Evidence for methane seepage in South Atlantic from the occurrence of authigenic gypsum and framboidal pyrite in deep-sea sediments

Dantas, R.C.; Hassan, M.B.; Cruz, F. W.; Jovane, Luigi

doi:10.1016/j.marpetgeo.2022.105727

Cited by 11 publications

(8 citation statements)

References 81 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Macroscopic observations of gypsum in methane-charged sediments reveal rhombic, bladed, lenticular, or trapezoidal shapes (Kocherla, 2013;Lin et al, 2016a). By now, crystal growth of gypsum microcrystals on foraminifera shells in the seep sediments of the Nansha Trough (Zhou et al, 2020) and the Santos Basin (Dantas et al, 2022) has been observed.…”

Section: Self-shaped Crystal Growthmentioning

confidence: 85%

“…An association of authigenic gypsum with pyrite tends to occur within the sulfate-methane transition zone (SMTZ), which also marks the methane seepage events (Figure 3A; Lin et al, 2016a, b;Zhou et al, 2020;Dantas et al, 2022). The fluid released by natural gas hydrate decomposition or seepage carries dissolved barium (Ba 2+ ) (Hu et al, 2014), resulting in a higher Ba content in bottom water and usually precipitated in the form of gypsum (CaSO 4 •2H 2 O) in surface sediments (Pierre, 2017).…”

Section: Self-shaped Crystal Growthmentioning

confidence: 99%

See 1 more Smart Citation

Foraminifera associated with cold seeps in marine sediments

Yang

Huang

et al. 2023

Front. Mar. Sci.

View full text Add to dashboard Cite

Cold seep foraminifera have attracted considerable attention as they provide valuable insights into the study of cold seeps. This study provides a comprehensive overview of the manifestations of foraminifera in cold seep environments and methane seepage activities. Certain taxa of benthic foraminifera, such as Uvigerina, Bolivina, Bulimina, Chilostomella, Globobulimina, Nonionella, Melonis, Epistominella, Cibicidoides, and Globocassidulina, are known to inhabit geochemical conditions induced by methane-rich environments and may feed on associated methanotrophic microbial communities. Secondary mineralization on foraminifera shells is a widespread manifestation in seep sediments, and alters the microstructure, elementary composition, and isotopic signatures of foraminifera. On one hand, the precipitation of secondary authigenic Mg-rich, Mn-rich, Sr-rich, and Ba-rich calcite coatings have been observed on microfossils. On the other hand, micron-sized crystal pyrite and gypsum aggregates can also grow on the foraminifera walls. The negative δ13C and positive δ18O anomalies in both planktonic and benthic foraminifera from seep-associated sediments can serve as proxies for tracing past seepage activities, either in their live form or being adulterated by methane-derived authigenic carbonate after deposition. Seeping activities are recognized with a significant impact on benthic foraminifera, and the presence of cold seep-related species and significant isotopic anomalies in shells can be used to reconstruct past methane seepage events. Intensive methane seepage tends to suppress benthic foraminifera populations, while moderate intensity seepage may lead to a thriving benthic foraminiferal community, with hypoxia-enduring taxa such as Uvigerina, Melonis, and Bulimina being predominant. In contrast, oxygen-loving epibenthic taxa such as Cibicidoides often occur in areas of low methane flux. Compared to planktonic foraminifera, the single species of benthic foraminifera can provide a more comprehensive record of seepage evolution. Live benthic specimens are preferred for in-situ seep studies, while the superimposition of secondary minerals on the original shells should not be ignored when observing dead individuals. The significance of the evolution of methane seepage, changes in environmental parameters of the living habitat, and species sensitivity in cold seeps are emphasized in explaining the variation in foraminiferal assemblages and fluctuations in stable isotopes.

show abstract

Section: Self-shaped Crystal Growthmentioning

confidence: 85%

Section: Self-shaped Crystal Growthmentioning

confidence: 99%

Foraminifera associated with cold seeps in marine sediments

Yang

Huang

et al. 2023

Front. Mar. Sci.

View full text Add to dashboard Cite

show abstract

“…Except for the individual crystal, pyrite microcrystals are mostly found assembled as framboids [37]. [38][39][40][41][42], octahedral form [8,38,[43][44][45], pyritohedral form [12,38,43,[45][46][47], and intermediate [13,33,44,48,49] [38][39][40][41][42], octahedral form [8,38,[43][44][45], pyritohedral form [12,38,43,[45][46][47], and intermediate [13,33,44,48,49] under different marine environments, among which (O6,C5,C6,I1,I5,P5,P6) are BSE images, (O1-O5, C1-C4,I2-I4,I6,P1-P4) are SE images.…”

Section: Shape Of Single Crystal Of Pyritementioning

confidence: 99%

“…Figure 2. The scanning electron micrographs of euhedral pyrite in cubic form[38][39][40][41][42], octahedral form[8,38,[43][44][45], pyritohedral form[12,38,43,[45][46][47], and intermediate[13,33,44,48,49] under…”

mentioning

confidence: 99%

See 1 more Smart Citation

The Morphological Characteristics of Authigenic Pyrite Formed in Marine Sediments

Chang

2022

JMSE

View full text Add to dashboard Cite

Pyrites are widely distributed in marine sediments, the morphology of which is applied as a proxy to infer the redox conditions of bottom water, and identify diagenetic stages and hydrocarbon leakage activities. In this review, the methods used for the morphological study of pyrite are summarized. The textural and size characteristics of euhedral pyrite and pyrite aggregates, as the formation and evolution mechanism of pyrite are discussed for their significance in reconstructing the geochemical environment. The morphological study of pyrite includes shape observation, size estimation, and surface feature analysis. Scanning electron microscope and optical microscope are the main methods for morphological observation; transmission electron microscope and scanning tunneling microscope are applicable to observe nanoscale morphological structures and crystal growth on the crystal surface, and X-ray computed tomography is capable of measuring pyrite size distribution at the scale of a micrometer. Under the marine sedimentary condition, the single crystal of pyrite appears in cube, octahedron, dodecahedron, and their intermediates, the size of which ranges from several nanometers to more than 100 µm. The morphology of euhedral pyrite is controlled by temperature, pH, the chemical composition of interstitial water, etc., and might have been experienced in later reformation processes. The pyrite aggregates occur as framboid, rod-like, fossil-infilling, etc., characterized by the comparatively large size of several microns to several millimeters. It is found that certain textures correspond with different formation mechanisms and geochemical environments. Particularly, under special geological conditions, for instance, the methane leakage and/or decomposition of gas hydrate, pyrite is anomaly enriched with morphological textures of massive framboid cluster, rod-like aggregates, etc., and framboid is found with a large mean diameter (>20 µm) and standard deviation (>10 µm). These typical features can be employed to ascertain the position of the paleo sulfate methane transition zone (SMTZ).

show abstract