The biogeochemistry of ferruginous lakes and past ferruginous oceans

“Candidatus Chlorobium masyuteum,” a Novel Photoferrotrophic Green Sulfur Bacterium Enriched From a Ferruginous Meromictic Lake

“…The lack of sulfur oxidation pathways in this organism or observed reduced sulfur oxidation in the enrichment suggests that it likely performs photoferrotrophy in the environment but may also be able to use fermentation by-products like H 2 or organic acids as electron donors for photosynthesis. The genome also encodes for a Mo-utilizing nitrogenase, suggesting a role for alleviation of nitrogen fixation in the redoxcline of Brownie Lake (Swanner et al, 2020).…”

“…Nitrogen fixation has been recognized in Chlorobium sp. for quite some time (Heda and Madigan, 1986;Bryant et al, 2012), and GSB may be important sources of fixed nitrogen in stratified water columns (Halm et al, 2009;Swanner et al, 2020). Although fixed nitrogen was always provided in the FW medium, the "Ca.…”

Depositional Conditions of Cretaceous Ironstones Deposit in the Chulym-Yenisey Basin (Western Siberia)

“…The absence of the Ce* and the positive Eu* are also characteristic of the studied sediments. The δ 13 C and δ 18 O values of the carbonate-bearing samples in the studied area display ranges from −5.4‰ to −12.6‰ V-PDB and −11.2‰ to −15.0‰ V-PDB, respectively. The siderite and calcite of the Ilek Formation exhibit δ 13 C ratios from ~−5.4 to −6.7‰ V-PDB and δ 18 O ratios from −11.2‰ to −11.7‰ V-PDB.…”

“…Factors controlling the origin, distribution, and sources of iron are still being debated [3,[7][8][9][10][11][12]. Continental ironstones [13][14][15][16] are comparatively rarer, but they are crucial for understanding the biogeochemical iron cycle in different periods of geological time [17,18]. These ironstones, known as channel iron deposits, occur in Oligocene sediments of Turgay and Aral regions of Kazakhstan [19][20][21] and in Miocene age paleochannel sediments in the Pilbara region of Western Australia [1,16,22,23].…”

“…Continental ironstones are predominantly of fluvial, alluvial, or lacustrine origin, including the entire spectrum from ferruginous mudstone to conglomerate [1,22,24]. A thorough investigation of these deposits is essential for the reconstruction of paleoenvironmental conditions of mineral formation [18,25,26], in addition to their commercial importance [22,27,28]. Fluvial, alluvial, lacustrine, or bog ironstones remain poorly understood, although they bear signs of global geological events [29][30][31][32][33].…”