1
|
Ge RF, Wilde SA, Zhu WB, Wang XL. Earth's early continental crust formed from wet and oxidizing arc magmas. Nature 2023; 623:334-339. [PMID: 37758955 DOI: 10.1038/s41586-023-06552-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 08/17/2023] [Indexed: 09/29/2023]
Abstract
Formation of continental crust has shaped the surface and interior of our planet and generated the land and mineral resources on which we rely. However, how the early continental crust of Earth formed is still debated1-7. Modern continental crust is largely formed from wet and oxidizing arc magmas at subduction zones, in which oceanic lithosphere and water recycle into the mantle8-10. The magmatic H2O content and redox state of ancient rocks that constitute the early continental crust, however, are difficult to quantify owing to ubiquitous metamorphism. Here we combine two zircon oxybarometers11,12 to simultaneously determine magmatic oxygen fugacity (fO2) and H2O content of Archaean (4.0-2.5 billion years ago) granitoids that dominate the early continental crust. We show that most Archaean granitoid magmas were ≥1 log unit more oxidizing than Archaean ambient mantle-derived magmas13,14 and had high magmatic H2O contents (6-10 wt%) and high H2O/Ce ratios (>1,000), similar to modern arc magmas. We find that magmatic fO2, H2O contents and H2O/Ce ratios of Archaean granitoids positively correlate with depth of magma formation, requiring transport of large amounts of H2O to the lower crust and mantle. These observations can be readily explained by subduction but are difficult to reconcile with non-subduction models of crustal formation3-7. We note an increase in magmatic fO2 and H2O content between 4.0 and 3.6 billion years ago, probably indicating the onset of subduction during this period.
Collapse
Affiliation(s)
- Rong-Feng Ge
- State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, Frontiers Science Center for Critical Earth Material Cycling, School of Earth Sciences and Engineering, Nanjing University, Nanjing, People's Republic of China.
| | - Simon A Wilde
- The Institute for Geoscience Research, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
| | - Wen-Bin Zhu
- State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, Frontiers Science Center for Critical Earth Material Cycling, School of Earth Sciences and Engineering, Nanjing University, Nanjing, People's Republic of China
| | - Xiao-Lei Wang
- State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, Frontiers Science Center for Critical Earth Material Cycling, School of Earth Sciences and Engineering, Nanjing University, Nanjing, People's Republic of China
| |
Collapse
|
2
|
Zhang Q, Zhao L, Zhou D, Nutman AP, Mitchell RN, Liu Y, Li QL, Yu HM, Fan B, Spencer CJ, Li XH. No evidence of supracrustal recycling in Si-O isotopes of Earth's oldest rocks 4 Ga ago. SCIENCE ADVANCES 2023; 9:eadf0693. [PMID: 37390214 DOI: 10.1126/sciadv.adf0693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 05/25/2023] [Indexed: 07/02/2023]
Abstract
Identifying the oldest evidence for the recycling of hydrated crust into magma on Earth is important because it is most effectively achieved by subduction. However, given the sparse geological record of early Earth, the timing of first supracrustal recycling is controversial. Silicon and oxygen isotopes have been used as indicators of crustal evolution on Archean igneous rocks and minerals to trace supracrustal recycling but with variable results. We present Si-O isotopes of Earth's oldest rocks [4.0 billion years ago (Ga)] from the Acasta Gneiss Complex, northwest Canada, obtained using multiple techniques applied to zircon, quartz, and whole rock samples. Undisturbed zircon is considered the most reliable recorder of primary Si signatures. By combining reliable Si isotope data from the Acasta samples with filtered data from Archean rocks globally, we observe that widespread evidence for a heavy Si signature is recorded since 3.8 Ga, marking the earliest record of surface silicon recycling.
Collapse
Affiliation(s)
- Qing Zhang
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Lei Zhao
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Dawn Zhou
- CSIT Group of Companies, Saskatoon S7K 2L8, Canada
| | - Allen P Nutman
- GeoQuEST Research Centre, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong 2522, Australia
| | - Ross N Mitchell
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Liu
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Qiu-Li Li
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hui-Min Yu
- School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Billy Fan
- CSIT Group of Companies, Saskatoon S7K 2L8, Canada
| | - Christopher J Spencer
- Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, ON K7L 2N8, Canada
| | - Xian-Hua Li
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
3
|
Huang G, Mitchell RN, Palin RM, Spencer CJ, Guo J. Barium content of Archaean continental crust reveals the onset of subduction was not global. Nat Commun 2022; 13:6553. [PMID: 36323691 PMCID: PMC9630499 DOI: 10.1038/s41467-022-34343-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 10/21/2022] [Indexed: 11/07/2022] Open
Abstract
Earth’s earliest continental crust is dominated by tonalite–trondhjemite–granodiorite (TTG) suites, making these rocks key to unlocking the global geodynamic regime operating during the Archaean (4.0–2.5 billion years ago [Ga]). The tectonic setting of TTG magmatism is controversial, with hypotheses arguing both for and against subduction. Here we conduct petrological modeling over a range of pressure–temperature conditions relevant to the Archaean geothermal gradient. Using an average enriched Archaean basaltic source composition, we predict Ba concentrations in TTG suites, which is difficult to increase after magma generated in the source. The results indicate only low geothermal gradients corresponding to hot subduction zones produce Ba-rich TTG, thus Ba represents a proxy for the onset of subduction. We then identify statistically significant increases in the Ba contents of TTG suites worldwide as recording the diachronous onset of subduction from regional at 4 Ga to globally complete sometime after 2.7 Ga. Only subduction zone can produce Ba-rich TTG, representing a proxy for the onset of subduction. Statistical increases in Ba contents of Archaean TTGs reveal the diachronous onset of subduction from regional at 4 Ga to globally complete after 2.7 Ga
Collapse
Affiliation(s)
- Guangyu Huang
- grid.9227.e0000000119573309State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China
| | - Ross N. Mitchell
- grid.9227.e0000000119573309State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China ,grid.410726.60000 0004 1797 8419College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Richard M. Palin
- grid.4991.50000 0004 1936 8948Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN UK
| | - Christopher J. Spencer
- grid.410356.50000 0004 1936 8331Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, ON K7L 3N6 Canada
| | - Jinghui Guo
- grid.9227.e0000000119573309State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China ,grid.410726.60000 0004 1797 8419College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, 100049 Beijing, China
| |
Collapse
|
4
|
Huang B, Johnson TE, Wilde SA, Polat A, Fu D, Kusky T. Coexisting divergent and convergent plate boundary assemblages indicate plate tectonics in the Neoarchean. Nat Commun 2022; 13:6450. [PMID: 36307406 PMCID: PMC9616927 DOI: 10.1038/s41467-022-34214-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 10/11/2022] [Indexed: 11/25/2022] Open
Abstract
The coexistence of divergent (spreading ridge) and convergent (subduction zone) plate boundaries at which lithosphere is respectively generated and destroyed is the hallmark of plate tectonics. Here, we document temporally- and spatially-associated Neoarchean (2.55–2.51 Ga) rock assemblages with mid-ocean ridge and supra-subduction-zone origins from the Angou Complex, southern North China Craton. These assemblages record seafloor spreading and contemporaneous subduction initiation and mature arc magmatism, respectively, analogous to modern divergent and convergent plate boundary processes. Our results provide direct evidence for lateral plate motions in the late Neoarchean, and arguably the operation of plate tectonics, albeit with warmer than average Phanerozoic subduction geotherms. Further, we surmise that plate tectonic processes played an important role in shaping Earth’s surficial environments during the Neoarchean and Paleoproterozoic. This study reports coexisting Neoarchean divergent and convergent plate boundary rock assemblages, providing new evidence for the operation of plate tectonics 2.55–2.51 billion years ago; and also suggests the subduction zone was warm then.
Collapse
Affiliation(s)
- Bo Huang
- Badong National Observation and Research Station for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China.
| | - Tim E Johnson
- School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Perth, WA, 6102, Australia
| | - Simon A Wilde
- School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Perth, WA, 6102, Australia
| | - Ali Polat
- School of the Environment, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | - Dong Fu
- Badong National Observation and Research Station for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China
| | - Timothy Kusky
- Badong National Observation and Research Station for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China.
| |
Collapse
|
5
|
Sun G, Liu S, Cawood PA, Tang M, van Hunen J, Gao L, Hu Y, Hu F. Thermal state and evolving geodynamic regimes of the Meso- to Neoarchean North China Craton. Nat Commun 2021; 12:3888. [PMID: 34162844 PMCID: PMC8222299 DOI: 10.1038/s41467-021-24139-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 06/01/2021] [Indexed: 11/23/2022] Open
Abstract
Constraining thickness and geothermal gradient of Archean continental crust are crucial to understanding geodynamic regimes of the early Earth. Archean crust-sourced tonalitic–trondhjemitic–granodioritic gneisses are ideal lithologies for reconstructing the thermal state of early continental crust. Integrating experimental results with petrochemical data from the Eastern Block of the North China Craton allows us to establish temporal–spatial variations in thickness, geothermal gradient and basal heat flow across the block, which we relate to cooling mantle potential temperature and resultant changing geodynamic regimes from vertical tectonics in the late Mesoarchean (~2.9 Ga) to plate tectonics with hot subduction in the early to late Neoarchean (~2.7–2.5 Ga). Here, we show the transition to a plate tectonic regime plays an important role in the rapid cooling of the mantle, and thickening and strengthening of the lithosphere, which in turn prompted stabilization of the cratonic lithosphere at the end of the Archean. Constraining the thermal state of the lithosphere is crucial to understanding geodynamic regime in early Earth. Here the authors reconstruct ~2.9–2.5 Ga thermal structure of continental lithosphere of the North China Craton using TTG and propose a systematic Archean geodynamic evolution process.
Collapse
Affiliation(s)
- Guozheng Sun
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, PR China
| | - Shuwen Liu
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, PR China.
| | - Peter A Cawood
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC, Australia.
| | - Ming Tang
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, PR China
| | | | - Lei Gao
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, PR China
| | - Yalu Hu
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, PR China
| | - Fangyang Hu
- Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China.,Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, China.,Department of Geosciences, University of Arizona, Tucson, AZ, USA
| |
Collapse
|
6
|
Archean continental crust formed by magma hybridization and voluminous partial melting. Sci Rep 2021; 11:5263. [PMID: 33664326 PMCID: PMC7933273 DOI: 10.1038/s41598-021-84300-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/15/2021] [Indexed: 11/08/2022] Open
Abstract
Archean (4.0-2.5 Ga) tonalite-trondhjemite-granodiorite (TTG) terranes represent fragments of Earth's first continents that formed via high-grade metamorphism and partial melting of hydrated basaltic crust. While a range of geodynamic regimes can explain the production of TTG magmas, the processes by which they separated from their source and acquired distinctive geochemical signatures remain uncertain. This limits our understanding of how the continental crust internally differentiates, which in turn controls its potential for long-term stabilization as cratonic nuclei. Here, we show via petrological modeling that hydrous Archean mafic crust metamorphosed in a non-plate tectonic regime produces individual pulses of magma with major-, minor-, and trace-element signatures resembling-but not always matching-natural Archean TTGs. Critically, magma hybridization due to co-mingling and accumulation of multiple melt fractions during ascent through the overlying crust eliminates geochemical discrepancies identified when assuming that TTGs formed via crystallization of discrete melt pulses. We posit that much Archean continental crust is made of hybrid magmas that represent up to ~ 40 vol% of partial melts produced along thermal gradients of 50-100 °C/kbar, characteristic of overthickened mafic Archean crust at the head of a mantle plume, crustal overturns, or lithospheric peels.
Collapse
|