LIFE ON EARTH BEFORE 3.83 BILLION YEARS AGO? THE AKILIA "CONTROVERSY" 10 YEARS ON

Detailed documentation of graphite associated with apatite is presented for magnetite-bearing banded quartz-pyroxene units from an early Archean supracrustal succession preserved on Akilia (island), West Greenland. This observation stands in contrast with some recent reports that graphite was absent in apatite crystals from these same units. Sample (G91-26) is a magnetite-bearing quartz pyroxene banded rock of sedimentary protolith with ¹²C-enriched carbon (δ ¹³C < -30 per mil vs. VPDB) in intimate association with apatite and previously presented as evidence for life on Earth before ca. 3.83 Ga. For comparison, further examples graphite+apatite in other pre-3.78 Ga rocks of sedimentary protolith from Akilia association enclaves on Innersuartuut island (West Greenland) and metasediments of the pre-3.75 Ga Nuvvuagittuq Supracrustal Belt (northern Québec, Canada) is also presented. Numerous challenges have been put forward that have questioned the validity of the interpretation that the Akilia rocks are the oldest known chemical sediments that also preserve biosignatures. Ten years on, geochemical evidence has accumulated to the point that the initial interpretation of the Akilia rocks as chemical sediments deposited before 3.83 Ga in a marine setting is significantly bolstered. In sum, the pre-3.83 Ga Akilia rocks provide crucial information on surface processes and biological activity on the early Earth.