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Article

Petrogenesis of Transitional Kimberlite: A Case Study of the Hypabyssal Wafangdian Kimberlite in the North China Craton

by
Renzhi Zhu
1,*,
Pei Ni
2,*,
Yan Li
3 and
Fanglai Wan
4,5
1
Deep Space Exploration Laboratory, Hefei 230088, China
2
State Key Laboratory for Mineral Deposit Research, Institute of Geo-Fluids, School of Earth Science and Engineering, Nanjing University, Nanjing 210023, China
3
Research Center for Petrogenesis and Mineralization of Granitoid Rocks, China Geological Survey, Wuhan 430205, China
4
School of Geosciences and Info-Physics, Central South University, Changsha 410083, China
5
Xu Hongbin Innovation Studio of Liaoning Province, Liaoning Sixth Geological Brigade Co., Ltd., Dalian 116200, China
*
Authors to whom correspondence should be addressed.
Minerals 2025, 15(10), 1009; https://doi.org/10.3390/min15101009
Submission received: 17 August 2025 / Revised: 16 September 2025 / Accepted: 22 September 2025 / Published: 24 September 2025
(This article belongs to the Special Issue Formation Study of Gem Deposits)
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Abstract

Kimberlite has attracted considerable interest among geologists as the primary source of natural gem-quality diamonds. The term “transitional kimberlite” was previously introduced to categorize rocks that exhibit bulk geochemical and Sr–Nd isotopic characteristics intermediate between those of archetypal kimberlite (formerly Group-I) and orangeite (formerly Group-II). Nevertheless, the petrogenesis of transitional diamond-bearing kimberlites remains poorly understood due to limited research. The diamondiferous transitional Wafangdian kimberlite in the North China Craton (NCC) thus provides a valuable opportunity for a detailed case study. We investigated fresh hypabyssal transitional Wafangdian kimberlites using bulk-rock major and trace element geochemistry to constrain near-primary parental magma compositions and decipher their petrogenesis. Geochemical compositions identify samples affected by crustal contamination based on elevated SiO2, Pb, heavy rare earth element (HREE) concentrations, and Sr isotopic ratios. Compositional variations among macrocrystic samples (MgO: 29.7–31.5 wt.%; SiO2: 30.6–34.7 wt.%; CaO: 3.9–7.5 wt.%; Mg# [atomic Mg/(Mg + Fe2+) × 100]: 85–88) result from substantial entrainment and partial assimilation of peridotite xenoliths (up to 35%). In contrast, variations within aphanitic samples (MgO: 24.0–29.7 wt.%; SiO2: 27.7–30.9 wt.%; CaO: 6.0–11.8 wt.%; Mg#: 81–85) are attributed to fractional crystallization of olivine and phlogopite (~1–32%). Based on these constraints, the near-primary parental magma composition for the Wafangdian kimberlite is estimated as ~29.7 wt.% SiO2, ~29.7 wt.% MgO, and Mg# 85. Trace element concentrations in the transitional Wafangdian kimberlites resemble those of archetypal kimberlites globally (e.g., Nb/U > 26, La/Nb < 1.4, Ba/Nb < 16, Th/Nb < 0.25), indicating a shared convective mantle source. However, the Wafangdian kimberlites exhibit distinct characteristics: εNd(t) values ranging from −3.44 to −1.77, higher Al2O3 and K2O contents, and lower Ce/Pb ratios (10–20) compared to archetypal kimberlites. These features suggest the mantle source region was profoundly influenced by deeply subducted oceanic material.

1. Introduction

Kimberlites are ultramafic, alkaline, silica-poor, volatile-rich volcanic rocks. Although they represent only a small volume of mantle-derived melts, they are highly significant as the primary source of natural diamonds and serve as important geochemical probes into the Earth’s mantle [1]. They originate from the Earth’s deepest known mantle sources (>150–250 km; [2]). During ascent, kimberlite magmas entrain diverse peridotite xenoliths, disaggregated xenocrysts, and diamonds [3], providing unique insights into lithospheric mantle composition and evolution [4,5]. Assimilation of these mantle fragments modifies primary magma compositions [6,7]. Simultaneously, fractional crystallization of olivine, phlogopite, and other minerals further alters melt chemistry [8]. Upon reaching shallow crustal levels, kimberlite magmas entrain and assimilate wall rocks while undergoing volatile (H2O-CO2) degassing [2,9], processes that significantly modify the melt composition [10,11,12,13]. Finally, after emplacement, deuteric alteration by residual fluids [1] and meteoric water infiltration [10,14,15] drive serpentinization and carbonation. Consequently, estimating primary kimberlite melt compositions faces substantial uncertainty.
These complex modifications during kimberlite ascent and emplacement significantly hinder our understanding of the nature and petrogenesis of parental melts. To reconstruct primary kimberlitic melt compositions, researchers have employed several approaches: (1) whole-rock analysis of aphanitic kimberlite [16] or groundmass [13]; (2) subtraction of xenocrystic components from whole-rock compositions [11,17]; (3) chemical variation trajectories between macrocrystic and aphanitic kimberlite [8]; (4) modal analysis with mineral chemistry determination [18]; and (5) analysis of melt inclusions hosted in kimberlite minerals [19]. Due to persistent uncertainties in evaluating primary melt composition, proposed models describe the kimberlite melt as ultramafic silicate melts [16]; carbonatitic melt [9]; and/or transitional silicate-carbonatite melt [17,18]. Furthermore, the source region(s) for kimberlite generation remain debated, with proposed origins including the sub-continental lithospheric mantle (SCLM) [8,12], asthenosphere mantle [13], and transition zone or lower mantle [20]. Similarly, the geodynamic triggers are controversial, invoking mantle plumes [8]; subduction of oceanic crust [21,22]; or tectonothermal events linked to supercontinent breakup [23,24].
Kimberlites have traditionally been classified into two broad varieties based on petrography and geochemistry [25]: archetypal kimberlite (formerly Group-I) and orangeite (formerly Group-II). Archetypal kimberlites are olivine phenocryst-rich, exhibit low K2O/Na2O ratios (3.3–6.2), and possess slightly less radiogenic Sr and more radiogenic Nd in their isotope composition compared to present-day Bulk Earth, resembling ocean island basalts (OIBs) (87Sr/86Sr(t) = 0.7033–0.7055 and 143Nd/146Nd = 0.51251–0.51277). In contrast, orangeites are more micaceous, have high K2O/Na2O ratios (17–22), and feature more radiogenic Sr and less radiogenic Nd in their isotope composition than Bulk Earth (87Sr/86Sr(t) = 0.7074–0.7125 and 143Nd/146Nd = 0.51208–0.51228) [26]. However, newly identified kimberlites, including the Wafangdian (Fuxian) kimberlites in China [27,28], Majhgawan and Narayanpet kimberlites in India [29,30], Arkhangelsk kimberlite in Russia [31], and kimberlites in South Africa [32,33] display transitional characteristics. These combine high olivine and phlogopite abundances with moderately radiogenic Sr and less radiogenic Nd isotope compositions relative to Bulk Earth. Understanding the primary magma composition and source of these transitional kimberlites is significantly hampered by scarce studies. Consequently, the Wafangdian kimberlites in China provide a crucial opportunity to decipher transitional kimberlite petrogenesis, which is the primary aim of this study.
Two diamondiferous kimberlite clusters, Mengyin and Wafangdian, are located in the eastern North China Craton (Figure 1; [34]). The Wafangdian kimberlites are classified as transitional based on mineralogical and isotopic compositions [27,35,36]. They intruded Archean–Paleoproterozoic wall rocks at ~480 Ma [37], although emplacement ages of ~465 Ma have also been proposed [35,38,39]. Their generation has been attributed to either a mantle plume, based on their coeval emplacement with regional lithospheric uplift during the Ordovician [35], or relation to subduction of the Mongolian oceanic lithosphere, as inferred from their lower εNd values (εNd ~ −2.3) and significant variations in Sr isotopic compositions [36]. While previous studies reported petrography and major/trace element geochemistry for NCC kimberlites [27,34] and discussed magma origins using whole-rock data [36], the nature of the near-primary parental melt and quantification of petrogenetic processes for the transitional Wafangdian kimberlites remain unexplored.
This study investigates comparatively fresh, hypabyssal kimberlites from four spatially proximal pipes within the Wafangdian cluster (NCC). Using whole-rock geochemical data, our objectives are to (1) evaluate melt composition modification during ascent and emplacement; (2) constrain the parental kimberlite melt composition; and (3) decipher the petrogenesis of kimberlite generation.

2. Wafangdian Kimberlite and Sampling

The Wafangdian kimberlite cluster is situated in the eastern NCC, approximately 60–80 km east of the Tanlu Fault (Figure 1A; [34]). The tectonic setting and evolution of the NCC are well-documented [40]. Diamond exploration prospecting in Wafangdian began in 1971, and 111 kimberlite bodies have been identified to date [41]. These kimberlites intrude a basement of Archean–Paleoproterozoic metagranite and gneiss overlain by Neoproterozoic–Sinian sedimentary cover [42]. They occur as both carrot-shaped vertical intrusions and tabular dykes. According to their distribution features, kimberlites have been divided into three parallel diamondiferous kimberlitic belts in an orientation of northeast–southwest 65–75° (Figure 1B). The kimberlitic I-belt is located in the northern part and extends in length by 20 km and width by 4 km, including the diamondiferous L30 and L42 kimberlites and diamond-barren L1 kimberlite. The kimberlitic II-belt is located in the central part with 15 km in length and 2 km in width and includes the L50 kimberlite pipe, which is well-known for high-diamond-grade and high-value, top-quality diamonds [28]. The kimberlites in the III-belt are barren [41]. Diamond grade and quality within these pipes are correlated positively with the volume of entrained diamondiferous mantle material, and also with the low calculated melt temperature, low oxygen fugacity, and high volatile content [28,43,44]. Recent drilling near the L50 pipe revealed a 10 m thick diamond-bearing kimberlite body, indicating significant deep exploration potential [45].
Twenty-eight samples of hypabyssal-facies kimberlite were collected from the L1, L30, L42, and L50 pipes. Sampling targeted both macrocrystic (abundant large, sub-rounded to anhedral olivine crystals) and aphanitic (rare or absent large olivine crystals) varieties, with strict selection for freshness. Detailed petrography is described in the following section.

3. Analytic Methods

All analyzed hypabyssal kimberlite samples were visually fresh. Samples were cleaned using a hydraulic rock splitter, then crushed in a jaw crusher. Crushed chips were meticulously hand-picked under a binocular microscope to exclude fragments containing macroscopic crustal xenoliths, mantle xenoliths, or carbonate veins. Selected clean chips were pulverized to powder using an agate mill. Sample petrography was characterized using optical microscopy and scanning electron microscopy (SEM).
The SEM analysis was conducted using a JEOL JXA-8100 Plus (JEOL, Tokyo, Japan) field emission electron probe micro-analyzer at Nanjing University. To enhance electrical conductivity and prevent charging effects, the samples were sputter-coated with a thin layer of carbon (~10 nm) prior to imaging. The analysis was conducted under high-vacuum conditions at an accelerating voltage of 15 kV.
Whole-rock major element compositions were determined at the Centre of Modern Analysis, Nanjing University. Approximately 0.5 g of sample powder was fused with 11 g of flux (Li2B4O7 + LiBO2 + LiBr) to create homogeneous glass disks. Major elements were analyzed using a Thermo Scientific ARL9800XP+ X-ray fluorescence (XRF) spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) operated at 50 kV accelerating voltage and 50 mA beam current. Loss on ignition (LOI) was measured as the weight loss of 2 g of powder after heating at 1000 °C for 10 h. Analytical precision was better than 1% for all major elements.
Whole-rock trace element (including rare earth element) abundances were determined at ALS Chemex (Guangzhou) Co., Ltd. (Guangzhou, China), Approximately 50 mg of powder was digested in high-pressure Teflon bombs using an HF + HNO3 mixture. Bombs were steel-jacketed and heated in an oven at 195 °C for 48 h. Digested samples were diluted to 50 mL and analyzed by inductively coupled plasma–mass spectrometry (ICP-MS; Element instrument, Thermo Fisher Scientific, Waltham, MA, USA). Analytical uncertainty was better than ±10% for all trace elements and better than ±5% for elements exceeding 50 ppm.
Whole-rock Sr-Nd isotopic compositions were measured using a Thermo Scientific Triton Ti thermal ionization mass spectrometer (TIMS) (Thermo Fisher Scientific, Waltham, MA, USA) at the State Key Laboratory for Mineral Deposit Research, Nanjing University, following methods outlined in [46]. Measured 87Sr/86Sr ratios were normalized to 86Sr/88Sr = 0.1194. Measured 143Nd/144Nd ratios were normalized to 146Nd/144Nd = 0.7219. Total procedural blanks were 5 × 10−11 g for Sm and Nd, and (2–5) × 10−10 g for Rb and Sr.

4. Petrography

The analyzed kimberlite samples display significant textural and mineralogical diversity. Following the classification method based on matrix mineralogy [47], all samples are classified as serpentine kimberlites, exhibiting variable proportions of phlogopite and calcite. Texturally, they can be subdivided into macrocrystic and aphanitic varieties (Figure S1). The term “macrocrystic” (a non-genetic textural descriptor) denotes the presence of abundant macrocrysts—anhedral crystals or fragments > 1.5 mm. Wafangdian macrocrystic kimberlites typically contain >10 vol.% macrocrysts (Figure S1A), locally reaching ~30 vol.% (e.g., sample L50-2). In contrast, aphanitic varieties contain rare (<5 vol.%) or no macrocrysts (Figure S1B). Macrocryst populations are dominated by olivine (Figure 2A), with minor phlogopite (Figure 2B) and rare garnet, ilmenite, and chromite; the latter three phases are volumetrically insignificant. Olivine macrocrysts (8–30 vol.% in macrocrystic samples) are characteristically rounded and anhedral (Figure 2A). They are frequently fragmented, with smaller fragments resembling smaller (0.5–1.5 mm) euhedral olivine phenocrysts. Extensive deuteric alteration along fractures has pervasively serpentinized most olivine macrocrysts. Phenocrysts comprise both olivine and phlogopite (Figure 2C,D). This distinct phenocryst assemblage contrasts with archetypal kimberlites, where olivine overwhelmingly dominates the phenocryst population [1,12,13]. The matrix is highly variable and dominated by fine-grained serpentine, phlogopite, and calcite, commonly exhibiting segregation textures (Figure 2E,F). Accessory groundmass phases include compositionally zoned spinel, ilmenite, apatite, titanite, and perovskite (Figure 2G,H). Xenolithic components include fragments of local crustal strata and rare disaggregated mantle peridotites. Notably, discrete kimberlite fragments are also present. These fragments display sharp boundaries with the surrounding kimberlite host but share an identical texture, structure, mineral composition, and alteration state.

5. Bulk-Rock Geochemistry

Twenty-eight predominantly visually fresh kimberlite samples from the L30 (n = 6), L42 (n = 6), L1 (n = 10), and L50 (n = 6) pipes were analyzed for major and trace elements, and the complete results are presented in Table 1. The Sr-Nd isotopic compositions of these samples are available in Table 2. These samples can be classified into two types: geochemically contaminated and uncontaminated (as discussed in the following section). Only data from the geochemically uncontaminated samples are shown in the subsequent text and in Figure 3, Figure 4 and Figure 5.

5.1. Major Elements

Major element compositions in the Wafangdian kimberlites are variable (Figure 3). Aphanitic kimberlites exhibit lower MgO (24.0–29.7 wt.%, n = 10) than macrocrystic samples (29.7–32.9 wt.%, n = 7). SiO2 correlates positively with MgO, ranging from 27.7–30.9 wt.% (aphanitic) to 29.7–34.7 wt.% (macrocrystic; Figure 3A). Al2O3 shows a weak positive correlation with MgO in aphanitic samples (3.9–5.2 wt.%) but an inverse trend in macrocrystic samples (2.1–4.9 wt.%; Figure 3B). TiO2 remains constant (1.1–1.4 wt.%) across Mg# values (Fe2O3/FeO = 0.1; Figure 3C), reflecting low perovskite and ilmenite contents. CaO decreases markedly with increasing SiO2 (Figure 3D), from 11.8 wt.% in evolved aphanitic samples to 3.9 wt.% in macrocrystic samples. Fe2O3* (total Fe) is stable (8.7–12.6 wt.%) against decreasing MgO (Figure 3E), with no distinction between textural types. Alkali elements (e.g., K2O) are scattered relative to MgO, though evolved aphanitic samples trend toward higher K2O (Figure 3F). No systematic compositional differences exist between pipes.

5.2. Trace Elements

Trace element abundances vary widely. Ni (521–1590 ppm) and Co (49–107 ppm) correlate strongly with Mg# (Figure 4A); lower concentrations occur in evolved aphanitic samples, while macrocrystic samples are enriched. Cr is high (794–1570 ppm) but uncorrelated with Mg#. High-field-strength elements (HFSE: Nb 139–346 ppm; Zr 147–336 ppm; Ta 9–21 ppm) and light rare earth elements (LREE: La 87–367 ppm; Th 20–75 ppm) are enriched in aphanitic samples and depleted in macrocrystic samples, showing strong mutual correlations (Figure 4B–D). Large-ion lithophile elements (LILEs: Rb 38–181 ppm; Ba 342–4660 ppm) are variably enriched but lack systematic correlations with HFSE or Mg# (Figure 4E,F). Sr (52–1050 ppm) broadly correlates with LREE and HFSE.
Chondrite-normalized REE patterns are smooth and parallel (Figure 5), displaying strong LREE enrichment (La/Smn = 6.55–11.76; La/Ybn = 127–245). La abundances are (280–1184) × chondrite, while Lu ranges from (1.2 to 5.3) × chondrite. Aphanitic samples show higher REE concentrations than macrocrystic samples (Figure 5A,C,E); patterns do not differ between pipes.
Primitive-mantle-normalized patterns (Figure 5B,D,F) are parallel and enriched in incompatible elements of (200–500) × primitive mantle. All samples exhibit negative anomalies (depletion relative to adjacent elements) at Rb, Sr, K, and Ti, quantified as K/K* = 0.07–0.15, Sr/Sr* = 0.10–0.44, and Ti/Ti* = 0.25–0.66 (* denotes interpolated primitive mantle value). Some samples show positive Pb anomalies from crustal contamination (discussed later). Aphanitic samples are more enriched in incompatible elements, but patterns show no pipe-specific variations.

5.3. Whole-Rock Sr-Nd Isotopes

Whole-rock Rb-Sr and Sm-Nd isotope data are in Table 2. Initial 87Sr/86Sr and 143Nd/144Nd ratios (calculated for 480 Ma crystallization; [37]) show limited variation in uncontaminated kimberlites: 87Sr/86Sr(t) = 0.7036–0.7053 and εNd(t) = −2.93 to −1.53. Contaminated samples exhibit broader ranges (87Sr/86Sr(t) = 0.6970–0.7122; εNd(t) = −3.83 to 1.90; Figure 6). Uncontaminated Wafangdian data overlap perovskite Sr-Nd isotopes from Mengyin kimberlites [35], while contaminated samples align with whole-rock kimberlite compositions from the North China Craton [35,50].

6. Discussion

The volatile-rich, hybrid nature of kimberlitic magma, referring to kimberlitic magmas which have entrained both mantle and crustal materials, complicates efforts at understanding its petrogenesis. A primary obstacle is identifying the composition of true primary kimberlitic melts [1,6], compounded by potential source heterogeneity between kimberlite clusters [52]. Furthermore, kimberlite compositions can be modified by secondary processes after magma generation, including (1) entrainment and assimilation of mantle and crustal rocks, (2) late-stage deuteric and crustal-derived hydrothermal alteration, and (3) magmatic processes like fractional crystallization. Before probing parental magma characteristics and source regions, these effects must be carefully evaluated. Below, we present constraints on the petrogenesis of the Wafangdian kimberlite by applying methods to mitigate identifiable late-stage processes.

6.1. Low-Temperature Alteration

Compared to volcaniclastic kimberlite, hypabyssal kimberlite exhibits lower permeability and reduced alteration [1]. Kimberlite magmas are volatile-rich, evidenced by widespread late-stage cryptocrystalline serpentine and calcite [53]. However, recent studies indicate that at least some serpentine-bound water originates from crustal sources [54,55,56]. Fluid influx—potentially including primary late-stage fluids, crustal-derived solutions, and meteoric water [14,55]—drives kimberlite alteration.
Petrographic observations of the Wafangdian kimberlite matrix reveal abundant fine-grained serpentine and calcite (the latter displaying segregationary textures; Figure 2) crystallized during late-stage processes. Combined with pervasive deuteric serpentinization and carbonatization, these features indicate significant low-temperature alteration.
Such alteration profoundly affects whole-rock geochemistry, particularly mobilizing alkali and alkaline earth elements (e.g., Rb, K, Sr, Ba; [8,12]). In contrast, high-field-strength elements (HFSE) and rare earth elements (REE) typically remain immobile. Alkali element mobility is evident when plotting against immobile incompatible elements (e.g., La, Zr, Nb, Hf, Th): coherent trends exist among immobile elements (Figure 4B–D), whereas alkali elements (K, Rb, Ba) show significant scatter (Figure 4E,F). Low-temperature alteration and serpentinization may also redistribute volatiles and major elements (K, Na, Si, Mg, Ca; [13,54]). Nevertheless, despite this variability, the absolute concentrations of these elements remain sufficiently high that their abundance variations retain petrogenetic significance when interpreted cautiously.

6.2. Crustal Contamination

Kimberlites typically entrain abundant mantle and crustal xenoliths during ascent, with mantle fragments dominating in hypabyssal varieties [1]. The Wafangdian kimberlites conform to this pattern, exhibiting ubiquitous crustal fragments in hand specimens and thin sections. Although visible crustal material was meticulously removed prior to powdering and analysis, partial or complete assimilation of crustal fragments by the kimberlite magma is likely, given the low melting temperatures of local shales and siltstones.
Geochemical evidence for crustal assimilation in the Wafangdian kimberlites is illustrated in Figure 7. Contaminated samples exhibit distinct signatures: (1) Elevated SiO2 and depressed MgO relative to uncontaminated samples (Figure 7A), consistent with the high-SiO2, low-MgO composition of local upper-crustal rocks. (2) Reduced Gd/Lu ratios (Figure 7B), reflecting the flatter HREE patterns and higher absolute HREE abundances of crustal rocks compared to the steep, HREE-depleted patterns of uncontaminated kimberlites (Figure 5). (3) Higher contamination indices (C.I. = 1.20–1.34; [57]) versus uncontaminated samples (C.I. = 1.00–1.20; Figure 7C). (4) Pronounced positive Pb anomalies in primitive mantle-normalized trace element patterns, contrasting with the near-absence of anomalies in uncontaminated samples (Figure 7D). (5) Broader ranges in initial Sr isotopic ratios relative to uncontaminated samples (Figure 6). Consequently, only uncontaminated samples (17 of 28) are plotted in all figures except Figure 6 and Figure 7 and are used exclusively in subsequent petrogenetic discussions.

6.3. Fractional Crystallization

Crystal fractionation of olivine ± phlogopite during kimberlite magma ascent or shallow emplacement has been proposed based on detailed kimberlite studies [12,15,59]. Aphanitic kimberlites are widely interpreted as the fractionated end-members of such processes.
Multiple lines of evidence indicate variable crystal fractionation in the Wafangdian kimberlites: (1) Olivine Fractionation. Systematic decreases in Ni and Co with declining Mg# and SiO2, coupled with significant Ni and Mg# variability, point strongly to olivine fractionation. (2) Phlogopite Fractionation. Near-constant K2O, slightly decreasing Al2O3 against falling MgO, and TiO2 enrichment levels inconsistent with olivine-only fractionation (Figure 3) suggest phlogopite co-precipitation [59]. This is further supported by the presence of phlogopite phenocrysts (Figure 2). (3) Limited Calcite Fractionation. Relatively constant Fe2O3* (Figure 3E), which shows no rapid increase with decreasing MgO, argues against significant calcite fractionation [12].
The dominance of olivine and phlogopite fractionation in Wafangdian aphanitic kimberlites is consistent with their low phenocryst abundances (Figure 2). Major element variations are broadly explained by 1–32% fractionation of an olivine–phlogopite assemblage (~65:35 ratio) from a primary magma (Figure 8B). This range is corroborated by Ni content and Mg# variations, where ~35% fractionation of these phases accounts for the observed trends (Figure 8A). Given the high incompatibility of REE in both olivine and phlogopite, fractionation produces uniform relative enrichment across the REE spectrum without altering pattern shapes, as observed (Figure 8D).

6.4. Macrocryst Entrainment

Numerous studies confirm that entrainment and disaggregation of mantle peridotite profoundly influence kimberlite geochemistry during magma ascent [6,8,56,59]. Anhedral olivine macrocrysts—morphologically identical to peridotitic olivine—are universally interpreted as xenocrysts from disaggregated mantle material rather than primary crystallizing phases [57]. This distinction is critical for reconstructing primary melt compositions.
The Wafangdian kimberlites exhibit abundant mantle-derived xenoliths (lherzolite, garnet lherzolite, pyroxenite; [51,62]) and xenocrysts (dominant olivine, minor garnet/chromite; [42,43,44]). Three geochemical signatures demonstrate entrainment effects: (1) Elevated Mg# and Ni. Macrocrystic samples show higher Ni and Mg# than inferred near-primary melts (Figure 8A), aligning with assimilation of high-Ni, high-Mg# peridotite [51,62]. (2) MgO-SiO2 Trends. Compositions extend toward mantle peridotite fields (Figure 8C). Modeling indicates that this requires ≤35% entrainment of garnet lherzolite (avg. 65% olivine, 18% orthopyroxene, 14% clinopyroxene, 3% garnet), consistent with observed xenolith abundances (Table S1, Figure S2). (3) REE Dilution: Uniformly lower REE concentrations in macrocrystic samples (Figure 8D) reflect dilution by REE-poor mantle minerals [42,51].

6.5. Close-to-Primary Magma Composition

Kimberlites in this study record crystal fractionation (evident in aphanitic samples) and mantle peridotite entrainment (evident in macrocrystic samples). Consequently, the close-to-primary magma composition should plot between these end-members on inter-element variation diagrams [12,59] As illustrated in Figure 3A, this composition is expected at the low-SiO2 and low-MgO end of the macrocrystic trend and the high-SiO2 and high-MgO end of the aphanitic kimberlite trend. Variation diagrams indicate a close-to-primary composition for the Wafangdian kimberlite of ~29.7 wt.% SiO2, ~29.7 wt.% MgO, Mg# ~85, ~5 wt.% Al2O3, ~1.3 wt.% TiO2, ~1.3 wt.% K2O, ~7.0 wt.% CaO, 10.0 wt.% Fe2O3*, and 950 ppm Ni. Samples L1-8, L1-10, and L50-6 most closely approach this composition. This composition broadly aligns with reconstructed parental melts of archetypal kimberlites from the Kaapvaal and Slave cratons (25–32 wt.% SiO2, 22–31 wt.% MgO, Mg# 82–87, ~2 wt.% Al2O3, 1–3 wt.% TiO2, 0.5–0.8 wt.% K2O, 9–17 wt.% CaO: [8,11,13,25,59]), except for higher Al2O3 and lower CaO. The elevated Al2O3 (~5 wt.%) resembles orangeite [8,25], while the lower CaO contrasts with typical archetypal and olivine kimberlites (8–17 wt.%). Notably, the inferred primary Mg# of 85 matches the global archetypal kimberlite average of 84 ± 1 [6]. This composition is also broadly consistent with experimental melts from low-degree melting of carbonated lherzolite (20–36 wt.% SiO2, 18–32 wt.% MgO, 26–30 wt.% Al2O3: [63]).
The Mg# (~85) of the inferred primary transitional kimberlite magma suggests equilibration with a fertile mantle source retaining residual olivine at Fo ~91.8 (using an olivine-melt K Mg · D Fe - of 0.5; [56]). This calculated olivine composition is lower than Fo values (92–94) reported for garnet lherzolites from the subcontinental lithospheric mantle beneath the North China Craton [31,62].

6.6. Partial Melting Models

Experimental studies indicate that archetypal kimberlite magmas form via low-degree partial melting (0.3–2.0%) of a carbonated garnet peridotite source at 3–8 GPa [63]. Specifically, melting of carbonate-bearing garnet lherzolite at ~200 km depth can produce a compositional continuum from carbonatite (~0.3% melting) to kimberlite (~1% melting) [64]. This is consistent with studies of natural kimberlites, which suggest melt generation by 0.5–2.0% melting of a garnet lherzolite source [12,59]. The source region for the Wafangdian kimberlite is constrained to ~8 GPa (Figure 9), slightly deeper than the 5.0–7.4 GPa estimated for garnet xenocrysts in these kimberlites [42]. This elevated pressure supports applying the partial melting model [63], which suggests that the Wafangdian kimberlite formed by 0.6–0.7% melting based on SiO2, Al2O3, and MgO systematics. However, the CaO content of the inferred primary magma here is significantly lower than predicted by their experiments. Additional evidence for low-degree melting includes strong incompatible element enrichment and relative HREE depletion in the Wafangdian kimberlites (Figure 5, Table 1). Consequently, we utilize a fixed melting degree (F = 1%) for modeling. This value aligns with both the experimental work [60] and estimates for parental kimberlite melts from South Africa [8,12,59].

6.7. Source for the Transitional Kimberlites

The transitional characteristics indicate a distinct source region compared to archetypal kimberlites (derived from convective mantle) and orangeites (derived from lithospheric mantle). Based on the analysis below, we propose a source of convective mantle contaminated by assimilated oceanic crust for the Wafangdian kimberlites. First, there are significant overlaps between Wafangdian and South African archetypal kimberlites: (1) the close-to-primary Wafangdian magma composition overlaps broadly in major elements (e.g., SiO2, MgO, TiO2) with archetypal kimberlites. (2) Its Mg# (~85) is consistent with the global archetypal kimberlite average (84 ± 1; [6]). (3) Primitive mantle-normalized trace element patterns are near-parallel to those of archetypal kimberlites from Kimberley [12] and Lac de Gras [68], differing markedly from orangeites (e.g., western Australia; [25]), which show higher Rb, Ba, Zr, Ti and lower Nb, Ta (Figure 10). (4) Melting degrees (0.6–0.7%) inferred for Wafangdian are similar to the ~1% melting proposed for archetypal kimberlites [8,12]. This similarity in source process and composition suggests a shared convective mantle origin. This interpretation is further supported by the following: (1) Convective mantle-like incompatible element ratios: Nb/U = 26–58 (Figure 11), La/Th = 4.4–7.6, Nb/Th = 4.1–7.3, La/Nb = 0.8–1.4, Ba/Nb = 7–16, Th/Nb = 0.12–0.24 (Table 1). (2) Olivine-melt equilibration modeling (Mg# ~85) indicating a fertile mantle source (Fo ~91.8; Figure 8), consistent with convective mantle. (3) Relatively low whole-rock Sr isotope compositions (87Sr/86Sri = 0.7036–0.7053; Figure 6) to the Sr isotope values of orangeite (0.7074–0.7125).
Despite these similarities, key differences point to source contamination: (1) Wafangdian samples have εNd(t) values (−2.93 to −1.53; Figure 6) lower than typical archetypal kimberlites (εNd(t) > 0; [26]), indicating involvement of recycled oceanic crust [2,33,69]. (2) Elevated Al2O3 and K2O in the primary magma correlate with high modal phlogopite (Figure 2) and significant phlogopite fractionation (Figure 8), suggesting addition of Al- and K-rich oceanic crust material. (3) Lower Ce/Pb ratios (10–20 vs. higher in archetypal kimberlites; Figure 11) indicate Pb enrichment, potentially sourced from recycled oceanic crust [69]. These features collectively suggest a minor oceanic crust component within the Wafangdian primary magma. This component could originate from either assimilation during magma ascent through the lithospheric mantle, or partial melting of convective mantle pre-contaminated by subducted oceanic crust.
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Figure 10. Graph of primitive mantle-normalized incompatible trace elements for the close-to-primary magma compositions of the transitional Wafangdian kimberlite, Kimberley archetypal kimberlite [12], Lac de Gras archetypal kimberlite [68], and western Australia orangeite [70].
Figure 10. Graph of primitive mantle-normalized incompatible trace elements for the close-to-primary magma compositions of the transitional Wafangdian kimberlite, Kimberley archetypal kimberlite [12], Lac de Gras archetypal kimberlite [68], and western Australia orangeite [70].
Minerals 15 01009 g010
Given the absence of evidence for Paleozoic subduction beneath Wafangdian or Mengyin during kimberlite emplacement [35], assimilation during transport is unlikely. Therefore, a source of contaminated convective mantle—assimilated by deeply subducted oceanic material prior to kimberlite magma generation—is the most plausible model.
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Figure 11. Trace element ratios in Wafangdian kimberlites. Fields for ocean island basalt (OIB), mid-ocean ridge basalt (MORB), archetypal kimberlites, and orangeites are from the Le Roex et al. [12] and Becker et al. [8]. Symbols are as shown in Figure 3. (A) Nb/U versus Nb; (B) Ce/Pb versus Ce; (C) Ce/Pb versus Th/Nb; (D) Ba/Nb versus La/Nb.
Figure 11. Trace element ratios in Wafangdian kimberlites. Fields for ocean island basalt (OIB), mid-ocean ridge basalt (MORB), archetypal kimberlites, and orangeites are from the Le Roex et al. [12] and Becker et al. [8]. Symbols are as shown in Figure 3. (A) Nb/U versus Nb; (B) Ce/Pb versus Ce; (C) Ce/Pb versus Th/Nb; (D) Ba/Nb versus La/Nb.
Minerals 15 01009 g011

7. Conclusions

Bulk-rock geochemistry of the Wafangdian kimberlites (North China Craton) reveals coherent trace element systematics, providing key constraints on their petrogenesis:
  • The HFSE and REE concentrations remain robust indicators of primary magmatic processes, whereas alkali and alkaline earth elements show evidence of disturbance during these late-stage alteration processes. Samples exhibiting elevated SiO2, HREE, and Pb abundances are identified as having experienced crustal contamination, distinguishing them from uncontaminated samples.
  • Composition variations in aphanitic kimberlites are consistent with up to 32% fractionation of olivine plus phlogopite, whereas those shown in macrocrystic kimberlites are consistent with up to 35% entrainment of mantle lherzolite. The close-to-primary kimberlite magma contains ~29.5 wt.% SiO2, 29.5 wt.% MgO, Mg# ~85, ~5 wt.% Al2O3, ~1.3 wt.%TiO2, ~1.3 wt.% K2O, ~7 wt.% CaO, and 950 ppm Ni.
  • Forward modeling of mantle melting processes indicates that the Wafangdian kimberlites were generated by approximately 1% partial melting of a carbonated garnet lherzolite source.
  • The combined geochemical evidence supports a model where the Wafangdian kimberlites originated from low-degree melting of convective upper mantle. Critically, this mantle source was contaminated by subducted oceanic crust material prior to kimberlite magma generation.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/min15101009/s1, Figure S1. Hand specimens showing macrocrystic kimberlite (A) and aphanitic kimberlite (B) from the Wafangdian kimberlite cluster; Figure S2. Measured macrocrysts phase abundances versus calculated macrocrysts phase abundances. Calculation is based on geochemical composition of the Wafangdian kimberlites and macrocrysts phase entrainment trend (Figure 8); Table S1. Measured and calculated modal macrocrysts abundances in the Wafangdian kimberlites.

Author Contributions

Conceptualization, R.Z. and P.N.; Methodology, R.Z. and P.N.; Investigation, R.Z.; Data curation, R.Z.; Writing—original draft, R.Z.; Writing—review & editing, R.Z., P.N., Y.L. and F.W.; Supervision, R.Z. and P.N.; Funding acquisition, R.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This work was funded by the National Natural Science Foundation of China (Grant No. 42103059) and China Postdoctoral Science Foundation (Grant No. 2021M703059).

Data Availability Statement

Data are contained within the article.

Acknowledgments

Great thanks go to Ning Kang, Hua Zhou, Yi Ju, Li-Li Chen, An-Dong Zhu and Bao Huang for their help during the fieldwork. We appreciate the State Key Laboratory for Mineral Deposit Research, Nanjing University for their assistance during the experiment. The authors are grateful to the Centre of Modern Analysis, Nanjing University, and ALS Chemex (Guangzhou) Co., Ltd.

Conflicts of Interest

Author Fanglai Wan was employed by the company Liaoning Sixth Geological Brigade Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Minerals 15 01009 g001
Figure 1. (A) Simplified sketch map showing the North China Craton in China and (B) simplified geological map of the diamondiferous Wafangdian kimberlite cluster [28].
Figure 1. (A) Simplified sketch map showing the North China Craton in China and (B) simplified geological map of the diamondiferous Wafangdian kimberlite cluster [28].
Minerals 15 01009 g001
Minerals 15 01009 g002
Figure 2. Petrographic photographs of Wafangdian kimberlites. (A,B) Photomicrograph of olivine macrocryst and phlogopite macrocryst; (C,D) photomicrograph of olivine phenocryst and phlogopite phenocryst; (E–G) photomicrograph of phlogopite, serpentine, calcite, and spinel in the matrix; (H) photomicrograph of titanite and ilmenite in the matrix. Abbreviations: Ol = olivine; Ol pheo = olivine pheocryst; Ol xeno = olivine xenocryst; Phl = phlogopite; Ser = serpentine; Cal = calcite; Mt = magnetite; Spl = spinel; Ttn = titanite; Ilm = ilmenite. (A–F) are photomicrographs taken under crossed polars, and (G,H) are back-scattered electron (BSE) images.
Figure 2. Petrographic photographs of Wafangdian kimberlites. (A,B) Photomicrograph of olivine macrocryst and phlogopite macrocryst; (C,D) photomicrograph of olivine phenocryst and phlogopite phenocryst; (E–G) photomicrograph of phlogopite, serpentine, calcite, and spinel in the matrix; (H) photomicrograph of titanite and ilmenite in the matrix. Abbreviations: Ol = olivine; Ol pheo = olivine pheocryst; Ol xeno = olivine xenocryst; Phl = phlogopite; Ser = serpentine; Cal = calcite; Mt = magnetite; Spl = spinel; Ttn = titanite; Ilm = ilmenite. (A–F) are photomicrographs taken under crossed polars, and (G,H) are back-scattered electron (BSE) images.
Minerals 15 01009 g002
Minerals 15 01009 g003
Figure 3. Selected major element variation diagrams for Wafangdian kimberlites. (A) SiO2 versus MgO; (B) Al2O3 versus MgO; (C) TiO2 versus Mg#; (D) CaO versus SiO2; (E) Fe2O3 versus MgO; (F) K2O versus MgO.
Figure 3. Selected major element variation diagrams for Wafangdian kimberlites. (A) SiO2 versus MgO; (B) Al2O3 versus MgO; (C) TiO2 versus Mg#; (D) CaO versus SiO2; (E) Fe2O3 versus MgO; (F) K2O versus MgO.
Minerals 15 01009 g003
Minerals 15 01009 g004
Figure 4. Selected trace element variation diagrams for Wafangdian kimberlites. (A) Ni versus Mg#; (B) Zr versus Hf; (C) Nb versus La; (D) Th versus La; (E) Rb versus La; (F) Ba versus La.
Figure 4. Selected trace element variation diagrams for Wafangdian kimberlites. (A) Ni versus Mg#; (B) Zr versus Hf; (C) Nb versus La; (D) Th versus La; (E) Rb versus La; (F) Ba versus La.
Minerals 15 01009 g004
Minerals 15 01009 g005
Figure 5. Chondrite-normalized REE abundances in selected kimberlites from the Wafangdian kimberlite cluster: L30 pipe (A) L1 pipe (C), and L50 pipe (E). Primitive mantle-normalized trace element abundances in the Wafangdian kimberlites: L30 pipe (B), L1 pipe (D), and L50 pipe (F). The values of chondrite are from Boynton [48]. The values of primitive mantle are after Sun and McDonough [49].
Figure 5. Chondrite-normalized REE abundances in selected kimberlites from the Wafangdian kimberlite cluster: L30 pipe (A) L1 pipe (C), and L50 pipe (E). Primitive mantle-normalized trace element abundances in the Wafangdian kimberlites: L30 pipe (B), L1 pipe (D), and L50 pipe (F). The values of chondrite are from Boynton [48]. The values of primitive mantle are after Sun and McDonough [49].
Minerals 15 01009 g005
Minerals 15 01009 g006
Figure 6. Sr-Nd isotopic compositions for Wafangdian kimberlites. Kimberlite emplacement age is 480 Ma [37]. Sources of data: archetypal kimberlites and orangeites [8,26]; peridotite xenoliths [51]; perovskites [35]; Mengyin kimberlites [36].
Figure 6. Sr-Nd isotopic compositions for Wafangdian kimberlites. Kimberlite emplacement age is 480 Ma [37]. Sources of data: archetypal kimberlites and orangeites [8,26]; peridotite xenoliths [51]; perovskites [35]; Mengyin kimberlites [36].
Minerals 15 01009 g006
Minerals 15 01009 g007
Figure 7. Distinguishing characteristics between crustal contaminated samples and crustal uncontaminated samples. (A) Binary plots showing MgO contents and (B) Gd/Lu versus SiO2 in crustal contaminated samples and no crustal contaminated samples from Wafangdian kimberlite cluster. (C) Crustal contamination index (C.I.) against CaO contents, and fields are after Taylor [58]; (D) primitive mantle-normalized trace element patterns for selected crustal contaminated and uncontaminated kimberlite samples. Positive Pb anomaly and raised HREE abundances in crustal contaminated samples should be highlighted. Normalizing values from Sun and McDonough [49].
Figure 7. Distinguishing characteristics between crustal contaminated samples and crustal uncontaminated samples. (A) Binary plots showing MgO contents and (B) Gd/Lu versus SiO2 in crustal contaminated samples and no crustal contaminated samples from Wafangdian kimberlite cluster. (C) Crustal contamination index (C.I.) against CaO contents, and fields are after Taylor [58]; (D) primitive mantle-normalized trace element patterns for selected crustal contaminated and uncontaminated kimberlite samples. Positive Pb anomaly and raised HREE abundances in crustal contaminated samples should be highlighted. Normalizing values from Sun and McDonough [49].
Minerals 15 01009 g007
Minerals 15 01009 g008
Figure 8. Distinguishing processes of fractional crystallization and macrocryst entrainment. (A) Ni versus Mg# and (B) Al2O3 versus MgO in Wafangdian kimberlites. The composition variations in the aphanitic samples are consistent with up to 32% fractionation of olivine (Ol) and phlogopite (Phl) in the proportion of 65:35 from inferred close-to-primary magma composition. Olivine fractionation curves were calculated assuming equilibrium crystallization. K Mg · D Fe - for olivine = 0.5 [56], D Ol Ni = 124/MgO − 0.9 [60], and D Phl Ni = D Ol Ni × 0.5 [61]. Grey circle shows composition of primary kimberlite magma (see text for further discussion). (C) SiO2 vs. MgO in Wafangdian kimberlite. Representative compositions of olivine (Ol), orthopyroxene (Opx), garnet (Grt), and clinopyroxene (Cpx) are from garnet lherzolite [62]. The position of the marked garnet lherzolite was calculated using the proportions and composition of mineral phases [62]. (D) Chondrite-normalized REE abundances in Wafangdian kimberlite samples and inferred primary magma composition (only selected kimberlites samples are plotted for clarity). The variations in absolute REE concentrations in macrocrystic samples are consistent with up to 35% entrainment of mantle peridotite into the inferred primary magma composition, and the variations in aphanitic samples are consistent with fractionation of up to 32% olivine plus phlogopite from the inferred primary magma composition. The values of chondrite are from Boynton [48]. Symbols are as shown in Figure 3.
Figure 8. Distinguishing processes of fractional crystallization and macrocryst entrainment. (A) Ni versus Mg# and (B) Al2O3 versus MgO in Wafangdian kimberlites. The composition variations in the aphanitic samples are consistent with up to 32% fractionation of olivine (Ol) and phlogopite (Phl) in the proportion of 65:35 from inferred close-to-primary magma composition. Olivine fractionation curves were calculated assuming equilibrium crystallization. K Mg · D Fe - for olivine = 0.5 [56], D Ol Ni = 124/MgO − 0.9 [60], and D Phl Ni = D Ol Ni × 0.5 [61]. Grey circle shows composition of primary kimberlite magma (see text for further discussion). (C) SiO2 vs. MgO in Wafangdian kimberlite. Representative compositions of olivine (Ol), orthopyroxene (Opx), garnet (Grt), and clinopyroxene (Cpx) are from garnet lherzolite [62]. The position of the marked garnet lherzolite was calculated using the proportions and composition of mineral phases [62]. (D) Chondrite-normalized REE abundances in Wafangdian kimberlite samples and inferred primary magma composition (only selected kimberlites samples are plotted for clarity). The variations in absolute REE concentrations in macrocrystic samples are consistent with up to 35% entrainment of mantle peridotite into the inferred primary magma composition, and the variations in aphanitic samples are consistent with fractionation of up to 32% olivine plus phlogopite from the inferred primary magma composition. The values of chondrite are from Boynton [48]. Symbols are as shown in Figure 3.
Minerals 15 01009 g008
Minerals 15 01009 g009
Figure 9. MgO/CaO versus SiO2/Al2O3 plot for the selected Wafangdian kimberlites. The gray field represents experimentally produced melt compositions from synthetic carbonated peridotite between 3 GPa and 8 GPa [65]. The dashed gray outlines represent experimentally produced melt compositions from synthetic carbonated peridotite between 4 and 6 GPa (phlogopite present) [66] and 6 and 10 GPa (phlogopite absent) [67].
Figure 9. MgO/CaO versus SiO2/Al2O3 plot for the selected Wafangdian kimberlites. The gray field represents experimentally produced melt compositions from synthetic carbonated peridotite between 3 GPa and 8 GPa [65]. The dashed gray outlines represent experimentally produced melt compositions from synthetic carbonated peridotite between 4 and 6 GPa (phlogopite present) [66] and 6 and 10 GPa (phlogopite absent) [67].
Minerals 15 01009 g009
Table 1. Bulk major and trace element analyses of selected hypabyssal transitional kimberlites from the Wafangdian kimberlite cluster. LOI: loss on ignition; Mg#: atomic Mg/(Mg + Fe2+) × 100 with Fe2O3/FeO = 0.1. aph: aphanitic; macro: macrocrystic. C.I. = (SiO2 + Al2O3 + Na2O)/(MgO + 2 × K2O).
Table 1. Bulk major and trace element analyses of selected hypabyssal transitional kimberlites from the Wafangdian kimberlite cluster. LOI: loss on ignition; Mg#: atomic Mg/(Mg + Fe2+) × 100 with Fe2O3/FeO = 0.1. aph: aphanitic; macro: macrocrystic. C.I. = (SiO2 + Al2O3 + Na2O)/(MgO + 2 × K2O).
PipeL30 PipeL40 PipeL1 Pipe
SampleL30-1L30-2L30-3L30-4L30-5L30-6L42-1L42-2L42-3L42-4L42-5L42-6L1-1L1-2L1-3
Textureaphaphaphmacroaphaphaphaphmacromacromacromacromacromacroaph
Major elements
SiO229.3334.6134.1235.4334.4529.1035.4234.7237.1836.5835.9736.1031.1230.5529.88
TiO21.231.451.511.401.421.142.031.952.192.052.062.211.301.271.38
Al2O34.675.154.644.624.754.464.784.904.634.944.404.384.814.513.91
Fe2O311.2310.0510.7310.339.839.557.147.317.628.658.779.239.619.9112.64
MnO0.130.160.140.130.130.140.170.180.250.260.250.200.340.330.11
MgO25.9127.4928.2027.3828.2025.9828.3728.1031.4231.2331.5129.3130.4330.6627.64
CaO7.546.145.724.465.818.795.406.142.321.682.232.737.087.496.76
K2O1.892.132.122.911.262.150.921.010.830.720.852.231.701.521.38
Na2O0.380.330.390.390.380.350.240.250.320.270.330.280.340.340.38
P2O50.870.470.760.320.460.510.720.810.950.780.751.091.050.611.37
SO30.020.040.080.070.060.100.020.030.170.030.010.020.180.110.03
Cr2O30.250.210.210.200.210.210.190.180.200.180.180.190.210.190.18
LOI16.3311.7510.9511.3812.9917.1514.4213.7412.3912.4412.4711.8612.0411.8214.32
SUM99.7899.9899.5799.0299.9599.6399.8299.32100.4799.8199.7799.83100.2199.3199.98
Mg#81.984.383.783.984.984.288.688.389.087.687.686.286.185.881.1
C.I.1.161.261.211.221.291.121.341.321.271.281.231.211.071.051.12
Trace elements
Zr252176251281343282345338365359346357329218294
Nb300173288192198320171160181165172175306207321
Y15.615.018.213.513.916.619.919.519.121.820.018.016.112.717.7
Rb127375273259276152576050435112813317097
Ba3160450033103130326046607938966695256911825417021802250
Sr7803934194145911015273262344285248647665441915
Co546369726969647741394239647749
Cr110010301130109010801060900869942928962999134012931040
Ni58474082985582188069573987567968977711291021521
V11076107781001002653052192452502896513060
Sc172019181912171718181817252525
Th64324836356622.822.423.823.422.124683365
U6.72.945.94.44.49.44.64.65.14.94.85.15.35.19.8
Pb3633563933476034323852116332859
Ta17.912.217.613.813.718.810.610.611.810.910.911.718.312.517.1
Hf6.04.15.76.17.46.28.08.28.98.58.09.37.14.67.1
La2561762971962093079210213816120087218193352
Ce485304485331345579228245292300371229388319595
Pr4627.94430315426.828.831323527.63728.154
Nd140871289291165961011021041159611582161
Sm15.210.614.710.510.619.814.214.414.014.414.714.113.89.217.6
Eu4.62.553.83.13.05.42.912.874.74.04.03.93.22.714.4
Gd8.36.48.46.46.29.78.48.88.68.98.79.07.95.39.4
Tb0.860.700.930.700.690.980.890.900.920.980.960.950.890.600.99
Dy3.93.44.53.43.24.54.34.34.44.74.44.54.02.904.5
Ho0.570.550.680.560.490.670.710.710.750.790.730.750.640.480.67
Er1.291.331.751.331.261.551.691.791.661.861.721.761.491.111.56
Tm0.160.160.210.170.160.190.220.230.210.240.220.220.190.150.19
Yb0.840.861.220.930.911.071.271.381.241.371.281.231.160.791.01
Lu0.110.120.160.140.130.140.190.210.170.200.190.180.170.120.14
La/Nb0.851.011.031.021.060.960.540.630.760.981.160.500.710.931.10
La/Th3.995.426.165.465.924.634.054.535.806.869.033.633.215.855.46
Ba/Nb10.5326.0111.4916.3016.4614.564.645.603.703.194.0310.4613.6310.537.01
Th/Nb0.210.190.170.190.180.210.130.140.130.140.130.140.220.160.20
Nb/Th4.685.345.985.365.614.837.507.147.617.037.767.274.506.294.98
Ce/Pb13.479.218.668.4910.4512.323.807.219.137.897.131.9711.7611.3910.08
Nb/U45.1158.8448.9844.1445.0033.9037.4234.9335.4933.9236.0334.3558.2940.9932.72
Nb/Th4.685.345.985.365.614.837.507.147.617.037.767.274.506.294.98
PipeL1 PipeL50 PipePrimary Magma
SampleL1-4L1-5L1-6L1-7L1-8L1-9L1-10L50-1L50-2L50-3L50-4L50-5L50-6
Textureaphaphaphaphaphaphaphaphmacromacromacromacromacro
Major elements
SiO227.7029.9930.8630.6229.5129.5629.7333.6834.7432.1930.6732.6629.8633.59
TiO21.371.351.251.221.271.201.321.431.281.241.391.221.351.77
Al2O34.185.194.754.694.834.635.221.872.132.662.612.704.934.91
Fe2O310.7710.9911.0310.8110.3310.7010.1411.358.848.6610.1310.1210.099.31
MnO0.200.220.230.270.270.270.220.200.240.340.200.330.330.24
MgO23.9528.4029.1228.7229.5528.1929.6628.2832.8830.7530.2031.4529.7329.91
CaO11.789.345.977.956.737.806.565.283.915.896.135.416.835.83
K2O1.402.221.341.381.421.291.620.690.650.450.540.700.781.53
Na2O0.320.310.300.280.290.270.340.300.350.310.290.300.290.32
P2O51.220.260.300.640.440.620.870.940.730.320.090.570.420.61
SO30.010.090.020.090.010.060.080.080.080.050.040.000.060.13
Cr2O30.180.240.210.190.280.190.220.370.310.310.390.290.320.22
LOI16.8510.8214.0212.6714.5615.5413.5915.0213.5716.6117.7915.0214.1211.61
SUM99.9299.4299.4099.5399.49100.3299.5799.4999.7199.78100.47100.7799.1199.95
Mg#81.383.583.883.984.983.885.283.087.987.485.485.985.286.3
C.I.1.201.081.131.131.071.121.071.211.091.111.071.091.121.18
Trace elements
Zr275267259312336291147296272241291251281316
Nb254309280295346295234168163139167139155245
Y19.917.617.917.523.116.313.58.68.16.89.510.011.118.4
Rb1661829510612887177676138394951116
Ba419038901200366030402460304036302400962342136512502280
Sr9663397591050371926498576445257194417380342
Co55715060565871881079873686556
Cr794123011209861270102010901790157014801450151012201086
Ni59772080167093384693614401590140012901430950797.5
V716558701258513011510029303530142
Sc2323242626262616141416151520.5
Th6075685768583422.319.819.8523.121.223.450
U9.18.410.89.88.99.45.14.04.03.33.73.94.56.8
Pb6344484746553342141917221638
Ta16.920.518.015.618.715.014.310.29.29.011.29.310.516.2
Hf6.96.86.57.07.26.32.96.35.75.66.96.16.97.9
La35636734132726833722910187104146150177253
Ce604645599560474550386194160195279282327469
Pr5560554944493519.116.019.829.227.53145
Nd1601781621461321411016152649490103140
Sm18.417.917.616.317.615.311.68.06.98.411.511.113.115.9
Eu5.05.24.84.24.83.93.42.031.872.363.02.823.14.9
Gd10.29.19.28.710.97.96.64.44.04.46.26.07.18.8
Tb1.060.950.930.881.150.830.710.480.440.480.630.600.630.94
Dy4.84.34.34.25.23.93.32.222.032.022.732.723.04.3
Ho0.760.640.670.660.820.590.520.330.310.290.390.400.460.70
Er1.681.451.451.541.811.311.190.690.690.600.800.820.961.56
Tm0.210.180.170.190.230.160.150.080.080.070.090.100.100.20
Yb1.191.010.971.071.200.910.810.430.410.350.450.520.501.13
Lu0.170.140.130.150.170.120.110.060.050.040.060.060.060.16
La/Nb1.401.191.221.110.771.140.980.600.530.750.871.081.141.03
La/Th5.934.875.025.753.945.846.744.534.395.216.307.087.565.10
Ba/Nb16.5012.594.2912.418.798.3412.9921.6114.726.952.059.868.069.30
Th/Nb0.240.240.240.190.200.200.150.130.120.140.140.150.150.20
Nb/Th4.234.104.125.185.095.116.887.538.236.987.236.536.624.94
Ce/Pb9.5914.6612.4811.9110.3010.0011.704.6211.4310.2616.4112.8220.4412.33
Nb/U27.8236.6125.9330.0138.8331.2845.8841.9041.2742.3545.3835.7934.8336.19
Nb/Th4.234.104.125.185.095.116.887.538.236.987.236.536.624.94
Table 2. Sr-Nd isotopic characteristics of the Wafangdian kimberlites. The age t is equal to 480 Ma.
Table 2. Sr-Nd isotopic characteristics of the Wafangdian kimberlites. The age t is equal to 480 Ma.
SampleRbSr87Rb87Sr/2s87Sr/SmNd147Sm143Nd2s143NdεNd(t)TDM1fSm/Nd
(ppm)(ppm)86Sr86Sr86Srt(ppm)(ppm)144Nd144Nd144Ndt(Ma)
L30 pipeL30-11277800.46910.7071950.0000050.7039915.251400.06610.5121460.0000030.51194−1.591036−0.66
L30-23753932.76260.7158710.0000050.6969810.55870.07320.5120540.0000030.51182−3.831188−0.63
L30-32734191.88650.7169170.0000040.7040114.651280.06920.5120780.0000060.51186−3.101130−0.65
L30-42594141.81120.7159170.0000080.7035310.5920.06930.5120900.0000100.51187−2.891119−0.65
L30-52765911.35200.7152010.0000040.7059610.55910.06970.5120590.0000050.51184−3.511154−0.65
L30-615210150.43180.7068370.0000070.7038819.81650.07250.5121310.0000040.51190−2.271099−0.63
L42 pipeL42-1572730.60080.7080100.0000030.7039014.2960.08910.5121450.0000040.51186−3.031229−0.55
L42-2602620.66280.7121390.0000030.7076114.351010.08580.5121320.0000040.51186−3.071212−0.56
L42-3503440.41720.7101630.0000040.7073113.951020.08300.5121270.0000030.51187−3.001193−0.58
L42-4432850.43970.7115090.0000030.7085014.351040.08340.5121610.0000020.51190−2.361156−0.58
L42-5512480.59730.7081710.0000030.7040914.71150.07720.5121340.0000040.51189−2.521135−0.61
L42-61286470.57000.7064060.0000040.7025114.05960.08840.5121510.0000030.51187−2.861214−0.55
L1 pipeL1-11336650.57860.7078960.0000040.7039413.751150.07260.5121500.0000040.51192−1.901079−0.63
L1-21704411.11550.7111990.0000030.703579.24820.06780.5121210.0000040.51191−2.191075−0.66
L1-3979150.30630.7062040.0000050.7041117.61610.06630.5121330.0000040.51192−1.861051−0.66
L1-41369660.40570.7068470.0000070.7040718.41600.06950.5121080.0000050.51189−2.541101−0.65
L1-51623391.37890.7132320.0000040.7038017.851780.06060.5120960.0000030.51191−2.231049−0.69
L1-6957590.36210.7068660.0000040.7043917.551620.06550.5121310.0000040.51192−1.851048−0.67
L1-710610500.29060.7062130.0000040.7042216.251460.06720.5121160.0000030.51190−2.251076−0.66
L1-81283710.99460.7121010.0000040.7053017.551320.08060.5121550.0000030.51190−2.311140−0.59
L1-9879260.27050.7060860.0000070.7042415.251410.06530.5121170.0000030.51191−2.121061−0.67
L1-101774981.02850.7112010.0000080.7041711.61010.06940.5120880.0000030.51187−2.931122−0.65
L50 pipeL50-1675760.33670.7144710.0000030.712177.99610.07940.5121720.0000030.51192−1.901110−0.60
L50-2614450.39850.7079390.0000040.705216.85520.07960.5121680.0000030.51192−1.991115−0.60
L50-3382570.43230.7081960.0000040.705248.41640.07910.5121610.0000040.51191−2.091119−0.60
L50-4391940.58610.7087790.0000030.7047711.5920.07540.5121590.0000040.51192−1.921093−0.62
L50-5494170.33990.7070790.0000040.7047511.1900.07490.5121490.0000030.51191−2.071099−0.62
L50-6513800.38750.7077500.0000040.7051013.051030.07660.5121820.0000040.51194−1.531076−0.61
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MDPI and ACS Style

Zhu, R.; Ni, P.; Li, Y.; Wan, F. Petrogenesis of Transitional Kimberlite: A Case Study of the Hypabyssal Wafangdian Kimberlite in the North China Craton. Minerals 2025, 15, 1009. https://doi.org/10.3390/min15101009

AMA Style

Zhu R, Ni P, Li Y, Wan F. Petrogenesis of Transitional Kimberlite: A Case Study of the Hypabyssal Wafangdian Kimberlite in the North China Craton. Minerals. 2025; 15(10):1009. https://doi.org/10.3390/min15101009

Chicago/Turabian Style

Zhu, Renzhi, Pei Ni, Yan Li, and Fanglai Wan. 2025. "Petrogenesis of Transitional Kimberlite: A Case Study of the Hypabyssal Wafangdian Kimberlite in the North China Craton" Minerals 15, no. 10: 1009. https://doi.org/10.3390/min15101009

APA Style

Zhu, R., Ni, P., Li, Y., & Wan, F. (2025). Petrogenesis of Transitional Kimberlite: A Case Study of the Hypabyssal Wafangdian Kimberlite in the North China Craton. Minerals, 15(10), 1009. https://doi.org/10.3390/min15101009

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