Dominance of felsic continental crust on Earth after 3 billion years ago is recorded by vanadium isotopes.

ABSTRACT: The transition from mafic to felsic upper continental crust (UCC) is crucial to habitability of Earth, and may be related to the onset of plate tectonics. Thus, defining when this crustal transition occurred has great significance for the evolution of Earth and its inhabitants. We demonstrate that V isotope ratios (reported as δ⁵¹V) provide insights into this transition because they correlate positively with SiO₂ and negatively with MgO contents during igneous differentiation in both subduction zones and intraplate settings. Because δ⁵¹V is not affected by chemical weathering and fluid-rock interactions, δ⁵¹V of the fine-grained matrix of Archean to Paleozoic (3 to 0.3 Ga) glacial diamictite composites, which sample the UCC at the time of glaciation, reflect the chemical composition of the UCC through time. The δ⁵¹V values of glacial diamictites systematically increase with time, indicating a dominantly mafic UCC at ~3 Ga; the UCC was dominated by felsic rocks only after 3 Ga, coinciding with widespread continental emergence and many independent estimates for the onset of plate tectonics.

SUBMITTER: Tian S 

PROVIDER: S-EPMC10243130 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature