Greigite as an Indicator for Salinity and Sedimentation Rate Change: Evidence From the Yangtze River Delta, China

Abstract

Ferrimagnetic greigite (Fe 3 S 4) is commonly regarded as a precursor to pyrite (FeS 2), or a product of pyrite oxidation, in sedimentary environments (

Exploring Spatiotemporal Paleoenvironmental and Paleoceanographic Changes on the Continental Shelf Using Authigenic Greigite: A Case Study From the East China Sea

“…These features agree with the criteria of rapidly screening sediments to identify stratigraphic intervals that may be magnetically dominated by greigite (Roberts, 1995). Moreover, the speculated greigite-enriched interval also possessed much higher S-ratio (Figure 3e) and SIRM (Figure 3f) values, similar to those reported in other studies for greigite-rich sediments (e.g., Chen et al, 2021;Sagnotti et al, 2005). Based on these variations in rock magnetic parameters and the reconstructed chronostratigraphy (Figure 2 and Table 1), the ∼8.7-39.3 m interval, which exhibited a distinct transition of magnetic assemblages (see later), was selected for further detailed analysis.…”

Greigite Formation Modulated by Turbidites and Bioturbation in Deep‐Sea Sediments Offshore Sumatra

“…Greigite formation at the expense of iron oxides (especially magnetite) would, thus, lead to a partial (or even complete) overprinting of the primary depositional remanent magnetization in sediments, which will complicate or compromise interpretation of their magnetic recording (e.g., Florindo & Sagnotti, 1995;Horng et al, 1992Horng et al, , 1998Jiang et al, 2001;Roberts & Turner, 1993;Roberts & Weaver, 2005;Robinson, 2001;Robinson & Sahota, 2000;Sagnotti et al, 2010). Knowledge of the mode and timing of greigite formation and its geological preservation potential are, therefore, key to resolving the fidelity of (paleo-)magnetic signals carried by greigite-bearing sediments, which is crucial for paleomagnetic and environmental magnetic studies (e.g., Aben et al, 2014;Y. Chen et al, 2021;Duan et al, 2020;Ebert et al, 2021;C.-F. Fu et al, 2015;Jiang et al, 2001;Just et al, 2019;Kelder et al, 2018;S.-Z.…”

Multiple Sulfur Isotopes of Iron Sulfides From Thick Greigite‐Bearing Sediments Indicate Anaerobic Oxidation and Possible Leakages of Coastal Methane

“…We applied a mass balance model following Crémière et al. (2020; Text S1 in Supporting Information ) and compiled all documented multiple sulfur isotope data from coastal to pelagic sediments to further discriminate OSR, AOM‐SR, and possible sulfide oxidation, all of which have been expected to be important in isotopically heavy pyrite and greigite formation (e.g., Chen et al., 2021; Liu et al., 2020; Roberts & Weaver, 2005; Rowan et al., 2009). The model predicts multiple sulfur isotope compositions of both porewater sulfide and pyrite (with mixing effect from porewater sulfide) in a δ 34 S‐Δ 33 S space, and pyrite is discerned into OSR dominated, OSR/AOM‐SR required, and AOM‐SR dominated fields from previous results and published field‐based measurements (Figure 4a; e.g., Crémière et al., 2020; Gong et al., 2022; Lin et al., 2017; Liu et al., 2020).…”

“…Nevertheless, methane in these reservoirs, especially in geological time, remain hotly debated as this greenhouse gas is readily consumed by methanotrophs via anaerobic oxidation of methane (AOM), mechanically liberated into the atmosphere, or even altered by late-stage methanogenesis (Beal et al, 2009;Egger et al, 2018;Segarra et al, 2015). Therefore, a proxy for identifying methane and its potential anaerobic oxidation and leakage in coastal sediments is highly needed.Ferrimagnetic greigite (Fe 3 S 4 ) has been extensively observed in gas hydrate (Larrasoaña et al, 2007), coastal (Chen et al, 2021), and lacustrine (Just et al, 2019) sediments. It is interpreted to form and preserve in environments where the AOM coupled to sulfate reduction (AOM-SR) prevails (Larrasoaña et al, 2007;Rowan et al, 2009), and therefore this easily detected magnetic mineral may be useful in tracing past methane activities in coastal sediments.…”