Magmatic thickening of crust in non-plate tectonic settings initiated the subaerial rise of Earth's first continents 3.3 to 3.2 billion years ago.
| Autor: | Chowdhury P; School of Earth, Atmosphere and Environment, Monash University, Clayton VIC 3800, Australia; priyadarshi.chowdhury@monash.edu., Mulder JA; School of Earth, Atmosphere and Environment, Monash University, Clayton VIC 3800, Australia.; School of Earth and Environmental Sciences, University of Queensland, St Lucia QLD 4067, Australia., Cawood PA; School of Earth, Atmosphere and Environment, Monash University, Clayton VIC 3800, Australia., Bhattacharjee S; Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125., Roy S; School of Earth, Atmosphere and Environment, Monash University, Clayton VIC 3800, Australia., Wainwright AN; School of Geography, Earth and Atmospheric Sciences, The University of Melbourne, Melbourne, VIC 3010, Australia., Nebel O; School of Earth, Atmosphere and Environment, Monash University, Clayton VIC 3800, Australia., Mukherjee S; Department of Geology, University of Delhi, Delhi 110007, India. |
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| Jazyk: | angličtina |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2021 Nov 16; Vol. 118 (46). |
| DOI: | 10.1073/pnas.2105746118 |
| Abstrakt: | When and how Earth's earliest continents-the cratons-first emerged above the oceans (i.e., emersion) remain uncertain. Here, we analyze a craton-wide record of Paleo-to-Mesoarchean granitoid magmatism and terrestrial to shallow-marine sedimentation preserved in the Singhbhum Craton (India) and combine the results with isostatic modeling to examine the timing and mechanism of one of the earliest episodes of large-scale continental emersion on Earth. Detrital zircon U-Pb(-Hf) data constrain the timing of terrestrial to shallow-marine sedimentation on the Singhbhum Craton, which resolves the timing of craton-wide emersion. Time-integrated petrogenetic modeling of the granitoids quantifies the progressive changes in the cratonic crustal thickness and composition and the pressure-temperature conditions of granitoid magmatism, which elucidates the underlying mechanism and tectonic setting of emersion. The results show that the entire Singhbhum Craton became subaerial ∼3.3 to 3.2 billion years ago (Ga) due to progressive crustal maturation and thickening driven by voluminous granitoid magmatism within a plateau-like setting. A similar sedimentary-magmatic evolution also accompanied the early (>3 Ga) emersion of other cratons (e.g., Kaapvaal Craton). Therefore, we propose that the emersion of Earth's earliest continents began during the late Paleoarchean to early Mesoarchean and was driven by the isostatic rise of their magmatically thickened (∼50 km thick), buoyant, silica-rich crust. The inferred plateau-like tectonic settings suggest that subduction collision-driven compressional orogenesis was not essential in driving continental emersion, at least before the Neoarchean. We further surmise that this early emersion of cratons could be responsible for the transient and localized episodes of atmospheric-oceanic oxygenation (O Competing Interests: The authors declare no competing interest. |
| Databáze: | MEDLINE |
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