Dynamic interplay of biogeochemical C, S and Ba cycles in response to the Shuram oxygenation event

Abstract

Compared with Phanerozoic strata, sulfate minerals are relatively rare in the Precambrian record likely due to the lower concentrations of sulfate in dominantly anoxic oceans. Here, we present a compilation of sulfate minerals that are stratigraphically associated with the Ediacaran Shuram excursion (SE) — the largest negative δ13C excursion in Earth history. We evaluated 15 SE sections, all of which reveal the presence of sulfate minerals and/or concentration enrichment in carbonate-associated sulfate, suggesting a rise in sulfate reservoir. Notably, where data are available, the SE also reveals considerable enrichments in [Ba] relative to pre- and post-SE intervals. We propose that elevated seawater sulfate concentrations during the SE may have faciliated authigenesis of sulfate minerals. At the same time, the rise of Ba concentrations in shelf environments further facilitated barite deposition. A larger sulfate reservoir would stimulate microbial sulfate reduction and anaerobic oxidation of organic matter (including methane), contributing to the genesis of the SE. The existence of sulfate minerals throughout the SE suggests that oxidant pools were not depleted at that time, which challenges previous modelling results. Our study highlights the dynamic interplay of biogeochemical C, S, and Ba cycles in response to the Shuram oxygenation event.Thematic collection: This article is part of the Sulfur in the Earth system collection available at: https://www.lyellcollection.org/cc/sulfur-in-the-earth-systemSupplementary material:https://doi.org/10.6084/m9.figshare.c.5602560

Paleomagnetismo, estratigrafia magnética e sedimentologia do Ediacarano na Formação Avellaneda (Argentina)

“…Global temperatures estimates using δ 18 O composition of Precambrian oceans suggest of tropical paleotemperatures for the late Precambrian (Ediacaran) was higher (>50•C) than in the Phanerozoic periods (Bergmann et al, 2018;Scotese et al, 2021). The improve in recognized of sulfate phases minerals in Ediacran depostis can be help to better contains paleoclimatic conditions (Cui et al, 2022).…”

“…The origin of the SE excursion has been attributed to the mineralization of a large global ocean dissolved inorganic carbon (DIC) reservoir due to oxidation of organic carbon or methane (Rothman et al, 2003;Fike et al, 2006;Kaufman et al, 2007;McFadden et al, 2008;Bjerrum and Canfield, 2011), or to large authigenic carbonate precipitation (Grotzinger et al, 2011;Macdonald et al, 2013;Schrag et al, 2013;Cui et al, 2017), or yet from burial or meteoric diagenesis (Knauth and Kennedy, 2009;. More recently Cui et al, (2022) propose a complex interplay of biogeochemical process involving bacterial sulfate reduction and C, S and Ba cycles in response to the Shuram oxygenation event. The age and duration of the anomaly are poorly constrained.…”

“…Barite can be formed in the water column, or within marine sediments or around hydrothermal vents and cold seeps or yet by deposition of older barite deposits as detrital material (Paytan et al, 2002;Griffith and Paytan, 2012;Okubo et al, 2018;Widanagamage et al, 2018;Martinez-Ruiz et al, 2019). The shape and size of barite crystals are useful to determine its environment formation (Bishop, 1988;Paytan et al, 1993;Paytan et al, 2002;Cui et al, 2022;Cheng et al, 2022).…”

“…During this interval, completely new organisms arose in the marine ecosystem, previously, essentially dominated by microbial mats communities (Grotzinger and Knoll, 1999). The shift in marine environment and diversification of early biota was accompanied by dramatic perturbations in global biogeochemical cycles, including some of the largest excursions in the carbon and sulfur isotope ratios (Halverson et al, 2005;Shields et al, 2019;Cui et al, 2022). All these innovations are attributed to irreversible changes on Earth's surface environments.…”

“…For instance, the largest carbon isotope excursion recorded at the time has been interpreted in a variety of ways, including local or global scales (Grotzinger et al, 2011). Mechanisms involve diagenetic overprints (Knauth and Kennedy, 2009;, destabilization of methane hydrate (Bjerrum and Canfield, 2011), a spike in mantle CO2 degassing (Paulsen et al, 2017), eruption of carbonatite volcanic ash (Liu et al, 2021) and/or the sudden increase in the ocean sulfate reservoir stimulating microbial sulfate reduction and anaerobic oxidation of organic matter (Shields et al, 2019;Cui et al, 2022). Therefore, to better separate global from local processes and understand the feedbacks between life evolution and environmental changes, it is of utmost importance to characterize in detail key Ediacaran successions in different paleo continents and the sedimentary product of these processes.…”