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Article

Tectonic Evolution of the Hainan Island, South China: Geochronological and Geochemical Constraints from Late Permian to Early Triassic Basalts

by
Jieting Ouyang
1,2,
Guoyu Chen
1,2,
Liya Yang
1,2,
Wenqian Lu
1,2 and
Yun Zhou
1,2,*
1
Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology, Guilin 541004, China
2
Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources, Guilin University of Technology, Guilin 541006, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(3), 293; https://doi.org/10.3390/min15030293
Submission received: 18 February 2025 / Revised: 8 March 2025 / Accepted: 10 March 2025 / Published: 13 March 2025
(This article belongs to the Special Issue Advances in Mantle–Crust Interactions for Petrogenesis and Ore-Forming Processes)
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Abstract

:
The tectonic evolution of Hainan Island during the Late Permian–Early Triassic period is still unclear. This study identified two types of basalts on the island and presented detailed geochronology, whole-rock geochemistry, and Hf isotope data of the Late Permian–Early Triassic basalts. U-Pb dating results indicated that baddeleyites and zircons of one sample from Group 1 basalts had formation ages of 256 ± 3 Ma and 255 ± 3 Ma, respectively, and two samples from Group 2 gave formation ages of 241 ± 2 Ma and 240 ± 3 Ma, respectively. Both groups are characterized by negative anomalies of Nb, Ta, and Ti, and enrichment in Ba, Th, U, and K. Group 1 belongs to sub-alkaline basalt and exhibited SiO2 contents ranging from 50.50% to 51.05%, with ΣREE concentration of 136–148 ppm. Hf isotope analysis showed that the εHf(t) values of baddeleyites and zircons were −10.56 to −4.70 and −14.94 to −6.95, respectively. Group 2 belongs to alkaline basalt and had a higher SiO2 content of 52.48%–55.49% and ΣREE concentration of 168–298 ppm. They showed more depleted Hf isotopic composition with εHf(t) values ranging from −2.82 to +4.74. These data indicate that the source area of Group 1 was an enriched mantle, likely derived from partial melting of spinel lherzolite mantle, and was modified by subduction-derived fluids. Group 2 was derived from depleted mantle, most likely originating from partial melting of garnet + spinel lherzolite mantle. They were contaminated by crustal materials and metasomatized by subduction-derived fluids with a certain degree of fractional crystallization. Comprehensive analysis suggests that Group 1 samples likely formed in an island arc tectonic setting, while Group 2 formed in a continental intraplate extensional (or initial rift) tectonic setting. Their formation was mainly controlled by the Paleo-Tethys tectonic domain. Group 1 basalts implied that subduction of the Paleo-Tethys oceanic crust lasted at least in the late Permian (ca. 255 Ma). Group 2 basalts revealed that the intra-plate extensional (or initial rift) stage occurred in the middle Triassic (ca. 240 Ma).

1. Introduction

The Southeast Asian region is composed of multiple microcontinental blocks, which began to drift northward from the northern margin of the Gondwana continent under the influence of the expansion of the Paleo-Tethys Ocean to the east [1,2,3,4]. During the Late Paleozoic to Early Mesozoic period, Indosinian Orogeny, a continental collision event, occurred between the North China, South China, Indochina, and Siberian blocks [5,6]. This orogeny event led to the closure of the Paleo-Tethys Ocean, marking the basic formation of the geological structural pattern in Southeast Asia [3,7,8,9,10,11].
Hainan Island, a continental island located on the southern margin of China, is separated from the South China Block by the Qiongzhou Strait and is connected to the Indochina Block by the Beibu Gulf. It has been subjected to the dual influences of the Paleo-Tethys and Paleo-Pacific tectonic domains, experiencing a complex multi-stage crustal evolutionary history. The unique tectonic position of Hainan Island makes it an important region for studying the evolution of the South China continental margin, the formation of the South China Sea, and the timing of the transition between the Paleo-Tethys and Paleo-Pacific tectonic domains, which are key scientific issues [12,13,14,15,16].
In recent years, the origin and tectonic evolution of Hainan Island have attracted widespread attention. Although some studies have been conducted on the widely distributed Late Permian–Early Triassic granites on Hainan Island and some important results have been achieved, the study of mafic volcanic rocks, which are closely related to the concurrent tectonic evolution, is relatively poor. Mafic volcanic rocks, as a key rock type from the mantle, play an important role in constraining petrogenesis, tectonic background, and dynamic mechanisms. This study presents detailed petrological, geochemical, U–Pb geochronological, and Hf isotopic data for Late Permian to Early Triassic basalts on Hainan Island. The aims were to (1) analyze the formation age of the basalts, (2) reveal the petrogenesis and tectonic background of the basalts, and (3) discuss the tectonic evolution of the South China Block during the Late Permian–Early Triassic period.

2. Geological Background and Petrography

2.1. Geological Background

Hainan Island is located on the northwestern side of the South China Sea (Figure 1a). In terms of tectonic position, it is located at the junction of the Indochina Block, South China Block, and Pacific (Philippine) Plate, representing an overlapping area of the Paleo-Tethys and Paleo-Pacific tectonic domains. The academic community generally considers Hainan Island to be part of the South China Block [17]. However, some studies have also suggested that Hainan Island has geotectonic affinity with the Indochina Block [12,14]. Within Hainan Island, a series of SW-trending faults have developed, including the Wangwu-Wenjiao, Changjiang-Qionghai, Jianfeng-Diaoluo, and Jiusuo-Lingshui faults (Figure 1b) [18].
The stratigraphy of Hainan Island mainly consists of Cambrian quartz sandstone, siliceous rocks, carbonate rocks, Ordovician carbonate rocks, shale, siltstone, phyllite, carbonaceous slate interlayered with volcanic rocks, and Silurian clastic rocks, limestone, slate, and shallow-sea sandstone. The Mesozoic–Cenozoic strata consist of Lower Triassic coarse clastic rocks, mud shale, and Cretaceous coarse clastic rocks, mudstone, and shale interlayered with volcanic rocks, and Paleogene and Neogene terrestrial sedimentary rocks, volcanic rocks, and marine sedimentary rocks. In addition, a small number of Mesoproterozoic strata (such as the Baoban Group) and Neoproterozoic strata (such as the Shilu Group) outcrop on the island. The Baoban Group underwent regional metamorphism from high greenschist to high amphibolite facies, including the lower Gezhencun Group, which is mainly composed of plagioclase gneiss, and the upper Ewenling Group, which is composed of flysch-like sedimentary assemblages. The Shilu Group consists mainly of a volcanic-sedimentary-carbonate sequence [19,20].
Hainan Island is characterized by intense magmatic activity, with granite being the most widely distributed rock type, covering approximately 40% of the island’s area (Figure 1b) [21,22,23,24]. In addition, some Mesoproterozoic metabasic rocks, Late Paleozoic to Early Mesozoic basalts, gabbros, diorites, and Cenozoic basalts outcrop along the Changjiang-Qionghai Fault Zone [22,25].

2.2. Sampling and Petrography

In this study, two groups of basalts were identified in the western part of Hainan Island, specifically in the Bangxi area along the north of the Changjiang-Qionghai Fault Zone (Group 1) and in the Dongfang area to the south of the fault zone (Group 2). Group 1 basalt samples interbedded with granite in the Ordovician Nanbigou Formation present a gray to dark gray color, porphyritic texture, and massive structure (Figure 2a,d). The main minerals include plagioclase and pyroxene, with plagioclase predominantly occurring as short prismatic crystals, most of which underwent saussuritization. The matrix contained randomly distributed tabular plagioclase filled with fine-grained pyroxene and magnetite, forming an intergranular texture (Figure 2g,j). Accessory minerals included zircon, apatite, and magnetite. Group 2 basalts outcrop within the epizonal metamorphic rock series, interlayered between phyllite and metamorphic sandstone, presenting a light gray color, porphyritic texture, and massive structure (Figure 2b,c,e,f). The main minerals are plagioclase, pyroxene, and amphibole, with plagioclase predominantly occurring as prismatic to long-prismatic crystals and pyroxene as short prismatic crystals, uniformly distributed in the fine-grained matrix, displaying an intergranular texture. The matrix consists of volcanic glass and microcrystals of amphibole and plagioclase, with accessory minerals including apatite, zircon, and magnetite (Figure 2h,i,k,l).

3. Analytical Methods

3.1. Analysis and Testing of Major, Trace, and Rare Earth Elements

We completed the major, trace, and rare earth element testing at the Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology (GUT), and all were conducted in a pollution-free environment. The test of the major oxide was completed by using X-ray fluorescence spectroscopy (XRF), with a precision of better than 5%. The analysis of the trace and rare earth elements is carried out using the acid dissolution method and tested using an inductively coupled plasma mass spectrometer (ICP-MS), with an analysis precision generally better than 5%.

3.2. Geochronological Analysis

The selection of zircon and baddeleyite was conducted using conventional heavy liquid and magnetic techniques. Zircon and baddeleyite with large grains and perfect crystallization were selected under a binocular microscope. The picked zircon and baddeleyite grains, together with the standard sample (Temora), were mounted in epoxy resin. Subsequently, it was polished to expose the center of the zircon and baddeleyite.
The photography of transmitted light, reflected light, cathodoluminescence (CL) images, and U-Pb geochronology testing of zircon and baddeleyite were completed at the Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, GUT. The CL image was captured using an electron microprobe. By observing the CL image of zircon and baddeleyite, the internal structural and crystal morphology characteristics can be identified, providing a basis for selecting age testing points and determining the genetic type of zircon.
Zircon and baddeleyite U-Pb isotope dating analysis was conducted using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The testing was conducted using the NWR-193 laser ablation sampling system from ESI (Elemental Scientific, Inc., Omaha, NA, USA) and the 7500 laser ablation inductively coupled plasma mass spectrometry from Agilent (Agilent Technologies, Santa Clara, CA, USA). The laser spot diameter used in this experiment is 32 μm. The calculation of zircon and baddeleyite age uses standard zircon TEM (the standard age is 416.75 ± 0.24 Ma) as the external standard, and the element content uses the artificially synthesized silicate NIST610 from the National Bureau of Standards and Materials of the United States as the external standard. The processing of analytical data, U-Th-Pb isotope ratios, and age calculations were all performed using ICPMSDataCal 7.2 software, while Andersen was used for the correction of common-Pb. The plotting of the U-Pb age concordia plots and the calculation of average weight used the international standard program Isoplot3, with an analysis and calculation error of 1σ; the confidence level of the weighted average age is 95%.

3.3. Zircon and Baddeleyite Hf Isotope Analysis

The Hf isotopic analysis of zircons was conducted at the Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, GUT. Zircon and baddeleyite grains that had undergone U-Pb isotopic dating were selected for Hf isotopic analysis, with measurement points positioned as close as possible to the U-Pb testing points or at symmetrical positions within the same growth ring or in larger zircon and baddeleyite grains. The analysis was performed using a laser ablation multi-collector inductively coupled plasma mass spectrometer (LA-MS-ICP-MS) and a resolution M-50 laser ablation system, with a laser ablation spot diameter of 44 μm. The specific experimental procedures followed those described by Griffin et al. (2002) and Wu et al. (2006) [26,27]. The calculation of εHf used the 176Lu decay constant of 1.867 × 10−10/a [28]. For the calculation of εHf(t) and Hf model ages, the 176Hf/177Hf ratios for chondritic and depleted mantle were adopted as 0.282772 [29] and 0.28325 [26], respectively. For the calculation of the single-stage Hf model age (tDM1), the 176Hf/177Hf ratio for the depleted mantle was 0.28325, and the 176Lu/177Hf ratio was 0.0384. For the two-stage model age calculation, the average crustal 176Lu/177Hf ratio was 0.015, and the fcc was −0.55 [26].

4. Results

4.1. Zircon and Baddeleyite Geochronology

The U-Pb dating results of zircon and baddeleyite grains from Group 1 and 2 basalts are presented in Table 1. The zircon grains are light brown to brown, subhedral to euhedral, prismatic, and semi-transparent to transparent, with a length of 40–120 μm. The majority of the zircons are morphologically intact, with significant oscillatory zoning developed within the crystal interiors (Figure 3), and their Th/U ratios are generally >0.1 (Table 1), which is consistent with the typical characteristics of magmatic zircons [30,31]. The baddeleyite grains are dark gray and prismatic, with a length of 30–100 μm (Figure 3a).
Group 1: Six baddeleyite grains and twenty-two zircon grains were obtained from basalt sample 16BX34B. The results showed that the Th/U ratios of the six baddeleyite grains are 1.07–13.13 (Table 1). They yielded a coherent group with a 206Pb/238U weighted mean age of 256 ± 3 Ma (MSWD = 0.10) (Figure 3a), interpreted to represent the eruption age of the sample. The Th/U ratios of the twenty-two zircon grains are mainly 0.89–25.85 (Table 1). Five of the grains had 206Pb/238U ages of 257–254 Ma with a weighted mean age of 255 ± 3 Ma (MSWD = 0.13) (Figure 3b), representing its formation age. A few ~95 Ma zircons were obtained, and they likely reflect a regional metamorphic thermal event during the Late Cretaceous, as evidenced by their bright morphology (Figure 3b). Some of them showed high Th/U ratios (>20), similar to zircon modified by fluid [30,32].
Group 2: Twenty zircons from sample 16DF48C were analyzed. Their Th/U ratios are mainly 0.02–1.14 (Table 1). Eleven of the spots yielded a coherent group with a 206Pb/238U weighted mean age of 241 ± 2 Ma (MSWD = 0.23) (Figure 3c), interpreted to represent the eruption age of the sample. Eighteen grains from sample 16DF48D were analyzed. Their Th/U ratios are 0.20–2.02 (Table 1). Fourteen of the grains had 206Pb/238U ages of 245–228 Ma with a weighted mean age of 240 ± 3 Ma (MSWD = 0.11) (Figure 3d), representing its formation age.

4.2. Zircon and Baddeleyite Hf Isotopes

Baddeleyite from the Group 1 basalt samples had 176Lu/177Hf values of 0.005814–0.043853 and 176Hf/177Hf values of 0.282425–0.282580 (Table 2). Their εHf(t) values (t is the formation age based on 206Pb/238U weighted mean age, i.e., t = 256 Ma) were −10.56 to −4.70 with two-stage model age (tDM2) of 1579–1291 Ma (Figure 4). Zircon from the Group 1 basalt samples had 176Lu/177Hf values of 0.016649–0.052749 and 176Hf/177Hf values of 0.282432–0.282525 (Table 2). Their εHf(t) values (t is the formation age based on 206Pb/238U weighted mean age, i.e., t = 255 Ma) were −14.94 to −6.95 with a two-stage model age (tDM2) of 1794–1402 Ma (Figure 4).
The Group 2 basalt samples had 176Lu/177Hf ratios of 0.000337–0.002559, with the majority being <0.002, indicating an extremely low accumulation of radiogenic Hf in the zircons after their formation. Their 176Hf/177Hf ratios were 0.282121–0.282768. The εHf(t) values (t is the formation age based on 206Pb/238U weighted mean age, i.e., t = 240 Ma) were −2.82 to +4.74 (Figure 4), with a two-stage model age (tDM2) of 1186–810 Ma.

4.3. Major and Trace Elements

The chemical composition data of the Late Permian–Early Triassic basalt samples are presented in Table 3. The Group 1 samples were similar to those of the sub-alkaline basalts (Figure 5). They have SiO2 contents of 50.50%–51.05% (average = 50.83%), MgO contents of 5.72%–5.77% (average = 5.76%), Fe2O3T contents of 11.47%–11.73% (average = 11.66%), TiO2 contents of 1.43%–1.47% (average = 1.45%), Al2O3 contents of 15.87%–16.14% (average = 16.00%), total alkali (K2O + Na2O) contents of 4.90%–5.01% (average = 4.95%), K2O/Na2O ratios of 0.76–0.82 (average = 0.80), Ni contents of 25.67–28.42 ppm (average = 27.36 ppm), Cr contents of 40.0–48.5 ppm (average = 44.2 ppm), and Mg# values of 53–54 (average = 54).
In contrast to Group 1, the Group 2 samples were alkaline basalts (Figure 5). They have higher SiO2 contents (52.48%–55.49%, average = 53.60%), Al2O3 contents (15.60%–15.77%, average = 15.67%), and total alkali (K2O + Na2O) contents (4.14%–7.71%, average = 5.37%), but lower MgO contents (3.46%–5.27%, average = 4.67%), Fe2O3T contents (6.84%–8.45%, average = 7.88%), TiO2 contents (1.04%–1.52%, average = 1.22%), and K2O/Na2O ratios (0.22–0.92, average = 0.45). Moreover, their Ni contents (26.84–48.80 ppm, average = 42.24 ppm), Cr contents (60–160.07 ppm, average = 125.06 ppm), and Mg# values (54–60, average = 58) are higher than those of Group 1.
The total rare earth element content (ΣREE) of Group 1 ranged from 136 to 148 ppm (average = 142 ppm). The total light rare earth element (ΣLREE) contents (112–123 ppm) were relatively enriched compared to the total heavy rare earth element (ΣHREE) contents (23.5–25.2 ppm), with ΣLREE/ΣHREE ratios ranging from 1.60 to 1.64. Their (La/Yb)N and (Gd/Yb)N were 4.56–4.61 and 1.21–1.36, respectively, with a slightly negative Eu anomaly (δEu = 0.81–0.86). The chondrite-normalized REE pattern diagrams (Figure 6a) exhibited a right-leaning REE-normalized pattern. In the trace element spider diagrams (Figure 6b), there are negative anomalies of Nb, Ta, and Ti, and enrichments in Ba, Th, U, and K. Compared to Group 1, Group 2 had higher ΣREE contents (168–298 ppm), with ΣLREE of 153–279 ppm, ΣHREE of 15.1–21.0 ppm, and ΣLREE/ΣHREE ratios of 10.11–14.32. They had higher (La/Yb)N (12.91–22.65) and (Gd/Yb)N (2.06–2.97) ratios and a slight negative Eu anomaly (δEu = 0.80–0.91) (Figure 6c). They showed obviously negative anomalies of Nb, Ta, and Ti and enrichment in Ba, Th, U, and K (Figure 6d).

5. Discussion

5.1. Petrogenesis of the Basalts

5.1.1. Group 1 Basalts

εHf(t) values are a key indicator to reveal the nature of the magma source area. Specifically, positive εHf(t) values suggest that the magma source area may originate from depleted mantle or newly formed crust derived from depleted mantle, while negative values imply that the source area is primarily enriched mantle or mainly composed of ancient crustal materials [26,38]. The εHf(t) values of baddeleyites and zircons from Group 1 samples range from −10.56 to −4.70 and −14.94 to −6.95, respectively, located below the chondritic evolution line, indicating an enriched mantle source (Figure 4).
The Nb/La (average = 0.37) and Ce/Pb (average = 9.2) ratios of Group 1 were significantly lower than the typical values for MORB and OIB, which were unaffected by crustal contamination (Nb/La = 1.0, Ce/Pb = 25 ± 5) [39]. The Th/La (average = 0.32) ratios were higher than that of N-MORB (0.05) but lower than that of the crust (0.3) [40]. These characteristics are similar to those of a mantle source modified by slab-derived fluids and melts [41,42,43]. In terms of trace elements, they are characterized by enrichment in LILEs and LREEs and depletion in Nb, Ta, and Ti (Figure 6a,b), which is consistent with the characteristics of typical arc volcanic rocks and is also similar to the mafic rocks from Hainan Island that have been modified by subduction-related fluids or melts [22]. Furthermore, Group 1 samples show high Ba/Y ratios but low Nb/Y ratios (Figure 7a), indicating fluid-related enrichment. The plot of Nb/Zr versus Th/Zr (Figure 7b) shows a fluid enrichment trend, suggesting that the mantle source may have experienced metasomatic events caused by fluids derived from the subducting slab.
The REE compositions of mafic rocks can reveal the nature of the magma source area and the degree of partial melting. When (Gd/Yb)N < 2 and (Tb/Yb)N < 1.8, it indicates that the magma source area is likely derived from spinel lherzolite mantle; conversely, higher ratios suggest that the source area is more likely to be garnet lherzolite mantle [44,45]. The (Gd/Yb)N (1.21–1.36) and (Tb/Yb)N (1.19–1.26) ratios of Group 1 are less than 2 and 1.8, respectively, indicating that its source area is from the spinel lherzolite mantle. In the plots of Sm/Yb versus Sm and Dy/Yb versus Yb (Figure 8a,b), the Group 1 samples are close to the melting curve of spinel lherzolite, further indicating that the magma source area is spinel lherzolite mantle, with a partial melting degree of approximately 3% to 5%.
Additionally, the average Mg# of Group 1 is 54, with average Cr and Ni contents of 44.2 ppm and 27.39 ppm, respectively, which are significantly lower than those of the primitive mantle (Mg# = 68–72; Cr = 300–500 ppm; Ni = 300–400 ppm) [46]. This indicates that the Group 1 magma underwent fractional crystallization of olivine and pyroxene during its evolution. The weak negative anomalies of Eu and Sr (Figure 6a,b) suggest fractional crystallization of plagioclase during the formation and evolution of the magma [47].
In summary, the source area of the Group 1 samples was enriched mantle. They were derived from the partial melting of the spinel lherzolite mantle and modified by subduction-derived fluids with a certain degree of fractional crystallization.

5.1.2. Group 2 Basalts

Group 2 samples exhibit predominantly positive εHf(t) values (Figure 4), indicating that the magma source area was primarily a depleted mantle. The Nb/U (average = 7.9), Nb/La (average = 0.38), and Ce/Pb (average = 5.2) ratios were significantly different from the typical values for MORB and OIB (Nb/U = 47 ± 10, Nb/La = 1.0, Ce/Pb = 25 ± 5) [39], suggesting that the magma was metasomatized by subduction-derived fluids during its formation. They showed high Ba/Y and low Nb/Y ratios (Figure 7a), indicating fluid-related elemental enrichment. In the Nb/Zr versus Th/Zr diagram (Figure 7b), they are also characterized by fluid enrichment, suggesting that they may have experienced interactions between fluids released from the subducting slab and the mantle wedge. Additionally, their Nb/Ta (average = 17.64) and Zr/Hf (average = 37.12) ratios were similar to that of primitive mantle (Nb/Ta = 17.5 ± 2.0, Zr/Hf = 36.27 ± 2.0) [48]. However, their Th/Ta (7.34–9.85) ratios are significantly higher than those of the primitive mantle (Th/Ta = 2.3) [49] but similar to that of the continental crust (Th/Ta = 10) [49]. Zircon Hf isotopic data show that some zircons have negative εHf(t) values (Figure 4). These data suggest that the mantle source was contaminated with crustal material. In the plots of Sm/Yb versus Sm and Dy/Yb versus Yb (Figure 8a,b), Group 2 samples are located within the distribution range of garnet + spinel lherzolite, indicating their magma source is garnet + spinel lherzolite mantle, with an estimated partial melting degree of 1%–5%.
The average Mg# of Group 2 is 58, with average Cr and Ni contents of 125 ppm and 27.2 ppm, respectively, which are significantly lower than those of the primitive mantle (Mg# = 68–72; Cr = 300–500 ppm; Ni = 300–400 ppm). This indicates that they underwent a certain degree of fractional crystallization of olivine and pyroxene. The weak negative Eu anomaly (Figure 6c,d) indicates that crystallization of plagioclase occurred during magma evolution.
In conclusion, the source area of Group 2 basalts is a depleted mantle contaminated by crustal materials. It is a product of the partial melting of garnet + spinel lherzolite mantle and has experienced metasomatism due to subduction-derived fluids, with a certain degree of fractional crystallization.

5.2. Tectonic Setting

The Chondrite-normalized REE pattern of Group 1 samples displays a rightward-inclined distribution pattern (Figure 6a,c), with a negative Eu anomaly. On the primitive mantle-normalized incompatible element spider diagrams (Figure 6b,d), they are characterized by enrichment in large ion lithophile elements (LILEs, such as Rb and Ba) and depletion in high field strength elements (HFSEs, such as Th and U), with distinctly negative Nb and Ta anomalies. These characteristics are similar to that of island arc volcanic rocks [50]. Group 1 samples had low Nb/Zr (average = 0.04) and Ta/Hf (average = 0.09) ratios, and high Th/Ta ratios (average = 13.7), similar to that of island arc basalts (Nb/Zr < 0.04, Ta/Hf < 0.1, Th/Ta > 1.6) [51,52]. As shown in Figure 9a, Group 1 exhibits characteristics of continental arc basalts (CAB). This evidence indicates that the Group 1 samples were formed in an island arc tectonic setting.
Group 2 samples generally show geochemical features similar to those of the OIB (Figure 6c,d). Their Nb/Zr ratios (average = 0.07) are similar to those of continental intraplate basalts (Nb/Zr > 0.04) [51]. Previous studies have shown that typical rift basalts have Th/Ta ratio of 1.6–4, basalts from intra-continental extensional zones (or initial rifts) have Th/Ta ratios greater than 4 (generally 4–10), and basalts from orogenic belts formed by continent–continent collision have Th/Ta ratios greater than 10 [52]. Group 2 samples have Th/Ta ratios (average = 9.0) greater than 4 but less than 10, similar to basalts from intra-continental extensional zones (or initial rifts). In the plot of Th/Zr-Nb/Zr (Figure 9b), Group 2 samples fall within the area of the continental extensional zone (or initial rift). The above evidence indicates that Group 2 basalts formed in a continental intraplate extensional (or initial rift) tectonic setting.

6. Geological Significance

Late Paleozoic to Early Mesozoic igneous rocks are widespread along the Jinshajiang, Ailaoshan, and Song Ma suture zones in the southwestern South China Block (Figure 1a), and their formation is related to subduction-collision events of Paleo-Tethys Ocean, as evidenced by the Carboniferous ophiolites or ophiolitic mélange in the Jinshajiang, Ailaoshan, and Song Ma areas. These ophiolites or ophiolitic mélange represent remnants of the Paleo-Tethys Ocean between the South China and Indochina blocks [53,54,55,56,57]. In addition, within the Ailaoshan suture zone, 287 Ma MORB-type basalts and 265 Ma subduction-related basalts have been identified, indicating that the Ailaoshan area was in an arc setting during the Late Permian [58]. The formation of 252 Ma and 248 Ma granites indicates the closure of the branch ocean basin [59]. In the Jinshajiang suture zone, there are 271 Ma granites [60] and 254–247 Ma tuffs [61], indicating the persistence of arc magmatic activity during the Late Permian to Early Triassic. The identification of 247–246 Ma rhyolites is considered a geological record of the initial collision between the Indochina and Yangtze blocks [62]. The 234–231 Ma granites formed in a post-collisional setting [63]. The development of ca. 275 Ma igneous rocks in the Song Ma suture zone indicates the presence of a branch ocean or back-arc basin of the Paleo-Tethys Ocean [64]. Late Permian (272–253 Ma) calc-alkaline, volcanic-plutonic, and peraluminous granite assemblages reflect the tectonic setting of an active continental margin [65,66]. The formation of the Early Triassic (ca. 250 Ma) S-type granites indicates that the branch ocean or back-arc basin of the Paleo-Tethys Ocean was closed, followed by a collision with the South China Block [67,68].
Previous studies have shown that Hainan Island records a large number of 345–245 Ma magmatic rocks, including basalts, andesites, mafic intrusive rocks, gabbro-diorites, and I-type granites, which are generally considered to have formed in an island arc setting [14,22,25,69,70,71,72,73,74,75,76]. This study identified 255 Ma basalts (Group 1) on Hainan Island that formed in an island arc tectonic setting, as discussed above. The widespread 272–262 Ma I-type granites along the Jiusuo-Lingshui and Changjiang-Qionghai faults were considered to have resulted from arc magmatism caused by the subduction of the Paleo-Tethys oceanic crust [69,75], further supporting an island arc tectonic setting during the Late Paleozoic. In addition, ca. 240 Ma basalts (Group 2), which formed in an intraplate extensional or initial rift tectonic setting, were also identified in this study. It is worth noting that the Carboniferous (ca. 330 Ma) Bangxi-Chenxing ophiolite outcrops in northwestern Hainan Island [14,73] indicate that the Late Paleozoic to Early Mesozoic tectonic evolution of Hainan Island was mainly controlled by the Paleo-Tethys tectonic domain. Taking the above data into consideration, the evolution of Paleo-Tethys recorded on Hainan Island can be summarized as follows. The opening of the Paleo-Tethys Ocean Basin occurred at least earlier than the Late Carboniferous, as evidenced by the ca. 330 Ma Bangxi-Chenxing ophiolite [14,73]. The subduction of the Paleo-Tethys oceanic crust lasted at least in the late Permian, as demonstrated by Group 1 ca. 255 Ma basalts in this study. The initial rift or intra-plate extensional stage occurred in the middle Triassic, as evidenced by Group 2 ca. 240 Ma basalts (this study) and 244–230 Ma A-type granites and bimodal volcanic rocks on the island [22,71,77]. The closure of the Paleo-Tethys Ocean Basin can be inferred at 255–244 Ma.

7. Conclusions

  • Hainan Island recorded two different types of basalts. Group 1 basalts formed at ca. 255 Ma and are sub-alkaline basalts. Their εHf(t) values of baddeleyites and zircons were −10.56 to −4.70 and −14.94 to −6.95, respectively. Two samples from Group 2 basalts dated to 241 ± 2 Ma and 240 ± 4 Ma, respectively. They belong to alkaline basalts, and their εHf(t) values were −2.82 to +4.74, with tDM2 of 1186–810 Ma.
  • Group 1 basalts were derived from enriched mantle, likely from partial melting of the spinel lherzolite mantle, and modified by subduction-derived fluids, with a certain degree of fractional crystallization. They were formed in an island arc tectonic setting. Group 2 basalts originated from depleted mantle and were contaminated by crustal material. They were likely produced by partial melting of the garnet + spinel lherzolite mantle and were metasomatized by subduction-derived fluids. They likely formed in a continental intraplate extensional (or initial rift) tectonic setting.
  • The formation of the two groups of basalt is related to the evolution of the Paleo-Tethys. Group 1 basalts revealed that subduction of the Paleo-Tethys oceanic crust lasted at least in the late Permian. Group 2 basalts indicate that the initial rift or intra-plate extensional stage occurred during the Middle Triassic.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/min15030293/s1, Table S1: Tectonic Evolution of the Hainan Island, South China: Geochronological and Geochemical Constraints from Late Permian to Early Triassic Basalts.

Author Contributions

Conceptualization, J.O. and Y.Z.; methodology, G.C., L.Y. and W.L.; software, J.O. and W.L.; validation, Y.Z.; formal analysis, G.C.; investigation, J.O., L.Y. and Y.Z.; resources, Y.Z.; data curation, Y.Z.; writing—original draft preparation, J.O.; writing—review and editing, Y.Z.; visualization, Y.Z.; supervision, Y.Z.; project administration, Y.Z.; funding acquisition, Y.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China (Grant No. 42372102) and the Guangxi Key R&D Program (Grant No. Guike AB22035045).

Data Availability Statement

The original contributions presented in this study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author(s).

Acknowledgments

We sincerely appreciate the insightful comments and constructive suggestions from the reviewers and editorial team, which have significantly improved the quality of this manuscript.

Conflicts of Interest

The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

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Figure 1. (a) Tectonic outline of Southeast Asia, and (b) regional geological map of Hainan Island.
Figure 1. (a) Tectonic outline of Southeast Asia, and (b) regional geological map of Hainan Island.
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Figure 2. Basalt samples (a–f) and microscopic images (g–l) from the Bangxi and Dongfang areas of Hainan Island; (a–c) massive texture; (d–f) porphyritic basalt with uniformly distributed dark phenocrysts; (g–i) intergranular texture with randomly distributed plagioclase microlites in the matrix; (j) Carlsbad twinning of orthoclase; (k) polysynthetic twinning in plagioclase; (l) alteration and saussuritization of garnet. Pl—plagioclase; Px—pyroxene; Chl—chlorite; Hbl—hornblende; Or—orthoclase.
Figure 2. Basalt samples (a–f) and microscopic images (g–l) from the Bangxi and Dongfang areas of Hainan Island; (a–c) massive texture; (d–f) porphyritic basalt with uniformly distributed dark phenocrysts; (g–i) intergranular texture with randomly distributed plagioclase microlites in the matrix; (j) Carlsbad twinning of orthoclase; (k) polysynthetic twinning in plagioclase; (l) alteration and saussuritization of garnet. Pl—plagioclase; Px—pyroxene; Chl—chlorite; Hbl—hornblende; Or—orthoclase.
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Figure 3. Concordia diagrams of the LA-ICP-MS zircon and baddeleyite analyses and representative cathodoluminescence (CL) images of the Late Permian to Early Triassic basalts from Hainan Island. (a) 16BX34B, baddeleyite; (b) 16BX34B, zircon; (c) 16DF48C, zircon; (d) 1 6DF48D, zircon.
Figure 3. Concordia diagrams of the LA-ICP-MS zircon and baddeleyite analyses and representative cathodoluminescence (CL) images of the Late Permian to Early Triassic basalts from Hainan Island. (a) 16BX34B, baddeleyite; (b) 16BX34B, zircon; (c) 16DF48C, zircon; (d) 1 6DF48D, zircon.
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Figure 4. Plot of zircon and baddeleyite U-Pb age (Ma) versus εHf(t) of the Late Permian to Early Triassic basalts from Hainan Island.
Figure 4. Plot of zircon and baddeleyite U-Pb age (Ma) versus εHf(t) of the Late Permian to Early Triassic basalts from Hainan Island.
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Figure 5. Plot of Zr/TiO2 × 10−4 versus Nb/Y of the Late Permian to Early Triassic basalts from Hainan Island. Data sources are listed in Table S1.
Figure 5. Plot of Zr/TiO2 × 10−4 versus Nb/Y of the Late Permian to Early Triassic basalts from Hainan Island. Data sources are listed in Table S1.
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Figure 6. Chondrite-normalized REE pattern (a,c) and primitive mantle-normalized incompatible element spider diagrams (b,d) of the Late Permian to Early Triassic basalts from Hainan Island. Chondrite- and primitive mantle-normalized values are from [33]. The Late-Permian subduction-related mafic rocks from the Sanjiang Orogenic Belt and the Indochina Block are from [34] and [35], respectively; the Early Triassic post-collisional mafic rocks from the Sanjiang Orogenic Belt and the Indochina Block are from [36] and [37], respectively.
Figure 6. Chondrite-normalized REE pattern (a,c) and primitive mantle-normalized incompatible element spider diagrams (b,d) of the Late Permian to Early Triassic basalts from Hainan Island. Chondrite- and primitive mantle-normalized values are from [33]. The Late-Permian subduction-related mafic rocks from the Sanjiang Orogenic Belt and the Indochina Block are from [34] and [35], respectively; the Early Triassic post-collisional mafic rocks from the Sanjiang Orogenic Belt and the Indochina Block are from [36] and [37], respectively.
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Figure 7. Plots of (a) Ba/Y versus Nb/Y and (b) Nb/Zr versus Th/Zr of the Late Permian to Early Triassic basalts from Hainan Island. Data sources are the same as in Figure 5.
Figure 7. Plots of (a) Ba/Y versus Nb/Y and (b) Nb/Zr versus Th/Zr of the Late Permian to Early Triassic basalts from Hainan Island. Data sources are the same as in Figure 5.
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Figure 8. Plots of (a) Sm/Yb versus Sm and (b) Dy/Yb versus Yb of the Late Permian to Early Triassic basalts from Hainan Island. Data sources are the same as in Figure 5.
Figure 8. Plots of (a) Sm/Yb versus Sm and (b) Dy/Yb versus Yb of the Late Permian to Early Triassic basalts from Hainan Island. Data sources are the same as in Figure 5.
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Figure 9. Plots of (a) ThN-MORB versus NbN-MORB (N-MORB normalize values are from [33]) and (b) Th/Zr versus Nb/Zr of the Late Permian to Early Triassic basalts from Hainan Island. Abbreviations: AB: alkaline ocean-island basalt; CAB: calc-alkaline basalt; D-MORB: depleted-type MORB; E-MORB: enriched-type MORB; G-MORB: garnet-influenced MORB; N-MORB: normal-type MORB; IAT: island arc tholeiite; MTB: medium-Ti basalt; SSZ: supra-subduction zone; I. N-MORB Zone; II. Plate Convergence Boundaries (II1. Oceanic Island Arc Basalts, II2. Continental Margin Arc Basalts); III. Oceanic Plate Interior; IV. Continental Plate Interior (IV₁. Continental Initial Rift and Continental Margin Rift Tholeiitic Basalts, IV2. Continental Extensional Zone Basalts, IV₃. Continent–Continent Collision Zone Basalts); V. Mantle Plume Basalts. Data sources are the same as in Figure 5.
Figure 9. Plots of (a) ThN-MORB versus NbN-MORB (N-MORB normalize values are from [33]) and (b) Th/Zr versus Nb/Zr of the Late Permian to Early Triassic basalts from Hainan Island. Abbreviations: AB: alkaline ocean-island basalt; CAB: calc-alkaline basalt; D-MORB: depleted-type MORB; E-MORB: enriched-type MORB; G-MORB: garnet-influenced MORB; N-MORB: normal-type MORB; IAT: island arc tholeiite; MTB: medium-Ti basalt; SSZ: supra-subduction zone; I. N-MORB Zone; II. Plate Convergence Boundaries (II1. Oceanic Island Arc Basalts, II2. Continental Margin Arc Basalts); III. Oceanic Plate Interior; IV. Continental Plate Interior (IV₁. Continental Initial Rift and Continental Margin Rift Tholeiitic Basalts, IV2. Continental Extensional Zone Basalts, IV₃. Continent–Continent Collision Zone Basalts); V. Mantle Plume Basalts. Data sources are the same as in Figure 5.
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Table 1. LA-ICP-MS zircon and baddeleyite U-Pb isotopic dating results of the basalts from the Bangxi-Dongfang in Hainan Island.
Table 1. LA-ICP-MS zircon and baddeleyite U-Pb isotopic dating results of the basalts from the Bangxi-Dongfang in Hainan Island.
NO.Th/UIsotope RatioAge (Ma)
207Pb/206Pb1σ207Pb/235U1σ206Pb/238U1σ207Pb/206Pb1σ207Pb/235U1σ206Pb/238U1σ
Sample 16BX34B, baddeleyite
13.410.05120.00350.28170.01820.04010.0007250157252142544
21.070.05130.00390.28620.02090.04040.0009257174256162556
36.550.05080.00160.28490.00940.04060.00042356925572562
413.130.05200.00290.28950.01580.04060.0006287128258122574
510.790.05150.00140.28610.00780.04030.00042655625562552
68.810.05150.00200.28830.01330.04040.000826589257102555
Sample 16BX34B, zircon
11.500.05010.00300.29090.01590.04060.0008198139259132575
23.910.06270.00250.12110.00480.01410.0002698881164901
35.200.06320.00510.13220.01050.01470.00027151381269941
43.040.06330.00840.14690.01920.01680.0004720290139171073
50.890.05050.00090.28170.00620.04030.00052203625252553
65.570.05740.00440.13880.00840.01540.00035062031327982
75.190.05530.00600.13340.00950.01510.00034332421278972
86.950.06650.00800.12370.01560.01370.000483325411814883
92.820.05210.00130.28980.00780.04010.00043005625862543
108.480.06320.00770.11170.01510.01280.000571725910814823
115.640.05380.00140.47340.01450.06340.001036559394103966
128.510.05110.00220.28110.01170.04050.00062569825292563
1318.840.06160.00980.13160.02110.01540.000666134412619994
1417.050.05510.00570.15630.01200.01710.0004417233147111093
1520.030.06770.00780.12800.01140.01410.000486124312210912
1620.390.06220.01230.12730.02580.01460.000668043212223944
1725.850.06000.00500.33360.02820.04050.0014606181292212569
1827.270.06530.00300.12960.00620.01440.0002783951246921
1922.460.06570.00380.14710.00890.01590.00027989213981021
2042.370.06510.00310.13760.00620.01490.00027891001316951
2124.050.06720.00790.12330.01460.01350.000684324111813864
226.280.06080.00230.53610.02920.06330.0020632864361939512
Sample 16DF48C, zircon
10.820.05300.00400.13600.00710.01490.00033321751296952
20.850.06300.00350.10760.00620.01240.00037061191046792
30.030.05310.00130.28040.00740.03830.00043325725162423
40.900.04920.00640.20150.01090.01790.000516727218691143
50.160.05990.00540.69660.06350.08410.00215981965373852013
61.140.06540.00290.11260.00470.01250.0002787881084801
70.870.05290.00210.28000.01120.03820.00043248925192423
80.200.04920.00170.25610.00930.03780.00061548023182393
90.020.05150.00180.26950.00990.03780.00042657724282393
100.020.05140.00100.27130.00550.03820.00042574324442422
110.090.07360.00420.62670.03820.06140.001010311104942438411
120.270.04940.00390.25460.01740.03780.0009165174230142395
130.090.05200.00090.27490.00550.03830.00042834124742422
140.030.07280.00420.38340.02170.03810.000810091173301624114
150.810.05190.00120.27120.00750.03780.00062805224462394
160.120.05260.00140.27430.00750.03780.00043095924662392
170.170.08560.00172.57320.05660.21730.0024132934129316126817
180.360.05070.00130.26640.00660.03800.00042285724052402
190.550.09310.00213.20220.07200.24890.0027150042145817143314
200.190.09370.00403.48480.13800.27040.0067150282152431154334
Sample 16DF48D, zircon
11.980.05430.00580.44640.02580.03790.0011383244375182407
21.490.05220.00920.40510.03700.03830.0013295359345272438
31.590.04770.00660.31660.03030.03760.001287313279232388
40.200.04880.00440.24970.02140.03760.0010139200226172386
51.760.04890.00680.40240.02650.03790.0013143296343192408
60.420.05560.00270.28730.01410.03790.0008435106256112405
70.290.05510.00180.45740.01500.06080.000641774382103814
82.020.05430.01010.36900.04080.03840.00233833703193024314
90.290.04870.00460.18820.01160.01720.0004200139175101103
101.040.05470.00430.36160.01770.03820.0007467176313132424
111.340.05730.01190.37900.03710.03880.00165064003262724510
121.780.05130.02060.37100.08050.03770.00222577263206023914
130.250.05370.00210.44690.02050.06020.001236795375143777
141.270.05640.00420.39250.01880.03810.0007478164336142414
151.230.05230.00910.33640.03900.03850.0015298356294302449
161.290.04730.00420.35020.01900.03770.000865200305142395
170.840.05450.00590.13070.01090.01590.0004394243125101023
181.330.09310.02960.37810.07390.03610.003815006373265422823
Table 2. Analyzed results of zircon and baddeleyite in situ Hf isotopic compositions of the basalts from the Bangxi-Dongfang in Hainan Island.
Table 2. Analyzed results of zircon and baddeleyite in situ Hf isotopic compositions of the basalts from the Bangxi-Dongfang in Hainan Island.
No.176Hf/177Hf2σ176Lu/177Hf2σ176Yb/177Hf2σAge/MaεHf(t)2σTDM2/Ma
Sample 16BX34B, baddeleyite
10.2825750.0000200.0352050.0010830.0011510.299921254−7.320.711420
20.2824250.0000190.0231030.0007960.0012890.458691255−10.560.671579
30.2824860.0000240.0295390.0010220.0010620.293931256−9.490.841527
40.2825470.0000240.0229460.0007600.0008770.325695257−6.250.831367
50.2825800.0000250.0438530.0015450.0014990.274112255−8.570.871482
60.2825080.0000250.0058140.0002390.0002560.302946255−4.700.871291
Sample 16BX34B, zircon
10.2825250.0000250.0226200.0007140.0007030.276865257−6.950.871402
50.2824320.0000250.0381540.0013040.0015270.331220255−12.850.861692
60.2826060.0000240.0157100.0005500.0005310.27316998−2.910.851202
90.2824430.0000210.0527490.0018650.0022040.333836254−14.940.741794
100.2826320.0000220.0221980.0009210.0011330.34738582−3.090.761211
120.2824430.0000220.0166490.0005740.0006240.307513256−8.850.761495
130.2826740.0000270.0259160.0008420.0008340.27988799−2.230.931169
160.2825980.0000250.0268900.0009550.0008780.25873094−5.100.891310
Sample 16DF48C, zircon
10.2826350.0000360.0018300.0000790.0604820.002213950.121.271040
20.2826330.0000290.0015370.0000090.0536660.000268790.121.031040
30.2826530.0000280.0005280.0000070.0191680.0002792420.990.98997
80.2825460.0000280.0006190.0000130.0212460.000363239−2.820.971186
90.2826850.0000280.0017850.0000620.0443420.0018632391.920.97950
100.2827160.0000260.0017480.0000080.0517230.0002432423.000.92896
130.2827680.0000200.0023920.0000650.0552430.0017462424.740.70810
150.2825880.0000430.0025590.0000200.0567630.000656239−1.631.501126
160.2826200.0000340.0003370.0000330.0110510.000932239−0.161.211054
170.2821210.0000220.0011790.0000620.0294180.0012991329−17.960.771929
180.2827160.0000420.0017190.0000690.0427850.0020742403.021.48896
Table 3. Major elements (in wt.%), trace elements, and REEs (in ppm) compositions of the basalts from the Bangxi-Dongfang in Hainan Island.
Table 3. Major elements (in wt.%), trace elements, and REEs (in ppm) compositions of the basalts from the Bangxi-Dongfang in Hainan Island.
SampleGroup1Group2
16BX34B16BX34B116BX34B216BX34B316DF48C16DF48C116DF48C216DF48C316DF48D16DF48D1
SiO251.0550.8150.9750.5052.4852.7352.8452.7355.4955.31
TiO21.431.471.471.441.041.101.101.101.441.52
Al2O316.1415.9616.0215.8715.6015.6015.6615.6715.7715.71
Fe2O3T11.4711.7311.6911.738.018.438.458.456.847.10
MgO5.725.775.775.775.195.265.275.243.463.60
CaO7.767.837.877.907.377.547.537.534.274.31
K2O2.142.232.232.180.780.820.820.823.513.68
Na2O2.802.732.782.713.493.333.363.384.204.01
MnO0.200.200.200.200.110.120.120.120.100.11
P2O50.240.250.250.250.390.390.390.390.700.69
LOI0.940.770.80.714.384. 474.484.583.333.41
Total99.8999.76100.0599.2698.8499.78100.02100.0299.1199.46
Mg#54535453605959595454
V214179192203163126138142135114
Cr40.043.744.848.51501451571606078.1
Ga22.33.433.743.8520.83.363.653.771913.5
Rb26726027829128.525.727.829.1113111
Sr321278295312997833888919657604
Y39.733.236.136.821.817.218.719.426.623.1
Zr241217232244212186203203360359
Nb9.78.979.379.9513.812.914.113.925.727.3
Cs52.651.55456.61.020.981.061.062.12.18
Ba1861801972042322142312231040999
La25.725.125.627.340.836.139.738.164.161.1
Ce55.652.953.858.483.973.781.477.3134130
Pr6.486.396.677.049.688.749.489.1414.715
Nd25.420.120.621.836.426.328.127.154.244
Sm5.816.046.086.476.66.356.846.439.5110.3
Eu1.741.61.641.751.831.541.681.582.492.56
Gd6.65.835.896.215.425.045.495.27.37.97
Tb1.051.091.11.150.790.790.870.811.16
Dy6.776.466.436.854.183.964.43.955.065.31
Ho1.461.361.341.450.860.760.830.770.950.99
Er4.133.613.543.862.331.912.081.942.512.42
Tm0.610.610.620.650.310.310.340.310.340.37
Yb4.013.943.984.261.921.992.21.962.032.4
Lu0.580.570.590.630.290.290.320.30.290.35
Hf5.86.136.216.475.45.556.065.428.210.3
Ta0.60.610.580.640.70.810.890.771.31.65
Th7.548.658.458.726.897.988.547.569.5412.2
U1.41.51.471.581.451.591.721.483.875.04
W43.393.113.6510.50.580.4910.89
∑HREE25.223.523.525.116.115.116.515.219.521
∑LREE121112114123179153167160279263
∑REE146136138148195168184175298284
δEu0.860.810.830.830.910.80.810.810.880.83
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Ouyang, J.; Chen, G.; Yang, L.; Lu, W.; Zhou, Y. Tectonic Evolution of the Hainan Island, South China: Geochronological and Geochemical Constraints from Late Permian to Early Triassic Basalts. Minerals 2025, 15, 293. https://doi.org/10.3390/min15030293

AMA Style

Ouyang J, Chen G, Yang L, Lu W, Zhou Y. Tectonic Evolution of the Hainan Island, South China: Geochronological and Geochemical Constraints from Late Permian to Early Triassic Basalts. Minerals. 2025; 15(3):293. https://doi.org/10.3390/min15030293

Chicago/Turabian Style

Ouyang, Jieting, Guoyu Chen, Liya Yang, Wenqian Lu, and Yun Zhou. 2025. "Tectonic Evolution of the Hainan Island, South China: Geochronological and Geochemical Constraints from Late Permian to Early Triassic Basalts" Minerals 15, no. 3: 293. https://doi.org/10.3390/min15030293

APA Style

Ouyang, J., Chen, G., Yang, L., Lu, W., & Zhou, Y. (2025). Tectonic Evolution of the Hainan Island, South China: Geochronological and Geochemical Constraints from Late Permian to Early Triassic Basalts. Minerals, 15(3), 293. https://doi.org/10.3390/min15030293

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