagnetic constraints on the Mesozoic tec-tonic evolution of South China. Journal of Geophysical Research 107 (B7),16137–16154.

Griffin, W.L., Zhang, A.D., O'Reilly, S.Y., Ryan, C.G., 1998. Phanerozoic evolution of thelithosphere beneath the Sino-Korean craton. In: Flower, M.F.J., Chung, S.L., Lo, C.H., Lee, T.Y. (Eds.), Mantle Dynamics and Plate Interactions in East Asia. AmericanGeophysical Union, Washington, DC, pp. 107–126.

Guo, F., Fan, W.M., Lin, K., 1997. Geochronology and petrogenesis of gabbroic xenolithsfrom Daoxian, Southern Hunan Province, China. Chinese Science Bulletin 42,1661–1664 (in Chinese with English abstract).

Guo, F., Fan, W.M., Lin, K., 1998. Petrogenesis of Mesozoic basaltic magmas and litho-sphere–asthenosphere interaction in South Hunan Province, China. Bulletin ofMineralogy Petrology and Geochemistry 17, 1–4 (in Chinese with Englishabstract).

Guo, F., Fan, W.M., Lin, K., Lin, Y.X., 1999. Neodynium isotopic composition and petro-genesis of peridotite xenoliths in Ningyuan region, South Hunan. Acta Mineralo-gica Sinica 19, 206–209 (in Chinese with English abstract).

Handler, M.R., Bennett, V.C., 1999. Behaviour of platinum-group elements in the sub-continental mantle of eastern Australia during variable metasomatism and meltdepletion. Geochimica et Cosmochimica Acta 63 (21), 3597–3618.

Harvey, J., et al., 2006. Ancient melt extraction from the oceanic upper mantle revealedby Re–Os isotopes in abyssal peridotites from the mid-Atlantic ridge. Earth andPlanetary Science Letters 244 (3–4), 606–621.

Hellebrand, E., Snow, J.E., Dick, H.J.B., Hofmann, A.W., 2001. Coupled major and traceelements as indicators of the extent of melting in mid-ocean-ridge peridotites. Na-ture 410 (6829), 677–681.

Holloway, N.H., 1982. North Palawan Block, Philippines—its relation to Asian Mainlandand role in evolution of South China Sea. American Association of Petroleum Geol-ogists Bulletin 66, 1335–1383.

Horan, M.F., Walker, R.J., Morgan, J.W., Grossman, J.N., Rubin, A.E., 2003. Highly sidero-phile elements in chondrites. Chemical Geology 196 (1–4), 5–20.

Huang, X.L., Xu, Y.G., 2010. Thermal state and structure of the lithosphere beneath east-ern China: a synthesis on basalt-borne xenoliths. Journal of Earth Science 21,711–730.

Jiang, Y.H., et al., 2009. Middle to late Jurassic felsic and mafic magmatism in southernHunan Province, southeast China: implications for a continental arc to rifting. Lith-os 107, 185–204.

Kong, H., Jin, Z.M., Lin, Y.X., 2000. Petrology and chronology of granulite xenolith inDaoxian county, Hunan Province. Journal of Changchun University of Science andTechnology 30, 115–119 (in Chinese with English abstract).

Li, X.H., 1999. U–Pb zircon ages of granites from the southern margin of the Yangtzemargin: timing of Neoproterozoic Jinning Orogen in SE China and implication forRodinia assembly. Precambrian Research 97, 43–57.

Li, X.H., Li, Z.X., 2007. Formation of the 1300-km-wide intracontinenal orogen andpostorogenic magmatic province in Mesozoic South China: a flat-slab subductionmodel. Geology 35, 179–182.

Li, X.H., Tatsumoto, M., Gui, X.T., 1989. Discovery of the Archean relict zircon (2.5 Ga inage) in Tanghu granite, south China and its significance. Chinese Science Bulletin34, 206–209 (in Chinese with English abstract).

Li, X.H., Chen, Z.G., Liu, D.Y., Li, W.X., 2003. Jurassic gabbro–granite–syenite suites fromsouthern Jiangxi Province (SE China): age, origin and tecontic significance. Interna-tional Geology Review 45, 898–921.

Li, X.H., et al., 2004. Jurassic intraplate magmatism in southern Hunan-easternGuangxi: 40Ar/39Ar dating, geochemistry, Sr–Nd isotopes and implications for thetectonic evolution of SE China. In: Malpas, J., Fletcher, C.J.N., Ali, J.R., Aitchison, J.C. (Eds.), Aspects of the Tectonic Evolution of China. The Geological Society of Lon-don, Special Publication, London, pp. 193–215.

Lin, W., et al., 2000. Tectonics of SE China: new insights from the Lushan massif (JiangxiProvince). Tectonics 19, 852–871.

Liu, G.L., Wang, X.W., Lü, X.M., 1993. Dahongshan Lamproites. Geological PublishingHouse, Bejing.

Liu, C.Z., et al., 2008. Ancient, highly heterogeneous mantle beneath Gakkel ridge, Arc-tic Ocean. Nature 452 (7185), 311–316.

Liu, C.Z., Snow, J.E., Brugmann, G., Hellebrand, E., Hofmann, A.W., 2009. Non-chondriticHSE budget in Earth's upper mantle evidenced by abyssal peridotites from Gakkelridge (Arctic Ocean). Earth and Planetary Science Letters 283 (1–4), 122–132.

Liu, C.Z., Wu, F.Y., Wilde, S.A., Yu, L.J., Li, J.L., 2010. Anorthitic plagioclase and pargasiticamphibole in mantle peridotites from Yungbwa ophiolite (southern Tibetan Pla-teau) formed by hydrous melt metasomatism. Lithos 114, 413–422.

McDonough, W.F., Sun, S.S., 1995. The composition of the Earth. Chemical Geology 120(3–4), 223–253.

McKenzie, D.P., Bickle, M.J., 1988. The volume and composition of melt generated byextension of the lithosphere. Journal of Petrology 29, 625–679.

Meisel, T., Walker, R.J., Irving, A.J., Lorand, J.P., 2001. Osmium isotopic compositions ofmantle xenoliths: a global perspective. Geochimica et Cosmochimica Acta 65 (8),1311–1323.

Norman, M.D., 1998. Melting and metasomatism in the continental lithosphere: laserablation ICPMS analysis of minerals in spinel lherzolites from eastern Australia.Contributions to Mineralogy and Petrology 130 (3), 240–255.

Pearce, N.J.G., et al., 1997. A compilation of new and published major and trace elementdata for NIST SRM 610 and NIST SRM 612 glass reference materials. GeostandardsNewsletter 21, 115–144.

Pearson, D.G., 1999. The age of continental roots. Lithos 48 (1–4), 171–194.Peng, T.P., et al., 2006. 39Ar/40Ar geochronology and geochemistry of the early Tertiary

baslatic rocks in the Jianghan area, China and its petrogenesis. Acta PetrologicaSinica 22 (6), 1617–1626 (in Chiense with English Abstract).

Peslier, A.H., Reisberg, L., Ludden, J., Francis, D., 2000a. Os isotopic systematics in man-tle xenoliths; age constraints on the Canadian Cordillera lithosphere. Chemical Ge-ology 166 (1–2), 85–101.

Peslier, A.H., Reisberg, L., Ludden, L., Francis, D., 2000b. Re–Os constraints on harzbur-gite and iherzolite formation in the lithospheric mantle: a study of Northern Cana-dian Cordillera xenoliths. Geochimica et Cosmochimica Acta 64 (17), 3061–3071.

Pollack, H.N., 1986. Cratonization and thermal evolution of the mantle. Earth and Plan-etary Science Letters 80, 175–182.

Qi, Q., Taylor, L.A., Zhou, X.M., 1995. Petrology and geochemistry of mantle peridotitexenoliths from SE China. Journal of Petrology 36, 55–79.

Qiu, Y.M., Gao, S., McNaughton, N.J., Groves, D.I., Ling, W., 2000. First evidence of>3.2 Ga continental crust in the Yangtze craton of south China and its implicationsfor Archean crustal evolution and Phanerozoic tectonics. Geology 28 (1), 11–14.

Reisberg, L., Lorand, J.P., 1995. Longevity of Sub-continental mantle lithosphere fromosmium isotope systematics in orogenic peridotite massifs. Nature 376 (6536),159–162.

Reisberg, L., et al., 2005. Re–Os and S systematics of spinel peridotite xenoliths fromeast central China: evidence for constrasting effects of melt percolation. ESPL239, 286–308.

Ru, K., Piggot, J.D., 1986. Episodic rifting and subsidence in the South China Sea. Amer-ican Association of Petroleum Geologists Bulletin 70, 1136–1155.

Rudnick, R.L., Walker, R.J., 2009. Interpreting ages from Re–Os isotopes in peridotites.Lithos 112S, 1083–1095.

Rudnick, R.L., Gao, S., Ling, W.L., Liu, Y.S., McDonough, W.F., 2004. Petrology and geo-chemistry of spinel peridotite xenoliths from Hannuoba and Qixia, North Chinacraton. Lithos 77, 609–637.

Shu, L.S., et al., 2009. Mesozoic tectonic evolution of the Southeast China Block: new in-sights from basin analysis. Journal of Asian Earth Sciences 34, 376–391.

Snow, J.E., Dick, H.J.B., 1995. Pervasive magnesium loss by marine weathering of peri-dotite. Geochimica et Cosmochimica Acta 59 (20), 4219–4235.

van Acken, D., Becker, H., Walker, R.J., 2008. Refertilization of Jurassic oceanic perido-tites from the Tethys Ocean — implications for the Re–Os systematics of theupper mantle. Earth and Planetary Science Letters 268 (1–2), 171–181.

Volkening, J., Walczyk, T., Heumann, K.G., 1991. Osmium isotope ratio determinationsby negative thermal ionization mass-spectrometry. International Journal of MassSpectrometry and Ion Processes 105 (2), 147–159.

Walker, R.J., Carlson, R.W., Shirey, S.B., Boyd, F.R., 1989. Os, Sr, Nd, and Pb isotope sys-tematics of Southern African peridotite xenoliths: implications for the chemicalevolution of subcontinental mantle. Geochimica et Cosmochimica Acta 53,1583–1595.

Wang, F.Z., Li, H.L., Zhu, Q.W., Lu, F.X., 1997. Assemblages of anatectic xenoliths fromvolcanic and the petrology model of lithosphere in south Hunan province. Geolog-ical Science and Technology Information 16, 1–7 (in Chinese with Englishabstract).

Wang, D.Z., Shu, L.S., Faure, M., Shen, W.Z., 2001. Mesozoic magmatism and graniticdome in the Wugongshan massif, Jiangxi Province and their genetical relationshipto the tectonic events in southeast China. Tectonophysics 339, 259–277.

Wang, Y.J., Fan, W.M., Guo, F., Peng, T.P., Li, C.W., 2003. Geochemistry of Mesozoic maficrocks around the Chenzhou–Linwu fault, South China: implications for the litho-spheric boundary between Yangtze and Cathaysia blocks. International GeologyReview 45 (4), 263–286.

Wang, Y.J., Liao, C.L., Fan, W.M., Peng, T.P., 2004. Early Mesozoic OIB-type alkaline ba-salt in central Jiangxi Province adn its tectonic implications. Geochimica 33,109–117 (in Chinese with English abstract).

Wang, Y.J., Fan, W.M., Peng, T.P., Guo, F., 2005. Elemental and Sr–Nd isotopic systemat-ics of the early Mesozoic volcanic sequence in southern Jiangxi Province, SouthChina: petrogenesis and tectonic implications. International Journal of Earth Sci-ences 94, 53–65.

Wang, X.C., Li, X.H., Li, W.X., Li, Z.X., 2007a. Ca. 825 Ma komatiitic basalts in SouthChina: First evidence for >1500 °C mantle melts by a Rodinian mantle plume. Ge-ology 35, 1103–1106.

Wang, Y.J., Fan, W.M., Zhao, G.C., C., J.S., Peng, T.P., 2007b. Zircon U–Pb geochronologyof gneissic rocks in the Yunkai massif and its implications on the Caledonian eventin the South China Block. Gondwana Research 12, 404–416.

Wells, P.R.A., 1977. Pyroxene thermometry in simple and complex systems. Contribu-tions to Mineralogy and Petrology 62, 129–139.

Witt-Eickschen, G., Seck, H.A., 1991. Solubility of Ca and Al in orthopyroxene from spi-nel peridotite: an improved version of an empirical geothermometer. Contribu-tions to Mineralogy and Petrology 104, 431–439.



Wood, B.J., Banno, S., 1973. Garnet-orthopyroxene and orthopyroxene-clinopyroxenerelationships in simple and complex systems. Contributions to Mineralogy and Pe-trology 42 (2), 109–124.

Wu, R.X., et al., 2006. Reworking of juvenile crust: element and isotope evidence fromNeoproterozoic granodiorite in South China. Precambrian Research 146 (3–4),179–212.

Xia, Q.K., et al., 2010. Water content and element geochemistry of peridotite xenolithshosted by early-Jurassic basalt in Ningyuan, Hunan Province. Acta Petrologica etMineralogica 29, 113–124 (in Chinese with English abstract).

Xie, X., et al., 2005. Early-middle Jurassic basaltic rocks: the beginning of later Mesozoicintensive magmatism in SE China. Science in China (Series D) 35, 587–605 (in Chi-nese with English abstract).

Xiong, Y.L., Wood, S.A., 1999. Experimental determination of the solubility of ReO2 andthe dominant oxidation state of rhenium in hydrothermal solutions. Chemical Ge-ology 158, 245–256.

Xu, X.S., 2008. Several problems worthy to be noticed in the research of granites andvolcanic rocks in SE China. Geological Journal of China Universities 14, 283–294(in Chinese with English abstract).

Xu, X.S., Xie, X., 2005. Late Mesozoic–Cenozoic basaltic rocks and crust–mantle interac-tion, SE China. Geological Journal of China Universities 11, 318–334 (in Chinesewith English abstract).

Xu, X.S., O'Reilly, S.Y., Griffin, W.L., Zhou, X.M., 2000. Genesis of young lithosphericmantle in Southeastern China: an LAM–ICPMS trace element study. Journal of Pe-trology 41 (1), 111–148.

Xu, Y.G., et al., 2002. Xenolith evidence for polybaric melting and stratification of theupper mantle beneath South China. Journal of Asian Earth Sciences 20, 937–954.

Yu, J.H., et al., 2003. The thermal state and composition of the lithospheric mantle be-neath the Leizhou Peninsula, South China. Journal of Volcanology and GeothermalResearch 122, 165–189.

Yu, J.H., O'Reilly, S.Y., Zhang, M., Griffin, W.L., Xu, X.S., 2006. Roles of melting and meta-somatism in the formation of the lithospheric mantle beneath the Leizhou Penin-sula, South China. Journal of Petrology 47, 355–383.

Yu, J.H., et al., 2007. Finding of ancient materials in Cathaysia and implication for theformation of Precambrian crust. Chinese Science Bulletin 52, 13–22.

Zhang, H.F., et al., 2001. Geochemical significance of a garnet lherzolite from theDahongshan kimberlite, Yangtze Craton, southern China. Geochemical Journal 35,315–331.

Zhang, H.F., et al., 2008. Evolution of subcontinental lithospheric mantle beneath east-ern China: Re–Os isotopic evidence from mantle xenoliths in Paleozoic kimberlitesand Mesozoic basalts. Contributions to Mineralogy and Petrology 155, 271–293.

Zhao, G.C., Cawood, P.A., 1999. Tectonothermal evolution of the Mayuan assemblage inthe Cathaysia block: implications for Neoproterozoic collision-related assembly ofthe south China craton. American Journal of Sciences 299, 309–339.

Zhao, Z.H., Bao, Z.W., Zhang, B.Y., 1998. The geochemistry of Mesozoic basalts in southHunan Province, South China. Science in China (Series D) 28 (Suppl), 7–14 (inChinese).

Zheng, J.P., et al., 2004. Nature and evolution of Mesozoic–Cenozoic lithospheric mantlebeneath the Cathaysia block, SE China. Lithos 74, 41–65.

Zheng, J.P., et al., 2006. Widespread Archean basement beneath the Yangtze craton. Ge-ology 34 (6), 417–420.

Zhou, X.M., Li, W.X., 2000. Origin of late Mesozoic igneous rocks in Southeastern China:implications for lithosphere subduction and underplating of mafic magmas. Tecto-nophysics 326, 269–287.

Zhou, X.M., Sun, T., Shen, W.Z., Shu, L.S., Niu, Y.L., 2006. Petrogenesis of Mesozoic gran-itoids and volcanic rocks in South China: a response to tectonic evolution. Episodes29, 26–33.

Zhu, B.Q., et al., 2004. Geochronological and geochemical constraint on the Cenozoicextension of Cathaysian lithosphere and tectonic evolution of the border sea basinsin East Asia. Journal of Asian Earth Sciences 24, 163–175.

Zhu, J.C., Zhang, P.H., Xie, C.F., Zhang, F., Yang, C., 2006. The Huashan-Guposhan A-typegranitoid belt in the western part of the Nanling Mountains: petrology, geochem-istry and genetic interpretations. Acta Geologica Sinica 80, 529–542 (in Chinesewith English abstract).


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