Figures

top

Introduction

Genetic relationships between ore formation and crustal evolution are long established (Sawkins, 1984

Sawkins, F.J. (1984) Metal Deposits in Relation to Plate Tectonics. Springer, New York. https://doi.org/10.1007/978-3-642-96785-6

; Cawood and Hawkesworth, 2015

Cawood, P.A., Hawkesworth, C.J. (2015) Temporal relations between mineral deposits and global tectonic cycles. In: Jenkin, G.R.T., Lusty, P.A.J., Mcdonald, I., Smith, M.P., Boyce, A.J., Wilkinson, J.J. (Eds.) Ore Deposits in an Evolving Earth. Geological Society, London, Special Publication 393, Geological Society of London, 9–21. https://doi.org/10.1144/SP393.1

). These relationships may, however, be difficult to identify due to the interplay between multiple geological processes (e.g., magmatism, sedimentary processes, and weathering) and the complexity of crustal evolution. Sediment hosted ore deposits commonly display evidence for a protracted sequence of mineralising events stretching from sedimentation to diagenesis to post-diagenetic metamorphism and/or metasomatism (Hitzman et al., 2005

Hitzman, M., Kirkham, R., Broughton, D., Thorson, J., Selley, D. (2005) The Sediment-Hosted Stratiform Copper Ore System. In: Hedenquist, J.W., Thompson, J.F.H., Goldfarb, R.J., Richards, J.P. (Eds.) Economic Geology One Hundreth Anniversary Volume, Society of Economic Geologists, Inc., Littleton, Colorado, 609–642. https://doi.org/10.5382/AV100.19

). Thus, these systems can help elucidate the relationship between ore formation and crustal evolution.

Although detrital zircon U-Pb geochronology of clastic sedimentary rocks is a well established tool for reconstructing crustal evolution (Košler et al., 2002

Košler, J., Fonneland, H., Sylvester, P., Tubrett, M., Pedersen, R.-B. (2002) U–Pb dating of detrital zircons for sediment provenance studies–a comparison of laser ablation ICPMS and SIMS techniques. Chemical Geology 182, 605–618. https://doi.org/10.1016/S0009-2541(01)00341-2

), xenotime U-Pb geochronology provides a unique glimpse into not only sedimentary sources (e.g., detrital xenotime; Kositcin et al., 2003

Kositcin, N., McNaughton, N.J., Griffin, B.J., Fletcher, I.R., Groves, D.I., Rasmussen, B. (2003) Textural and geochemical discrimination between xenotime of different origin in the Archaean Witwatersrand Basin, South Africa. Geochimica et Cosmochimica Acta 67, 709–731. https://doi.org/10.1016/S0016-7037(02)01169-9

) but also into the post-depositional history of the sedimentary sequences (e.g., diagenetic xenotime; McNaughton et al., 1999

McNaughton, N.J., Rasmussen, B., Fletcher, I.R. (1999) SHRIMP Uranium-Lead Dating of Diagenetic Xenotime in Siliciclastic Sedimentary Rocks. Science 285, 78–80. https://doi.org/10.1126/science.285.5424.78

). Xenotime is a widespread heavy rare earth (HREE) mineral which can form by magmatic, sedimentary, and hydrothermal processes but typically has small grain sizes (<20 μm); this has previously hampered routine U-Pb dating of xenotime. However, recent advances in microanalytical in situ U-Pb dating methods have improved the spatial resolution (∼10 μm) achievable by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) (Wu et al., 2020

Wu, S., Yang, M., Yang, Y., Xie, L., Huang, C., Wang, H., Yang, J. (2020) Improved in situ zircon U–Pb dating at high spatial resolution (5–16 μm) by laser ablation–single collector–sector field–ICP–MS using Jet sample and X skimmer cones. International Journal of Mass Spectrometry 456, 116394. https://doi.org/10.1016/j.ijms.2020.116394

). Contemporary microanalysis thus can circumvent the common problem of small grain size (<20 μm) and allows routine U-Pb xenotime dating of clastic sedimentary rocks.

We present in situ LA-ICP-MS U-Pb ages for xenotime and uraninite from the Yushui deposit (South China), a sediment hosted high grade Cu deposit. We integrate these data with petrography and Nd isotope data for the footwall sandstone, and propose that the HREEs and U were leached from the red footwall sandstone via oxidised basinal brines. The U-Pb dates from clastic xenotime and detrital zircon show that the footwall sandstone is mainly sourced from Silurian S-type granites, which were formed in the South China block when it represented the northern margin of East Gondwana. Given that the amalgamation of Gondwana is the most important period of S-type granite production in geological history, we suggest that the final assembly of Gondwana enhanced crustal metal (HREE and U) endowment in China, but also worldwide. Therefore, similar processes may be important in other S-type granite provinces, a finding that carries significant global implications for rare earth exploration, which can be further pivotal to pursuing a successful green energy transition.

top

Geological Background and Samples

The Yushui Cu deposit is located in eastern Guangdong Province. The economically important bedded/massive mineralisation is hosted at an unconformity between the lower Carboniferous red sandstone of the Zhongxin Formation and a dark grey dolostone/limestone of the upper Carboniferous Hutian Formation (Fig. S-1). The >300 m thick Zhongxin Formation comprises hematite-bearing red sandstone with abundant detrital minerals including xenotime, rutile, and zircon (Figs. 1b, S-2a–c). The Hutian Formation is predominantly composed of >350 m thick dolomite and limestone with organic- and apatite-rich beds in the lower part (Fig. S-2d). The bedded/massive mineralisation comprises Cu sulfides, barite, hematite, anhydrite, sphalerite, galena (Fig. S-2e,f), and U and HREE-rich minerals, with local HREE grades up to 6.1 wt. % (Fig. S-3, Table S-1). The HREE-rich domains include uraninite (Fig. 1c), hingganite-[Y] (Y₂Be₂[SiO₄]₂[OH]₂, Fig. 1d), thortveitite ([Sc,Y]₂Si₂O₇, Fig. 1e), jingwenite-[Y] (Y₂Al₂V⁴⁺₂[SiO₄]₂O₄[OH]₄, Fig. 1f; Liu et al., 2023

Liu, P., Gu, X., Zhang, W., Hu, H., Chen, X., Wang, X., Song, W., Yu, M., Cook, N.J. (2023) Jingwenite-(Y) from the Yushui Cu deposit, South China: The first occurrence of a V-HREE-bearing silicate mineral. American Mineralogist 108, 192–196. https://doi.org/10.2138/am-2022-8373

), xenotime (Fig. 1g), iimoriite-[Y] (Y₂[SiO₄] [CO₃], Fig. S-4a), synchysite-[Y] (CaY[CO₃]₂F, Fig. S-4b), kamphaugite-[Y] (CaY[CO₃]₂[OH]·H₂O, Fig. S-4c), and chernovite-[Y] (Y[AsO₄], Fig. S-4d). Samples with hingganite-[Y], uraninite, and xenotime were collected from the bedded/massive mineralisation, and detrital zircon and xenotime were sampled from the lower Carboniferous red sandstone. There are three types of xenotime grains in the sandstone: xenotime-(I) occurring as anhedral grains intergrown with hematite forming veinlets (Fig. S-4e), xenotime-(II) occurring as fine grained (5–15 μm) anhedral grains (Fig. S-4f), and xenotime-(III) occurring as euhedral to subhedral grains intergrown with detrital zircon and quartz (Figs. S-2c, S-4g,h). Sample details are given in Figure S-5; analytical methods in Supplementary Information.

Full size image

top

Results

In situ U-Pb dating of xenotime, zircon, and uraninite. Fifty seven spot analyses of 26 uraninite grains yielded a weighted mean ²⁰⁶Pb/²³⁸U age of 223.7 ± 0.8 Ma (2σ, MSWD = 0.7) (Fig. 2a, Table S-2). Thirty spot analyses of 25 xenotime grains from the bedded/massive orebody returned a lower intercept age of 221.8 ± 3.5 Ma (2σ, MSWD = 2.2) on a Tera-Wasserburg plot. The ²⁰⁷Pb corrected ²⁰⁶Pb/²³⁸U ages yielded a weighted mean of 222.4 ± 2.4 Ma (2σ, MSWD = 1.5) (Fig. 2b, Table S-2).

Full size image

Seventy nine spot analyses of xenotime-I, -II, and -III from the footwall red sandstone yielded three ranges of U-Pb ages at 228–218 Ma (n = 3), 387–329 Ma (n = 11), and 486–404 Ma (n = 65) (Fig. 2c, Table S-3), respectively. Three spot analyses on xenotime-I with the range at 228–218 Ma yielded a weighted mean ²⁰⁶Pb/²³⁸U age of 218.2 ± 5.9 Ma. Fifty nine spot analyses on xenotime-III from the major peak at 431–404 Ma returned a lower intercept age of 421.2 ± 3.8 Ma (2σ, MSWD = 0.26) on the Tera-Wasserburg plot, and a ²⁰⁷Pb corrected weighted mean ²⁰⁶Pb/²³⁸U age of 421.2 ± 2.6 Ma (2σ, MSWD = 0.27) (Fig. 2d). 197 spot analyses of detrital zircon of the footwall red sandstone yielded three major peaks at 470–410 Ma (n = 45), 1100–900 Ma (n = 42), and 2600–2300 Ma (n = 24) (Fig. 2e, Table S-4).

In situ and bulk rock Sm-Nd isotope composition. Thirty in situ spot analyses on 30 hingganite-[Y] grains yielded a Sm-Nd isochron age of 233 ± 12 Ma (2σ, MSWD = 0.8) (Fig. S-6a, Table S-5). Twenty one in situ spot analyses on 20 xenotime grains from the orebody returned a Sm-Nd isochron age of 225 ± 26 Ma (2σ, MSWD = 0.19) (Fig. S-6b, Table S-5), similar to the U-Pb age of 222.4 ± 2.4 Ma within uncertainty. The ɛ_Nd(t) values of hingganite-[Y] and xenotime were calculated using an age of 223 Ma, and range from −13.2 to −12.0 and −13.3 to −11.4, respectively (Fig. 2f). Bulk rock Sm-Nd isotope analyses of the lower Carboniferous red sandstone yielded ¹⁴³Nd/¹⁴⁷Nd values ranging from 0.511747 to 0.512008 (Table S-5). Initial ɛ_Nd(t) values were calculated using the formation ages of 323 Ma for the red sandstone, ranging from −14.5 to −10.8 (Fig. 2f).

top

Discussion

Source of rare earths and uranium. This contribution focuses on the genesis of the HREE and U mineralisation of the Yushui Cu deposit. The new combined radioisotopic data from multiple minerals provide a consistent dataset with a concordant mineral formation age of ca. 223 ± 1 Ma. This age corresponds to a period of significant post-orogenic extension of the South China block (Zhao et al., 2018

Zhao, G., Wang, Y., Huang, B., Dong, Y., Li, S., Zhang, G., Yu, S. (2018) Geological reconstructions of the East Asian blocks: From the breakup of Rodinia to the assembly of Pangea. Earth-Science Reviews 186, 262–286. https://doi.org/10.1016/j.earscirev.2018.10.003

). There is no magmatism at Yushui coeval with HREE and U mineralisation.

The ɛ_Nd(t) values (−13.3 to −11.4) of HREE minerals from the unconformity at Yushui are consistent with those (−14.8 to −10.8) of the underlying red sandstone. Abundant detrital heavy minerals such as xenotime, monazite, rutile, and zircon occur in the footwall red sandstone sequence. These minerals show dissolution and alteration textures (Fig. S-7), which indicate fluid leaching of HREEs and U. This is also supported by the Y, Yb, and U distributions revealed by EPMA elemental mapping of xenotime in the red sandstone (Fig. 3).

Full size image

Genetic links between unconformity-related U deposits and HREE mineralisation have been proposed elsewhere, for example in the Northern Territory, Australia (Nazari-Dehkordi et al., 2018

Nazari-Dehkordi, T., Spandler, C., Oliver, N.H.S., Wilson, R. (2018) Unconformity-Related Rare Earth Element Deposits: A Regional-Scale Hydrothermal Mineralization Type of Northern Australia. Economic Geology 113, 1297–1305. https://doi.org/10.5382/econgeo.2018.4592

; Richter et al., 2018

Richter, L., Diamond, L.W., Atanasova, P., Banks, D.A., Gutzmer, J. (2018) Hydrothermal formation of heavy rare earth element (HREE)–xenotime deposits at 100 °C in a sedimentary basin. Geology 46, 263–266. https://doi.org/10.1130/G39871.1

), and the Athabasca Basin, Saskatchewan, Canada (Quirt et al., 1991

Quirt, D.H., Kotzer, T., Kyser, T.K. (1991) Tourmaline, phosphate minerals, zircon, and pitchblende in the Athabasca Group: Maw Zone and McArthur River areas, Saskatchewan. In: Summary of Investigations 1991. Saskatchewan Geological Survey, Saskatchewan Ministry of Energy and Mines, Miscellaneous Report 91-4, 181–191. https://pubsaskdev.blob.core.windows.net/pubsask-prod/88108/88108-Quirt-Kotzer-Kyser_1991_MiscRep91-4.pdf

; Fayek and Kyser, 1997

Fayek, M., Kyser, T.K. (1997) Characterization of multiple fluid-flow events and rare-earth-element mobility associated with formation of unconformity-type uranium deposits in the Athabasca Basin, Saskatchewan. The Canadian Mineralogist 35, 627–658. https://pubs.geoscienceworld.org/canmin/article-pdf/35/3/627/3420516/627.pdf

). Both these examples formed in extensional settings via the large scale circulation of oxidised, relatively low temperature saline fluids, with ore deposition taking place at redox interfaces (Quirt et al., 1991

Quirt, D.H., Kotzer, T., Kyser, T.K. (1991) Tourmaline, phosphate minerals, zircon, and pitchblende in the Athabasca Group: Maw Zone and McArthur River areas, Saskatchewan. In: Summary of Investigations 1991. Saskatchewan Geological Survey, Saskatchewan Ministry of Energy and Mines, Miscellaneous Report 91-4, 181–191. https://pubsaskdev.blob.core.windows.net/pubsask-prod/88108/88108-Quirt-Kotzer-Kyser_1991_MiscRep91-4.pdf

; Fayek and Kyser, 1997

Fayek, M., Kyser, T.K. (1997) Characterization of multiple fluid-flow events and rare-earth-element mobility associated with formation of unconformity-type uranium deposits in the Athabasca Basin, Saskatchewan. The Canadian Mineralogist 35, 627–658. https://pubs.geoscienceworld.org/canmin/article-pdf/35/3/627/3420516/627.pdf

; Nazari-Dehkordi et al., 2018

Nazari-Dehkordi, T., Spandler, C., Oliver, N.H.S., Wilson, R. (2018) Unconformity-Related Rare Earth Element Deposits: A Regional-Scale Hydrothermal Mineralization Type of Northern Australia. Economic Geology 113, 1297–1305. https://doi.org/10.5382/econgeo.2018.4592

; Richter et al., 2018

Richter, L., Diamond, L.W., Atanasova, P., Banks, D.A., Gutzmer, J. (2018) Hydrothermal formation of heavy rare earth element (HREE)–xenotime deposits at 100 °C in a sedimentary basin. Geology 46, 263–266. https://doi.org/10.1130/G39871.1

). Similar fluids have been identified in primary fluid inclusions at Yushui (i.e. 8–15 wt. % NaCl equiv., 110–287 °C; Jiang et al., 2016

Jiang, B.-b., Zhu, X.-y., Cheng, X.-y., Wang, H. (2016) Characteristics and geological significance of fluid inclusions in the Yushui copper polymetallic deposit, Guangdong Province. Geology in China 43, 2163–2172 (in Chinese with English abstract). http://doi.org/10.12029/gc20160624

). In general, the hydrothermal transport of REEs requires complexation with a dominance of Cl⁻, CO₃²⁻, and SO₄²⁻ species (Williams-Jones et al., 2012

Williams-Jones, A.E., Migdisov, A.A., Samson, I.M. (2012) Hydrothermal Mobilisation of the Rare Earth Elements – a Tale of “Ceria” and “Yttria”. Elements 8, 355–360. https://doi.org/10.2113/gselements.8.5.355

; Migdisov et al., 2016

Migdisov, A., Williams-Jones, A.E., Brugger, J., Caporuscio, F.A. (2016) Hydrothermal transport, deposition, and fractionation of the REE: Experimental data and thermodynamic calculations. Chemical Geology 439, 13–42. https://doi.org/10.1016/j.chemgeo.2016.06.005

; Zhou et al., 2016

Zhou, L., Mavrogenes, J., Spandler, C., Li, H. (2016) A synthetic fluid inclusion study of the solubility of monazite-(La) and xenotime-(Y) in H₂-Na-K-Cl-F-CO₂ fluids at 800 °C and 0.5 GPa. Chemical Geology 442, 121–129. https://doi.org/10.1016/j.chemgeo.2016.09.010

). The occurrence of hydrothermal barite, anhydrite, hematite, synchysite-[Y], kamphaugite-[Y], and iimoriite-[Y] in the Yushui mineralisation indicates that the ore fluids were oxidised with a dominance of CO₃²⁻ and SO₄²⁻. However, although redox reactions cannot effectively drive the formation of HREE-bearing minerals (Migdisov et al., 2016

Migdisov, A., Williams-Jones, A.E., Brugger, J., Caporuscio, F.A. (2016) Hydrothermal transport, deposition, and fractionation of the REE: Experimental data and thermodynamic calculations. Chemical Geology 439, 13–42. https://doi.org/10.1016/j.chemgeo.2016.06.005

), the presence of phosphorus in hydrothermal fluids can significantly lower the solubilities of HREEs (Williams-Jones et al., 2012

Williams-Jones, A.E., Migdisov, A.A., Samson, I.M. (2012) Hydrothermal Mobilisation of the Rare Earth Elements – a Tale of “Ceria” and “Yttria”. Elements 8, 355–360. https://doi.org/10.2113/gselements.8.5.355

; Gysi et al., 2015

Gysi, A.P., Williams-Jones, A.E., Harlov, D. (2015) The solubility of xenotime-(Y) and other HREE phosphates (DyPO₄, ErPO₄, and YbPO₄) in aqueous solutions from 100 to 250 °C and p_sat. Chemical Geology 401, 83–95. https://doi.org/10.1016/j.chemgeo.2015.02.023

), and, notably, there are apatite-rich beds in the lower part of the overlying dolostone/limestone at Yushui. Therefore, we suggest that HREEs and U were leached from detrital minerals in the underlying hematite-bearing red sandstone by saline, oxidised basinal fluids and were then precipitated in organic-rich beds in the overlying dolostone/limestone, which acted as a reductant and also provided P for efficient REE fixation.

Metal Endowment from the Final Assembly of Gondwana. The age range of 228–218 Ma for xenotime-I from the footwall red sandstone is coeval with the formation age (223 Ma) of HREE- and U-bearing minerals from the bedded mineralisation. The 387–329 Ma range for xenotime-II is comparable to the formation age of the Late Devonian to early Carboniferous sedimentary sequence. By contrast, the 486–404 Ma age range for detrital xenotime-III is coincident with the principal age peak at 470–410 Ma of detrital zircon in the footwall sandstone. The Devonian to Carboniferous successions in the South China block are dominated by siliciclastic units with minor coeval magmatism (Wang et al., 2010

Wang, Y., Zhang, F., Fan, W., Zhang, G., Chen, S., Cawood, P.A., Zhang, A. (2010) Tectonic setting of the South China Block in the early Paleozoic: Resolving intracontinental and ocean closure models from detrital zircon U-Pb geochronology. Tectonics 29, TC6020. https://doi.org/10.1029/2010TC002750

), and contain significant amounts of detrital xenotime, monazite, rutile, and zircon. Triassic extension produced rifting-related, basinal fluid circulation and leaching of metals (e.g., HREEs and U) by oxidised basinal fluids from the underlying red sandstone sequence. Notably, Late Devonian to early Carboniferous sedimentary red bed basins are found elsewhere (Song et al., 2017

Song, H., Jiang, G., Poulton, S.W., Wignall, P.B., Tong, J., Song, H., An, Z., Chu, D., Tian, L., She, Z., Wang, C. (2017) The onset of widespread marine red beds and the evolution of ferruginous oceans. Nature Communications 8, 399. https://doi.org/10.1038/s41467-017-00502-x

), such as the Chu-Sarysu basin of Kazakhstan, which also hosts major redox-controlled U deposits (Dahlkamp, 2009

Dahlkamp, F.J. (2009) Uranium Deposits of the World: Asia. Springer-Verlag, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-78558-3

). Therefore, this finding strongly suggests that analogous Carboniferous red bed sedimentary basins in South China and elsewhere may also host HREE and U mineralisation.

Crucially, the principal peak (421.2 ± 2.6 Ma) of detrital xenotime corresponds to the age of Silurian S-type granites in South China (Zhao et al., 2018

Zhao, G., Wang, Y., Huang, B., Dong, Y., Li, S., Zhang, G., Yu, S. (2018) Geological reconstructions of the East Asian blocks: From the breakup of Rodinia to the assembly of Pangea. Earth-Science Reviews 186, 262–286. https://doi.org/10.1016/j.earscirev.2018.10.003

), suggesting that the footwall sandstone is ultimately derived from Silurian S-type granites. Such granites in South China are mainly peraluminous two mica/garnet granites. They have been interpreted as a far field response to early Palaeozoic continental collision and then orogenic collapse events (Wang et al., 2010

Wang, Y., Zhang, F., Fan, W., Zhang, G., Chen, S., Cawood, P.A., Zhang, A. (2010) Tectonic setting of the South China Block in the early Paleozoic: Resolving intracontinental and ocean closure models from detrital zircon U-Pb geochronology. Tectonics 29, TC6020. https://doi.org/10.1029/2010TC002750

) (Fig. 4a), which led to the South China block becoming accreted to the northern margin of East Gondwana leading to the final Gondwana assembly (Fig. 4b) (Cawood et al., 2013

Cawood, P.A., Wang, Y., Xu, Y., Zhao, G. (2013) Locating South China in Rodinia and Gondwana: A fragment of greater India lithosphere? Geology 41, 903–906. https://doi.org/10.1130/G34395.1

; Zhao et al., 2018

Zhao, G., Wang, Y., Huang, B., Dong, Y., Li, S., Zhang, G., Yu, S. (2018) Geological reconstructions of the East Asian blocks: From the breakup of Rodinia to the assembly of Pangea. Earth-Science Reviews 186, 262–286. https://doi.org/10.1016/j.earscirev.2018.10.003

).

Full size image

S-type granites generally have a metapelitic source characterised by accessory assemblages comprising xenotime, monazite, and zircon (Chappell et al., 1987

Chappell, B.W., White, A.J.R., Wyborn, D. (1987) The Importance of Residual Source Material (Restite) in Granite Petrogenesis. Journal of Petrology 28, 1111–1138. https://doi.org/10.1093/petrology/28.6.1111

; Bea and Montero, 1999

Bea, F., Montero, P. (1999) Behavior of accessory phases and redistribution of Zr, REE, Y, Th, and U during metamorphism and partial melting of metapelites in the lower crust: an example from the Kinzigite Formation of Ivrea-Verbano, NW Italy. Geochimica et Cosmochimica Acta 63, 1133–1153. https://doi.org/10.1016/S0016-7037(98)00292-0

). Partial melting of metapelites can enhance the HREE and U concentrations in peraluminous melts (Bea and Montero, 1999

Bea, F., Montero, P. (1999) Behavior of accessory phases and redistribution of Zr, REE, Y, Th, and U during metamorphism and partial melting of metapelites in the lower crust: an example from the Kinzigite Formation of Ivrea-Verbano, NW Italy. Geochimica et Cosmochimica Acta 63, 1133–1153. https://doi.org/10.1016/S0016-7037(98)00292-0

; Villaseca et al., 2003

Villaseca, C., Martín Romera, C., De la Rosa, J., Barbero, L. (2003) Residence and redistribution of REE, Y, Zr, Th and U during granulite-facies metamorphism: behaviour of accessory and major phases in peraluminous granulites of central Spain. Chemical Geology 200, 293–323. https://doi.org/10.1016/S0009-2541(03)00200-6

). In addition, P has a high solubility in strongly peraluminous S-type granitic magmas and there is substitution of REE³⁺ + Y³⁺ for Zr (ZrSiO₄ ↔ [REE,Y]PO₄) in zircon from S-type granites which is charge balanced by P⁵⁺ (Burnham and Berry, 2017

Burnham, A.D., Berry, A.J. (2017) Formation of Hadean granites by melting of igneous crust. Nature Geoscience 10, 457–461. https://doi.org/10.1038/ngeo2942

). Consequently, subsequent crystallisation of the S-type granites would produce abundant zircon, xenotime, and monazite.

The amalgamation of Gondwana is the most important period of S-type granite production in geological history, especially in Australia, Europe, and South China (Spencer et al., 2014

Spencer, C.J., Cawood, P.A., Hawkesworth, C.J., Raub, T.D., Prave, A.R., Roberts, N.M.W. (2014) Proterozoic onset of crustal reworking and collisional tectonics: Reappraisal of the zircon oxygen isotope record. Geology 42, 451–454. https://doi.org/10.1130/G35363.1

; Zhu et al., 2020

Zhu, Z., Campbell, I.H., Allen, C.M., Burnham, A.D. (2020) S-type granites: Their origin and distribution through time as determined from detrital zircons. Earth and Planetary Science Letters 536, 116140. https://doi.org/10.1016/j.epsl.2020.116140

). Rapid erosion led to clastic sedimentary rocks that contain abundant HREE-U-bearing minerals which can then be leached by younger mineralising events. Furthermore, these HREE-U-bearing clastic sedimentary rocks may undergo partial melting and generate younger HREE-U-rich granites (Fig. 4c) which may then be upgraded by processes in the critical zone to form the recent/subrecent regolith-hosted (or ion adsorption) HREE deposits of South China (Li et al., 2017

Li, Y.H.M., Zhao, W.W., Zhou, M.-F. (2017) Nature of parent rocks, mineralization styles and ore genesis of regolith-hosted REE deposits in South China: An integrated genetic model. Journal of Asian Earth Sciences 148, 65–95. https://doi.org/10.1016/j.jseaes.2017.08.004

). Our study highlights that the final assembly of Gondwana established a long term metal reservoir in South China which was tapped repeatedly by ore forming fluids.

top

Acknowledgements

This research was jointly funded by the National Natural Science Foundation of China (Grants 42272070 and 42130102), the Young Star of Science and Technology Plan Projects in Shaanxi Province, China (Grant 2023KJXX-037) and the Natural Science Basic Research Program in Shaanxi Province of China (2022JC-DW5-01). PL is funded by the China Scholarship Council. SAG is funded by a Helmholtz Recruitment Initiative.

Editor: Raúl Fonseca

top

References

top

Supplementary Information

The Supplementary Information includes:

Sample Descriptions

Analytical Methods

Supplementary Figures S-1 to S-7

Supplementary Tables S-1 to S-5

Supplementary Information References

Download Tables S-1 to S-5 (xlsx)

Download the Supplementary Information (PDF)