The Cretaceous igneous rocks in southeastern Guangxi and their implication for tectonic environment in southwestern South China Block

Yang Liu 1 , Nianqiao Fang 1 , Menglin Qiang 2 , Lei Jia 3 ,  and Chaojie Song 4
  • 1 School of Ocean Sciences, China University of Geosciences, 100083, Beijing, China
  • 2 Ecologic Geological Center, No. 3 Exploration Institute of Geology Mineral Research, 264000, Shandong, China
  • 3 Marine Ecological Environment Institute, Guangzhou Marine Geological Survey, Ministry of Natural Resources, 510760, Guangzhou, China
  • 4 Department of Quality Measurement, Minmetals Mining Holdings Limited, 230091, Hefei, China
Yang Liu, Nianqiao Fang, Menglin Qiang
  • Ecologic Geological Center, No. 3 Exploration Institute of Geology Mineral Research, Shandong, 264000, China
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, Lei Jia
  • Marine Ecological Environment Institute, Guangzhou Marine Geological Survey, Ministry of Natural Resources, Guangzhou, 510760, China
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and Chaojie Song
  • Department of Quality Measurement, Minmetals Mining Holdings Limited, Hefei, 230091, China
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Abstract

Southeastern Guangxi is located in the southwestern South China Block and to the northwest of the South China Sea (SCS), with abundant records of the Cretaceous magmatism. A detailed study of igneous rocks will contribute to a better understanding of the late Mesozoic tectonic environment. Zircon U–Pb dating yields ages of 93.37 ± 0.43 Ma for Yulin andesites and 107.6 ± 1.2 Ma for Luchuan granites. Yulin andesites are hornblende andesites, of which w(MgO) is between 7.72% and 8.42%, and Mg# is between 66.7 and 68.0, belonging to high magnesian andesites (HMAs) from peridotite sources. Luchuan granites are medium- to fine-grained monzogranites. Monzogranites and clastoporphyritic lava are high-K calc-alkaline series and metaluminum to weakly peraluminous series, which belong to the I-type granites. Those are enriched in Rb, Th, K and LREEs and depleted in Nb, Ta, P and Eu, showing the geochemical characteristics related to subduction. Unlike the contemporary “bimodal igneous rock assemblages” in Zhejiang and Fujian, the intermediate-acid magmatites in the southeastern Guangxi imply the compressive tectonic environment. The assemblage of HMAs and adakitic rocks indicates that the southwestern South China Block was under the Neo-Tethyan subduction during Cretaceous, and slab melting contributed to the magma in this area.

1 Introduction

South China Block lies between the Tethyan tectonic belt and Pacific tectonic belt [1]. It is a crucial period for magmatic rocks and mineralization in southwestern South China Block in Cretaceous, especially in the range of 100–90 Ma [2]. These magmatic rocks are a key to study the tectonic evolution in this region. More research has been done by predecessors, including Kunlunguan batholith, Dali rock mass and Dachang dike group with concealed rock mass, Sanchachong rock mass, Chehe rock mass, Michang rock mass, Songwang rock mass and acidic volcanic rocks in Shuiwen basin and so on [2,3,4,5,6,7,8,9,10,11,12,13,14,15]. Because of eye-catching polymetallic ore deposits there, those mineralization-related granitoids and ore-forming process become main objectives, especially in western Guangxi and eastern Yunnan [3,4,5,6]. Besides, some little rock masses are seldom studied in eastern Guangxi [7,8,9,10,11], and the Luchuan batholith, the biggest Cretaceous rock body in Guangxi, is much less studied. Conversely, there are a lot of other types of igneous rocks, such as andesites in Guangxi and Guangdong, which are also poorly studied. As to the magmatic activity, mineralization characteristics and tectonic setting in the Cretaceous period, discussion is still continuing. Most studies proposed that southwestern part of the South China Block is influenced by Pacific’s subduction [2,3,6,7,8,9,10,11,12,13,14,15]. There are a few studies on Tethyan subduction as well [4,5]. Without a comprehensive study of different types of igneous rocks, it is difficult to make an accurate judgment of the characteristics of the Cretaceous magmatic activities and tectonic setting.

There are abundant Cretaceous magmatic records in Southeastern Guangxi, such as Luchuan batholith and intermediate-acidic volcanic rocks. In this article, we present the U–Pb dating of zircon, mineralogical and geochemical compositions of the Luchuan granites and andesites in Yulin during Cretaceous. By combining with the study of late Cretaceous acidic magmatites in the Shuiwen basin [2], the petrogenesis and tectonic setting of Cretaceous magmatites in southeastern Guangxi are analyzed to have a better understanding of the tectonic setting of the southeastern Guangxi. Moreover, the influence of Tethyan subduction on the northern continental margin of the SCS during Cretaceous is discussed.

2 Geological setting

2.1 Regional geology

Guangxi lies in South China and on the northwest margin of the South China Sea (SCS). Besides, Guangxi lies on the south margin of Nanling, which is a critical metallogenic province. The study area is located at the southwest margin of the Cathaysia orogenic belt, where the Tethyan tectonic belt meets the Pacific tectonic belt and therefore is the crucial area for the research of the east extension of the Tethyan tectonic belt [16]. In that area, the outcropping strata are from Mesoproterozoic to Quaternary strata (Figure 1) [1]. Besides, there are plenty of granite records from Neoproterozoic to Cretaceous (Figure 1) [1].

Figure 1
Figure 1

Maps of the Southeastern Guangxi (modified after reference 1): (a) the studied area in the context of the South China Block; (b) geological map of the studied area. The location of porphyroclastic lava samples in Shuiwen Basin is considered from Ref. 2. (1) Cretaceous acid volcanic rocks; (2) Cretaceous andesites; (3) Cretaceous granites; (4) Jurassic granites; (5) Indosinian granites; (6) Hercynian granites; (7) Caledonian granites; (8) neoproterozoic granites; (9) quaternary; (10) Paleogene sedimentary rocks; (11) Cretaceous sedimentary rocks; (12) late Paleozoic sedimentary rocks; (13) early Paleozoic sedimentary rocks; (14) faults; and (15) sample location.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

2.2 Local geology

Volcanic activities, occurring in the Xidong Formation of the Upper Cretaceous in southeastern Guangxi, are one of the most remarkable volcanic activities in the continental margins in the northern SCS. Along the Bobai-Cenxi deep fault belt, there is an intermediate-acidic volcanic rock belt with 360 km length and 10–60 km width in the northeast-southwest direction [1]. Volcanic rocks are mainly acidic and intercalated with intermediate volcanic rocks with a thickness of 102–738 m. The volcanic rocks in Shuiwen Basin have the most extensive distribution area, which is mainly composed of tuff breccia, felsophyre, quartz porphyry and tuff. Andesites are mainly distributed in the Yulin-Bobai basin, Santan, Wangmao. It is unconformable over Devonian and Silurian Systems and is covered by sediments of Luowen Formation of the upper Cretaceous system and Paleogene system. The area of andesitic outcropping is about 38 km2 with a thickness of over 481 m. Volcanic rocks in the Yulin-Bobai basin are mainly andesites with a small amount of dacite, rhyolite and acidic tuff breccia.

The outcropping area of Luchuan batholith is 372 km2 with N-S distribution and intruded into the lower Paleozoic and Caledonian migmatite [1]. The outer contact zone is characterized by amphibolitization, greisenization, marmorization and silicatization. The batholith comprises a marginal fine-grained monzogranite and a central medium-grained monzogranite. Subsequently, felsic dykes were emplaced with several meters and lengths of several kilometers. The Rb–Sr age data of Luchuan granites is 116 Ma, belonging to the late Yanshanian plutonic rocks [1].

3 Samples and analytic methods

3.1 Petrology of the igneous rocks

The andesites in Yulin are porphyritic with phenocryst (11%–16%) of hornblende (50%–65%), pyroxene (20%–35%), plagioclase and biotite (Figure 2a–c). Hornblende and pyroxene are euhedral to subhedral with chloritization and epidotization. The matrix displays andestic texture and mainly contains subhedral plagioclase grains that surround and enclose phenocrysts.

Figure 2
Figure 2

(a) Hand specimen of andesites from Yulin; (b and c) photomicrographs of andesites, containing phenocryst of hornblende, pyroxene, and plagioclase, with matrix displaying andestic texture. (d) Hand specimen of monzogranites from Luchuan; (e and f) photomicrographs of monzogranites, containing semi-euhedral plagioclase, alkali feldspar and granular quartz with minor biotite. Abbreviations: Pl, plagioclase; Hb, hornblende; Px, clinopyroxene; Qtz, quartz; Kfs, potassium feldspar; Bi, biotite.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

The samples from Luchuan batholith are reddish, and the granitic texture is medium to fine grained (0.5–3 mm; Figure 2d–f). The minerals present include plagioclase (30%–35%), alkali feldspar (25%–30%) and quartz (20%–30%). Besides, trace amounts (<1%) of magnetite, apatite and zircon also occur. The plagioclase is semi-euhedral with the development of polysynthetic twinning and zoning textures, and some plagioclase is partially sericitized or kaolinized. The alkali feldspars are mainly microcline and perthite.

3.2 Zircon U–Pb analyses

Zircon grains were separated by conventional magnetic and density techniques from approximately 10 kg per sample. Then, under a binocular microscope, zircons were selected by hand-picking. By using CL images and transmitted as well as reflected light micrographs of the polished zircon grains, potential analytical spots were selected. At the Laboratory Center, Xi’an Center of Geological Survey, Xi’an, China, U–Pb isotopic analysis of the monzogranite sample was carried out with Agilent 7500a quadrupole ICP-MS. A 193 nm excimer laser was focused on the surface of the zircon grains with an energy density of 10 J/cm2. The laser beam diameter was 24 µm, and the repetition rate was 5 Hz. Helium, as a carrier gas, transported the ablation aerosol to the laser ablation inductively coupled plasma mass spectrometer (ICP-MS). Harvard zircon 91500 was used as an external standard for zircon U–Th–Pb analyses, and NIST610 was used as an external standard to calculate the contents of U, Th and Pb. Details of the analytical procedures and data processing methods are presented in Refs. [17,18]. Table 1 presents the zircon U–Pb dating results.

Table 1

U–Pb data of zircon crystals from andesite sample (15LC1-1) and monzogranite sample (15LC8-1)

232Th (ppm)238U (ppm)Th/UIsotopic ratiosAge (Ma)
207Pb/206Pb±1σ207Pb/235U±1σ206Pb/238U±1σ207Pb/206Pb±1σ207Pb/235U±1σ206Pb/238U±1σ
15LC1-1
101369.90311097.4150.3370680.0693940.0009461.4792640.0220430.1546990.001383910.18527.78921.92899.03927.24797.72
102351.6855814.32510.4318740.0732160.0010171.5424070.0233260.1526040.0011371020.3728.55947.46559.32915.54266.36
1035.788257722.09780.0080160.1516310.0015528.8423950.0973760.4225110.0026682364.5118.362321.87610.052271.86912.09
105359.85381970.830.182590.0601370.0006860.8426280.0107560.101390.000711609.2824.07620.59465.93622.55164.16
106375.30261075.6820.3488970.0891750.0009672.8831950.0326980.2342260.0015421409.2620.831377.5288.551356.6098.05
107213.9288722.03710.2962850.0702260.0010391.5001390.0253990.1545760.001463100029.63930.442710.32926.56348.17
109570.043870.86910.6545680.0726710.0011291.5331270.0270940.1524020.0013521005.55531.48943.752410.86914.41187.57
111613.8774895.87910.6852230.0972840.0011313.598950.0464540.2675130.0021561572.5321.761549.310.261528.16710.96
1142118.73662.1693.1996810.0641430.0010410.9932330.0155290.1121860.000638746.333.33700.36857.91685.43253.70
115536.4898506.62731.0589440.0596970.001110.8389940.0160530.1017370.00075592.3140.73618.59038.86624.58064.39
116432.4318551.29170.7843970.0647110.0010991.1039150.0194050.123530.000941764.82236.11755.2429.37750.84995.40
104778.0538659.61521.1795570.0529430.0020280.1058630.004260.014550.000162327.83587.03102.1743.9193.118361.03
108215.2011319.41180.6737420.0554020.0056890.1064840.009310.0146420.000365427.825226.82102.7448.5493.706622.32
110784.9412647.16181.2128980.0484310.0021140.0958190.0040780.0144370.00016120.46103.6992.909743.7892.402991.02
112661.9847887.14980.7461930.0528190.0022510.1050230.0043520.0145480.000155320.4398.14101.40284.0093.10570.98
11351.65246563.1060.0917280.0474870.0045530.0953950.0092010.0147210.00030872.315214.7992.516328.5394.207261.95
117807.32681006.8480.8018360.0487140.0018890.0972360.0037510.0145770.000148200.07597.2194.221843.4793.292110.94
118288.32781657.8610.1739160.0480540.0016210.0976940.0033390.0147830.000153101.9484.2594.645463.0994.601890.97
15LC8-1
B1-011224.022189.70.558990.050960.001350.119580.003490.017020.0004123960.16114.73.17108.82.58
B1-02240.82205.991.1690860.050120.003390.112820.007590.016330.00046200.3149.9108.56.93104.42.89
B1-04377.21541.610.6964610.050190.002260.101670.004640.014690.00038203.6101.2798.34.28942.4
B1-051185.131832.220.6468270.050970.001350.121220.003530.017250.00041239.459.92116.23.2110.22.61
B1-06927.781686.720.550050.048530.001540.116150.003910.017360.00042125.373.06111.63.56110.92.68
B1-07500.14727.10.6878560.04740.001790.106420.004150.016280.000468.887.96102.73.81104.12.57
B1-08309.7517.630.5983040.049420.00250.113050.005750.016590.00044167.8114.11108.85.25106.12.77
B1-11500.86398.461.2569890.06810.004430.147060.009440.015660.00045871.5129.29139.38.36100.22.88
B1-12233.53282.460.8267720.044270.004490.099720.010050.016340.000480.1136.5296.59.28104.53.08
B1-13703.941152.840.6106140.048280.001870.113830.004540.01710.00043112.888.86109.54.14109.32.71
B1-14491.27671.180.731950.048440.002280.109670.005220.016420.00043121107.39105.74.781052.7
B1-15696.33960.370.7250640.052660.002080.121450.004920.016720.00042314.287.28116.44.45106.92.66
B1-161127.741979.130.5698160.047810.001530.114560.003880.017380.0004289.175.26110.13.54111.12.68
B1-17549.77391.711.4035130.057410.005650.13590.013090.017170.00059507203.5129.411.7109.73.72
B1-18415.41258.211.6088070.054920.005070.12180.011020.016080.00053408.8194.25116.79.97102.93.35
B1-19924.991745.10.530050.051280.001720.114950.004050.016260.0004253.575.49110.53.691042.53
B1-20845.932001.50.4226480.050760.001560.119920.003940.017130.00041230.169.691153.57109.52.63
B1-21411.87661.110.6229980.048430.002290.115060.005510.017230.00044120.4107.71110.65.01110.12.8
B1-22892.0216380.5445790.049290.001810.112030.004250.016480.00041161.783.51107.83.88105.42.6
B1-23919.052210.60.4157470.051080.001490.121980.003820.017320.00042244.465.84116.93.46110.72.64
B1-24484.64446.111.0863690.049660.002350.114230.005490.016680.00043179.3106.88109.85106.62.7
B1-25372.44316.271.1776010.049440.00360.116180.008380.017040.00048168.8161.55111.67.62108.93.07

3.3 Whole-rock geochemistry

Major elements were analyzed by X-ray fluorescence (Axios max) at the Hebei Institute of Geology and Mineral Resources, China Geological Survey. Analytical precision was generally better than 5% for most oxides. Trace element data were also measured by an ICP-MS with the use of a X Serise 2 machine. The analytical precisions for most trace elements are higher than 3%. Table 2 presents samples’ major and trace elemental data.

Table 2

Major element (wt%) and trace element (ppm) compositions of the Cretaceous magmatic rocks in Southeast Guangxi

AndesitesMonzogranites
15LC1-115LC4-115LC2-115LC2-215LC7-115LC8-115LC-H215LC-H3
SiO254.67 54.07 54.39 54.31 77.17 75.72 78.04 77.80
Al2O315.72 15.16 15.48 15.46 12.34 12.88 11.41 12.16
TiO20.81 0.80 0.80 0.80 0.08 0.14 0.14 0.08
Fe2O33.44 3.58 4.35 4.48 0.33 0.42 0.48 0.24
FeO3.32 3.72 3.02 2.96 0.20 0.42 0.33 0.23
CaO7.83 7.54 7.35 7.32 0.61 0.95 0.61 0.51
MgO7.61 8.28 7.84 7.85 0.07 0.19 0.19 0.09
K2O2.06 2.02 2.05 2.09 4.56 5.22 4.95 4.53
Na2O2.80 2.88 2.83 2.88 3.90 3.40 2.95 3.80
MnO0.13 0.12 0.13 0.12 0.071 0.041 0.031 0.044
P2O50.17 0.17 0.17 0.17 0.011 0.022 0.023 0.011
LOI1.24 1.47 1.37 1.33 0.64 0.57 0.77 0.49
Total99.80 99.80 99.77 99.77 99.99 99.96 99.92 99.99
FeOT6.42 6.94 6.93 6.99 0.50 0.79 0.77 0.45
Mg#67.88 68.03 66.85 66.67 20.89 29.98 30.55 25.44
A/CNK0.75 0.73 0.76 0.76 0.99 0.99 1.01 1.01
Sc22.2 23.2 25.4 20.3 6.64 2.95 2.69 5.92
V 174 163 146 142 8.01 12.6 18.9 8.02
Cr369 353 424 415 0.49 12.0 2.96 1.43
Co 33.1 34.3 34.6 33.8 0.084 2.10 0.62 0.09
Ni 147 148 134 128 0.074 4.37 0.78 0.17
Ga16.7 16.7 17.8 17.3 17.6 15.9 13.4 19.8
Rb 61.3 65.0 66.2 65.1 432 250 233 488
Sr 530 533 509 515 12.8 102 76.9 12.9
Zr164 125 167 164 58.7 90.6 103 58.6
Hf 4.51 3.35 4.40 4.30 4.41 4.99 5.68 4.45
Nb 8.97 8.73 8.04 8.27 57.5 18.3 13.4 37.2
Ta 0.90 0.50 0.51 0.51 3.47 1.31 1.05 2.61
Th8.00 7.89 7.51 7.36 26.2 38.0 40.8 28.1
U 1.81 1.73 1.59 1.48 30.5 9.20 7.62 19.8
Pb 12.7 12.4 13.0 11.0 72.0 45.2 41.5 65.5
Ba 570 589 549 556 28.7 176 185 38.3
Y16.5 13.1 17.2 17.5 28.7 12.4 9.87 17.2
La28.7 24.3 27.0 26.7 20.0 38.6 33.8 19.5
Ce51.8 40.6 49.9 50.7 41.5 59.4 56.1 36.9
Pr6.44 5.25 6.13 6.12 4.88 6.59 6.00 4.05
Nd24.5 19.5 24.0 23.4 15.3 20.2 18.3 11.8
Sm4.41 3.51 4.38 4.39 2.98 2.91 2.49 1.99
Eu1.11 0.87 1.23 1.25 0.06 0.41 0.36 0.08
Gd3.51 2.89 3.77 3.82 2.58 2.66 2.34 1.90
Tb0.62 0.49 0.58 0.60 0.51 0.39 0.31 0.32
Dy3.19 2.50 3.25 3.27 3.20 1.85 1.50 1.93
Ho0.63 0.50 0.62 0.62 0.82 0.42 0.32 0.49
Er1.73 1.35 1.76 1.77 2.78 1.25 1.02 1.68
Tm0.31 0.25 0.28 0.27 0.69 0.26 0.20 0.43
Yb1.80 1.52 1.81 1.82 4.86 1.54 1.23 3.09
Lu0.45 0.40 0.26 0.27 0.89 0.25 0.22 0.63
∑REE129.15 104.00 125.05 125.05 100.96 136.67 124.14 84.77
δEu0.84 0.81 0.90 0.91 0.06 0.45 0.45 0.13
LREE/HREE9.55 9.50 9.13 9.06 5.19 14.86 16.38 7.11
(La/Yb)N6.80 6.54 10.97 10.65 2.41 16.23 16.28 3.35
Rb/Sr0.12 0.12 0.13 0.13 33.68 2.44 3.03 37.97
Ba/La19.88 24.22 20.31 20.80 1.44 4.57 5.47 1.96
Zr/Hf36.48 37.25 38.02 38.21 13.30 18.16 18.17 13.18
Sr/Y32.09 40.82 29.53 29.34 0.45 8.25 7.79 0.75

4 Results

4.1 Zircon U–Pb ages

Zircon CL images reveal that the zircon crystals were mostly colorless and semi-euhedral. Most are of short-column or sub-rounded shape with a length-to-width ratio of about 1:1–1:3. The zircons display typical magmatic oscillatory zoning and rhythmically zoned texture. The Th/U ratios of the five youngest zircon crystals are between 0.09 and 1.21 (Table 1), six of which are bigger than 0.10 and are within the range of typical igneous zircons [19]. The seven youngest zircon crystals together yield a weighted mean 206Pb/238U age of 93.38 ± 0.83 Ma (2σ) (MSWD = 0.47; Table 1 and Figure 3), the early stage of late Cretaceous.

Figure 3
Figure 3

Cathodoluminescence images and U–Pb ages of zircons from Yulin andesites. The red circles indicate the analytical area for U–Pb dating, and age error is given at 2 sigma level.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

Zircons are abundant in the studied monzogranite samples. Zircons are euhedral and range up to 100 µm in size; most of them are transparent to light brown in color and exhibit magmatic oscillatory zoning. Twenty-five grains were analyzed from sample 15LC8-1, of which 19 may be pooled to yield a weighted mean 206Pb/238U age of 107.6 ± 1.2 Ma (2σ) (MSWD = 0.96; Table 1 and Figure 4). The other Cretaceous igneous rocks’ ages are from 113 to 83 Ma in southeastern Guangxi [2,7,10,20], indicating that the Cretaceous igneous rocks crystallized from late early Cretaceous to early late Cretaceous in the studied area.

Figure 4
Figure 4

Cathodoluminescence images and U–Pb ages of zircons from Luchuan monzogranites. The red circles indicate the analytical area for U–Pb dating, and age error is given at 2 sigma level.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

4.2 Whole-rock major and trace elements

These monzogranites are compositionally similar to each other and are characterized by high SiO2 and low Al2O3, FeOT, P2O5, TiO2, MgO and CaO. Total alkalis and K2O/Na2O values of samples are high, with the characteristic of high-K calc-alkaline rocks (Figure 5a and b). They are metaluminous-weakly peraluminous with A/CNK values (molar Al2O3/[CaO + K2O + Na2O], 0.99–1.04, Figure 5c). Andesites fall within the range of basaltic andesites (Figure 5a), with low K2O/Na2O values. They are high-magnesian andesites (HMAs), significantly characterized by high MgO and high Mg contents. The HMAs are calc-alkaline similar to clastoporphyritic lava (Figure 5b).

Figure 5
Figure 5

(a) Geochemical classification diagrams for Cretaceous magmatic rocks in southeastern Guangxi: plot of Na2O + K2O versus SiO2 (after reference 26). The green line between alkaline and sub-alkaline igneous rocks is taken from Ref. 27; (b) diagram of SiO2 versus K2O (after reference 28); and (c) A/NK versus A/CNK diagram (after reference 29). A/NK: molar Al2O3/[K2O + Na2O]; A/CNK: molar Al2O3/[CaO + K2O + Na2O]. The data of porphyroclastic lava are from Reference 2.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

The REE of the monzogranites and HMAs are lower than that of clastoporphyritic lava. LREE/HREE ratios of the monzogranites and HMAs vary between 5.16 and 16.38. The (La/Yb)N values of the monzogranites and HMAs range from 2.41 to 16.28, which are less negative than the clastoporphyritic lava (Figure 5a; (La/Yb)N = 18.98–22.04). The chondrite-normalized REE patterns of Cretaceous igneous rocks show a gently right-inclined “V” shape characterized by the LREE enrichment with apparent negative Eu anomalies (Figure 6a). Moreover, the monzogranites’ negative Eu anomalies are more strong than that of volcanics.

Figure 6
Figure 6

(a) Chondrite-normalized REE patterns and (b) the primary-mantle-normalized trace elements spider diagrams for Cretaceous magmatic rocks in southeastern Guangxi. Normalizing values are taken from Ref. 30.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

In the primitive-mantle-normalized spidergram, all the samples have similar distribution patterns (Figure 6b), showing enrichment in large ion lithophile elements (LILEs; such as Rb, Th and K) while depletion or negative anomaly in high-field strength elements (HFSEs; such as Nb, Ti, Sr and P). The phenomenon of the “TNT (Ti-Nb-Ta) anomaly” was most characteristic of island arc volcanics and the continental crust in general [21].

5 Discussion

5.1 Samples’ tectonic implications

The ratios of HFSEs in magmatic rocks can accurately reflect the characteristics of the magmatic sources. With high Rb/Sr ratios, and low Ba/La as well as Zr/Hf ratios, monzogranites and clastoporphyritic lava are mainly crust derived. Granitic rocks can be categorized into the following four main genetic types: M-type, I-type, S-type and A-type. With low (Zr + Nb + Ce + Y) and A/CNK values, the monzogranites and clastoporphyritic lava are similar to I-type granites without alkaline dark-colored minerals (Figure 7a). Moreover, I-type granites are formed by partial melting of intermediate-basic metamorphic igneous rocks of the crust [22]. In the Rb versus (Yb + Ta) discriminant diagrams (Figure 7b), monzogranites and clastoporphyritic lava samples are plotted in the volcanic arc granites and syn-collisional granites, which indicates that the formation of monzogranites and clastoporphyritic lava is closely related to the subduction.

Figure 7
Figure 7

Tectonic discriminant diagrams of Cretaceous monzogranites and clastoporphyritic lava in southeastern Guangxi: (a) Zr + Nb + Ce + Y versus FeOT/MgO plot for the identification of A-type granites from I- and S-type granites (after Ref. 31); (b) Yb + Ta versus Rb plot for discriminating syn-collisional granites, volcanic-arc granites, within-plate granites and ocean-ridge granites (after Ref. 32).

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

HMAs are mostly formed in a convergent plate boundary. HMAs in Yulin share similar geochemical characteristics with bajaites in Baja California Peninsula, Mexico, such as the high fractionation of light and heavy rare earth elements and the high contents of Sr, Cr, Ni, V and Co. It indicates that the HMAs in Yulin, like the bajaites, was formed in a convergent tectonic environment with probable origin by melting of mantle peridotites previously metasomatized by slab melts [23]. Besides, magmatites with similar geochemical characteristics of HMAs are found in Gangdese Belt contemporaneously [24,25], which means that Neo-Tethys extended to the present location of SCS and the tectonic environment in the northern margin of SCS was affected by the subduction of Neo-Tethys during Cretaceous.

The ratios of HFSEs in magmatic rocks can accurately reflect the characteristics of magmatic source. HMAs have lower Rb/Sr ratios, higher Ba/La and Zr/Hf ratios. In Figure 8a, showing the picture of (La/Yb)N versus δEu, the magma source of HMAs is crust mantle derived, while the clastoporphyritic lava and monzogranites are mainly crust derived. The differentiation degree of monzogranites’ magma, especially the medium-grained monzogranites’, is much higher with lower (La/Yb)N. These geochemical characteristics indicate that the andesitic magma is obviously mixed with mantle source. Besides, the HMAs in Yulin have low FC3MS values lower than 0.65, suggesting peridotitic sources (Figure 8b).

Figure 8
Figure 8

Origin discriminant diagrams of Cretaceous igneous rocks in southeastern Guangxi: (a) (La/Yb)N versus δEu (after reference 33) and (b) FC3MS versus MgO plot for HMAs (after Ref. 34). FC3MS = FeOT/CaO-3*MgO/SiO2.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

5.2 Cretaceous magmatism’s geochronology and regional tectonics in southwestern South China Block

Beside the magmatism in southeastern Guangxi, there are numerous igneous rocks in Cretaceous, which can be found in the surrounding area, such as Yangchun Basin, western Guangxi, eastern Yunnan and northern Vietnam [4,35,36,37,38,39,40,41]. The ages of those rocks are from 113 to 70 Ma, similar to samples in southeastern Guangxi. Furthermore, Cretaceous ore mineralization is often related to those igneous rocks, especially granitoids. So it is a meaningful period for magma and mineralization from late early Cretaceous to early late Cretaceous in southwestern South China Block.

The volcanic rocks during this period in the northern continental margin of the SCS are mainly concentrated in the Yunkai region at the border of Guangdong and Guangxi, and there are a lot of extrusive rocks in Hainan island mainly in early Cretaceous. Most of them are most intermediate-acid volcanic rocks and seldom basic volcanic rocks, which do not conform to the “bimodal igneous rock assemblages” in Southeastern China, especially in late Cretaceous. Besides, according to zircon solubility simulation formula at 700–1,300°C [42], the diagenetic temperature of clastoporphyritic lava in Shuiwen basin clastoporphyritic lava is 764–812°C, much lower than that of the clastoporphyritic lava in Zhejiang (803–820°C) and rhyolite in Fujian (861–930°C) [43,44]. Moreover, the diagenetic temperature of monzogranites in Luchuan is 706–754°C, much lower than the average diagenetic temperature of I-type granites (781°C) [45]. Cretaceous S-type granites have also been discovered in southeastern Guangxi in recent years, such as Youmapo muscovite granites [46], which is also different from the assemblages of I-type and A-type granites in Zhejiang and Fujian. From late early Cretaceous to early late Cretaceous, the subduction of the paleo-Pacific plate only influences the area east of Wuyi Mountain [35,47]. Therefore, it may not be suitable to mechanically apply the tectonic model in Zhejiang and Fujian to the southeastern Guangxi during this period. The assemblage of I- and S-type granites is suggested the symbol of convergent environment [48], which also differs from the extensional environment in Southeast China.

In recent years, studies on the influence of the Tethyan subduction on the northern continental margin of the SCS increased [36,49,50,51,52,53,54]. In the northern part of the SCS and nearby area, there was an E-W trending magmatic belt, and the northern continental margin of the SCS was in the tectonic environment of the Tethyan subduction in Cretaceous [35,37,38,55]. These Cretaceous igneous rocks in Guangxi and Hainan islands are the product of northward subduction of Neo-Tethys. Moreover, HMAs in Guangxi and adakitic rocks in Hainan should form in subduction settings and be produced by partial melting of subducting young and hot slabs followed by interaction with the overlying mantle during ascent [56,57,58,59,60,61] (Figure 9). Due to the relatively young and high temperature of the subducted oceanic crust when Tethyan ridge subducted underneath South China Block [38,55], or tearing and breaking off, the subducted oceanic crust would melt, and the melt replaced mantle wedge and crustal materials in southeastern Guangxi to form Cretaceous magmatic rocks in this region, which share similarities with HMAs and adakitic rocks in Gangdese magmatic arc at a similar time [24,25,62,63,64]. In this case, andesites in Yulin were characterized by high magnesium content, almost at the same time that adakitic rocks formed in Hainan island. As the same with those igneous rocks in Gangdese belt, magmatisms from both southwestern South China Block and Gangdese magmatic arc may generate under the subduction of Neo-Tethyan ridge during the middle period of Cretaceous. Neo-Tethyan subduction influences both magmatic activity and mineralization in southwestern South China Block.

Figure 9
Figure 9

(a) Sr/Y versus Y diagrams (after Ref. 65), Hainan granites’ data are taken from Refs. 3941. (B) Schematic diagram of the tectonic setting of magmatic activities in northern margin of SCS during late early Cretaceous to early late Cretaceous.

Citation: Open Geosciences 12, 1; 10.1515/geo-2020-0160

6 Conclusions

Yulin andesites and Luchuan monzogranites are emplaced at 93.37 ± 0.43 Ma and 107.6 ± 1.2 Ma, respectively. There is intense magmatic activity occurring in the late early Cretaceous to early late Cretaceous in southeastern Guangxi. The andesites exhibit high MgO and Mg#, enriched in Sr, Cr, Ni, V and Co, which imply that Cretaceous andesites belong to HMAs with similarity with bajaites. Luchuan granites are monzogranites and are highly differentiated I-type granites. These Cretaceous magmatic rocks are enriched in LREEs and LILEs, but depleted in HFSEs. The formation of Yulin HMAs, Luchuan batholith and Shuiwen clastoporphyritic lava is associated with subduction. Different from the NE-trending magmatic belt under the subduction of paleo-Pacific along the east coast of the South China Block, the northern continental margin of the SCS is in the tectonic environment of the Tethyan subduction during the Cretaceous. The subduction of Neo-Tethyan ridge may contribute to magmatism.

Acknowledgments

This research was supported by the National Natural Science Foundation of China (Grant No. 41572207, 41276047, 41030853). The authors acknowledge Yongyang Huang from the Institute of Guangzhou Marine Geological Survey and Guangxi Institute of Marine Geological Survey their support during the field investigation. The authors are grateful to the editor and the anonymous referees for constructive review comments. The authors thank Hailing Zhao and Dapeng Li from the China University of Geosciences, Beijing, for their helpful discussions.

Conflict of interest: No potential conflict of interest was reported by the authors.

Author contributions: Yang Liu: fieldwork; analysis of petrology, U–Pb ages and geochemical data of samples; and original draft. Nianqiao Fang: fieldwork; funding acquisition; and review and editing of manuscript. Menglin Qiang: methodology and analysis of petrology, U–Pb ages and geochemical data of samples. Lei Jia: fieldwork and analysis of petrology of samples. Chaojie Song: visualization and curation of data.

Data availability statement: All data related to the research have appeared in the article and can be available upon request to the corresponding author.

References

  • [1]

    Guangxi Bureau of Geology, Mineral Prospecting and Exploitation. Geological records of Guangxi Zhuang autonomous region. Beijing: Geological Publishing House; 1985, (in Chinese).

  • [2]

    Pan D, Wu RG, Deng WQ, Xie J X, Zhang ZS. LA-ICP-MS zircon U–Pb dating and geochemical characteristics of clastoporphyritic lava in Shuiwen Basin. J East China Inst Technol. 2013;36(1):25–34, (in Chinese with English abstract).

  • [3]

    Cai MH, He LQ, Liu GQ, Wu DC, Huang HM. SHRIMP zircon U–Pb dating of the intrusive rocks in the Dachang Tin-polymetallic ore field, Guangxi and their geological significance. Geol Rev. 2006;52(3):409–14, (in Chinese with English abstract).

  • [4]

    Xu R, Deng J, Cheng H, Cui X, Wang C. Geochronology, geochemistry and geodynamic setting of Late Cretaceous magmatism and Sn mineralization in the western South China and Tengchong-Baoshan. Acta Petrol Sin. 2018;34(5):1271–84, (in Chinese with English abstract).

  • [5]

    Huang W, Liang H, Zhang J, Wu J, Chen X, Ren L. Genesis of the Dachang Sn-polymetallic and Baoshan Cu ore deposits, and formation of a Cretaceous Sn–Cu ore belt from southwest China to western Myanmar. Ore Geol Rev. 2019;112:1–17.

  • [6]

    Wang T, Li G, Wang Q, Santosh M, Zhang Q, Deng J. Petrogenesis and metallogenic implications of late Cretaceous I- and S-type granits in Dachang-Kunlunguan ore belt, Southwestern South China Block. Ore Geol Rev. 2019;113:1–15.

  • [7]

    Wang JH, Wang ZQ, Chen B. Geochronology, petrology, geochemistry and Nd isotopic constraints on the origin of the Sanchachong tungsten-related pluton, Guangxi, South China. Geochimica. 2014;6:549–73, (in Chinese with English abstract).

  • [8]

    Fu Q, Ge WS, Wen CS, Cai KQ, Li SF, Zhang ZW, et al. Geochemistry and genesis of Michang granites and their dark microgranular enclaves in Guangxi. Acta Geosci Sin. 2011;3:293–303, (in Chinese with English abstract).

  • [9]

    Wang ZQ, Chen B, Ma XH. Multiple magmatism in the Luchuan–Bobai metallogenic belt of Guangxi and its relationship with W–Mo mineralization. Acta Geol Sin. 2017;91(2):421–39, (in Chinese with English abstract).

  • [10]

    Yang QJ, Sun MH, Qin A, Zhang QW. Study on geochronology and geological significance of Dali granitoids of Dayaoshan, Guangxi. Min Resour Geol. 2017;31(5):843–53, (in Chinese with English abstract).

  • [11]

    Hu SQ, Zhou GF, Peng SB, Zhang XJ, Yi SH, Tang GS. Chronology and geochemical characteristics of quartz monzonite (porphyry) in the Dali copper-molybdenum deposit and its geological significance. Acta Geosci Sin. 2012;33(1):23–37, (in Chinese with English abstract).

  • [12]

    Tan J, Wei JH, Li SR, Wang ZM, Fu LB, Zhang KQ. Geochemical characteristics and tectonic significance of Kunlunguan A-type granite, Guangxi. Earth Sci J China Univ Geosci. 2008;33(6):743–54, (in Chinese with English abstract).

  • [13]

    Fu L, Wei J, Li Y, Tan J, Li S, Li H. LA-ICP-MS zircon U–Pb dating of the Kunlunguan A-type granites in Guangxi Province, South China and its geological significance. Chinese J Geochem. 2010;29(3):223–32.

  • [14]

    Liang T, Wang DH, Hou KJ, Li HQ, Huang HM, Cai MH, et al. LA-MC-ICP-MS zircon U–Pb dating of Longxianggai pluton in Dachang of Guangxi and its geological significance. Acta Petrol Sin. 2011;27(6): 1624–36, (in Chinese with English abstract).

  • [15]

    Luo JH, Che ZC, Guo AL, Cheng SY, Pei XZ. Late Cretaceous lithospheric extension in the Nandan–Hechi tectonic zone of northern Guangxi Province and its influence on hydrocarbon accumulation conditions. Oil Gas Geol. 2009;30(5):619–25, (in Chinese with English abstract).

  • [16]

    Zhang KX, Pan GT, He WH, Xiao QH, Xu YD, Zhang ZY, et al. New division of tectonic-strata superregion in China. Earth Sci J China Univ Geosci. 2015;40(2):206–33.

  • [17]

    Song S, Niu Y, Wei C, Ji J, Su L. Metamorphism, anatexis, zircon ages and tectonic evolution of the Gongshan block in the northern Indochina continent – an eastern extension of the Lhasa Block. Lithos. 2010;120(3–4):327–46.

  • [18]

    Liu YS, Hu ZC, Gao S, Günther D, Xu J, Gao CG, et al. In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard. Chem Geol. 2008;257(1–2):34–43.

  • [19]

    Belousova E, Griffin W, O’Reilly SY, Fisher N. Igneous zircon: trace element composition as an indicator of source rock type. Contribut Min Petrol. 2002;143(5):602–22.

  • [20]

    Wang YX. Study on deposit geological characteristics and genetic analysis of San Cha Chong Tungsten Mine in Bobai City of Guangxi Province [Master Thesis]. Chengdu University of Technology; 2015, (in Chinese with English abstract).

  • [21]

    Jahn BM, Usuki M, Usuki T, Chung SL. Generation of Cenozoic granitoids in Hokkaido (Japan): constraints from zircon geochronology, Sr–Nd–Hf isotopic and geochemical analyses, and implications for crustal growth. Am J Sci. 2014;314:704–50.

  • [22]

    Chappell BW, White AJR, Hine R. Granite provinces and basement terranes in the Lachlan Fold Belt, southeastern Australia. Australian J Earth Sci. 1988;35(4):505–21.

  • [23]

    Calmus T, Aguillón-Robles A, Maury RC, Bellon H, Benoit M, Cotton J, et al. Spatial and temporal evolution of basalts and magnesian andesites (“ bajaites”) from Baja California, Mexico: the role of slab melts. Lithos. 2003;66:77–105.

  • [24]

    Zhu DC, Zhao ZD, Pan GT, Lee HY, Kang ZQ, Liao ZL, et al. Early Cretaceous subduction-related adakite-like rocks of the Gangdese belt, southern Tibet: products of slab melting and subsequent melt-peridotite interaction? J Asian Earth Sci. 2009;34(3):298–309.

  • [25]

    Jiang ZQ, Wang Q, Li ZX, Wyman DA, Tang GJ, Jia XH, et al. Late Cretaceous (ca. 90 Ma) adakitic intrusive rocks in the Kelu area, Gangdese Belt (southern Tibet): slab melting and implications for Cu–Au mineralization. J Asian Earth Sci. 2012;53:67–81.

  • [26]

    Middlemost EAK. Naming materials in the magma/igneous rock system. Earth Sci Rev. 1994;37(3–4):215–24.

  • [27]

    Irvine TN, Baragar WRA. A guide to the chemical classification of the common volcanic Rocks. Canadian J Earth Sci. 1971;8(5):523–48.

  • [28]

    Peccerillo A, Taylor SR. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Min Petrol. 1976;58(1):63–81.

  • [29]

    Maniar PD, Piccoli PM. Tectonic discrimination of granitoids. Geol Soc Am Bull. 1989;101(5):635–43.

  • [30]

    Sun SS, McDonough WF. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geol Soc Lond Spec Publ. 1989;42(1):313–45.

  • [31]

    Whalen JB, Currie KL, Chappell BW. A-type granite: geochemical characteristics, discrimination and petrogenesis. Contribut Min Petrol. 1987;95:407–19.

  • [32]

    Pearce JA, Harris NBW, Tindle AG. Trace element discrimination diagram for the tectonic interpretation of granitic rocks. J Petrol. 1984;25(4):956–83.

  • [33]

    Chen YW, Bi XW, Hu RZ, and Qi HW. Comparison of geochemical characteristic of uranium- and non-uranium-bearing Indosinian granites in Guidong composite pluton. J Mineral Petrol. 2009;3:106–14, (in Chinese with English abstract).

  • [34]

    Yang ZF, and Zhou JH. Can we identify source lithology of basalt? Sci Rep. 2013;3:1–7.

  • [35]

    Zhang LP. The closure of Tethys and Cretaceous mineralization: a case study of the Yangchun basin [PhD Thesis]. University of Chinese Academy of Sciences; 2017, (in Chinese with English abstract).

  • [36]

    Xiao CH, Shen YK, Wei CS, Su XK, Le XM, Zhang L. LA-ICP-MS zircon U–Pb dating, Hf isotopic composition and Ce4+/Ce3+ characteristics of the Yanshanian acid magma in the Xidamingshan Cluster, southeastern margin of the Youjiang fold belt, Guangxi. Geoscience. 2018;32(2):289–304, (in Chinese with English abstract).

  • [37]

    Zhang LP, Hu YB, Liang JL, Ireland T, Chen YL, Zhang RQ, et al. Adakitic rocks associated with the Shilu copper–molybdenum deposit in the Yangchun Basin, South China, and their tectonic implications. Acta Geochim. 2017;36(2):1–19.

  • [38]

    Sun SJ, Zhang LP, Zhang RQ, Ding X, Zhu HL, Zhang ZF, et al. Mid-late Cretaceous igneous activity in South China: the Qianjia example, Hainan Island. Int Geol Rev. 2018;60(11–14):1665–83.

  • [39]

    Yuan XB, Fang NQ, Dong HL. Geochronology, geochemistry and tectonic significance of Gaofeng and Baocheng Granite Batholiths in Hainan Island. Geoscience. 2019;33(1):85–97, (in Chinese with English abstract).

  • [40]

    Chen ML. Petrogenesis of the Qianjia Composite pluton in Hainan Island and its relationship to Mo polymetallic mineralization [PhD Thesis]. Wuhan: China University of Geosciences; 2014, (in Chinese with English abstract).

  • [41]

    Xu DR, Wu CJ, Hu GC, Chen ML, Fu YR, Wang ZL, et al. Late Mesozoic molybdenum mineralization on Hainan Island, South China: geochemistry, geochronology, and geodynamic setting. Ore Geol Rev. 2016;72:402–33.

  • [42]

    Watson EB, and Harrison TM. Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types. Earth Planet Sci Lett. 1983;64(2):295–304.

  • [43]

    Zhang Y, Ma HJ, Fan YC, Qi YX. Geological characteristics and origin of the felsic porphyroclastic lavas in the Zhedaikou area in Suichang, Zhejiang Province. East China Geol. 2017;38(1):1–11.

  • [44]

    Yan LL. The petrogenetic link between volcanic and plutonic rocks of the Cretaceous caldera complexes in the coastal area of the Zhejiang and Fujian provinces [PhD Thesis]. Beijing: China University of Geosciences; 2018, (in Chinese with English abstract).

  • [45]

    King PL, White AJR, Chappell BW, Allen CM. Characterization and origin of aluminous A-type granites from the Lachlan Fold Belt, Southeastern Australia. J Petrol. 1997;38(3):371–91.

  • [46]

    Wang XY. Late Yanshanian Magmatism and W-mineralization in Yunkai region, Guangxi Province [PhD Thesis]. Wuhan: China University of Geosciences; 2017, (in Chinese with English abstract).

  • [47]

    Chen WF, Chen PR, Xu XS, Zhang M. Geochemical characteristics of basaltic rocks in South China in Cretaceous and Their constraints on the subduction of the Pacific plate. Sci China Earth Sci. 2005;35(11):1007–18, (in Chinese).

  • [48]

    Lu FX, Sang LK. Petrology. Beijing: Geological Publishing House; 2002.

  • [49]

    Xia KY, Huang CL. The discovery of Meso-Tethys sedimentary basins in the South China Sea and their oil and gas perspective. Earth Sci Front. 2000;7(3): 227–38, (in Chinese with English abstract).

  • [50]

    Yan JX, Zhou D. Advancement on the Meso-Tethys along the northern margin of the South China Sea. Mar Geol Quater Geol. 2001;21(4):49–54, (in Chinese with English abstract).

  • [51]

    Shao L, You HQ, Hao HJ, Wu GX, Qiao PJ, Lei YC. Petrology and depositional environments of Mesozoic strata in the Northeastern South China Sea. Geol Rev. 2007;53(2):164–9, (in Chinese with English abstract).

  • [52]

    Min H, Ren JY, Gao JY, and Zuo YS. Location of the ancient subduction zone in the Northern South China Sea and its constrains on the spreading of the South China Sea Basin. Geotecton Metall. 2010;34(4):599–605, (in Chinese with English abstract).

  • [53]

    Fang NQ. A new model on the Mesozoic “South China Sea” (SCS): reconstructing the Hainan marginal arc and recognizing the Tethyan SCS. Earth Sci Front. 2016;23(6):107–19, (in Chinese with English abstract).

  • [54]

    Zhu WL, Xie XN, Wang ZF, Zhang DJ, Zhang CL, Cao LC, et al. New insights on the origin of the basement of the Xisha Uplift, South China Sea. Sci Sin Terrae. 2017;47(12):1460–8, (in Chinese).

  • [55]

    Sun WD, Lin CT, Zhang LP, Liao RQ, Li CY. The formation of the South China Sea resulted from the closure of the Neo-Tethys: a perspective from regional geology. Acta Petrol Sin. 2018;34(12):3467–78, (in Chinese with English abstract).

  • [56]

    Kay RW. Aleutian magnesian andesites: melts from subducted Pacific ocean crust. J Volcanol Geotherm Res. 1978;4(1–2):117–32.

  • [57]

    Tatsumi Y. Geochemical modeling of partial melting of subducting sediments and subsequent melt-mantle interaction: generation of high-Mg andesites in the Setouchi volcanic belt, southwest Japan. Geology. 2001;29(4):323–6.

  • [58]

    Tsuchiya N, Suzuki S, Kimura J, Kagami H. Evidence for slab melt/mantle reaction: petrogenesis of early Cretaceous and Eocene high-Mg andesites from the Kitakami Mountains, Japan. Lithos. 2005;79(1–2):179–206.

  • [59]

    Yogodzinski GM, Volynets ON, Koloskov AV, Seliverstov NI, Matvenkov VV. Magnesian andesites and the subduction component in a strongly Calc-alkaline series at Piip Volcano, Far Western Aleutians. J Petrol. 1994;35(1):163–204.

  • [60]

    Yogodzinski GM, Kay RW, Volynets ON, Koloskov AV, Kay SM. Magnesian andesite in the western Aleutian Komandorsky Region: implications for slab melting and processes in the mantle wedge. Geol Soc Am Bull. 1995;107(5):505–19.

  • [61]

    Yogodzinski GM, Kelemen PB. Slab melting in the Aleutians: implications of an ion probe study of clinopyroxene in primitive adakite and basalt. Earth Planet Sci Lett. 1998;158(1–2):53–65.

  • [62]

    Zhang ZM, Ding HX, Dong X. Formation and evolution of the Gangdese magmatic arc, southern Tibet. Acta Petrol Sin. 2018;35(2):275–94, (in Chinese with English abstract).

  • [63]

    Zhang LL, Zhu DC, Wang Q, et al. Late Cretaceous volcanic rocks in the Sangri area, southern Lhasa Terrane, Tibet: evidence for oceanic ridge subduction. Lithos. 2019;326–327:144–57.

  • [64]

    Zheng YC, Hou ZQ, Gong YL, Liang W, Sun QZ, Zhang S, et al. Petrogenesis of Cretaceous adakite-like intrusions of the Gangdese Plutonic Belt, southern Tibet: implications for mid-ocean ridge subduction and crustal growth. Lithos. 2014;190–191:240–63.

  • [65]

    Defant MJ, Xu JF, Kepezhinskas P, Wang Q, Zhang Q. Adakites: some variations on a theme. Acta Petrol Sin. 2002;18(2):129–42, (in Chinese and English abstract).

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  • [1]

    Guangxi Bureau of Geology, Mineral Prospecting and Exploitation. Geological records of Guangxi Zhuang autonomous region. Beijing: Geological Publishing House; 1985, (in Chinese).

  • [2]

    Pan D, Wu RG, Deng WQ, Xie J X, Zhang ZS. LA-ICP-MS zircon U–Pb dating and geochemical characteristics of clastoporphyritic lava in Shuiwen Basin. J East China Inst Technol. 2013;36(1):25–34, (in Chinese with English abstract).

  • [3]

    Cai MH, He LQ, Liu GQ, Wu DC, Huang HM. SHRIMP zircon U–Pb dating of the intrusive rocks in the Dachang Tin-polymetallic ore field, Guangxi and their geological significance. Geol Rev. 2006;52(3):409–14, (in Chinese with English abstract).

  • [4]

    Xu R, Deng J, Cheng H, Cui X, Wang C. Geochronology, geochemistry and geodynamic setting of Late Cretaceous magmatism and Sn mineralization in the western South China and Tengchong-Baoshan. Acta Petrol Sin. 2018;34(5):1271–84, (in Chinese with English abstract).

  • [5]

    Huang W, Liang H, Zhang J, Wu J, Chen X, Ren L. Genesis of the Dachang Sn-polymetallic and Baoshan Cu ore deposits, and formation of a Cretaceous Sn–Cu ore belt from southwest China to western Myanmar. Ore Geol Rev. 2019;112:1–17.

  • [6]

    Wang T, Li G, Wang Q, Santosh M, Zhang Q, Deng J. Petrogenesis and metallogenic implications of late Cretaceous I- and S-type granits in Dachang-Kunlunguan ore belt, Southwestern South China Block. Ore Geol Rev. 2019;113:1–15.

  • [7]

    Wang JH, Wang ZQ, Chen B. Geochronology, petrology, geochemistry and Nd isotopic constraints on the origin of the Sanchachong tungsten-related pluton, Guangxi, South China. Geochimica. 2014;6:549–73, (in Chinese with English abstract).

  • [8]

    Fu Q, Ge WS, Wen CS, Cai KQ, Li SF, Zhang ZW, et al. Geochemistry and genesis of Michang granites and their dark microgranular enclaves in Guangxi. Acta Geosci Sin. 2011;3:293–303, (in Chinese with English abstract).

  • [9]

    Wang ZQ, Chen B, Ma XH. Multiple magmatism in the Luchuan–Bobai metallogenic belt of Guangxi and its relationship with W–Mo mineralization. Acta Geol Sin. 2017;91(2):421–39, (in Chinese with English abstract).

  • [10]

    Yang QJ, Sun MH, Qin A, Zhang QW. Study on geochronology and geological significance of Dali granitoids of Dayaoshan, Guangxi. Min Resour Geol. 2017;31(5):843–53, (in Chinese with English abstract).

  • [11]

    Hu SQ, Zhou GF, Peng SB, Zhang XJ, Yi SH, Tang GS. Chronology and geochemical characteristics of quartz monzonite (porphyry) in the Dali copper-molybdenum deposit and its geological significance. Acta Geosci Sin. 2012;33(1):23–37, (in Chinese with English abstract).

  • [12]

    Tan J, Wei JH, Li SR, Wang ZM, Fu LB, Zhang KQ. Geochemical characteristics and tectonic significance of Kunlunguan A-type granite, Guangxi. Earth Sci J China Univ Geosci. 2008;33(6):743–54, (in Chinese with English abstract).

  • [13]

    Fu L, Wei J, Li Y, Tan J, Li S, Li H. LA-ICP-MS zircon U–Pb dating of the Kunlunguan A-type granites in Guangxi Province, South China and its geological significance. Chinese J Geochem. 2010;29(3):223–32.

  • [14]

    Liang T, Wang DH, Hou KJ, Li HQ, Huang HM, Cai MH, et al. LA-MC-ICP-MS zircon U–Pb dating of Longxianggai pluton in Dachang of Guangxi and its geological significance. Acta Petrol Sin. 2011;27(6): 1624–36, (in Chinese with English abstract).

  • [15]

    Luo JH, Che ZC, Guo AL, Cheng SY, Pei XZ. Late Cretaceous lithospheric extension in the Nandan–Hechi tectonic zone of northern Guangxi Province and its influence on hydrocarbon accumulation conditions. Oil Gas Geol. 2009;30(5):619–25, (in Chinese with English abstract).

  • [16]

    Zhang KX, Pan GT, He WH, Xiao QH, Xu YD, Zhang ZY, et al. New division of tectonic-strata superregion in China. Earth Sci J China Univ Geosci. 2015;40(2):206–33.

  • [17]

    Song S, Niu Y, Wei C, Ji J, Su L. Metamorphism, anatexis, zircon ages and tectonic evolution of the Gongshan block in the northern Indochina continent – an eastern extension of the Lhasa Block. Lithos. 2010;120(3–4):327–46.

  • [18]

    Liu YS, Hu ZC, Gao S, Günther D, Xu J, Gao CG, et al. In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard. Chem Geol. 2008;257(1–2):34–43.

  • [19]

    Belousova E, Griffin W, O’Reilly SY, Fisher N. Igneous zircon: trace element composition as an indicator of source rock type. Contribut Min Petrol. 2002;143(5):602–22.

  • [20]

    Wang YX. Study on deposit geological characteristics and genetic analysis of San Cha Chong Tungsten Mine in Bobai City of Guangxi Province [Master Thesis]. Chengdu University of Technology; 2015, (in Chinese with English abstract).

  • [21]

    Jahn BM, Usuki M, Usuki T, Chung SL. Generation of Cenozoic granitoids in Hokkaido (Japan): constraints from zircon geochronology, Sr–Nd–Hf isotopic and geochemical analyses, and implications for crustal growth. Am J Sci. 2014;314:704–50.

  • [22]

    Chappell BW, White AJR, Hine R. Granite provinces and basement terranes in the Lachlan Fold Belt, southeastern Australia. Australian J Earth Sci. 1988;35(4):505–21.

  • [23]

    Calmus T, Aguillón-Robles A, Maury RC, Bellon H, Benoit M, Cotton J, et al. Spatial and temporal evolution of basalts and magnesian andesites (“ bajaites”) from Baja California, Mexico: the role of slab melts. Lithos. 2003;66:77–105.

  • [24]

    Zhu DC, Zhao ZD, Pan GT, Lee HY, Kang ZQ, Liao ZL, et al. Early Cretaceous subduction-related adakite-like rocks of the Gangdese belt, southern Tibet: products of slab melting and subsequent melt-peridotite interaction? J Asian Earth Sci. 2009;34(3):298–309.

  • [25]

    Jiang ZQ, Wang Q, Li ZX, Wyman DA, Tang GJ, Jia XH, et al. Late Cretaceous (ca. 90 Ma) adakitic intrusive rocks in the Kelu area, Gangdese Belt (southern Tibet): slab melting and implications for Cu–Au mineralization. J Asian Earth Sci. 2012;53:67–81.

  • [26]

    Middlemost EAK. Naming materials in the magma/igneous rock system. Earth Sci Rev. 1994;37(3–4):215–24.

  • [27]

    Irvine TN, Baragar WRA. A guide to the chemical classification of the common volcanic Rocks. Canadian J Earth Sci. 1971;8(5):523–48.

  • [28]

    Peccerillo A, Taylor SR. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Min Petrol. 1976;58(1):63–81.

  • [29]

    Maniar PD, Piccoli PM. Tectonic discrimination of granitoids. Geol Soc Am Bull. 1989;101(5):635–43.

  • [30]

    Sun SS, McDonough WF. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geol Soc Lond Spec Publ. 1989;42(1):313–45.

  • [31]

    Whalen JB, Currie KL, Chappell BW. A-type granite: geochemical characteristics, discrimination and petrogenesis. Contribut Min Petrol. 1987;95:407–19.

  • [32]

    Pearce JA, Harris NBW, Tindle AG. Trace element discrimination diagram for the tectonic interpretation of granitic rocks. J Petrol. 1984;25(4):956–83.

  • [33]

    Chen YW, Bi XW, Hu RZ, and Qi HW. Comparison of geochemical characteristic of uranium- and non-uranium-bearing Indosinian granites in Guidong composite pluton. J Mineral Petrol. 2009;3:106–14, (in Chinese with English abstract).

  • [34]

    Yang ZF, and Zhou JH. Can we identify source lithology of basalt? Sci Rep. 2013;3:1–7.

  • [35]

    Zhang LP. The closure of Tethys and Cretaceous mineralization: a case study of the Yangchun basin [PhD Thesis]. University of Chinese Academy of Sciences; 2017, (in Chinese with English abstract).

  • [36]

    Xiao CH, Shen YK, Wei CS, Su XK, Le XM, Zhang L. LA-ICP-MS zircon U–Pb dating, Hf isotopic composition and Ce4+/Ce3+ characteristics of the Yanshanian acid magma in the Xidamingshan Cluster, southeastern margin of the Youjiang fold belt, Guangxi. Geoscience. 2018;32(2):289–304, (in Chinese with English abstract).

  • [37]

    Zhang LP, Hu YB, Liang JL, Ireland T, Chen YL, Zhang RQ, et al. Adakitic rocks associated with the Shilu copper–molybdenum deposit in the Yangchun Basin, South China, and their tectonic implications. Acta Geochim. 2017;36(2):1–19.

  • [38]

    Sun SJ, Zhang LP, Zhang RQ, Ding X, Zhu HL, Zhang ZF, et al. Mid-late Cretaceous igneous activity in South China: the Qianjia example, Hainan Island. Int Geol Rev. 2018;60(11–14):1665–83.

  • [39]

    Yuan XB, Fang NQ, Dong HL. Geochronology, geochemistry and tectonic significance of Gaofeng and Baocheng Granite Batholiths in Hainan Island. Geoscience. 2019;33(1):85–97, (in Chinese with English abstract).

  • [40]

    Chen ML. Petrogenesis of the Qianjia Composite pluton in Hainan Island and its relationship to Mo polymetallic mineralization [PhD Thesis]. Wuhan: China University of Geosciences; 2014, (in Chinese with English abstract).

  • [41]

    Xu DR, Wu CJ, Hu GC, Chen ML, Fu YR, Wang ZL, et al. Late Mesozoic molybdenum mineralization on Hainan Island, South China: geochemistry, geochronology, and geodynamic setting. Ore Geol Rev. 2016;72:402–33.

  • [42]

    Watson EB, and Harrison TM. Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types. Earth Planet Sci Lett. 1983;64(2):295–304.

  • [43]

    Zhang Y, Ma HJ, Fan YC, Qi YX. Geological characteristics and origin of the felsic porphyroclastic lavas in the Zhedaikou area in Suichang, Zhejiang Province. East China Geol. 2017;38(1):1–11.

  • [44]

    Yan LL. The petrogenetic link between volcanic and plutonic rocks of the Cretaceous caldera complexes in the coastal area of the Zhejiang and Fujian provinces [PhD Thesis]. Beijing: China University of Geosciences; 2018, (in Chinese with English abstract).

  • [45]

    King PL, White AJR, Chappell BW, Allen CM. Characterization and origin of aluminous A-type granites from the Lachlan Fold Belt, Southeastern Australia. J Petrol. 1997;38(3):371–91.

  • [46]

    Wang XY. Late Yanshanian Magmatism and W-mineralization in Yunkai region, Guangxi Province [PhD Thesis]. Wuhan: China University of Geosciences; 2017, (in Chinese with English abstract).

  • [47]

    Chen WF, Chen PR, Xu XS, Zhang M. Geochemical characteristics of basaltic rocks in South China in Cretaceous and Their constraints on the subduction of the Pacific plate. Sci China Earth Sci. 2005;35(11):1007–18, (in Chinese).

  • [48]

    Lu FX, Sang LK. Petrology. Beijing: Geological Publishing House; 2002.

  • [49]

    Xia KY, Huang CL. The discovery of Meso-Tethys sedimentary basins in the South China Sea and their oil and gas perspective. Earth Sci Front. 2000;7(3): 227–38, (in Chinese with English abstract).

  • [50]

    Yan JX, Zhou D. Advancement on the Meso-Tethys along the northern margin of the South China Sea. Mar Geol Quater Geol. 2001;21(4):49–54, (in Chinese with English abstract).

  • [51]

    Shao L, You HQ, Hao HJ, Wu GX, Qiao PJ, Lei YC. Petrology and depositional environments of Mesozoic strata in the Northeastern South China Sea. Geol Rev. 2007;53(2):164–9, (in Chinese with English abstract).

  • [52]

    Min H, Ren JY, Gao JY, and Zuo YS. Location of the ancient subduction zone in the Northern South China Sea and its constrains on the spreading of the South China Sea Basin. Geotecton Metall. 2010;34(4):599–605, (in Chinese with English abstract).

  • [53]

    Fang NQ. A new model on the Mesozoic “South China Sea” (SCS): reconstructing the Hainan marginal arc and recognizing the Tethyan SCS. Earth Sci Front. 2016;23(6):107–19, (in Chinese with English abstract).

  • [54]

    Zhu WL, Xie XN, Wang ZF, Zhang DJ, Zhang CL, Cao LC, et al. New insights on the origin of the basement of the Xisha Uplift, South China Sea. Sci Sin Terrae. 2017;47(12):1460–8, (in Chinese).

  • [55]

    Sun WD, Lin CT, Zhang LP, Liao RQ, Li CY. The formation of the South China Sea resulted from the closure of the Neo-Tethys: a perspective from regional geology. Acta Petrol Sin. 2018;34(12):3467–78, (in Chinese with English abstract).

  • [56]

    Kay RW. Aleutian magnesian andesites: melts from subducted Pacific ocean crust. J Volcanol Geotherm Res. 1978;4(1–2):117–32.

  • [57]

    Tatsumi Y. Geochemical modeling of partial melting of subducting sediments and subsequent melt-mantle interaction: generation of high-Mg andesites in the Setouchi volcanic belt, southwest Japan. Geology. 2001;29(4):323–6.

  • [58]

    Tsuchiya N, Suzuki S, Kimura J, Kagami H. Evidence for slab melt/mantle reaction: petrogenesis of early Cretaceous and Eocene high-Mg andesites from the Kitakami Mountains, Japan. Lithos. 2005;79(1–2):179–206.

  • [59]

    Yogodzinski GM, Volynets ON, Koloskov AV, Seliverstov NI, Matvenkov VV. Magnesian andesites and the subduction component in a strongly Calc-alkaline series at Piip Volcano, Far Western Aleutians. J Petrol. 1994;35(1):163–204.

  • [60]

    Yogodzinski GM, Kay RW, Volynets ON, Koloskov AV, Kay SM. Magnesian andesite in the western Aleutian Komandorsky Region: implications for slab melting and processes in the mantle wedge. Geol Soc Am Bull. 1995;107(5):505–19.

  • [61]

    Yogodzinski GM, Kelemen PB. Slab melting in the Aleutians: implications of an ion probe study of clinopyroxene in primitive adakite and basalt. Earth Planet Sci Lett. 1998;158(1–2):53–65.

  • [62]

    Zhang ZM, Ding HX, Dong X. Formation and evolution of the Gangdese magmatic arc, southern Tibet. Acta Petrol Sin. 2018;35(2):275–94, (in Chinese with English abstract).

  • [63]

    Zhang LL, Zhu DC, Wang Q, et al. Late Cretaceous volcanic rocks in the Sangri area, southern Lhasa Terrane, Tibet: evidence for oceanic ridge subduction. Lithos. 2019;326–327:144–57.

  • [64]

    Zheng YC, Hou ZQ, Gong YL, Liang W, Sun QZ, Zhang S, et al. Petrogenesis of Cretaceous adakite-like intrusions of the Gangdese Plutonic Belt, southern Tibet: implications for mid-ocean ridge subduction and crustal growth. Lithos. 2014;190–191:240–63.

  • [65]

    Defant MJ, Xu JF, Kepezhinskas P, Wang Q, Zhang Q. Adakites: some variations on a theme. Acta Petrol Sin. 2002;18(2):129–42, (in Chinese and English abstract).

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Open Geosciences (formerly Central European Journal of Geosciences - CEJG) is an international, peer-reviewed journal publishing original research results from all fields of Earth Sciences such as: Geology, Geophysics, Geography, Geomicrobiology, Geotourism, Oceanography and Hydrology, Glaciology, Atmospheric Sciences, Speleology, Volcanology, Soil Science, Geoinformatics, Geostatistics. The journal is published in the Open Access model.

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    Maps of the Southeastern Guangxi (modified after reference 1): (a) the studied area in the context of the South China Block; (b) geological map of the studied area. The location of porphyroclastic lava samples in Shuiwen Basin is considered from Ref. 2. (1) Cretaceous acid volcanic rocks; (2) Cretaceous andesites; (3) Cretaceous granites; (4) Jurassic granites; (5) Indosinian granites; (6) Hercynian granites; (7) Caledonian granites; (8) neoproterozoic granites; (9) quaternary; (10) Paleogene sedimentary rocks; (11) Cretaceous sedimentary rocks; (12) late Paleozoic sedimentary rocks; (13) early Paleozoic sedimentary rocks; (14) faults; and (15) sample location.

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    (a) Hand specimen of andesites from Yulin; (b and c) photomicrographs of andesites, containing phenocryst of hornblende, pyroxene, and plagioclase, with matrix displaying andestic texture. (d) Hand specimen of monzogranites from Luchuan; (e and f) photomicrographs of monzogranites, containing semi-euhedral plagioclase, alkali feldspar and granular quartz with minor biotite. Abbreviations: Pl, plagioclase; Hb, hornblende; Px, clinopyroxene; Qtz, quartz; Kfs, potassium feldspar; Bi, biotite.

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    Cathodoluminescence images and U–Pb ages of zircons from Yulin andesites. The red circles indicate the analytical area for U–Pb dating, and age error is given at 2 sigma level.

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    Cathodoluminescence images and U–Pb ages of zircons from Luchuan monzogranites. The red circles indicate the analytical area for U–Pb dating, and age error is given at 2 sigma level.

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    (a) Geochemical classification diagrams for Cretaceous magmatic rocks in southeastern Guangxi: plot of Na2O + K2O versus SiO2 (after reference 26). The green line between alkaline and sub-alkaline igneous rocks is taken from Ref. 27; (b) diagram of SiO2 versus K2O (after reference 28); and (c) A/NK versus A/CNK diagram (after reference 29). A/NK: molar Al2O3/[K2O + Na2O]; A/CNK: molar Al2O3/[CaO + K2O + Na2O]. The data of porphyroclastic lava are from Reference 2.

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    (a) Chondrite-normalized REE patterns and (b) the primary-mantle-normalized trace elements spider diagrams for Cretaceous magmatic rocks in southeastern Guangxi. Normalizing values are taken from Ref. 30.

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    Tectonic discriminant diagrams of Cretaceous monzogranites and clastoporphyritic lava in southeastern Guangxi: (a) Zr + Nb + Ce + Y versus FeOT/MgO plot for the identification of A-type granites from I- and S-type granites (after Ref. 31); (b) Yb + Ta versus Rb plot for discriminating syn-collisional granites, volcanic-arc granites, within-plate granites and ocean-ridge granites (after Ref. 32).

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    Origin discriminant diagrams of Cretaceous igneous rocks in southeastern Guangxi: (a) (La/Yb)N versus δEu (after reference 33) and (b) FC3MS versus MgO plot for HMAs (after Ref. 34). FC3MS = FeOT/CaO-3*MgO/SiO2.

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    (a) Sr/Y versus Y diagrams (after Ref. 65), Hainan granites’ data are taken from Refs. 3941. (B) Schematic diagram of the tectonic setting of magmatic activities in northern margin of SCS during late early Cretaceous to early late Cretaceous.