Search results for "Great Oxygenation Event"
showing 4 items of 4 documents
2018
AbstractWhile significant efforts have been invested in reconstructing the early evolution of the Earth’s atmosphere–ocean–biosphere biogeochemical nitrogen cycle, the potential role of an early continental contribution by a terrestrial, microbial phototrophic biosphere has been largely overlooked. By transposing to the Archean nitrogen fluxes of modern topsoil communities known as biological soil crusts (terrestrial analogs of microbial mats), whose ancestors might have existed as far back as 3.2 Ga ago, we show that they could have impacted the evolution of the nitrogen cycle early on. We calculate that the net output of inorganic nitrogen reaching the Precambrian hydrogeological system c…
Climate Over the Ages; Is the Environment Stable?
2010
As described in Chaps. 3 and 4, the advent of oxygenic photosynthesis triggered worldwide environmental changes. A world that had been reductive passed over into a state in which free dioxygen was available in the oceans and the atmosphere. We have already described the likely catastrophic effects on an anaerobic biota, but the changes were much broader than that. Dioxygen in the seas led to major changes in seawater chemistry. Iron, which had previously been soluble as ferrous salts, was precipitated in the ferric form. Copper, which had been insoluble in the anaerobic ocean as cuprous sulphide (Cu+-state), now became moderately soluble in the cupric form (Cu++-state).
Multiple sulfur and carbon isotope composition of sediments from the Belingwe Greenstone Belt (Zimbabwe): A biogenic methane regulation on mass indep…
2013
Abstract To explore the linkage between mass-independent sulfur isotope fractionation (MIF-S) and δ13Corg excursions during the Neoarchean, as well as the contemporary redox state and biogeochemical cycling of carbon and sulfur, we report the results of a detailed carbon and multiple sulfur (δ34S, δ33S, δ36S) isotopic study of the ∼2.7 Ga Manjeri and ∼2.65 Ga Cheshire formations of the Ngezi Group (Belingwe Greenstone Belt, Zimbabwe). Multiple sulfur isotope data show non-zero Δ33S and Δ36S values for sediments older than 2.4 Ga (i.e. prior to the Great Oxidation Event, GOE), indicating MIF-S thought to be associated with low atmospheric oxygen concentration. However, in several 2.7–2.5 Ga …
Nitrogen isotope evidence for stepwise oxygenation of the ocean during the Great Oxidation Event
2019
24 pages; International audience; The Earth’s oxygenation represents one of the most important environmental drivers of life’s evolution, with the first rise, known as ‘the Great Oxidation Event’ (GOE), corresponding to unpreceded accumulation of atmospheric O2, changes in the flux of marine nutrients and possibly global glaciations. However, the detailed evolution of the GOE is still debated, as for instance the accumulation trends of oceanic versus atmospheric oxygen and the nature of biogeochemical responses to oxygenation. Here, we combine organic carbon and bulk nitrogen isotope compositions with major element concentrations and iron speciation data of sedimentary rocks recovered from …