In-Situ Trace Element and Sr Isotopic Compositions of Mantle Xenoliths Constrain Two-Stage Metasomatism Beneath the Northern North China Craton

Lithos 288–289 (2017) 338–351

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In-situ trace element and Sr isotopic compositions of mantle xenoliths constrain two-stage metasomatism beneath the northern North China Craton

Dan Wu a,YongshengLiua,⁎, Chunfei Chen a, Rong Xu a, Mihai N. Ducea b,c, Zhaochu Hu a,KeqingZonga a State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China b Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA c Faculty of Geology and Geophysics, University of Bucharest, Bucharest, Romania article info abstract

Article history: Subduction and collision are the key processes triggering geochemical refertilization of the lithospheric mantle Received 29 March 2017 beneath cratons. However, the way that the subducted plate inﬂuences the cratonic lithospheric mantle remains Accepted 27 July 2017 unclear. Here, in-situ major and trace-element and Sr isotopic compositions of peridotite and pyroxenite xeno- Available online 04 August 2017 liths carried by the Dongbahao Cenozoic basalts, located close to the northern margin of North China Craton (NCC), were examined to investigate the effects of the subducted Paleo-Asian oceanic plate on the lithospheric Keywords: mantle of the NCC. Based on petrographic and geochemical features, peridotites were subdivided into two Peridotite xenolith Pyroxenite xenolith types recording two-stage metasomatism. Clinopyroxene (Cpx) in both types of peridotites show chemical zon- Paleo-Asian oceanic plate ing. In those peridotites we refer to as Type 1 peridotites, Cpx exhibit uniform convex-upward rare earth element Mantle metasomatism (REE) patterns but core-rim variations in 87Sr/86Sr ratios (0.7065–0.7082 in the cores and 0.7043–0.7059 in the

North China Craton spongy rims), and have high (La/Yb)N ratios (N1.12) (N means normalized to chondrite), relatively low Ti/Eu Subduction-related melt/ﬂuid ratios (b3756) and negative high ﬁeld strength element (HFSE) (Nb, Ta, Zr, Hf and Ti) anomalies in the cores, indicating early-stage metasomatism by carbonatitic melts derived from the subducted sedimentary carbonate rocks. Cpx in the Type 2 peridotites have highly variable REE patterns (from light rare earth element (LREE)- depleted to LREE-enriched) and feature zoned Sr isotopic compositions contrasting to those in Type 1, i.e., increasing 87Sr/86Sr ratios from the cores (0.7020–0.7031) to the spongy rims (0.7035–0.7041). Accompany- ing variations of 87Sr/86Sr ratios, Cpx in both types of peridotites display increasing Nb/La ratios from the cores to

the spongy rims. In addition, Cpx in the Type 2 peridotites show remarkably increased (La/Yb)N, Ca/Al, Sm/Hf and Zr/Hf ratios but decreased Ti/Eu and Ti/Nb ratios from the cores to the spongy rims. These features imply a later-

stage metasomatism by CO2-rich silicate melts derived from carbonated eclogites. Pyroxenites were also classi- ﬁed into two types. Both types of pyroxenites show higher Ni content in Cpx and orthopyroxene than peridotites at the same Mg# (=100 ∗ Mg/(Mg + Fe), atomic number) level. Their Cpx show high Ti/Eu, Ti/Sr ratios and similar 87Sr/86Sr ratios (0.7039–0.7055) to the Cpx spongy rims in peridotites, suggesting that pyroxenites originated from silicate melt-peridotite reactions in the later-stage metasomatism. These observations collectively indicate that the lithospheric mantle beneath the northern NCC presents evidence for two distinct mantle metasomatic events. We propose that both were caused by the subduction of the Paleo-Asian oceanic plate, which could have contributed signiﬁcantly to the transformation of the lithospheric mantle beneath the northern NCC. © 2017 Elsevier B.V. All rights reserved.

1. Introduction understanding the tectonic evolution of the Earth over time. In general, the SCLMs beneath Archean cratons such as the Kaapvaal craton The nature and composition of the subcontinental lithospheric mantle (Pearson, 1999) and the Siberian Craton (Griffin et al., 1999)areancient. (SCLM) and of the cratonic mantle are particularly of great importance for However, in some regions, the ages of the SCLM and crust are decoupled, for example, the North China Craton (Gao et al., 2002; Griffin et al., 1998; Xu, 2001), the South China Block (Zheng et al., 2004), the North Atlantic ⁎ Corresponding author at: State Key Laboratory of Geological Processes and Mineral Craton (Hughes et al., 2014) and the Wyoming Craton (Carlson et al., Resources, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China. 2004), which are located near plate boundary and have been subjected E-mail addresses: [email protected], [email protected] (Y. Liu). to significant modification during the Phanerozoic.

The SCLM beneath the North China Craton (NCC) was transformed anhydrous pyroxenites and peridotites. Different geochemical reservoirs from a pre-Paleozoic cold, thick and refractory cratonic mantle to a feature different Sr isotopic compositions, and thus in-situ Sr isotopes of hot, thin and fertile “oceanic-type” lithospheric mantle in the Cenozoic, Cpx could be used as a powerful tracer to distinguish the origin of the achangethatrequiressignificant lithospheric thinning during the metasomatic agent (Schmidberger et al., 2003; Sun et al., 2012; Wang Phanerozoic (Gao et al., 2002; Griffin et al., 1998; Menzies et al., et al., 2016; Xu et al., 2013b). 1993). Therefore, the NCC offers an excellent natural laboratory to In this research, we studied peridotite and pyroxenite xenoliths study the processes and mechanisms of continental lithospheric entrained in the Dongbahao Cenozoic basalts in the Siziwangqi region, thinning and craton destruction. Asthenosphere upwelling (Fan and close to the northern margin of the NCC (Fig. 1a) (Zhao et al., 2001). Menzies, 1992; Griffin et al., 1998; Xu, 2001; Zheng et al., 2007) and/ We presented a petrographic analysis and in-situ, spatially controlled or lithospheric delamination (Gao et al., 2004; Wu et al., 2005) could major and trace elemental and Sr isotopic data on peridotite and pyrox- have resulted in the transformation of the ancient SCLM beneath the enite xenoliths. Our data document trace element and Sr isotopic vari- NCC, but multiple slab subductions and collisions around the NCC ability between the core and spongy-rim within the individual Cpx might have triggered such modifications (Chen and Zhou, 2005; grain, which we interpreted to provide direct insights into the PAOP Zhang et al., 2002, 2003). Many studies have suggested that the north- subduction-related modification of the lithospheric mantle beneath ward subduction of the Yangtze block in the Triassic (Gao et al., 2002; the NCC. Zhang et al., 2002) and the westward subduction of the Pacific plate during the Mesozoic-Cenozoic (Sun et al., 2007; Wu et al., 2005)hada 2. Geological setting great influence on the destruction of the NCC. Moreover, the southward subduction of the Paleo-Asian oceanic plate (PAOP) during the Based on age, lithological assemblage, tectonic evolution and P–T–t Paleozoic-Mesozoic additionally contributed to the modification of the paths, the NCC could be divided into the Eastern Block, the Western northern NCC (Chen et al., 2016; Cope et al., 2005; Davis et al., 2001; Block and the intervening Trans-North China Orogen/Central Orogenic Liu et al., 2010; Wang et al., 2016; Xu, 2002; Zhang et al., 2003). However, Belt (Zhao et al., 2001). The NCC is bounded by the Central Asian Oro- details of the PAOP subduction styles and the influence on the NCC litho- genic Belt (CAOB) to the north (Windley et al., 2007), the Qinling- spheric mantle remain unclear. Dabie-Sulu Orogenic Belt to the south (Meng and Zhang, 2000) and a Reactions between subducted slab-derived melts/fluids and perido- Pacific convergent system to the east (Fig. 1a). The NCC is one of the tites are critical processes in the modification of the lithospheric mantle oldest Archean cratons, with the oldest crustal age of approximately (Benard and Ionov, 2013; Chen and Zhou, 2005; Gregoire et al., 2008; 3.8 Ga (Liu et al., 1992) and had undergone a series of tectonic events Soustelle et al., 2010), which could have widely occurred beneath the in the Late Archean and Paleoproterozoic (Wilde et al., 2002). The NCC northern NCC during the southward subduction of the PAOP (Liu was stabilized after the collision between the Eastern and Western et al., 2010; Wang et al., 2016). Fluids/melts derived from the subducted Blocks along the Trans-North China Orogen during the late Proterozoic. oceanic crust could react to varying degrees with the surrounding Since the Phanerozoic, the NCC has experienced subduction of different mantle peridotites. Reaction between SiO2-rich fluids/melts (mostly oceans and collision with surrounding blocks and plates (Cope et al., aqueous and carbonic fluids but in some rare cases also small degree 2005; Gao et al., 2002; Sun et al., 2007). These tectonic processes result- melts of subducted slab) and previously depleted peridotites could pro- ed in modification of the cratonic lithospheric mantle beneath the NCC duce fertile pyroxene-rich peridotites (Kelemen et al., 1998), as sug- during the Late Paleozoic to Cenozoic, and the NCC lost its stability gested by the composite xenoliths of garnet pyroxenite + peridotite and experienced great transformation during the Mesozoic to Cenozoic (Liu et al., 2005, 2010). Continuous melt–rock reaction between a silicic (Gao et al., 2004, 2008; Liu et al., 2011; Wu et al., 2005; Xu, 2001). melt and depleted peridotite can convert olivine to orthopyroxene, The long-lived Paleo-Asian Ocean, defined as the Paleozoic oceanic ultimately resulting in the formation of pyroxenite (Rapp et al., 1999), basin between the Siberian Platform on one side and the Tarim and as demonstrated by pyroxenites formed via reactions between North China blocks on the opposite side (Windley et al., 2007), began eclogite-derived melt and peridotite (Sobolev et al., 2007). In addition, to form near Lake Baikal in Siberia by at least 1000 Ma. The northern carbonatitic melt–peridotite reaction could precipitate clinopyroxene NCC was strongly influenced by the Paleo-Asian tectonic system during at the expense of orthopyroxene and/or olivine (Brey et al., 1983; the Carboniferous to Permian, because the PAOP was subducted south- Dalton and Wood, 1993; Wyllie et al., 1983), and thus transform refrac- ward beneath the NCC, and the northern margin of the NCC evolved into tory harzburgite or lherzolite to wehrlite (Coltorti et al., 1999; Green a Late Carboniferous-Late Permian Andean-style continental margin and Wallace, 1988; Yaxley et al., 1998)orpyroxenite(Liuetal., (Zhang et al., 2007, 2008). The Solonker suture zone marks the final clo- 2015b), depending on the composition of the carbonatitic melt. There- sure of the Paleo-Asian Ocean and amalgamation of the NCC with the fore, fertile peridotites and pyroxenites could record the metasomatism southern Mongolian composite terranes during the late Permian to by melt/fluid–peridotite reactions, and the expectation is that the SCLM Middle Triassic (Xiao et al., 2015; Zhang et al., 2008). above the subduction zone will carry modal (mineralogical) and cryptic The Siziwangqi locates close to the northern margin of the NCC (chemical) signatures of slab-induced metasomatism. The longer the (Fig. 1a). The Dongbahao Cenozoic basalts in the Siziwangqi region subduction process last, the intenser metasomatic reactions will occur. were erupted during the Early Miocene - 21.89 ± 1.65 Ma (whole A recent review of the Andean arc magmatism (Chapman et al., 2017) rock K–Ar isotopic age) and are characterized by alkaline-rich and shows that in the long-lived Andean margins, the lithospheric mantle high Ti compositions (Chen et al., 2005). A suite of mantle xenoliths in- is the major source of basaltic magmas in subduction systems due to cluding peridotites and pyroxenites were collected in the Dongbahao metasomatism, which lowered the solidus temperature of the mantle. basalts (Fig. 1b). In-situ analysis of Sr isotopic compositions using laser ablation multiple collector inductively coupled plasma mass spectrometry (LA-MC-ICP- 3. Samples MS) has been developed rapidly over the last decade (Christensen et al., 1995; Ramos et al., 2004; Tong et al., 2016; Waight et al., 2002). Com- Both peridotite and pyroxenite xenoliths from the Dongbahao ba- pared to the whole-rock or whole grain (clinopyroxene in mantle salts (Fig. 1b) are relatively small (less than 5 cm in diameter), with a rocks) Sr isotopic compositions, in-situ Sr isotopic ratios of clinopyroxene rounded or ellipsoidal shape. Ten relatively large and fresh samples (Cpx), although measured with worse precision than by standard TIMS were selected for detailed work. Based on the petrographic (mineral as- techniques, could record the extent of isotopic heterogeneity within a semblages) and geochemical (major elements and rare earth element single grain and provide detailed information on complex geological pro- (REE) patterns) features, they were subdivided into four groups cesses. Cpx is the major carrier for incompatible elements (e.g., Sr, REE) in (Table 1): Type 1 peridotites (lherzolites, Mg# = 91.7–91.9 and CaO = 340 D. Wu et al. / Lithos 288–289 (2017) 338–351

110o 120o 130o 111 40'o 111 45'o a b Huinan Siziwangqi 4km Central Asian Orogenic Belt 41 30'o 40o

t Zone Siziwangqi l Hannuoba u Sanyitang Beijing a

Datong u F o 40 Fanshi n L Seoul

Tan

o ina Oroge 35 k

estern Block

W Pacific Ocean rth Ch o o Hebi 41 25' 41o25' Xi’an Sulu ns-N

Eastern Bloc Qi Tra nling -D 0 1000km abie g T ngmen Quternary sediment ian Xi sha Dongbahao Yangtze Craton Tarim n Miocene limestone WB O Miocene olivine basalt s Wuhan EB 30o 0 400km Tibet TNC Cretaceous sandstone Precambrian plagioclase YZ amphibolite SC Hercynian granite Sourth-China Orogen Sampling location 110o 120o 111 4o 0' 111o 45'

Fig. 1. (a) Simpliﬁed tectonic map of the North China Craton. The tectonic subdivisions of the North China Craton are based on Zhao et al. (2001). (b) Geological map of the Siziwangqi region and distribution of the basalts (modiﬁed from a 1:200,000 geological map). The sampling location is marked with a solid star.

0.10–0.12 wt% in olivine), Type 2 peridotites (harzburgites and all studied peridotites. Both olivines and orthopyroxenes in peridotites lherzolites, Mg# = 89.9–91.5 and CaO = 0.009–0.060 wt% in olivine), are generally 0.2–5 mm. Olivines are subhedral and have typical kink Type 1 pyroxenites (websterites, orthopyroxene: 47–84%, light rare bands (Fig. 3d), indicating that the xenoliths have experienced some earth element (LREE)-depleted REE patterns in Cpx), Type 2 pyroxenites deformation. Both clinopyroxenes and spinels are relatively small (websterites, Cpx: 63–74%, convex-upward REE patterns in Cpx). (b2 mm). Clinopyroxenes in some peridotites have a dark, spongy rim Peridotite xenoliths are spinel harzburgites and lherzolites (Fig. 2), and display well-deﬁned boundaries between the core and spongy which exhibit a protogranular texture with curved grain boundaries rim (Fig. 3e). (Fig. 3a). Some samples have a well-equilibrated texture showing triple Pyroxenite xenoliths are websterites (Fig. 2) and are characterized junctions among mineral grains (Fig. 3b). In addition, cracks develop in by a coarse-grained texture and irregular mineral boundaries (Fig. 3f). some peridotites (Fig. 3c). The typical mineral assemblages are olivine The Type 1 pyroxenites consist of Opx (47–84%) + Cpx (16%) ± Ol (Ol, 46–81% modal abundance by volume), orthopyroxene (Opx, (0–34%) ± Sp (0–3%) (Table 1). Exsolution lamellae (2–5 μm wide) in 12–38%), Cpx (2–12%) and spinel (Sp, 0–4%) (Table 1). Metasomatic orthopyroxenes were found in sample DBH34. The Type 2 pyroxenites minerals, such as amphibole, phlogopite, or carbonate, are absent from are composed of Opx (24–37%) + Cpx (63–74%) ± Sp (0–2%) (Table 1).

Table 1 Petrological information on the samples studied.

Sample Lithology Texture Mg# Mode(vol%) T(°C)

Ol Opx Cpx Sp rim core

Type 1 peridotite DBH55 Spinel lherzolite Protogranular 92.3 59.5 32 8 b0.5 1123 1103

Type 2 peridotite DBH20 Spinel lherzolite Protogranular 90.2 46 38 12 4 885 937 DBH39 Spinel harzburgite Protogranular 91.8 81 15 2 2 968 983 DBH42 Spinel lherzolite Protogranular 91.4 78.5 14 7 0.5 897 922 DBH45 Spinel harzburgite Protogranular 91.7 77 18 3 2 933 1008 DBH57 Spinel lherzolite Protogranular 91.5 79 12 7 2 949 1021

Type 1 pyroxenite DBH26 Olivine-bearing websterite Coarse grained 89.7 34 47 16 3 931 938 DBH34 Spinel-free websterite Coarse grained 86.6 84 16 922 978

Type 2 pyroxenite DBH61 Spinel-free websterite Coarse grained 89.2 37 63 902 896 DBH63 Spinel-bearing websterite Coarse grained 89.7 24 74 2 931 996

Ol = olivine, Opx = orthopyroxene, Cpx = clinopyroxene, Sp = spinel. Mg# = 100 ∗ Mg/(Mg + Fe) (atomic number), Mg# in Opx is the average. T = temperature, calculated using thermometer of Ca-in-Opx (Brey and Köhler, 1990). D. Wu et al. / Lithos 288–289 (2017) 338–351 341

Ol Table 2. The sources of the standard materials, as well as detailed analyt- Dunite ical procedures and data reduction strategies, have been described by Tong et al. (2016).

harzburgite wehrlite 5. Results

lherzolite 5.1. Major and trace element

5.1.1. Olivine olivine PERIDOTITE Olivines in all samples are chemically homogeneous, and their major orthopyroxenite PYROXENITE and trace element compositions are listed in Table S1. Ol in the Type 1 peridotites (DBH55) have higher Mg# (91.7–91.9), higher CaO olivine websterite olivine – – clinopyroxenite (0.10 0.12 wt%) and Al2O3 (0.043 0.047 wt%) contents and lower MnO (0.13 wt%) content than those in the Type 2 peridotites (Mg#:

89.9–91.5; CaO: 0.009–0.060 wt%; Al2O3:0.006–0.011 wt%; MnO: websterite 0.12–0.15 wt%). Ol in the Type 2 peridotites exhibit higher Mg# Opx Cpx (89.9–91.5) and lower MnO (0.12–0.15 wt%) content than those in the orthopyroxenite clinopyroxenite Type 1 pyroxenites (Mg#: 88.8–89.2; MnO: 0.15 wt%). Ni content of Type 1 peridotite Type 1 pyroxenite Type 2 pyroxenite – DBH55 DBH26 DBH34 DBH61 DBH63 Ol exhibit no obvious difference between peridotites (3121 3178 ppm Type 2 peridotite for the Type 1 peridotites, 3005–3404 ppm for the Type 2 peridotites), DBH20 DBH39 DBH42 DBH45 DBH57 and Ni content of Ol in the Type 1 pyroxenites vary from 3201 ppm to

ﬁ 3304 ppm. Mg# of Ol in the Type 2 peridotites correlate negatively Fig. 2. Petrological classi cation of peridotite and pyroxenite xenoliths carried by the – Dongbahao basalts. with CaO, Al2O3, MnO and Ni contents (Fig. 4a d).

5.1.2. Orthopyroxene 4. Analytical methods Like olivines, most of the highly incompatible trace elements are below detection limits for orthopyroxenes and thus are not listed in All of the following analyses were conducted at the State Key Labo- Table S2. All Opx show no visible compositional zoning. Opx in the ratory of Geological Processes and Mineral Resources, China University Type 1 peridotites (DBH55) have higher Mg# (92.2–92.3) and higher of Geosciences (GPMR-CUG), Wuhan. The major and trace element CaO (1.07–1.18 wt%), Al2O3 (4.79–4.89 wt%), Cr2O3 (0.75–0.76 wt%), compositions of minerals were in-situ measured by laser ablation Ni (861–872 ppm) contents than those in the Type 2 peridotites inductively coupled plasma mass spectrometry (LA-ICP-MS) (GeoLas (Mg#: 90.1–91.9; CaO: 0.42–0.79 wt%; Al2O3:2.14–4.57 wt%; Cr2O3: 2005 + Agilent 7700x) with a spot size of 44 μm. Helium was used as 0.25–0.62 wt%; Ni: 680–787 ppm). Mg# of Opx in the Type 2 peridotites a carrier gas, and nitrogen was added into the central gas ﬂow (Ar correlate negatively with CaO, Al2O3 and Ni contents but positively with + He) of the Ar plasma to increase the sensitivity (Hu et al., 2008). Cr2O3 content (Fig. 4e–h). In addition, Opx in pyroxenites have lower The detailed operating conditions for the laser ablation system and Mg# (86.3–89.9) and higher Ni (658–904 ppm) content than those in ICP-MS instrument were previously described (Liu et al., 2008b). The the Type 2 peridotites (Mg#: 90.1–91.9; Ni: 680–787 ppm). elemental concentrations were calibrated against multiple reference Using the Ca-in-Opx thermobarometer of Brey and Köhler (1990), materials (BCR-2G, BHVO-2G and BIR-1G), and a summed metal oxide the equilibrium temperatures were estimated and listed in Table 1. normalization was applied (Liu et al., 2008b). The off-line selection and The Type 1 peridotites have higher equilibrium temperatures (1103 °C) integration of the background and analyte signals, time-drift correction than the Type 2 peridotites (922–1021 °C). Pyroxenites have relatively and quantitative calibration, were performed using ICPMSDataCal (Lin low equilibrium temperatures of 896–996 °C. et al., 2016; Liu et al., 2008b). The Sr isotopic compositions of Cpx were in-situ analyzed by a MC- 5.1.3. Clinopyroxene ICP-MS (Neptune Plus, Thermo Fisher Scientiﬁc, Germany) coupled The major and trace element compositions in Cpx are listed in with a 193 nm laser ablation system (GeoLas 2005, Coherent Lambda Table S3. Cpx in the Type 1 peridotites have lower Mg# (91.0–92.6)

Physik GmbH, Germany). The VOLM cell was used to eliminate the and lower MgO (16.7–17.3 wt%), FeO (2.45–2.96 wt%), Na2O position-effect related fractionation (Liu et al., 2007), and helium was (0.58–1.46 wt%), Al2O3 (4.12–6.27 wt%), Cr2O3 (1.34–1.52 wt%) and Ni used as the carrier gas and was mixed with Ar by a T-connector before (296–438 ppm) contents than those in the Type 2 peridotites (Mg#: entering the ICP. The Neptune Plus MC-ICP-MS has a breakthrough in 90.0–93.6; MgO: 14.5–17.6 wt%; FeO: 1.99–3.23 wt%; Na2O: sensitivity because of its highly sensitive interface system (Hu et al., 0.59–2.06 wt%; Al2O3:3.01–7.59 wt%; Cr2O3:0.71–1.64 wt%; Ni: 2012). All measurements were conducted using low resolution and 277–474 ppm). In addition, Cpx of the Type 2 peridotites show negative static multi-collector mode. Each analysis consists of an approximately correlation between Mg# and Na2O content, but positive correlations 30 s of background acquisition (gas blank) followed by 50 s of data ac- between Mg# and Cr2O3 and Ni contents (Fig. 5). Cpx in peridotites quisition (laser ablation) from the sample. An array from L4 to H3 to with spongy textures (e.g., DBH20, DBH42, DBH55) show obvious com- monitor Kr, Rb, Er, Yb and Sr composed the mass system of the Faraday positional zoning. The spongy rims have lower Mg#, lower Al2O3 and collector conﬁguration. Detailed experimental conditions are shown in Na2O contents and higher Ni content than the cores (Fig. 5). Cpx of Tong et al. (2016). In this work, BIR-1G, CPX05G and HNB08 were the Type 1 peridotites show convex-upward REE patterns, and weak used as monitor standards, and our analytical results (BIR-1G: anomalies in high ﬁeld strength elements (HFSE) (e.g., Nb, Ta, Zr, Hf 87Sr/86Sr = 0.70310 ± 0.00042 (2SE), n = 10, CPX05G: 87Sr/86Sr = and Ti) (Fig. 6a–b). Their Cpx spongy rims show only higher contents 0.70738 ± 0.00014 (2SE), n = 19, and HNB08: 87Sr/86Sr = 0.70371 ± of large ion lithophile elements (LILE) (e.g., Rb, Ba, Pb and Sr) than the 0.00072 (2SE), n = 10) are consistent with the recommended values cores (Fig. 6a–b). In contrast, Cpx of the Type 2 peridotites show highly (BIR-1G: 87Sr/86Sr = 0.70311 ± 0.00040 (2SE), CPX05G: 87Sr/86Sr = variable REE patterns, varying from LREE depletion to LREE enrichment 0.70741 ± 0.00008 (2SE), and HNB08: 87Sr/86Sr = 0.70385 ± 0.00080 (Fig. 6c). Their LREE-depleted and convex-upward Cpx show weak de- (2SE)) within the analytical uncertainty. The analytical uncertainty pletions in Zr and Hf relative to the Nd and Sm, and a negative anomaly about 87Sr/86Sr ratios of Cpx in samples studied here are listed in of Ti relative to the Eu and Tb (Fig. 6c–d). Both Nb and Ta exhibit weak 342 D. Wu et al. / Lithos 288–289 (2017) 338–351 (a) (b)

Opx Cpx Ol Ol

1 mm 1 mm (c) (d)

Ol Opx

Cpx

1 mm 0.5 mm (e) (f)

Cpx

Cpx Opx

Opx 0.1 mm 1 mm

Fig. 3. Photomicrographs of representative textures of the Dongbahao spinel-facies peridotites and pyroxenites. (a) Shows protogranular texture in the Type 2 peridotites. (b) Shows triple-junction points in the Type 2 peridotites. (c) Shows crack development in peridotite. (d) Shows kink band in olivine. (e) Shows spongy texture in clinopyroxene. (f) Shows coarse-grained texture in the Type 1 pyroxenites. or no anomaly compared to elements with similar incompatibilities 5.1.4. Spinel (Fig. 6c–d). Cpx with spongy rims show core-rim variations, i.e., Rb, Spinels of peridotites and pyroxenites are homogeneous in composi- Ba, Th, U, Sr and LREE increase from the cores to the spongy rims tion (Table S4). Sp in peridotites show highly various compositions in

(Fig. 6c–d). REE patterns of Cpx in sample DBH42 are highly variable MgO (16.0–22.1 wt%), FeO (10.3–14.8 wt%), Al2O3 (31.5–55.4 wt%) from the LREE-depleted core to the LREE-enriched spongy rims and Cr2O3 (9.39–36.0 wt%) relative to those in pyroxenites (MgO = (Fig. 6c). The LREE-enriched spongy rims have much higher contents 17.8–22.1 wt%, FeO = 12.2–14.7 wt%, Al2O3 =44.3–58.4 wt% and of all incompatible trace elements and show distinctly negative anoma- Cr2O3 = 6.47–21.9 wt%). In addition, Sp in peridotites display a wide lies in Ta, Zr, Hf, Ti and Pb (Fig. 6c–d). range of Cr# (=100 ∗ Cr/(Cr + Al), atomic number: 10.1–43.1) and Cpx in the Type 1 pyroxenites have lower Mg# (87.9–90.3) and Mg# (65.8–78.2), suggesting that they have been subjected to variable

Cr2O3 (0.36–0.73 wt%) content, but higher Na2O(1.30–2.25 wt%), degrees of melt extraction. Al2O3 (7.62–8.28 wt%) and Ni (282–394 ppm) contents than those in the Type 2 pyroxenites (Mg#: 91.7–92.2; Cr2O3:1.04–1.49 wt%; Na2O: 5.2. In-situ Sr isotopic compositions of clinopyroxenes 0.66–1.18 wt%; Al2O3:3.49–4.84 wt%; Ni: 312–363 ppm) (Table S3). 87 86 Cpx in pyroxenites have lower Mg# (87.9–92.2) and lower Cr2O3 In-situ Sr isotopic compositions of Cpx are listed in Table 2. Sr/ Sr (0.36–1.49 wt%) and Ni (282–394 ppm) contents than those in the ratios of peridotites have a wide range from 0.7020 to 0.7082. 87Sr/86Sr Type 2 peridotites (Mg#: 90.0–93.6; Cr2O3: 0.71–1.64 wt%; Ni: ratios of Cpx in the Type 1 peridotites decrease from 0.7065–0.7082 in 277–474 ppm). Cpx in the Type 1 pyroxenites have LREE-depleted REE the cores to 0.7043–0.7059 in the spongy rims. In contrast, Cpx in the patterns, with negative Nb, Ta anomalies and weakly negative Ti anomaly Type 2 peridotites feature increasing 87Sr/86Sr ratios from the cores but no Zr, Hf anomalies (Fig. 6e–f). In contrast, Cpx in the Type 2 pyroxe- (0.7020–0.7031) to the spongy rims (0.7035–0.7041). 87Sr/86Sr ratios nites have convex-upward REE patterns and evidently negative anoma- of Cpx in pyroxenites are relatively uniform (0.7044–0.7052 for the lies in HFSE (Nb, Ta, Zr, Hf and Ti) (Fig. 6g–h). Type 1 pyroxenites, and 0.7039–0.7055 for the Type 2 pyroxenites). D. Wu et al. / Lithos 288–289 (2017) 338–351 343

Table 2 extraction of basaltic magma (e.g., high Mg# and Ni content and low Sr isotopic compositions of clinopyroxenes from the Dongbahao xenoliths. CaO content in Ol, negative correlations between Mg# and MnO and

Sample Spot Note Rb (ppm) Sr (ppm) 87Sr/86Sr 2SE Al2O3 contents in Ol and Opx, and positive correlation between Yb and Al O contents in Cpx (Figs. 4 and 5)). In the process of partial melting, DBH55 1-01 spongy rim 1.71 178 0.70456 0.00024 2 3 1-02 spongy rim 1.30 175 0.70444 0.00025 incompatible elements tend to incorporate into melts. Although highly 1-03 mantle bDL 96.5 0.70705 0.00035 incompatible elements can be significantly modified by metasomatism, 1-04 core 0.028 95.8 0.70648 0.00034 the moderately incompatible elements are commonly affected to much b 1-05 mantle DL 96.8 0.70653 0.00038 less extents. Previous studies have shown that the Y and Yb contents of 1-06 spongy rim 0.20 165 0.70434 0.00023 1-07 spongy rim 0.54 130 0.70465 0.00026 clinopyroxenes can be used to estimate the degree of partial melting ex- 2-01 spongy rim 1.01 120 0.70527 0.00027 perienced by spinel peridotites. According to the Y and Yb contents in 2-02 mantle bDL 95.9 0.70665 0.00037 Cpx (0–10%) (Norman, 1998) and Cr# in Sp (Cr# is less sensitive to 2-03 core 0.009 97.9 0.70696 0.00032 metasomatism) (1–16%) (Hellebrand et al., 2001), these peridotites are 2-04 mantle bDL 98.7 0.70823 0.00016 estimated to be residues after b16% of fractional melting. However, Cpx 2-05 spongy rim 0.39 127 0.70594 0.00029 DBH20 1-01 spongy rim 3.57 284 0.70365 0.00018 in both types of peridotites show variable enrichments in Rb, Ba, Th, U, 1-02 mantle 0.023 75.7 0.70249 0.00055 Sr and LREE, and negative anomalies in Nb, Ta, Zr, Hf and Ti (Fig. 6a–d). 1-03 core 0.028 74.3 0.70291 0.00063 These features are inconsistent with partial melting but imply a metaso- 1-04 mantle 0.029 74.6 0.70261 0.00057 matic origin. 1-05 spongy rim 0.27 74.9 0.70351 0.00052 2-01 spongy rim 2.04 331 0.70366 0.00014 2-02 spongy rim 1.50 422 0.70393 0.00025 6.1.1. Early-stage metasomatism encoded in the Cpx cores 2-03 mantle bDL 74.6 0.70214 0.00067 In general, Cpx in peridotites from a depleted mantle have low Rb/Sr 2-04 core 0.020 72.6 0.70202 0.00070 ratios and thus are characterized by low time-integrated 87Sr/86Sr ratios, 2-05 spongy rim 0.97 144 0.70405 0.00034 as is the case with the depleted mantle-derived MORB (0.7027) (Salters 2-06 spongy rim 0.98 129 0.70414 0.00045 DBH42 1-03 spongy rim 1.60 467 0.70370 0.00016 and Stracke, 2004). In contrast, Cpx in a fertile mantle metasomatized 87 86 1-04 mantle 0.003 34.4 0.70219 0.00168 by slab subduction-related fluid/melt can have high Sr/ Sr ratios, as 1-05 core 0.050 31.2 0.70307 0.00134 demonstrated by Cpx from many subcontinental mantle regions globally b 1-08 mantle DL 31.6 0.70296 0.00139 (Pearson et al., 2014). Here, the Cpx cores in the Type 1 peridotites feature 2-02 spongy rim 0.97 408 0.70361 0.00013 87 86 2-03 spongy rim 1.02 428 0.70364 0.00014 enrichments in LREE (Fig. 6a) and much higher Sr/ Sr ratios 2-04 spongy rim 0.98 411 0.70381 0.00014 (0.7065–0.7082) than their spongy rims (0.7043–0.7059) (Fig. 7a). The 2-07 mantle 0.019 32.7 0.70288 0.00100 high 87Sr/86Sr ratios in the Cpx cores could result from either a metasoma- DBH45 1-02 rim bDL 84.4 0.70334 0.00044 tism by a high-87Sr/86Sr fluid/melt or record an ancient metasomatism by 1-03 mantle 0.009 90.3 0.70296 0.00035 ahigh-Rb/Srfluid/melt. However, these Cpx cores have very low Rb/Sr ra- 1-04 core bDL 98.0 0.70281 0.00038 b 1-06 rim 0.15 85.9 0.70350 0.00041 tios ( 0.0003). According to the evolutionary model of Sr isotopic compo- 87 86 DBH26 1-01 rim 0.013 50.7 0.70444 0.00076 sitions, these Cpx cores could not obtain the Sr/ Sr ratio of 0.7082 1-03 mantle 0.23 91.6 0.70440 0.00071 merely by accumulation of radiogenic Sr. Therefore, these Cpx cores 1-04 core 0.52 68.5 0.70445 0.00075 could only form via metasomatism by a high-87Sr/86Sr fluid/melt. 1-06 mantle 0.14 53.3 0.70521 0.00092 DBH61 1-01 rim 0.030 57.9 0.70446 0.00058 Metasomatic agents in the lithospheric mantle generally include 1-02 mantle bDL 58.1 0.70474 0.00056 alkaline-rich, volatile-bearing silicic melts (Wulff-Pedersen et al., 1-03 core bDL 57.0 0.70431 0.00064 1996; Yogodzinski and Kelemen, 2007), carbonatitic melts (Rudnick 1-04 mantle 0.21 97.1 0.70438 0.00061 et al., 1993; Yaxley et al., 1998)orCO2-H2O fluids (Ionov et al., 1997; 1-05 rim 0.024 59.2 0.70482 0.00076 Stalder et al., 1998). The Cpx cores with convex-upward REE patterns DBH63 1-02 rim bDL 49.3 0.70390 0.00088 1-03 mantle 0.050 49.5 0.70487 0.00079 in the Type 1 peridotites exhibit negative HFSE (Nb, Ta, Zr, Hf and Ti) 1-06 rim 0.024 50.0 0.70548 0.00071 anomalies (Fig. 6a–b), which could be attributed to metasomatism by carbonatitic melts due to the evidently negative HFSE anomalies in av- The Spot in this table are corresponded to those in Table S3. DL = detected limit, 2SE = 2 standard error. erage carbonatite or average limestone (data from a worldwide data- base, refer to Chen et al. (2016)). TiO2 content of the carbonatite and partition coefficient of Ti in clinopyroxene-melt in the carbonate system 6. Discussion are low, and the fractionation between LREE and HREE is extremely high (Green and Wallace, 1988; Nelson et al., 1988; Yaxley et al., 1998).

6.1. Two-stage metasomatic episodes recorded by peridotites Therefore, the plot of (La/Yb)N vs. Ti/Eu ratios for Cpx has been widely used to discriminate silicate- or carbonatite-related metasomatism The heterogeneity of petrology and geochemistry of the lithospheric (Coltorti et al., 1999). The Cpx cores in the Type 1 peridotites have rela- mantle is mainly caused by partial melting and metasomatism. Partial tively high (La/Yb)N ratios (N1.12) and low Ti/Eu ratios (b3756), falling melting of mantle peridotites results in depletion of basaltic compo- in the trend of carbonatitic metasomatism (Fig. 8a). In general, Mg# in nents (such as Na, Ca, Mn, Al and Fe) and produces a refractory SCLM Ol correlate negatively with CaO and Al2O3 contents and positively (Frey and Green, 1974; Takazawa et al., 2000; Xu et al., 1998), whereas with Ni content. However, compared to the Type 2 peridotites, Ol in metasomatism causes refertilization of the SCLM (Beyer, 2006; Norman, the Type 1 peridotites feature low Ni content (3121–3178 ppm) but

1998). Metasomatism includes both cryptic and modal metasomatism. high Mg# (91.7–91.9) and high CaO (0.10–0.12 wt%) and Al2O3 Cryptic metasomatism causes enrichments in incompatible elements (0.043–0.047 wt%) contents (Fig. 4b–d), implying that the Type 1 peri- but does not produce new phases, while modal metasomatism is always dotites could have experienced metasomatism by a Ca-Mg-Al-rich melt. accompanied by the presence of newly formed phases (e.g., amphibole, Moreover, the Cpx cores in the Type 1 peridotites show higher Ni con- apatite and/or phlogopite) (Bailey, 1987; Frey and Green, 1974; tent than those in the Type 2 peridotites at the same Mg# level Norman, 1998). As the major carrier for incompatible trace elements (Fig. 5d), implying that the Cpx cores in the Type 1 peridotites could in anhydrous mantle peridotites (Zangana et al., 1999), Cpx can be have been formed at the expense of Ol during melt-peridotite reaction used to trace these processes. (Kelemen et al., 1998). These observations indicate that the Type 1 pe- The Dongbahao peridotite xenoliths show geochemical features of ridotites experienced metasomatism by Ca-Mg-Al-rich carbonatitic fragments of a lithospheric mantle depleted by variable degrees of melts with high 87Sr/86Sr ratios (N0.7082) in the early stage. 344 D. Wu et al. / Lithos 288–289 (2017) 338–351

0.25 1.6 (a) (e)

0.2 1.2

0.15 0.8

0.1 0.4 MnO in Ol (wt%) CaO in Opx (wt%)

0.05 0 0.15 88 7 (b) (f)

0.1 5 in Opx (wt%) 0.05 3 3 O 2 CaO in Ol (wt%) Al

0 1 0.05 0.8 (c) (g) 0.04 0.6 0.03 in Ol (wt%) in Opx (wt%)

3 0.02 3 O

O 0.4 2 2 Al 0.01 Cr

0 0.2 3500 1000 (d) (h) 3400 900 3300 800 3200 Ni inOl (ppm)

Ni inOpx (ppm) 700 3100

3000 600 88 89 90 91 92 93 86 88 90 92 94 Mg# in Ol Mg# in Opx

Fig. 4. Plots of Mg# versus MnO, CaO, Al2O3,Cr2O3 and Ni contents in olivines and orthopyroxenes.

6.1.2. Later-stage metasomatism recorded by the Cpx spongy rims exhibit higher 87Sr/86Sr ratios (up to 0.7041) than their Cpx Spongy textures are found in Cpx of both types of peridotites cores (0.7020–0.7031) (Fig. 7a), so the melt reacted with the peridotites (DBH20, DBH42 and DBH55) (Fig. 3e). Some authors attributed the would have high 87Sr/86Sr ratios (N0.7041), higher than the host basalts spongy textures to interaction of xenolith with the host magma during (0.7035–0.7037; Zhang et al., 2017)(Fig. 7a). Therefore, the contamina- transport (Shaw et al., 2006) or with exotic melts prior to the entrain- tion of host basalts could be excluded. All these features indicate that ment (Coltorti et al., 1999). Other authors attributed the spongy the spongy-textured Cpx in peridotites could have been formed in meta- textures to partial melting induced by fluid penetration (Carpenter somatism by exotic melts prior to entrainment. et al., 2002) or to mineral breakdown induced by decompression Cpx in both types of peridotites exhibit evident core-spongy rim (Nelson and Montana, 1992). The spongy-textured minerals in variations in incompatible trace elements. In the Type 1 peridotites, peridotites from the Dongbahao basalts preserve primary shapes and the Cpx spongy rims show only higher contents of aqueous fluid- well-defined grain boundaries and show no apparent interaction with mobile elements (Rb, Ba, Pb and Sr) than their Cpx cores (Fig. 6a–b), contact minerals or melts (Fig. 3e). Compositionally, the spongy suggesting that the metasomatism could have been caused by aqueous rims show high incompatible trace element contents and different Sr fluids and only partly changed the LILE. However, Cpx in the Type 2 pe- isotopic compositions relative to their cores (Figs. 6a–dand7a). These ridotites show variable increments of REE, LILE and HFSE contents from characteristics could argue against partial melting and mineral the cores to the spongy rims, indicating metasomatism by silicate/ breakdown-induced spongy rims and support the metasomatic origin carbonatitic melts rather than aqueous fluids due to the very low instead. Moreover, the Cpx spongy rims in the type 2 peridotites solubility of HFSE in aqueous fluids (Kogiso et al., 1997). Cpx in the D. Wu et al. / Lithos 288–289 (2017) 338–351 345

2.5 (a) (b) 3 2

1.5 2

O inCpx (wt%) Depletion 2 1 Yb in Cpx (ppm) Yb in Cpx

Na 0.5 Depletion 0 0 87 89 91 93 2468

Mg# in Cpx Al2O3 in Cpx (wt%)

1.6 (c) 500 (d)

1.2 400 Depletion

0.8 Depletion in Cpx (wt%) 3 300 O 2 0.4 Ni inCpx (ppm) Cr

0 200 87 89 91 93 87 89 91 93 Mg# in Cpx Mg# in Cpx

Type 1 peridotite DBH55 (spongy rim) DBH55 (core) Type 2 peridotite DBH20 (spongy rim) DBH20 (core) DBH39 (rim) DBH39 (core) DBH42 (spongy rim) DBH42 (core) DBH45 (rim) DBH45 (core) DBH57 (rim) DBH57 (core) Type 1 pyroxenite Type 2 Pyroxenite DBH26 DBH34 DBH61 DBH63

Fig. 5. Plots of Mg# versus Na2O, Cr2O3 and Ni contents, Yb versus Al2O3 contents in clinopyroxenes.

Type 2 peridotites feature positive correlation between Nb/La and 6.2. Pyroxenite: product of melt-peridotite interaction 87Sr/86Sr ratios (Fig. 7b) and increased Nb/La ratios from the cores to the spongy rims, agreeing well with metasomatism by silicate melt Pyroxenites in the lithospheric mantle were generally suggested to with high Nb/La and 87Sr/86Sr ratios. In addition, Cpx in the Type 2 peri- be formed by fractional crystallization from melts at high pressures dotites show features of carbonatitic metasomatism, e.g., remarkably in- (Bodinier et al., 1987; Fan et al., 2001; Xu, 2002), solid-state recycling creased (La/Yb)N, Ca/Al, Sm/Hf and Zr/Hf ratios but decreased Ti/Eu and of the oceanic crust (Yu et al., 2010) or metasomatism via melt– Ti/Nb ratios from the cores to the spongy rims (Fig. 8a–d) and depletions peridotite reactions (Dantas et al., 2009; Liu et al., 2005). Cpx in the of Zr, Hf and Ti in the spongy rims (Fig. 6c–d) (Blundy and Dalton, 2000; Type 2 pyroxenites have high Mg# (91.7–92.2) (Fig. 5), and show enrich- Coltorti et al., 1999; Ionov et al., 1993; Rudnick et al., 1993). Combina- ments in incompatible trace elements (e.g., LREE) (Fig. 6g–h). These geo- tions of these features imply that individual silicate or carbonatite meta- chemical observations are paradoxical because enrichments in highly somatism cannot interpret all the observed geochemical features, and incompatible elements imply derivation from melts with either an the later metasomatism could have been caused by a CO2-rich silicate evolved characteristic (enriched in highly incompatible elements) or a melt. significant fluid component, but the high Mg# suggests a primitive origin Cpx in the Type 1 peridotites show decreasing 87Sr/86Sr ratios from (Liu et al., 2005). These features could not be interpreted by fractional 0.7065–0.7082 in the cores to 0.7043–0.7059 in the spongy rims. In con- crystallization from melts at high pressures. The lack of cumulative tex- trast, Cpx in the Type 2 peridotites feature increasing 87Sr/86Sr ratios ture in pyroxenites also precludes such an origin. Pyroxenites from the from the cores (0.7020–0.7031) to the spongy rims (0.7035–0.7041) Dongbahao basalts consist of Cpx + Opx ± Ol ± Sp (Table 1), and thus (Fig. 7a). Although spongy textures and trace-element zoning for Cpx incompatible trace element compositions of Cpx can roughly reflect the are absent in sample DBH45, this sample shows similar core-rim features of bulk pyroxenite. The subducted oceanic crust generally variations in 87Sr/86Sr ratios (Fig. 7a). The core-spongy rim variations consists of abundant gabbros, which possibly show positive Eu and Sr in 87Sr/86Sr ratios could record later-stage metasomatism by melt with anomalies (Yu et al., 2010). Thus the lack of an Eu anomaly in Cpx from moderate 87Sr/86Sr ratios (0.7041–0.7059). The compositional zoning pyroxenites could preclude the origin of solid-state recycling of the oce- will disappear over time due to diffusion. Thus, the Sr content zoning anic crust. Furthermore, the compositional continuum of constituent of Cpx could provide a constraint on the interaction time between minerals for major elements (Figs. 4 and 5) and the similarity of trace peridotite and melt. Using the data of Sneeringer et al. (1984) for Sr elements of Cpx between peridotites and pyroxenites (Fig. 6e–h) also diffusion in natural Cpx (10−19 to 10−22 m2/s, extrapolated to 900 °C), do not favor such a metamorphic origin. our calculations show that the zoning of Sr will be obliterated within ap- A metasomatic origin related to reaction processes between melt proximately 40 Ma for a 2 mm wide Cpx grain (e.g., DBH55) at 900 °C, and mantle peridotite could explain the petrographic and geochemical suggesting that the metasomatic event could have occurred at a much characteristics of these pyroxenites. The upper mantle sampled by the later (geological) time prior to the host basalt eruption. Dongbahao xenoliths is indeed characterized by a modal continuum 346 D. Wu et al. / Lithos 288–289 (2017) 338–351

100 100 (a) Type 1 peridotite (b) 10 10 1

0.1 1 DBH39

PM-normalized value 0.01 CI-normalized value CI-normalized

0.1 0.001 100 100 (c) Type 2 peridotite (d) 10 10 1

0.1 1 value normalized

PM- 0.01 CI-normalized value CI-normalized

0.1 0.001 100 100 (e) Type 1 pyroxenite (f) 10 10 1

0.1 1 FDBH20 0.01 CI-normalized value CI-normalized PM-normalized value

0.1 0.001 100 100 (g) Type 2 pyroxenite (h) 10 10 1

0.1 1 FDBH55

CI-normalized value CI-normalized 0.01 PM-normalized value

0.1 0.001 La Ce Pr NdSmEuGdTbDyHo ErTmYbLu RbBaTh U NbTaLaCePb SrNdZr HfSmEuTi Tb YTmYb

Fig. 6. CI-normalized REE patterns and PM-normalized trace element patterns in clinopyroxenes. Sample DBH39 represents depleted peridotite (DBH39). Average of fresh Cpx in sample DBH20 (FDBH20) and sample DBH55 (FDBH55). The data for chondrite (CI) and the primitive mantle (PM) are from Taylor and McLennan (1985) and McDonough and Sun (1995), respectively. between peridotites and pyroxenites, with increasing orthopyroxene demonstrating that the melts reacted with peridotites could be silicate and/or clinopyroxene abundances and decreasing olivine abundance melts rather than carbonatitic melts. These observations suggest that (Fig. 2). The higher Ni content in Opx and Cpx of pyroxenites both types of pyroxenites could originate from silicate melt–peridotite (658–904 ppm for Opx, 282–394 ppm for Cpx) than those of peridotites reactions. at the same Mg# level (Figs. 4h and 5d) could be explained by the re- lease of Ni during the transformation from olivine to pyroxene in 6.3. Origin and evolution of the metasomatic agents melt-peridotite reaction (Kelemen et al., 1998). It is interesting to note that fresh Cpx in the Type 1 pyroxenites and the Type 2 peridotites As discussed above, both types of peridotites and pyroxenites (e.g., DBH20) share similar geochemical features (e.g., LREE-depleted from the Dongbahao basalts could have been metasomatized or REE patterns, negative Nb and Ta anomalies and weak negative Ti anom- formed by the injection of exotic melts/fluids before their entrain- aly but no Zr, Hf anomalies in trace element patterns) (Fig. 6e–f), and ment in the host magma. However, their different geochemical fea- fresh Cpx in the Type 2 pyroxenites and the Type 1 peridotites tures indicate different nature and origin for the metasomatic (e.g., DBH55) exhibit similarly convex-upward REE patterns, evidently agents. It has been suggested that metasomatic agents could be fluids negative Nb, Ta, Zr, Hf and Ti anomalies (Fig. 6g–h). This phenomenon or melts derived from recycled continental crust, subducted oceanic suggests that the Type 1 pyroxenites and Type 2 pyroxenites could be crust or asthenosphere. Investigations of mantle xenoliths suggest products of reactions between melt and the Type 2 and Type 1 perido- that asthenosphere-derived melt–peridotite reactions could con- tites, respectively. If this is correct, the decreasing (La/Yb)N but increasing tribute to modification of the lithospheric mantle beneath the north- Ti/Eu ratios of fresh Cpx from peridotites (Type 2 and Type1) to pyroxe- ern NCC (Tang et al., 2008; Xu et al., 2003; Zhang et al., 2009a). nites (Type 1 and Type 2) (Fig. 8a) imply that the melts reacted with pe- Basaltic melts derived from an asthenospheric source show 87 86 ridotites could be low-(La/Yb)N and high-Ti/Eu silicate melts. In addition, Sr/ Sr ratios of b0.7046 (Song et al., 1990; Tang et al., 2006), Cpx metasomatized by carbonatitic melt from eastern Australia have low which is inconsistent with the Sr isotopic compositions of Cpx in Ti/Sr ratios between 2 and 4 (Norman, 1998), but Cpx in both types of py- this study (0.7035–0.7082). On the other hand, studies of the late roxenites studied here have high Ti/Sr ratios ranging from 8.57 to 123, Paleozoic-Cenozoic magmatic rocks (Gao et al., 2008; Liu et al., D. Wu et al. / Lithos 288–289 (2017) 338–351 347

0.709 (a) melts could have been derived from dehydration or melting of a RCCM subducted slab, as discussed below. Geochemical features of Cpx and Ol in the Type 1 peridotites imply 0.707 metasomatism by Ca-Mg-Al-rich carbonatitic melts, as discussed in Section 6.1.1. In addition, their Cpx cores show only elevated LREE contents compared to Cpx in sample DBH39 (depleted peridotite) SR-1

Sr in Cpx Sr in 0.705 Pyroxenite (Fig. 6a–b), implying that the metasomatic melt could have low REE, 86 SR-2 LILE and HFSE contents, like the melt of recycled sedimentary carbonate Sr/

87 rocks (Chen et al., 2016; Liu et al., 2015b). The high Sr content 0.703 Host basalt (96–99 ppm) (Fig. 6b) and 87Sr/86Sr ratios (0.7065–0.7082) (Fig. 7a) of the Cpx cores in the Type 1 peridotites suggest metasomatism by fluids/melts with high Sr content (N480 ppm) (Cpx/Carbonatitic meltD = 0.701 Sr 87 86 N 1000 2000 3000 4000 5000 0.206; Blundy and Dalton, 2000) and high Sr/ Sr ratios ( 0.7082), fl Ti/Eu in Cpx consistent with subduction-related uids/melts produced in the initial stage of slab subduction (Fig. 9a), characterized by high Sr content 0.709 and 87Sr/86Sr ratios, inherited from the subducted oceanic crust (b) (Kessel et al., 2005; Kogiso et al., 1997; Tatsumi, 1986). This is consistent with the previous studies that the recycled oceanic crustal materials or 0.707 RCCM sediments may have been involved in the transformation of the SCLM beneath the northern NCC (Chen et al., 2016; Liu et al., 2010; Tang 87 86 CO2-rich et al., 2007; Xu, 2002; Zhang et al., 2012). Sr/ Sr ratios of marine silicate melt Sr in Cpx Sr in 0.705 carbonate rock vary with time (Veizer and Mackenzie, 2003). Marine 86 carbonates show high 87Sr/86Sr ratios (N0.7082) during 560–355 Ma Sr/ b fl

87 or 35 Ma (Castillo, 2015), so uids/melts derived from these rocks 0.703 have high 87Sr/86Sr ratios (N0.7082), like the early-stage carbonatitic DM melts, recorded by the Cpx cores in the Type 1 peridotites. No subduction is known in less than 35 Ma near the northern margin of the NCC. 0.701 However, the subduction of the Paleo-Asian Ocean has commenced in 0.01 0.1 1 10 the early Paleozoic (Xu et al., 2013a; Xu and Chen, 1997), which is con- Nb/La in Cpx sistent with the time indicated by Sr isotopic ratios of mantle xenoliths. Like the 87Sr/86Sr ratios of the Cpx spongy rims (0.7035–0.7059) in 0.709 (c) peridotites, Cpx in pyroxenites show moderately high 87Sr/86Sr ratios (0.7039–0.7055) (Fig. 7a), implying that the pyroxenite-related melt could share the same origin as the ﬂuid/melt interacted with peridotite 0.707 to form the Cpx spongy rims. However, their trace element compositions vary remarkably in different samples (Fig. 6a–h). Their similar 87Sr/86Sr ratios but different REE patterns varying from LREE depletion 0.705 CO2-rich Sr in Cpx Sr in to LREE enrichments suggest metasomatism by different agents evolved

86 silicate melt from a CO2-rich silicate melt rather than variable degree of metasoma- Sr/

87 tism by a single melt. Partial melting of carbonated eclogites has been 0.703 shown to produce CO2-rich silicate melt at low-pressure and high- temperature conditions, but carbonatitic melts at high pressures N b 0.701 ( 6 GPa) and low temperature ( 1000 °C) (Hammouda, 2003). Seawater 0.1 1 10 100 in both Cenozoic and early-middle Paleozoic (about 560–355 Ma) has La in Cpx (ppm) high 87Sr/86Sr ratios (Veizer et al., 1999) and thus altered oceanic crust at that time should theoretically be characterized by a high 87Sr/86Sr Fig. 7. Plots of 87Sr/86Sr ratios versus (a) Ti/Eu ratios, (b) Nb/La ratios and (c) La content in ratio, as demonstrated by the altered oceanic crust collected from the clinopyroxenes. Spongy rims in the Type 1 peridotites (SR-1) and the Type 2 peridotites western Atlantic Ocean (0.7036–0.7074; Staudigel et al., 1995). There- (SR-2). Depleted mantle (DM) data are from Salters and Stracke (2004) for Sr isotopic 87 86 fore, the moderately high Sr/ Sr ratios (0.7041–0.7059) of the CO2- composition and Nb/La ratio. Data of the recycled continental crust-derived melt rich silicate melt could imply an origin of altered oceanic crustal materials (RCCM) are represented by the high-Mg# adakites and diorites (Gao et al., 2004; Xu et al., 2008). The host basalts (Data from Zhang et al. (2017)) are shown for comparison. formed in the early-middle Paleozoic (Fig. 9b). 87 86 Arrows in (a) indicate Sr/ Sr ratios change in the later-stage metasomatism, As CO2-rich silicate melt infiltrates the peridotite, the silicic melt re- (b) indicate later-stage metasomatism by high-Nb/La melt and (c) indicate the trend of acts with the peridotite, consuming olivine in peridotite and precipitat- melt evolution in the later-stage metasomatism. ing pyroxene, and forming ultimately pyroxenite, as demonstrated by experiments (Rapp et al., 1999) and composite mantle xenoliths (Liu 2008a; Xu et al., 2017; Zhang et al., 2003; Zhang et al., 2009b)and et al., 2005). Due to the consumption of silicic melt components by reac- mantle xenoliths (Liu et al., 2010; Wang et al., 2016; Xu, 2002)sug- tion of olivine + silicic melt → pyroxene and the low KdCpx/melt and gest that the lithospheric mantle beneath the northern NCC was KdOpx/melt of incompatible trace elements at high pressure (Green strongly refertilized by melts and/or fluids from the recycled ocean- et al., 2000; Hart and Dunn, 1993) and some of the initial melt also ic/continental crust. In the plot of Ti/Eu-87Sr/86Sr and Nb/La-87Sr/86Sr being consumed in these reactions, abundances of incompatible trace for Cpx (Fig. 7a–b), peridotites and pyroxenites deviate from those elements increase. If the fraction of melt is large enough during melt/ mixed ranges between the recycled continental crust-derived melt fluid-peridotite reaction, the carbonatitic melt with enriched incompat- and the depleted mantle, precluding the origin of recycled continen- ible trace elements could finally be formed from the CO2-rich silicate tal crust. Altered oceanic crust and subducted sediments could con- melt (Davide et al., 2014). Due to the low radiogenic Sr isotopic compo- tribute to the high 87Sr/86Sr ratios (Chen et al., 2016; Staudigel sition of depleted mantle peridotite and extremely low KdCpx/melt and et al., 1995; Wang et al., 2016), and thus we prefer that the fluids/ KdOpx/melt of La (Green et al., 2000; Hart and Dunn, 1993), melt– 348 D. Wu et al. / Lithos 288–289 (2017) 338–351

100 9 (a) Carbonatite (b) metasomatism Carbonatite (66.4,80.2) 10 7 in Cpx N 1 Silicate 5 metasomatism Ca/Al in Cpx (La/Yb) (La/Yb) 0.1 3

0.01 1 0 2000 4000 6000 8000 0 2000 4000 6000 8000 Ti/Eu in Cpx Ti/Eu in Cpx 5 100000 (c) Carbonatite (d) metasomatism 4 10000

Carbonatite Sm/Hf in Cpx in Sm/Hf Ti/Nb inTi/Nb Cpx 1000 2 metasomatism

1 100 20 30 40 50 20 30 40 50 Zr/Hf in Cpx Zr/Hf in Cpx

Fig. 8. (a) Plots of (La/Yb)N versus Ti/Eu ratios in clinopyroxenes. The signatures of the metasomatism by silicate and carbonatite are from Coltorti et al. (1999). (b) Plots of Ca/Al versus Ti/ Eu ratios in clinopyroxenes. Carbonatite data are from Mourão et al. (2010).(c–d) Plots of Zr/Hf versus Sm/Hf and Ti/Nb ratios in clinopyroxenes for sample DBH42. Gray arrows in (a–d) indicate the carbonatite metasomatism. Red arrows in (a) indicate (La/Yb)N and Ti/Eu ratios change from peridotites (Type 2 and Type1) to pyroxenites (Type 1 and Type 2) during melt– peridotite reaction to form pyroxenites. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) peridotite reaction could thus simultaneously reduce 87Sr/86Sr ratios pyroxenites from other regions in the northern NCC, e.g., Sanyitang and increase La content of the melt to produce an evolved melt with a (0.7069; Zhang et al., 2012), Hannuoba (0.7066; Xu, 2002)andHuinan moderate 87Sr/86Sr ratio and enriched La content. The negative correla- (0.7113; Xu et al., 2003)(Fig. 1a), suggesting that the lithospheric mantle tion between 87Sr/86Sr ratios and La content in these Cpx (Fig. 7c) agrees under the northern NCC, from the west to the east, could have experi- well with the trend of melt evolution during the melt-peridotite enced the Paleo-Asian Ocean southward subduction-related mantle reaction. Cpx in pyroxenites have higher 87Sr/86Sr ratios and lower La modification. However, from the north to the center of the NCC, content than the Cpx spongy rims in peridotites (Fig. 7c), implying e.g., Siziwangqi, Sanyitang, Datong (0.7093; Wang et al., 2016) and Fanshi that the melt/fluid–peridotite reactions first formed pyroxenites, then (0.7072; Chen et al., 2017), peridotites/pyroxenites in the lithospheric formed the Cpx spongy rims in peridotites. mantle show similarly high 87Sr/86Sr ratios. This is consistent with the trend demonstrated by the Cenozoic basalts in Trans-North China 6.4. Implications for the Paleo-Asian ocean subduction-related modification Orogen, which were thought to be predominantly derived from a pyrox- of the NCC enitemantlesourceformedbyreaction between recycled oceanic crust- derived melt and depleted asthenospheric mantle (Liu et al., 2015a; Xu Davis et al. (2001) and Cope et al. (2005) suggested that the NCC et al., 2017). These basalts show isotopic and chemical compositions could have been strongly influenced by the southward subduction of varying simultaneously from the north to the center, e.g., SiO2 content the Paleo-Asian Ocean through studying the tectonics and sediments and 87Sr/86Sr ratios decrease, FeOT content and 143Nd/144Nd, Sm/Yb and of the northern margin of the NCC. Subduction-related Carboniferous Ce/Pb ratios increase (Xu et al., 2017). These observations indicate exten- granitoid plutons and latest Carboniferous-earliest Permian volcanic sive modification of the lithospheric mantle beneath the NCC in a north- rocks also support the assertion that southward subduction of the south direction, attributed to the low angle southward subduction of the Paleo-Asian Oceanic lithosphere beneath the northern NCC was occur- Paleo-Asian Ocean beneath the NCC. ring during the late Paleozoic (Zhang et al., 2007). Liu et al. (2010) and Wang et al. (2016) provided direct evidence for the role of the 7. Conclusions subducted Paleo-Asian Oceanic slab in melt–peridotite reactions beneath the northern NCC by zircon dating of composite xenoliths and Mantle xenoliths from the Dongbahao basalts consist of spinel peri- Sr isotopic, trace elemental compositions of peridotite xenoliths. More- dotites and pyroxenites. Peridotites have experienced b16% fractional over, carbonatite formed by melting of subducted sedimentary carbon- partial melting and subsequent metasomatism. In-situ major, trace ate rocks, intruding into the Hannuoba Neogene alkali basalts, witness element and Sr isotopic data on peridotite and pyroxenite xenoliths the presence of the Paleo-Asian oceanic slab beneath the NCC (Chen suggest that the SCLM beneath the Siziwangqi region could have et al., 2016). All those observations indicate that the southward subduc- experienced two-stage subduction-related mantle modification. The tion of the Paleo-Asian Ocean could have contributed significantly to the early-stage metasomatic agent recorded by the Type 1 peridotites is transformation of the lithospheric mantle beneath the northern NCC. interpreted to be a Ca-Mg-Al-rich carbonatitic melt with elevated Peridotites from the Dongbahao basalts show high 87Sr/86Sr ratios (up 87Sr/86Sr ratios (N0.7082), derived from a subducted sedimentary to 0.7082), and such high 87Sr/86Sr ratios are also found in peridotites/ carbonate rock at the initial stage of slab subduction. The later-stage D. Wu et al. / Lithos 288–289 (2017) 338–351 349

(a) Early-stage metasomatism Processes and Mineral Resources, China University of Geosciences (MSFGPMR01). M.N. Ducea acknowledges funds from the Romanian Paleo-Asian Ocean North China Craton Executive Agency for Higher Education, Research, Development and In- Oceanic crust Continental crust novation Funding project PN-III-P4-ID-PCE-2016-0127.

References Oceanic lithosphere Continental lithosphere Bailey, D.K., 1987. Mantle metasomatism—perspective and prospect. Geological Society, Dehydration London, Special Publications 30 (1), 1–13. Benard,A.,Ionov,D.A.,2013.Melt- and fluid-rock interaction in supra-subduction Melt lithospheric mantle: evidence from andesite-hosted veined peridotite xenoliths. Asthenosphere Journal of Petrology 54 (11), 2339–2378. Carbonate Beyer, E.E., 2006. Transformation of Archaean lithospheric mantle by refertilization: sediment evidence from exposed peridotites in the Western Gneiss Region, Norway. Journal of Petrology 47 (8), 1611–1636. Blundy, J., Dalton, J., 2000. Experimental comparison of trace element partitioning between clinopyroxene and melt in carbonate and silicate systems, and implications for mantle metasomatism. Contributions to Mineralogy and Petrology 139 (3), 356–371. Bodinier, J.L., Guiraud, M., Fabries, J., Dostal, J., Dupuy, C., 1987. Petrogenesis of layered (b) Later-stage metasomatism pyroxenites from the Lherz, Freychinede and Prades ultramafic bodies (Ariege, – Paleo-Asian Ocean North China Craton French Pyrenees). Geochimica et Cosmochimica Acta 51 (2), 279 290. Brey,G.P.,Köhler,T.,1990.Geothermobarometry in four-phase lherzolites II. New Oceanic crust thermobarometers, and practical assessment of existing thermobarometers. Journal Continental crust of Petrology 31 (6), 1353–1378. Brey, G., Brice, W.R., Ellis, D.J., Green, D.H., Harris, K.L., Ryabchikov, I.D., 1983. Pyroxene- carbonate reactions in the upper mantle. Earth and Planetary Science Letters 62 Oceanic lithosphere Continental lithosphere (1), 63–74. Carlson, R.W., Irving, A.J., Schulze, D.J., Hearn Jr., B.C., 2004. Timing of Precambrian melt depletion and Phanerozoic refertilization events in the lithospheric mantle of the Wyoming Craton and adjacent Central Plains Orogen. Lithos 77 (1–4), 453–472. Carpenter, L.R., Edgar, D.A., Thibault, Y., 2002. Origin of spongy textures in clinopyroxene and spinel from mantle xenoliths, Hessian Depression, Germany. Mineralogy and Asthenosphere – C Petrology 74 (2), 149 162. arbonated ec Melt Castillo, P.R., 2015. The recycling of marine carbonates and sources of HIMU and FOZO ocean island basalts. Lithos 216-217, 254–263. Chapman, J.B., Ducea, M.N., Kapp, P., Gehrels, G.E., DeCelles, P.G., 2017. Spatial and temporal radiogenic isotopic trends of magmatism in Cordilleran Orogens. Gondwana Research 48, 189–204. Chen, L.H., Zhou, X.H., 2005. Subduction-related metasomatism in the thinning litho- lo sphere: evidence from a composite dunite-orthopyroxenite xenolith entrained in g i te Mesozoic Laiwu high-Mg diorite, North China Craton. Geochemistry, Geophysics, Geosystems 6 (6), 453–468. Chen, Y., Wu, T.R., Xu, X., Zhang, S.T., 2005. Discovery of mantle xenoliths bearing Miocene potassium-rich olivine basalt and its significance in Siziwangqi area, inner Mongolia. Fig. 9. Schematic illustration of the two-stage mantle metasomatism by the PAOP Geological Journal of China Universities 10 (4), 586–593. 87 86 subduction-related melt beneath the NCC. (a) Formation of the high Sr/ Sr ratio of Chen, C.F., Liu, Y.S., Foley, S.F., Ducea, M.N., He, D.T., Hu, Z.C., Chen, W., Zong, K.Q., 2016. 87 86 Cpx cores in the Type 1 peridotites. (b) Formation of the moderate Sr/ Sr ratio of Cpx Paleo-Asian oceanic slab under the North China craton revealed by carbonatites spongy rims in peridotites and Cpx in pyroxenites. derived from subducted limestones. Geology 44 (12), 1039–1042. Chen, C.F., Liu, Y.S., Foley, S.F., Ducea, M.N., Geng, X.L., Zhang, W., Xu, R., Hu, Z.C., Zhou, L., Wang, Z.C., 2017. Carbonated sediment recycling and its contribution to lithospheric metasomatic agent, recorded by both types of peridotites and pyroxe- refertilization under the northern North China Craton. Chemical Geology 466, 87 86 – nites, was a CO2-rich silicate melt with less elevated Sr/ Sr ratios 641 653. (0.7041–0.7059), possibly derived from carbonated eclogites (residual Christensen, J.N., Halliday, A.N., Lee, D.C., Hall, C.M., 1995. In situ Sr isotopic analysis by laser ablation. Earth and Planetary Science Letters 136 (1), 79–85. subducted slab) at a later stage of slab subduction. Type 1 pyroxenites Coltorti, M., Bonadiman, C., Hinton, R.W., Siena, F., Upton, B.G.J., 1999. Carbonatite metaso- and Type 2 pyroxenites could originate from interaction between matism of the oceanic upper mantle: evidence from clinopyroxenes and glasses in ultra- fi – silicate melt and Type 2 peridotites and Type 1 peridotites, respectively. ma c xenoliths of Grande Comore, Indian Ocean. Journal of Petrology 40 (1), 133 165. Cope, T., Ritts, B.D., Darby, B.J., Fildani, A., Graham, S.A., 2005. Late Paleozoic sedimentation Considering the regional tectonic setting, we tentatively propose that the on the Northern margin of the North China Block: implications for regional tectonics mantle xenoliths from the Dongbahao basalts were genetically related to and climate change. International Geology Review 47 (3), 270–296. the southward subduction of the Paleo-Asian ocean beneath the NCC. The Dalton, J.A., Wood, B.J., 1993. The partitioning of Fe and Mg between olivine and carbonate fi and the stability of carbonate under mantle conditions. Contributions to Mineralogy extensive modi cation of the lithospheric mantle beneath the northern and Petrology 114 (4), 501–509. NCC, as triggered by the Paleo-Asian Ocean subduction, could have lasted Dantas, C., Grégoire, M., Koester, E., Conceição, R.V., Rieck, N., 2009. The lherzolite– from the early Paleozoic to the early Cenozoic. Such modification led to a websterite xenolith suite from Northern Patagonia (Argentina): evidence of mantle–melt reaction processes. Lithos 107 (1), 107–120. highly heterogeneous lithospheric mantle. Petrographically, the mantle Davide, N., Shantanu, K., Gudfinnsson, G.H., Shaunak, G., 2014. Melting phase relations of underwent enrichment in pyroxenes and resulted in local development model carbonated peridotite from 2 to 3 GPa in the system CaO-MgO-Al2O3-SiO2-CO2 of pyroxenites. Geochemically, the lithospheric mantle changed from and further indication of possible unmixing between carbonatite and silicate liquids. Journal of Geophysical Research Solid Earth 119 (4), 2780–2800. being refractory and depleted (high Mg# and LREE depletions) to fertile Davis, G.A., Zheng, Y.D., Wang, C., Darby, B.J., Zhang, C.H., Gehrels, G., 2001. Mesozoic and enriched (low Mg# and LREE enrichments), and from low (down tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and to 0.7020) to high (up to 0.7082) 87Sr/86Sr ratios in isotopic compositions. Liaoning provinces, northern China. Memoir - Geological Society of America 171–198. Supplementary data to this article can be found online at http://dx. Fan, W.M., Menzies, M.A., 1992. Destruction of aged lower lithosphere and accretion of asthenosphere mantle beneath eastern China. Geotectonica et Metallogenia 16 (3–4), doi.org/10.1016/j.lithos.2017.07.018. 171–180. Fan, Q.C., Sui, J.L., Liu, R.X., Zhou, X.M., 2001. Eclogite facies garnet-pyroxenolite xenolith Acknowledgments in Hannuoba area: new evidence of magma underplating. Acta Petrologica Sinica 17 (1), 1–6. Frey, F.A., Green, D.H., 1974. The mineralogy, geochemistry and origin of Iherzolite This research is co-supported by the 973 project of the Ministry of inclusions in Victorian basanites. Geochimica et Cosmochimica Acta 38 (7), Science and Technology of China (2013CB429806), NSFC (41530211, 1023–1059. Gao, S., Rudnick, R.L., Carlson, R.W., McDonough, W.F., Liu, Y.S., 2002. Re–Os evidence for 41125013), the State Administration of Foreign Expert Affairs of China replacement of ancient mantle lithosphere beneath the North China craton. Earth and (B07039), MOST Special Funds of the State Key Laboratory of Geological Planetary Science Letters 198 (3), 307–322. 350 D. Wu et al. / Lithos 288–289 (2017) 338–351

Gao, S., Rudnick, R.L., Yuan, H.L., Liu, X.M., Liu, Y.S., Xu, W.L., Ling, W.L., Ayers, J., Wang, Liu, Y.S., He, D.T., Gao, C.G., Foley, S., Gao, S., Hu, Z.C., Zong, K.Q., Chen, H.H., 2015b. First X.C., Wang, Q.H., 2004. Recycling lower continental crust in the North China craton. direct evidence of sedimentary carbonate recycling in subduction-related xenoliths. Nature 432 (7019), 892–897. Scientific Reports 5, 11547. Gao, S., Rudnick, R.L., Xu, W.L., Yuan, H.L., Liu, Y.S., Walker, R.J., Puchtel, I.S., Liu, X.M., McDonough, W.F., Sun, S.-S., 1995. The composition of the Earth. Chemical Geology 120 Huang, H., Wang, X.R., Yang, J., 2008. Recycling deep cratonic lithosphere and gener- (3), 223–253. ation of intraplate magmatism in the North China Craton. Earth and Planetary Science Meng, Q.R., Zhang, G.W., 2000. Geologic framework and tectonic evolution of the Qinling Letters 270 (1–2), 41–53. orogen, central China. Tectonophysics 323 (3), 183–196. Green, D.H., Wallace, M.E., 1988. Mantle metasomatism by ephemeral carbonatite melts. Menzies, M.A., Fan, W.M., Zhang, M., 1993. Palaeozoic and Cenozoic lithoprobes and Nature 336 (6198), 459–462. the loss of N120 km of Archaean lithosphere, Sino-Korean craton, China. Geological Green, T.H., Blundy, J.D., Adam, J., Yaxley, G.M., 2000. SIMS determination of trace element Society, London, Special Publications 76 (1), 71–81. partition coefficients between garnet, clinopyroxene and hydrous basaltic liquids at Mourão, C., Mata, J., Doucelance, R., Madeira, J., Silveira, A.B.d., Silva, L.C. and Moreira, M., 2–7.5 GPa and 1080–1200 °C. Lithos 53 (3), 165–187. 2010. Quaternary extrusive calciocarbonatite volcanism on Brava Island (Cape Gregoire, M., Jego, S., Maury, R.C., Polve, M., Payot, B., Tamayo, R.A., Yumul, G.P., 2008. Verde): a nephelinite-carbonatite immiscibility product. Journal of African Earth Metasomatic interactions between slab-derived melts and depleted mantle: insights Sciences 56 (2–3), 59–74. from xenoliths within Monglo adakite (Luzon arc, Philippines). Lithos 103 (3–4), Nelson, S.T., Montana, A., 1992. Sieve-textured plagioclase in volcanic rocks produced by 415–430. rapid decompression. American Mineralogist 77, 1242–1249. Griffin, W.L., Andi, Z., O'reilly, S.Y., Ryan, C.G., 1998. Phanerozoic evolution of the litho- Nelson, D.R., Chivas, A.R., Chappell, B.W., Mcculloch, M.T., 1988. Geochemical and isotopic sphere beneath the Sino-Korean craton. Mantle Dynamics and Plate Interactions in systematics in carbonatites and implications for the evolution of ocean-island East Asia, pp. 107–126. sources. Geochimica et Cosmochimica Acta 52 (1), 1–17. Griffin, W.L., Ryan, C.G., Kaminsky, F.V., O'Reilly, S.Y., Natapov, L.M., Win, T.T., Kinny, P.D., Norman, M.D., 1998. Melting and metasomatism in the continental lithosphere: laser Ilupin, I.P., 1999. The Siberian lithosphere traverse: mantle terranes and the assembly ablation ICPMS analysis of minerals in spinel lherzolites from eastern Australia. of the Siberian Craton. Tectonophysics 310, 1–35. Contributions to Mineralogy and Petrology 130 (3–4), 240–255. Hammouda, T., 2003. High-pressure melting of carbonated eclogite and experimental Pearson, D.G., 1999. The age of continental roots. Lithos 48, 171–194. constraints on carbon recycling and storage in the mantle. Earth and Planetary Science Pearson, D.G., Canil, D., Shirey, S.B., 2014. Mantle samples included in volcanic rocks: Letters 214 (1–2), 357–368. xenoliths and diamonds. Treatise on Geochemistry 169–253. Hart, S.R., Dunn, T., 1993. Experimental cpx/melt partitioning of 24 trace elements. Ramos, F.C., Wolff, J.A., Tollstrup, D.L., 2004. Measuring 87Sr/86Sr variations in minerals Contributions to Mineralogy and Petrology 113 (1), 1–8. and groundmass from basalts using LA-MC-ICP-MS. Chemical Geology 211 (1–2), Hellebrand, E., Snow, J.E., Dick, H.J.B., Hofmann, A.W., 2001. Coupled major and trace 135–158. elements as indicators of the extent of melting in mid-ocean-ridge peridotites. Nature Rapp, R.P., Shimizu, N., Norman, M.D., Applegate, G.S., 1999. Reaction between 410 (6829), 677–681. slab-derived melts and peridotite in the mantle wedge: experimental constraints at Hu, Z.C., Gao, S., Liu, Y., Hu, S., Chen, H., Yuan, H., 2008. Signal enhancement in laser abla- 3.8GPa.ChemicalGeology160(4),335–356. tion ICP-MS by addition of nitrogen in the central channel gas. Journal of Analytical Rudnick, R.L., McDonough, W.F., Chappell, B.W., 1993. Carbonatite metasomatism in the Atomic Spectrometry 23 (8), 1093. northern Tanzanian mantle: petrographic and geochemical characteristics. Earth Hu, Z.C., Liu, Y.S., Gao, S., Liu, W.G., Zhang, W., Tong, X.R., Lin, L., Zong, K.Q., Li, M., Chen, and Planetary Science Letters 114 (4), 463–475. H.H., 2012. Improved in situ Hf isotope ratio analysis of zircon using newly designed Salters, V.J.M., Stracke, A., 2004. Composition of the depleted mantle. Geochemistry, Geo- X skimmer cone and jet sample cone in combination with the addition of nitrogen by physics, Geosystems 5 (5), 469–484. laser ablation multiple collector ICP-MS. Journal of Analytical Atomic Spectrometry Schmidberger, S.S., Simonetti, A., Francis, D., 2003. Small-scale Sr isotope investigation of 27 (9), 1391–1399. clinopyroxenes from peridotite xenoliths by laser ablation MC-ICP-MS—implications Hughes, H.S.R., McDonald, I., Goodenough, K.M., Ciborowski, T.J.R., Kerr, A.C., Davies, for mantle metasomatism. Chemical Geology 199 (3–4), 317–329. J.H.F.L., Selby, D., 2014. Enriched lithospheric mantle keel below the Scottish margin Shaw, C.S.J., Heidelbach, F., Dingwell, D.B., 2006. The origin of reaction textures in mantle of the North Atlantic Craton: evidence from the Palaeoproterozoic Scourie Dyke peridotite xenoliths from Sal Island, Cape Verde: the case for “metasomatism” by the Swarm and mantle xenoliths. Precambrian Research 250, 97–126. host lava. Contributions to Mineralogy and Petrology 151 (6), 681–697. Ionov, D.A., Dupuy, C., O'Reilly, S.Y., Kopylova, M.G., Genshaft, Y.S., 1993. Carbonated Sneeringer, M., Hart, S.R., Shimizu, N., 1984. Strontium and samarium diffusion in diop- peridotite xenoliths from Spitsbergen: implications for trace element signature of side. Geochimica et Cosmochimica Acta 48, 1589–1608. mantle carbonate metasomatism. Earth and Planetary Science Letters 119 (3), Sobolev, A.V., Hofmann, A.W., Kuzmin, D.V., Yaxley, G.M., Arndt, N.T., Chung, S.L., 283–297. Danyushevsky, L.V., Elliott, T., Frey, F.A., Garcia, M.O., 2007. The amount of recycled Ionov, D.A., Griffin, W.L., O'Reilly, S.Y., 1997. Volatile-bearing minerals and lithophile trace crust in sources of mantle-derived melts. Science 316 (5823), 412–417. elements in the upper mantle. Chemical Geology 141 (3), 153–184. Song, Y., Frey, F.A., Zhi, X., 1990. Isotopic characteristics of Hannuoba basalts, eastern Kelemen, P.B., Hart, S.R., Bernstein, S., 1998. Silica enrichment in the continental China: implications for their petrogenesis and the composition of subcontinental upper mantle via melt/rock reaction. Earth and Planetary Science Letters 164 (1), mantle. Chemical Geology 88 (1–2), 35–52. 387–406. Soustelle, V., Tommasi, A., Demouchy, S., Ionov, D.A., 2010. Deformation and fluid-rock Kessel, R., Schmidt, M.W., Ulmer, P., Pettke, T., 2005. Trace element signature of interaction in the supra-subduction mantle: microstructures and water contents in subduction-zone fluids, melts and supercritical liquids at 120–180 km depth. Nature peridotite xenoliths from the Avacha Volcano, Kamchatka. Journal of Petrology 51 437 (7059), 724–727. (1–2), 363–394. Kogiso, T., Tatsumi, Y., Nakano, S., 1997. Trace element transport during dehydration Stalder, R., Foley, S.F., Brey, G.P., Horn, I., 1998. Mineral-aqueous fluid partitioning of trace processes in the subducted oceanic crust: 1. Experiments and implications for the origin elements at 900–1200 C and 3.0–5.7 GPa: new experimental data for garnet, of ocean island basalts. Earth and Planetary Science Letters 148 (1), 193–205. clinopyroxene, and rutile, and implications for mantle metasomatism. Geochimica Lin, J., Liu, Y.S., Yang, Y.H., Hu, Z.C., 2016. Calibration and correction of LA-ICP-MS and et Cosmochimica Acta 62 (10), 1781–1801. LA-MC-ICP-MS analyses for element contents and isotopic ratios. Solid Earth Sciences Staudigel, H., Davies, G.R., Hart, S.R., Marchant, K.M., Smith, B.M., 1995. Large scale isotopic 1(1),5–27. Sr, Nd and O isotopic anatomy of altered oceanic crust: DSDP/ODP sites 417/418. Liu, D.Y., Nutman, A.P., Compston, W., Wu, J.S., Shen, Q.H., 1992. Remnants of ≥3800 Ma Earth and Planetary Science Letters 130 (1), 169–185. crust in the Chinese part of the Sino-Korean craton. Geology 20 (4), 339–342. Sun, W.D., Ding, X., Hu, Y.H., Li, X.H., 2007. The golden transformation of the Cretaceous Liu, Y.S., Gao, S., Lee, C.-T.A., Hu, S.H., Liu, X.M., Yuan, H.L., 2005. Melt–peridotite interac- plate subduction in the west Pacific. Earth and Planetary Science Letters 262 (3–4), tions: links between garnet pyroxenite and high-Mg# signature of continental crust. 533–542. Earth and Planetary Science Letters 234 (1–2), 39–57. Sun, J., Liu, C.Z., Wu, F.Y., Yang, Y.H., Chu, Z.Y., 2012. Metasomatic origin of clinopyroxene Liu, Y.S., Hu, Z.C., Yuan, H.L., Hu, S.H., Cheng, H.H., 2007. Volume-optional and low- in Archean mantle xenoliths from Hebi, North China Craton: trace-element and memory (VOLM) chamber for laser ablation-ICP-MS: application to fiber analyses. Sr-isotope constraints. Chemical Geology 328, 123–136. Journal of Analytical Atomic Spectrometry 22 (5), 582–585. Takazawa, E., Frey, F.A., Shimizu, N., Obata, M., 2000. Whole rock compositional variations Liu, Y.S., Gao, S., Kelemen, P.B., Xu, W., 2008a. Recycled crust controls contrasting source in an upper mantle peridotite (Horoman, Hokkaido, Japan): are they consistent with compositions of Mesozoic and Cenozoic basalts in the North China Craton. a partial melting process? Geochimica et Cosmochimica Acta 64 (4), 695–716. Geochimica et Cosmochimica Acta 72 (9), 2349–2376. Tang, Y.J., Zhang, H.F., Ying, J.F., 2006. Asthenosphere–lithospheric mantle interac- Liu, Y.S., Hu, Z.C., Gao, S., Gunther, D., Xu, J., Gao, C.G., Chen, H.H., 2008b. In situ analysis of tion in an extensional regime: implication from the geochemistry of Cenozoic major and trace elements of anhydrous minerals by LA-ICP-MS without applying an basalts from Taihang Mountains, North China Craton. Chemical Geology 233 internal standard. Chemical Geology 257 (1–2), 34–43. (3–4), 309–327. Liu, Y.S., Gao, S., Hu, Z.C., Gao, C.G., Zong, K.Q., Wang, D.B., 2010. Continental and oceanic Tang, Y.J., Zhang, H.F., Nakamura, E., Moriguti, T., Kobayashi, K., Ying, J.F., 2007. Lithium crust recycling-induced melt-peridotite interactions in the trans-North China isotopic systematics of peridotite xenoliths from Hannuoba, North China Craton: Orogen: U-Pb dating, Hf isotopes and trace elements in zircons from mantle xeno- implications for melt–rock interaction in the considerably thinned lithospheric man- liths. Journal of Petrology 51 (1–2), 537–571. tle. Geochimica et Cosmochimica Acta 71 (17), 4327–4341. Liu, J.G., Rudnick, R.L., Walker, R.J., Gao, S., Wu, F.y., Piccoli, P.M., Yuan, H.L., Xu, W.L., Xu, Tang, Y.J., Zhang, H.F., Ying, J.F., Zhang, J., Liu, X.M., 2008. Refertilization of ancient litho- Y.G., 2011. Mapping lithospheric boundaries using Os isotopes of mantle xenoliths: spheric mantle beneath the central North China Craton: evidence from petrology an example from the North China Craton. Geochimica et Cosmochimica Acta 75 and geochemistry of peridotite xenoliths. Lithos 101 (3–4), 435–452. (13), 3881–3902. Tatsumi, Y., 1986. Formation of the volcanic front in subduction zones. Geophysical Liu, J., Xia, Q.K., Deloule, E., Ingrin, J., Chen, H., Feng, M., 2015a. Water content and oxygen Research Letters 13 (8), 717–720. isotopic composition of alkali basalts from the Taihang Mountains, China: Taylor, S.R., McLennan, S.M., 1985. The Continental Crust: Its Composition and Evolution. recycled oceanic components in the mantle source. Journal of Petrology 56 (4), Tong, X.R., Liu, Y.S., Hu, Z.C., Chen, H.H., Zhou, L., Hu, Q.H., Xu, R., Deng, L.X., Chen, C.F., 681–702. Yang, L., Gao, S., 2016. Accurate determination of Sr isotopic compositions in D. Wu et al. / Lithos 288–289 (2017) 338–351 351

clinopyroxene and silicate glasses by LA-MC-ICP-MS. Geostandards and Geoanalytical into Pacific slab subduction-related mantle modification. Chemical Geology 354, Research 40 (1), 85–99. 107–123. Veizer, J., Mackenzie, F.T., 2003. Evolution of sedimentary rocks. Treatise on Geochemistry Xu, R., Liu, Y., Wang, X., Zong, K., Hu, Z., Chen, H., Zhou, L., 2017. Crust recycling induced 7, 369–407. compositional-temporal-spatial variations of Cenozoic basalts in the Trans-North Veizer, J., Ala, D., Azmy, K., Bruckschen, P., Buhl, D., Bruhn, F., Carden, G.A.F., Diener, A., China Orogen. Lithos 274-275, 383–396. Ebneth, S., Godderis, Y., Jasper, T., Korte, C., Pawellek, F., Podlaha, O.G., Strauss, H., Yaxley, G.M., Green, D.H., Kamenetsky, V., 1998. Carbonatite metasomatism in the south- 1999. 87Sr/86Sr, δ13Candδ18O evolution of Phanerozoic seawater. Chemical Geology eastern Australian lithosphere. Journal of Petrology 39 (11–12), 1917–1930. 161 (1–3), 59–88. Yogodzinski, G.M., Kelemen, P.B., 2007. Trace elements in clinopyroxenes from Aleutian Waight, T., Baker, J., Peate, D., 2002. Sr isotope ratio measurements by double-focusing xenoliths: implications for primitive subduction magmatism in an island arc. Earth MC-ICPMS: techniques, observations and pitfalls. International Journal of Mass Spec- and Planetary Science Letters 256 (3–4), 617–632. trometry 221 (3), 229–244. Yu, S.Y., Xu, Y.G., Ma, J.L., Zheng, Y.F., Kuang, Y.S., Hong, L.B., Ge, W.C., Tong, L.X., 2010. Wang, C.Y., Liu, Y.S., Min, N., Zong, K.Q., Hu, Z.C., Gao, S., 2016. Paleo-Asian oceanic Remnants of oceanic lower crust in the subcontinental lithospheric mantle: trace el- subduction-related modification of the lithospheric mantle under the North China ement and Sr–Nd–O isotope evidence from aluminous garnet pyroxenite xenoliths Craton: evidence from peridotite xenoliths in the Datong basalts. Lithos 261, from Jiaohe, Northeast China. Earth and Planetary Science Letters 297 (3–4), 109–127. 413 –422. Wilde, S.A., Zhao, G.C., Sun, M., 2002. Development of the North China Craton during the Zangana, N.A., Downes, H., Thirlwall, M.F., Marriner, G.F., Bea, F., 1999. Geochemical vari- late Archaean and its final amalgamation at 1.8 Ga: some speculations on its position ation in peridotite xenoliths and their constituent clinopyroxenes from Ray Pic within a global Palaeoproterozoic supercontinent. Gondwana Research 5 (1), 85–94. (French Massif Central): implications for the composition of the shallow lithospheric Windley, B.F., Alexeiev, D., Xiao, W., Kroner, A., Badarch, G., 2007. Tectonic models for ac- mantle. Chemical Geology 153, 11–35. cretion of the Central Asian Orogenic Belt. Journal of the Geological Society 164 (1), Zhang, H.F., Sun, M., Zhou, X.H., Fan, W.M., Zhai, M.G., Yin, J.F., 2002. Mesozoic lithosphere 31–47. destruction beneath the North China Craton: evidence from major-, trace-element Wu, F.Y., Lin, J.Q., Wilde, S.A., Zhang, X.O., Yang, J.H., 2005. Nature and significance of the and Sr–Nd–Pb isotope studies of Fangcheng basalts. Contributions to Mineralogy Early Cretaceous giant igneous event in eastern China. Earth and Planetary Science and Petrology 144 (2), 241–254. Letters 233 (1–2), 103–119. Zhang, H.F., Sun, M., Zhou, X.H., Zhou, M.F., Fan, W.M., Zheng, J.P., 2003. Secular evolution Wulff-Pedersen, E., Neumann, E.R., Jensen, B.B., 1996. The upper mantle under La Palma, of the lithosphere beneath the eastern North China Craton: evidence from Mesozoic Canary Islands: formation of Si− K− Na-rich melt and its importance as a metaso- basalts and high-Mg andesites. Geochimica et Cosmochimica Acta 67 (22), matic agent. Contributions to Mineralogy and Petrology 125 (2–3), 113–139. 4373–4387. Wyllie, P.J., Huang, W.L., Otto, J., Byrnes, A.P., 1983. Carbonation of peridotites and Zhang, S.H., Zhao, Y., Song, B., Yang, Z.Y., Hu, J.M., Wu, H., 2007. Carboniferous granitic plu-

decarbonatiou of siliceous dolomites represented in the system CaO-MgO-SiO2-CO2, tons from the northern margin of the North China block: implications for a late to 30 kbar. Tectonophysics 100, 359–388. Palaeozoic active continental margin. Journal of the Geological Society 164 (2), Xiao, W.J., Windley, B.F., Sun, S., Li, J.L., Huang, B.C., Han, C.M., Yuan, C., Sun, M., Chen, H.L., 451–463. 2015. A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: Zhang, S.H., Zhao, Y., Kröner, A., Liu, X.M., Xie, L.W., Chen, F.K., 2008. Early Permian plu- oroclines, sutures, and terminal accretion. Annual Review of Earth and Planetary Sci- tons from the northern North China Block: constraints on continental arc evolution ences 43 (1), 477–507. and convergent margin magmatism related to the Central Asian Orogenic Belt. Inter- Xu, Y.G., 2001. Thermo-tectonic destruction of the Archaean lithospheric keel beneath the national Journal of Earth Sciences 98 (6), 1441–1467. Sino-Korean Craton in China: evidence, timing and mechanism. Physics and Chemis- Zhang, H.F., Goldstein, S.L., Zhou, X.H., Sun, M., Cai, Y., 2009a. Comprehensive try of the Earth, Part A: Solid Earth and Geodesy 26 (9), 747–757. refertilization of lithospheric mantle beneath the North China Craton: further Os- Xu, Y.G., 2002. Evidence for crustal components in the mantle and constraints on crustal Sr-Nd isotopic constraints. Journal of the Geological Society 166 (2), 249–259. recycling mechanisms: pyroxenite xenoliths from Hannuoba, North China. Chemical Zhang, S.H., Zhao, Y., Liu, X.C., Liu, D.Y., Chen, F.K., Xie, L.W., Chen, H.H., 2009b. Late Paleo- Geology 182 (2), 301–322. zoic to Early Mesozoic mafic–ultramafic complexes from the northern North China Xu, B., Chen, B., 1997. Framework and evolution of the middle Paleozoic orogenic belt be- Block: constraints on the composition and evolution of the lithospheric mantle. Lithos tween Siberian and North China Plates in northern Inner Mongolia. Science in China 110 (1–4), 229–246. Series D: Earth Sciences 40 (5), 463–469. Zhang, H.F., Sun, Y.L., Tang, Y.J., Xiao, Y., Zhang, W.H., Zhao, X.M., Santosh, M., Menzies, Xu, Y.G., Menzies, M.A., Vroon, P., Mercier, J.C., Lin, C.Y., 1998. Texture–temperature– M.A., 2012. Melt-peridotite interaction in the pre-Cambrian mantle beneath the geochemistry relationships in the upper mantle as revealed from spinel peridotite xe- western North China Craton: petrology, geochemistry and Sr, Nd and Re isotopes. noliths from Wangqing, NE China. Journal of Petrology 39 (3), 469–493. Lithos 149, 100–114. Xu, Y.G., Menzies, M.A., Thirlwall, M.F., Huang, X.L., Liu, Y., Chen, X.M., 2003. “Reactive” Zhang, H.T., Liu, Y.S., Hu, Z.C., Zong, K.Q., Chen, H.H., Chen, C.F., 2017. Low-δ13Ccarbonates harzburgites from Huinan, NE China: products of the lithosphere-asthenosphere in- in the Miocene basalt of the northern margin of the North China Craton: implications teraction during lithospheric thinning? Geochimica et Cosmochimica Acta 67 (3), for deep carbon recycling. Journal of Asian Earth Sciences 144, 110–125. 487–505. Zhao, G.C., Wilde, S.A., Cawood, P.A., Sun, M., 2001. Archean blocks and their boundaries Xu, W.L., Hergt, J.M., Gao, S., Pei, F.P., Wang, W., Yang, D.B., 2008. Interaction of adakitic in the North China Craton: lithological, geochemical, structural and P–T path con- melt-peridotite: implications for the high-Mg# signature of Mesozoic adakitic rocks straints and tectonic evolution. Precambrian Research 107 (1), 45–73. in the eastern North China Craton. Earth and Planetary Science Letters 265 (1), Zheng, J.P., O'Reilly, S.Y., Griffin, W.L., Zhang, M., Lu, F.X., Liu, G.L., 2004. Nature and evolu- 123–137. tion of Mesozoic–Cenozoic lithospheric mantle beneath the Cathaysia block, SE Xu, B., Charvet, J., Chen, Y., Zhao, P., Shi, G., 2013a. Middle Paleozoic convergent orogenic China. Lithos 74 (1–2), 41–65. belts in western Inner Mongolia (China): framework, kinematics, geochronology and Zheng, J.P., Griffin, W.L., O'Reilly, S.Y., Yu, C.M., Zhang, H.F., Pearson, N., Zhang, M., 2007. implications for tectonic evolution of the Central Asian Orogenic Belt. Gondwana Re- Mechanism and timing of lithospheric modification and replacement beneath the search 23 (4), 1342–1364. eastern North China Craton: Peridotitic xenoliths from the 100 Ma Fuxin basalts Xu, R., Liu, Y.S., Tong, X.R., Hu, Z.C., Zong, K.Q., Gao, S., 2013b. In-situ trace elements and Li and a regional synthesis. Geochimica et Cosmochimica Acta 71 (21), 5203–5225. and Sr isotopes in peridotite xenoliths from Kuandian, North China Craton: insights