In the volume 96(1–2) of ‘Precambrian Research’, Beaumont and Robert (1999) presented the first complete study on the nitrogen isotopic composition of kerogens preserved in Archean and Proterozoic rocks. This is an important contribution, which adds compelling data to the rather scarce N isotopic record in Precambrian rocks (Hayes et al., 1983; Gibson et al., 1985, 1986; Zhang, 1988; Sano and P...

Geologists are acquainted with the principle of uniformitarianism, which holds that present day processes are the key to those that operated in the past. But the extent this applies to the processes driving the growth and differentiation of the continental crust throughout the Earth history remains a major controversy in earth sciences. An important part of the discussion circles around the pre...

Conditions at the surface of the young (Hadean and early Archean) Earth were suitable for the emergence and evolution of life. After an initial hot period, surface temperatures in the late Hadean may have been clement beneath an atmosphere containing greenhouse gases over an ocean-dominated planetary surface. The first crust was mafic and it internally melted repeatedly to produce the felsic ro...

Komatiites are rare ultramafic lavas that were produced most commonly during the Archean and Early Proterozoic and less frequently in the Phanerozoic. These magmas provide a record of the thermal and chemical characteristics of the upper mantle through time. The most widely cited interpretation is that komatiites were produced in a plume environment and record high mantle temperatures and deep ...

The most notable trend in the sedimentary iron isotope record is a shift at the end of the Archean from highly variable δ56 Fe values with large negative excursions to less variable δ56 Fe values with more limited negative values. The mechanistic explanation behind this trend has been extensively debated, with two main competing hypotheses: (i) a shift in marine redox conditions and the transit...

The reaction sequences of central metabolism, glycolysis and the pentose phosphate pathway provide essential precursors for nucleic acids, amino acids and lipids. However, their evolutionary origins are not yet understood. Here, we provide evidence that their structure could have been fundamentally shaped by the general chemical environments in earth's earliest oceans. We reconstructed potentia...

[1] During Earth’s early history, greenhouse warming by atmospheric methane helped to maintain elevated surface temperatures. Here, we estimate the present-day abiogenic CH4 flux generated by mineral alteration (serpentinization) at midocean ridges, volcanic emissions, and geothermal sources; in addition, we assess the impact that abiogenicmethanemay have had on greenhouse warming during the ea...

The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled th...

The ocean and atmosphere were largely anoxic in the early Precambrian, resulting in an Fe cycle that was dramatically different than today’s. Extremely Fe-rich sedimentary deposits—i.e., Fe formations—are the most conspicuous manifestation of this distinct Fe cycle. Rare Earth Element (REE) systematics have long been used as a tool to understand the origin of Fe formations and the corresponding...