Introduction Conclusions References Tables Figures Back Close Full Screen / Esc This discussion paper is/has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP if available. Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Abstract Previous research has shown that methane may have been sustained...

Some of Earth's largest iron-nickel (Fe-Ni) sulfide ore deposits formed during the Archean and early Proterozoic. Establishing the origin of the metals and sulfur in these deposits is critical for understanding their genesis. Here, we present multiple sulfur isotope data implying that the sulfur in Archean komatiite-hosted Fe-Ni sulfide deposits was previously processed through the atmosphere a...

High-resolution chemostratigraphy reveals an episode of enrichment of the redox-sensitive transition metals molybdenum and rhenium in the late Archean Mount McRae Shale in Western Australia. Correlations with organic carbon indicate that these metals were derived from contemporaneous seawater. Rhenium/osmium geochronology demonstrates that the enrichment is a primary sedimentary feature dating ...

While the Apex chert is one of the most well-studied Archean deposits on Earth, its formation history is still not fully understood. Here, we present Raman spectroscopic data collected on the carbonaceous material (CM) present within the matrix of the Apex chert. These data, collected within a paragenetic framework, reveal two different phases of CM deposited within separate phases of quartz ma...

The oldest fossils found thus far on Earth are c. 3.49- and 3.46-billion-year-old filamentous and coccoidal microbial remains in rocks of the Pilbara craton, Western Australia, and c. 3.4-billion-year-old rocks from the Barberton region, South Africa. Their biogenicity was recently questioned and they were reinterpreted as contaminants, mineral artefacts or inorganic carbon aggregates. Morpholo...

Early Earth may have hosted a biologically mediated global organic haze during the Archean eon (3.8-2.5 billion years ago). This haze would have significantly impacted multiple aspects of our planet, including its potential for habitability and its spectral appearance. Here, we model worlds with Archean-like levels of carbon dioxide orbiting the ancient Sun and an M4V dwarf (GJ 876) and show th...

The mantle plume hypothesis is widely accepted for the formation of large igneous provinces and many modern day hotspot volcanoes. Petrologic models suggest that plume-derived melts originate at high mantle temperatures (>1500 °C) relative to those generated at ambient midocean ridge conditions (~1350 °C). Earth’s mantle has also appreciably cooled during its history due to heat loss and decrea...

Fe isotopes can provide new insight into redox-dependent biogeochemical processes. Precambrian iron formations (IF) are deserving targets for Fe isotope studies because they are composed predominantly of authigenic Fe phases and record a period of unprecedented iron deposition in Earth’s history. We present Fe isotope data for bulk samples from 24 Archean and Proterozoic IF and eight Phanerozoi...

Possible geodynamic regimes that may have prevailed in the Archean are investigated by back-tracking the thermal history of Earth from the present-day conditions. If the temporal evolution of plate-tectonic convection is modulated by strong depleted lithosphere created at mid-ocean ridges, more sluggish plate tectonics is predicted when the mantle was hotter, contrary to commonly believed, more...