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
Abstract
Significance Understanding when and how subaerial continental crust first formed is crucial, as it likely played a critical role in establishing Earth’s habitability. Although debated, the broad consensus is that the subaerial rise of continents began ∼2.5 billion years ago and was driven by plate tectonics. Here, we integrate the igneous and sedimentary history of Archean cratons to demonstrate that stable continental landmasses started to emerge above sea level 3.3 to 3.2 billion years ago (i.e., over 700 million years earlier than most models predict). We also demonstrate that these initial episodes of continental emersion were driven by voluminous granitoid magmatism in non–plate tectonic settings that formed ∼50-km-thick, silica-rich crust, which rose above the oceans due to isostasy. 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…
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