September 2024
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58 Reads
Applied Geochemistry
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September 2024
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58 Reads
Applied Geochemistry
August 2024
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79 Reads
Precambrian Research
July 2024
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128 Reads
International Journal of Earth Sciences
The organic geochemistry and coal petrology of Palaeogene coals from northeast Greenland (Thyra Ø Island and Kronprins Christian Land) and central Spitsbergen (Longyearbyen and Grumantbyen) were studied using Rock–Eval and gas chromatography–mass spectrometry, as well as microphotometry and maceral group analyses. Bulk data and biomarker distributions of the coals demonstrate a low coal rank for both, but a lower coalification degree of coals from Greenland (0.49–0.55% VRr) compared to those from Svalbard (0.68–0.75% VRr). Maceral group analyses revealed relatively similar distributions with a strong predominance of vitrinite. The generally high abundance of hopanoids (hopanes/hopenes and hopanoic acids) implies a strong bacterial reworking of the organic matter, whereas sulphur occurrences indicate a marine influence after organic matter deposition. A great variety of higher plant biomarkers was detected in all coals. Distinctive compounds recorded in the coals are aliphatic and aromatic diterpenoids as well as partly hydrogenated picenes, suggesting strong input of conifers and angiosperms. Pristane/phytane ratios indicate that the organic matter in the ancient swamps was deposited in an oxic, fluvio-deltaic setting at both sites. This study provides a detailed geochemical investigation of understudied coals from northeast Greenland. Moreover, it enhances our understanding of probably interrelated Palaeogene depositional settings from Greenland and Spitsbergen in terms of their palaeoecology, primary input into coal swamps, and individual thermal history. Graphical abstract
February 2024
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218 Reads
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3 Citations
Precambrian Research
Carbonaceous matter (CM) in Archean rocks represents a valuable archive for the reconstruction of early life. Here we investigate the nature of CM preserved in ~ 3.5 Ga old black bedded barites from the Dresser Formation (Pilbara Carton, Western Australia). Using light microscopy and high-resolution Raman mapping, three pop- ulations of CM were recognized: (i) CM at the edges of single growth bands of barite crystals (most frequent), (ii) CM within the barite matrix, and (iii) CM in 50–300 µm wide secondary quartz veins that cross-cut the black bedded barite. Raman spectra of CM inside black bedded barite indicated peak metamorphic temperatures of ~350 ◦C, consistent with those reached during the main metamorphic event in the area ~ 3.3 Ga ago. By contrast, CM in quartz veins yielded much lower temperatures of ~ 220 ◦C, suggesting that quartz-vein associated CM entered the barite after 3.3 Ga. Near edge X-ray absorption fine structure (NEXAFS) and solid-state nuclear magnetic resonance (NMR) revealed a highly aromatic nature of the CM with a lower aliphatic content, which is in line with the relatively elevated thermal maturity. Catalytic hydropyrolysis (HyPy) did not yield any hydro- carbons detectable with gas chromatography–mass spectrometry (GC–MS). Secondary ion mass spectrometry (SIMS) based δ13C values of individual CM particles ranged from − 33.4 ± 1.2 ‰ to − 16.5 ± 0.6 ‰ and are thus in accordance with a biogenic origin, which is also consistent with stromatolitic microbialites associated with the black bedded barite. Based on these results we conclude that CM at growth bands and inside the barite matrix is syngenetic and only the CM inside quartz veins, which represents a minor portion of the total CM, is a later addition to the system. Furthermore, we discuss different pathways for the input of CM into the barite-forming environment, including the cycling of biological organic material within the hydrothermal system.
January 2024
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286 Reads
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6 Citations
Precambrian Research
Microbial life on Earth was well established in the Paleoarchean, but insight into early ecosystem diversity and thus, the complexity of the early biological carbon cycle is limited. Here we investigated four carbonaceous chert samples from the lower platform facies of the ca. 3.42-billion-year-old Buck Reef Chert, Barberton greenstone belt. The analysis on multiple scales revealed exceptionally well-preserved carbonaceous matter, even on molecular level (aliphatic and aromatic hydrocarbons), resulting from rapid silicification. Geochemical evidence from stable carbon and multiple sulfur isotopes supports the presence of different microbial metabolisms in the Paleoarchean ecosystem. The local biological carbon cycle was dominated by photoautotrophs, but autotrophic sulfate reducers and methane-or acetate-producing microbes were also present. In areas of microbial methane or acetate release, methanotrophs or acetotrophs contributed to the overall biomass. These results highlight the metabolic diversity in the lower platform environment of the Buck Reef Chert, and underline that an advanced biological carbon cycle already existed in the early Archean.
October 2023
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205 Reads
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1 Citation
Geochimica et Cosmochimica Acta
In impact crater lakes, the lacustrine sedimentary records may not solely reflect climatic changes but also potential erosional effects from lithologically distinct impactite formations. The hydrochemical and biogeochemical processes during the deposition of the Nördlinger Ries impact crater lake, which fall in the range of the mid-Miocene Climate Transition, were studied by analysing microcrystalline authigenic carbonates in a drill core succession, using stable oxygen and carbon isotopes in conjunction with biomarkers. These investigations revealed an early sulfidic interval characterized by thiophenes, iso- and anteiso-C15:0 acids derived from sulfate reducing bacteria, and dolomites with low to intermediate δ13Ccarb values. The subsequent distinctive interval is characterized by extremely 13C-enriched dolomite (δ13Ccarb up to +20.93 ± 0.05 ‰ V-PDB), decline of iso- and anteiso-C15:0 acids and is rich in an Archaea-derived archaeol that is 13C-enriched (-14.7‰), indicating extensive methanogenesis in sulfate-depleted lake porewater during early diagenesis. The sulfate decline results from successive sulfate reduction when replenishment of sulfate-bearing runoff water is limited. The carbonates exhibit enriched 18O due to pronounced evaporation in a long-resided water body and enriched 13C by methanogenesis. A change in provenance of water derived from the sulfur-rich suevite (impact melt-bearing breccia) and crystalline source rocks to the sulfur-poor Bunte Breccia (continuous ejecta blanket) is required. Intermittently high Si/Al and Zr/Al at the high δ13C interval suggests sporadic short-term runoff increase, leading to fluctuating physiochemical lake conditions. A subsequent decline in both δ13Ccarb and archaeol indicates a decreasing lake level with intermittent subaerial exposure events, supported by bioturbation and mud cracks. The concomitant lake oxygenation is well supported by increasing Pr/Ph ratios and lipids derived from aerobic methanotrophs (13C-depleted 3-methyl-hopanoids). In the youngest unit, allochthonous lignites and biomarkers from lacustrine/soil sources appear, high total sulphur contents and thiophenes recur, and stable C and O isotope values decrease again. These observations suggest another major provenance change of the inflowing solutes, with increasing influx from weathered pyrite-bearing Jurassic claystones. These findings demonstrate that the climatic record expected from the stable carbon and oxygen isotopes of the Ries carbonates is strongly overprinted by hydrochemical and biogeochemical processes due to changing ion influx from substrate rocks, along the course of the successive ejecta erosion and catchment changes. Such an intrinsic control of lacustrine biogeochemical processes is also expected for other hydrologically closed impact crater lake basins, where catchment rocks with distinctively different lithologies are present.
March 2023
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119 Reads
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4 Citations
Organic Geochemistry
Major extractable lipid biomarkers (hydrocarbons, sterols and fatty acids) were assessed in Lake Seeburg, a shallow eutrophic lake that has increasingly been suffering from cyanobacterial blooms due to continued anthropogenic nutrient inputs over the last decades. Over the course of one year (2018/19), the distributions of these compounds were analyzed in the inflow, the lake water, and the topmost sediments (0–2 cm) to assess their origin and transfer into the lake deposits. Principal component analysis (PCA) was used to cluster the studied biomarkers into 5 groups with similar characteristics. These groups were comprised of (i) compounds delivered from external sources via the inflow, (ii) autochthonous compounds formed in the lake by eukaryotes or (iii) bacteria, (iv) compounds accumulating in the surface sediment, and (v) C27 to C29 stenols together with their degradation products, C27 to C29 5α(H)-stanols. Their seasonal partition clearly revealed that C27 stenols mainly derived from autochthonous sources within the lake, whereas C29 stenols largely reflect allochthonous material reaching the lake via the inflow. Analysis of stenol plus stanol concentrations with depth in two lake sediment cores (≈30 and 50 cm) found highest C27 to C29 ratios in surface sediments with lowest ratios at depth. These signals are interpreted to reflect the increasing trend of eutrophication of Lake Seeburg and, thus, enhanced autochthonous organic matter production in the lake over the last decades. The abundances of C27 vs. C29 stenols, summed with their respective degradation products, 5α(H)-stanols, are considered as suitable molecular indicators to qualitatively reconstruct historical eutrophication trends.
January 2023
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25 Reads
January 2023
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224 Reads
Carbonates and Evaporites
The boundary between the Kolosh and Sinjar Formations (BKS) studied along the northwestern side of Haibat Sultan Mountain near the village Kalka Simaq, Sulaimani area, Iraqi Kurdistan Region. Here, we reported, for the first time, on a new investigation of stratigraphy and calcareous nannofossils that dated the BKS back to the Thanetian Stage of the Late Paleocene. Furthermore, we assigned the boundary as a transitional zone between both formations that show a gradual change of facies and refute the previous unconformity at the boundary. The continuous deposition and conformability through the boundary ascertained according to the biostratigraphic zonation of calcareous nannofossils, which indicates the coincidence of the upper part of the Kolosh Formation to the NP7-NP8 nannofossil Zone (58.8–57.4 Ma), whereas the overlaying transitional zone (BKS) corresponds to the NP8-NP9 Zone (57.4–57.0 Ma) and the lower part of the Sinjar Formation to the NP9 Zone (57.0–55.8 Ma). The acme of Fasciculithus tympaniformis is located at the top of the BKS, indicating the NP9 Zone of the Late Paleocene. Additionally, the present study recorded the last occurrence of Prinsius martinii and Prinsius bisulcus, in the NP9 Zone, in the transitional zone of BKS, and in the lower part of the Sinjar Formation; it also supported by the occurrence of microfossils and macrofossils. The transitional zone is characterized by high energy with intermittent turbidity influxes and developed/progressed when detritus supply is decreased, and the carbonates deposited. The study offered the diachronicity of deposition of the Sinjar Formation along the paleo-strike of Iraqi Zagros Foreland Basin; it attributed to basin physiography and turbidity influx into the shelf of the basin. The depositional environment of BKS determined as a carbonate–siliciclastic shelf that changed to an open lagoon and patchy reef during the deposition of the Sinjar sediments.
January 2023
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21 Reads
... Despite these years of intense research, carbonate factories are still poorly understood, particularly during the Archean eon (4.0 to 2.5 billion years ago, Ga), when life on Earth was just in its infancy. During this eon, which accounts for about one-third of our planet's history, the Earth system experienced significant geobiological developments, such as declining volcanic activity and decreasing surface temperatures (Nisbet and Sleep, 2001;Lowe and Tice, 2007;Lunine, 2013;Sengupta et al., 2020;Lowe et al., 2020;Reinhardt et al., 2024). Hence, geological and biological key processes -and by extension Archean carbonate factories -must have been very different compared to any later stage in Earth's history. ...
January 2024
Precambrian Research
... Additionally, the use of fossil fuels and synthetic organic products can result in the accumulation of organic contaminants in lake sediments (Cabral and Martins, 2018;Huang et al., 2023). Thus, temporal analyses of OM origin and changing OM export from various sources have become important methods for assessing historical environmental evolution within and around lakes (Silva et al., 2008;Lu and Meyers, 2009;Holtvorth et al., 2010;Carrizo et al., 2019;Zhang et al., 2022;Zeman-Kuhnert et al., 2023). ...
March 2023
Organic Geochemistry
... L⁻ 1 diesel concentration was also reported for Acinetobacter beijerinckii after 7 days (Hong et al. 2005). The biodegradation rate of total hydrocarbons, an essential parameter for estimating the bioremediation time scale, was also determined for the bacterial isolates (Eze et al. 2022). ...
August 2022
... After the extreme rain event, oxygen depletion was observed in the lake. Within its organic-rich soils [68] and overlying waters, the microbial decomposition of the organic matter might have been intensified, resulting in consumption of the available oxygen [69]. The ammonium concentrations of the lake water were greatly influenced by the extreme event. ...
June 2022
Water
... This precondition has a tremendous geographic difference, and the alkenone is further regarded as a proxy that contains MAT signal [11]. Long chain Diol Index (LDI) was recently recognized to record warm season temperatures, but it can only be realized in marine environments [12]. Recently, sediment pollen was also used to reconstruct summer temperatures. ...
April 2022
Proceedings of the National Academy of Sciences
... It is crucial to identify plant growth-promoting rhizobacteria (PGPR) capable of tolerating hydrocarbons, palliating plant stress, and promoting growth despite harsh conditions. Boosting the PGPR microbes is an essential step in maximising the efficacy of plant-based bioremediation (Eze et al. 2022). Thus, estimating the microbial community holobiont using high-throughput sequencing technologies together with computational methods to understand the phytocoenosis in hydrocarbon bioremediation is one of the key procedures to begin with. ...
December 2021
Chemosphere
... Currently, only a few studies have investigated the temperature sensitivity of anaerobic CH 4 oxidation. 20,21 Despite confirming the similarity in temperature sensitivity between anaerobic CH 4 oxidation and CH 4 production in a paddy field, 20 a comprehensive investigation into the difference in temperature sensitivity between aerobic and anaerobic CH 4 oxidation has not yet been undertaken. Moreover, there remains a knowledge gap regarding the temperature sensitivity of the anaerobic CH 4 oxidation process on a larger scale, and it is unclear whether the relationship between the temperature sensitivity of CH 4 production and oxidation remains consistent from local values to that at a larger scale. ...
October 2021
Global Change Biology
... In the inoculated soils, there is a variation in the profile of the cenoantibiogram, which has as its most plausible cause a substitution in the composition and relative distribution of the original edaphic microbiota. In this same sense, other studies in which similar approaches are tested concluded that the taxonomic groups of inoculated microorganisms significantly increase their presence in the community that hosts them [67,72]. ...
March 2021
... 13−16 During transportation, CH 4 can be consumed through both aerobic and anaerobic oxidation. 17,18 Critical drivers for these processes include oxygen availability, soil moisture, electron acceptors, microbial communities, temperature, and pH. 2,7,19,20 These factors collectively influence the activity of aerobic and anaerobic methanotrophs, thereby determining the efficiency and extent of CH 4 oxidation before it reaches the atmosphere. ...
March 2021
Soil Biology and Biochemistry
... Samples from Archaean hydrothermal environments are known to have preserved OM that may (at least partially) derive from abiotic production that could have been accelerated by higher concentrations of H 2 (ref. 58). Less metamorphism has occurred https://doi.org/10.1038/s41550-024-02435-0 on Mars, so it may be more straightforward to understand the origin of OM in Martian hydrothermal samples; learning about abiotic OM production on Mars may therefore provide a window into the early Earth that is obscured by the active history of our planet 59 . ...
February 2021