Revisiting the Eoarchean Akilia quartz-pyroxene rock with potassium isotopes: Implications for early-ocean sedimentation.

ABSTRACT: The Eoarchean quartz-pyroxene rock from Akilia Island in Greenland has been proposed as one of Earth's oldest banded iron formations (BIF) and a potential host for the earliest biosignatures. However, the origin of its protolith, whether it metamorphosed from an igneous or sedimentary precursor, remains debated. Here, we revisit this longstanding Akilia controversy using potassium isotope analyses, comparing Akilia samples with BIFs and black shales spanning the Eoarchean to Mesoproterozoic. Our results demonstrate that BIFs and black shales show systematic potassium isotope variations correlated with their potassium contents. Potassium-poor BIF layers display heavier isotopic compositions close to seawater values, whereas clay-rich layers exhibit elevated potassium contents and lighter is

SUBMITTER: Long ZY 

PROVIDER: S-EPMC12337291 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature