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Journal articles on the topic 'Paleo-redox'

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Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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1

Dideriksen, K., B. C. Christiansen, C. Frandsen, T. Balic-Zunic, S. Mørup, and S. L. S. Stipp. "Paleo-redox boundaries in fractured granite." Geochimica et Cosmochimica Acta 74, no. 10 (May 2010): 2866–80. http://dx.doi.org/10.1016/j.gca.2010.02.022.

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2

Asahina, Kenta, Satoshi Takahashi, Ryosuke Saito, Kunio Kaiho, and Yasuhiro Oba. "Maleimide index: a paleo-redox index based on fragmented fossil-chlorophylls obtained by chromic acid oxidation." RSC Advances 12, no. 48 (2022): 31061–67. http://dx.doi.org/10.1039/d2ra04702k.

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3

Liu, Y. G., M. R. U. Miah, and R. A. Schmitt. "Cerium: A chemical tracer for paleo-oceanic redox conditions." Geochimica et Cosmochimica Acta 52, no. 6 (June 1988): 1361–71. http://dx.doi.org/10.1016/0016-7037(88)90207-4.

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4

Madukwe, Henry Y. "Source-Area Weathering, Composition and Paleo-Redox Condition of Stream Sediments from Ijero-Ekiti, Nigeria." International Journal of Trend in Scientific Research and Development Volume-1, Issue-5 (August 31, 2017): 446–65. http://dx.doi.org/10.31142/ijtsrd2365.

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5

Devi, Salam Ranjeeta. "Geochemistry of the Transitional beds between Disang and Barail Successions of the Imphal Valley, Indo-Myanmar Ranges." Journal of The Indian Association of Sedimentologists 39, no. II (December 31, 2022): 10–16. http://dx.doi.org/10.51710/jias.v39iii.247.

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Major and trace element concentrations were studied from the tansitional beds between Disang and Barail Successions of the Imphal valley, Indo-Myanmar Ranges. Various major and trace element ratios and discrinant diagrams were used to descipher paleoclimate, paleo-redox condition and sedimentary depositional environment of the Disang-Barail Transitional beds. SiO2 vs Al2O3+K2O+ Na2O diagram and Rb/Sr ratios indicates that paleoclimate during the deposition of the sediments changed from arid to semi-arid and humid climate. Ni/Co, V/Cr, V/(Ni+V), V/Sc ratios suggest that these sediments were deposited in oxic, suboxic to anoxic conditions. V/(Ni+V) vs V/Cr diagram suggests paleo-redox environment dominated by sub-reduction to oxidization during Disang –Barail Transitional deposition. The sediments were deposited in transitional to marine depositional environment.

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6

Stylo, Malgorzata, Nadja Neubert, Yuheng Wang, Nikhil Monga, Stephen J. Romaniello, Stefan Weyer, and Rizlan Bernier-Latmani. "Uranium isotopes fingerprint biotic reduction." Proceedings of the National Academy of Sciences 112, no. 18 (April 20, 2015): 5619–24. http://dx.doi.org/10.1073/pnas.1421841112.

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Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. Additionally, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium.

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7

Wei, Mingyang, Zhidong Bao, Axel Munnecke, Wei Liu, G. Harrison, Hua Zhang, Demin Zhang, et al. "Paleoenvironment of the Lower–Middle Cambrian Evaporite Series in the Tarim Basin and Its Impact on the Organic Matter Enrichment of Shallow Water Source Rocks." Minerals 11, no. 7 (June 22, 2021): 659. http://dx.doi.org/10.3390/min11070659.

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Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this study, two wells in the central uplift of the Tarim Basin were systematically sampled and analyzed for a basic geochemical study, including major elements, trace elements, and total organic carbon (TOC), to understand the relationship between TOC and the paleoenvironmental parameters, such as paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity. The results show that the Lower–Middle Cambrian mainly developed in a fluctuating salinity, weak anoxic to anoxic, continuous dry and hot, and proper shallow water environment. The interfingering section of evaporites, carbonates, and claystones of the Awatag Fm. have higher paleoproductivity and higher enrichment of organic matter. Paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity jointly control the organic matter enrichment of shallow water source rocks in the evaporite series. The degree of enrichment of organic matter in shallow water source rocks first increases and then decreases with the increase in paleosalinity. All the samples with high content of organic matter come from the shallower environment of the Awatag Fm.

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8

Mansour, Ahmed, Thomas Gentzis, Ibrahim M. Ied, Mohamed S. Ahmed, and Michael Wagreich. "Paleoenvironmental Conditions and Factors Controlling Organic Carbon Accumulation during the Jurassic–Early Cretaceous, Egypt: Organic and Inorganic Geochemical Approach." Minerals 12, no. 10 (September 26, 2022): 1213. http://dx.doi.org/10.3390/min12101213.

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The Jurassic–Early Cretaceous was a time of variable organic carbon burial associated with fluctuations of marine primary productivity, weathering intensity, and redox conditions in the pore and bottom water at paleo-shelf areas in north Egypt. This time interval characterized the deposition of, from old to young, the Bahrein, Khatatba, Masajid, and Alam El Bueib Formations in the north Western Desert. Although several studies have been devoted to the excellent source rock units, such as the Khatatba and Alam El Bueib Formations, studies on paleoenvironmental changes in redox conditions, paleoproductivity, and continental weathering and their impact on organic carbon exports and their preservation for this interval are lacking. This study presents organic and inorganic geochemical data for the Jurassic–Lower Cretaceous sediments from the Almaz-1 well in the Shushan Basin, north Western Desert. A total of 32 cuttings samples were analyzed for their major and trace elements, carbonates, and total organic carbon (TOC) contents. Data allowed the reconstruction of paleoenvironmental conditions in the southern Tethys Ocean and assessment of the changes in paleo-redox, paleo-weathering, and marine primary productivity, and the role of sediment supply. Additionally, factors that governed the accumulation of organic matter in the sediment were interpreted. Results showed that the Khatatba Formation was deposited during a phase of enhanced marine primary productivity under prevalent anoxia, which triggered enhanced organic matter production and preservation. During the deposition of the Khatatba Formation, significant terrigenous sediment supply and continental weathering were followed by a limited contribution of coarse clastic sediment fluxes due to weak continental weathering and enhanced carbonate production. The Bahrein, Masajid, and Alam El Bueib Formations were deposited during low marine primary productivity and prevalent oxygenation conditions that led to poor organic matter production and preservation, respectively. A strong terrigenous sediment supply and continental weathering predominated during the deposition of the Bahrein Formation and the lower part of the Alam El Bueib Formation compared to the limited coarse clastic supply and continental weathering during the deposition of the carbonate Masajid Formation and the upper part of the Alam El Bueib Formation. Such conditions resulted in the enhanced dilution and decomposition of labile organic matter, and, thus, organic carbon-lean accumulation in these sediments.

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9

Mahu, Edem, Daniel K. Asiedu, Elvis Nyarko, Samuel Hulme, Kenneth H. Coale, and Chris Y. Anani. "Provenance, paleo-weathering and -redox signatures of estuarine sediments from Ghana, Gulf of Guinea." Quaternary International 493 (November 2018): 176–86. http://dx.doi.org/10.1016/j.quaint.2018.06.005.

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10

van der Land, Cees, Furu Mienis, Henk de Haas, Henko C. de Stigter, Rudy Swennen, John J. G. Reijmer, and Tjeerd C. E. van Weering. "Paleo-redox fronts and their formation in carbonate mound sediments from the Rockall Trough." Marine Geology 284, no. 1-4 (June 2011): 86–95. http://dx.doi.org/10.1016/j.margeo.2011.03.010.

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11

Chen, Xiaoyan, Menghan Li, Erik A. Sperling, Tonggang Zhang, Keqing Zong, Yongsheng Liu, and Yanan Shen. "Mesoproterozoic paleo-redox changes during 1500–1400 Ma in the Yanshan Basin, North China." Precambrian Research 347 (September 2020): 105835. http://dx.doi.org/10.1016/j.precamres.2020.105835.

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12

Kechiched, Rabah, Rabah Laouar, Olivier Bruguier, Sihem Laouar-Salmi, Ouafi Ameur-Zaimeche, and Atif Foufou. "Preliminary Data of REE in Algerian Phosphorites: A Comparative Study and Paleo-redox Insights." Procedia Engineering 138 (2016): 19–29. http://dx.doi.org/10.1016/j.proeng.2016.02.048.

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13

He, Ruliang, Wanyi Lu, Christopher K. Junium, Charles A. Ver Straeten, and Zunli Lu. "Paleo-redox context of the Mid-Devonian Appalachian Basin and its relevance to biocrises." Geochimica et Cosmochimica Acta 287 (October 2020): 328–40. http://dx.doi.org/10.1016/j.gca.2019.12.019.

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14

Yang, Rui, Sheng He, Xiao Wang, Qinhong Hu, Dongfeng Hu, and Jizheng Yi. "Paleo-ocean redox environments of the Upper Ordovician Wufeng and the first member in lower Silurian Longmaxi formations in the Jiaoshiba area, Sichuan Basin." Canadian Journal of Earth Sciences 53, no. 4 (April 2016): 426–40. http://dx.doi.org/10.1139/cjes-2015-0210.

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A study of paleo-ocean redox environments is important for understanding the deposition of black shale and has practical implications for shale gas exploration. Here, we selected a total of 52 shale samples from JY1 Well, the first shale gas well of commercial exploitation in China, to analyze the redox conditions of Upper Ordovician Wufeng (O3w) and the first member in lower Silurian Longmaxi shale (S1l1) in the Jiaoshiba area. Abundant pyrite framboids are observed in these units, with average framboid diameters ranging from 3.1 to 4.7 μm and maximum diameter about 10 μm. Analyses of redox-sensitive trace elements suggest the redox environment has evolved from an anoxic condition in the bottom of Member A to a dysoxic condition in the top of Member A, and to a dysoxic–oxic environment in Members B and C. Graptolite and radiolarian are discovered in these shale samples, indicating an oxygenated seafloor, which seems to be contradictory to the results from pyrite framboids and redox-sensitive trace elements. This contradiction is explained as follows: when the shale was deposited, the sedimentation was dominated by euxinic conditions; however, some oxygen may also occasionally migrate to the bottom water due to oxygen-deficient environment, deglaciation, and (or) strong upwelling of nutrient-enriched seawater, while the limited oxygen and anoxic environment is favorable for the preservation and accumulation of organic matter. Combined with the geological characteristics and redox conditions, Member A, especially the shales at the bottom of Member A, is expected to be the most favorable shale gas reservoir in the Jiaoshiba area.

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15

Hetzel, Almut, Michael E. Böttcher, Ulrich G. Wortmann, and Hans-Jürgen Brumsack. "Paleo-redox conditions during OAE 2 reflected in Demerara Rise sediment geochemistry (ODP Leg 207)." Palaeogeography, Palaeoclimatology, Palaeoecology 273, no. 3-4 (March 2009): 302–28. http://dx.doi.org/10.1016/j.palaeo.2008.11.005.

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16

Schirmer, Thomas, Andrea Koschinsky, and Michael Bau. "The ratio of tellurium and selenium in geological material as a possible paleo-redox proxy." Chemical Geology 376 (May 2014): 44–51. http://dx.doi.org/10.1016/j.chemgeo.2014.03.005.

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17

Nakada, Ryoichi, Yoshio Takahashi, and Masaharu Tanimizu. "Cerium stable isotope ratios in ferromanganese deposits and their potential as a paleo-redox proxy." Geochimica et Cosmochimica Acta 181 (May 2016): 89–100. http://dx.doi.org/10.1016/j.gca.2016.02.025.

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18

Lu, Zunli, Hugh C. Jenkyns, and Rosalind E. M. Rickaby. "Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events." Geology 38, no. 12 (December 2010): 1107–10. http://dx.doi.org/10.1130/g31145.1.

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19

Locmelis, Marek, Ricardo D. Arevalo, Igor S. Puchtel, Marco L. Fiorentini, and Euan G. Nisbet. "Transition metals in komatiitic olivine: Proxies for mantle composition, redox conditions, and sulfide mineralization potential." American Mineralogist 104, no. 8 (August 1, 2019): 1143–55. http://dx.doi.org/10.2138/am-2019-6914.

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AbstractWe present the results of a comprehensive study on the concentrations of first-row transition elements (FRTE: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn), as well as Ga and Ge, in liquidus olivine from 2.7–3.5 Ga old Al-undepleted and Al-depleted komatiites from the Kaapvaal and Zimbabwe Cratons in southern Africa, the Yilgarn Craton in Australia, and the Superior Craton in Canada. The sample set includes komatiites that remained sulfur-undersaturated upon emplacement, as well as komatiites that reached sulfide saturation owing to assimilation of crustal sulfur.All olivine grains display concentrations of Mn, Zn, Ge, Co, Fe, Mg, and Ni similar to the Bulk Silicate Earth (BSE) values, with significant negative anomalies in Sc, Ti, V, Cr, Ga, and Cu. Olivine from the studied Al-depleted komatiites displays on average higher 100×Ga/Sc ratios (>5) than olivine from Al-undepleted komatiites (≤5). Because garnet preferentially incorporates Sc over Ga, the data suggest that elevated Ga/Sc ratios in komatiitic olivine are indicative of garnet retention in the source region of komatiites, highlighting the potential of olivine trace element chemistry as a proxy for the depth of komatiite melting and separation of the magma from the melting residue. Copper concentrations in the studied olivine grains are controlled by sulfur saturation of the host komatiite during olivine crystallization. Olivine from sulfur-undersaturated komatiite systems displays Cu concentrations mostly between 1 and 10 ppm, whereas olivine from sulfide-bearing komatiites has Cu contents of <0.5 ppm. Because komatiites contain some of the world's highest metal tenor magmatic Ni-Cu sulfide deposits, the Cu variability in olivine as a function of the sulfide-saturation state highlights a potential application of olivine chemistry in the exploration for sulfide ore deposits.Olivine from the Paleo-Archean (3.5–3.3 Ga) komatiites displays overall higher V/Sc ratios (V/Sc = 2.1 ± 0.96; 2 S.D.) than olivine from their Neo-Archean (2.7 Ga) counterparts (V/Sc = 1.0 ± 0.81, 2 S.D.). Vanadium and Sc behave similarly during partial melting of the mantle and are similarly compatible in majorite garnet. However, V is redox-sensitive and its compatibility in olivine increases as the system becomes less oxidized, whereas Sc is redox-insensitive. We argue that olivine from the studied Paleo-Archean komatiites crystallized from more reduced magmas than their Neo-Archean counterparts. Elevated Fe/Mn ratios in olivine from Paleo-Archean komatiites mimic the V/Sc signatures and are interpreted to reflect that Fe2+ is more compatible in olivine than Fe3+. These results imply that V/Sc and Fe/Mn in komatiitic olivine may potentially provide insight into the evolution of the oxidation state of the Archean mantle. Additional studies that integrate the chemistry of komatiitic olivine with those of relict interstitial glass and melt/fluid inclusions are encouraged to fully understand and quantify the potential of FRTE in olivine as a proxy for the oxidation state of the mantle sources of komatiite magmas.

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20

Lan, Zhengkai, and Junjun Shen. "Depositional Paleo-Environments of Lower Cambrian Qiongzhusi Formation in the Western Middle Yangtze Block and Its Controlling Effect on the Organic Matter Enrichment." Energies 15, no. 10 (May 20, 2022): 3761. http://dx.doi.org/10.3390/en15103761.

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No systematic comparative study has been conducted on the factors controlling organic matter enrichment in the different depositional environments of the Lower Cambrian Qiongzhusi Formation in the western Middle Yangtze Block, leading to a large discrepancy in our understanding. Based on organic geochemical and elemental analyses of core, outcrop, rock, and mineral samples from the slope, deep-water shelf, and shallow-water shelf, in this study, comparative analysis of the organic matter content, sedimentological characteristics, and depositional paleoenvironments of the Lower Cambrian Qiongzhusi Formation in the western Middle Yangtze Block was conducted, and the main controlling factors and models of the organic matter enrichment were investigated. The results revealed that the organic matter enrichment in the Qiongzhusi Formation was jointly controlled by redox conditions, water restriction, upwelling currents, terrigenous inputs, and paleo-productivity, but the main factors controlling the enrichment during the different periods were significantly different. (1) During the deposition of the Qiong 1 Member, the extensional rifting was strong, and the sea level was always high. The low degree of terrigenous dilution and anoxic conditions favored organic matter preservation. In this period, the upwelling currents were the main factor controlling organic matter enrichment. The paleo-productivity decreased as the intensity of the upwelling currents gradually weakened from the slope to the shelf, leading to a decrease in the total organic carbon (TOC) content and thereby a gradual decrease in the biogenic silica content of the shale. (2) During the deposition of the Qiong 2 Member, the extensional rifting weakened, and the sea level continued to drop. The upwelling currents, terrigenous input, and redox conditions were all important factors controlling the organic matter enrichment in the region. From the slope to the shelves, the conditions favorable for organic matter enrichment gradually worsened, and the TOC content gradually decreased, with the lithofacies gradually transitioning from biogenic siliceous shale to clayey shale or clayey-calcareous shale. (3) During the deposition of the Qiong 3 Member, the Yangzi Platform underwent a filling and leveling-up process, and the redox conditions played a major role in controlling the organic matter enrichment. The entire region was dominated by an oxygen-rich environment, and the conditions were no longer favorable for organic matter preservation, leading to a low average TOC content. Overall, the spatial variability of the TOC content was closely associated with changes in the depositional paleoenvironment caused by sea-level changes.

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21

Chowdhury, Masuma, Sarmin Sultana, Md Atikul Islam, Aziz Hasan, and Kazi Matin Uddin Ahmed. "Hydrogeochemical Properties Providing Links to Methanogenesis in Deep Aquifer of Bhola Island, Bangladesh." Journal of the Asiatic Society of Bangladesh, Science 45, no. 2 (December 28, 2019): 217–28. http://dx.doi.org/10.3329/jasbs.v45i2.46595.

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This paper compares the hydrogeochemical signatures between naturally flowing wells with methane (FWs) and non-flowing wells (require pumping) without methane (NFWs) by analyzing a total of 59 groundwater samples to find possible links for methane gas generation. Relatively higher concentration of HCO3 ⁻ indicates oxidation of organic matter (OM) for both the cases which is corroborated by the dominance of Na-Mg-HCO3 and Na- Mg-HCO3-Cl water type. Low concentrations of redox sensitive parameters i.e., NO3 ⁻, SO4 2⁻, Fe2+ and Mn2+ are indicating prevalence of extremely reducing condition and relatively lower concentrations of SO₄²⁻ in FWs suggest microbial sulphate reduction reaching final stage of redox ladder i.e., methanogenesis. Comparatively higher temperature and subsequent higher electrical conductivity (EC) in FWs possibly attributed by the chemical reactions of methane generation or vice versa. Low geothermal gradient, presence of OM and distribution of the FWs over a paleo valley in the deep confined aquifer zone refer to the existence of favourable environment for biogenic methane production rather than the upward migration or leakage of thermogenic gas from the reservoir below. Asiat. Soc. Bangladesh, Sci. 45(2): 217-228, December 2019

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22

Rolison, John M., Claudine H. Stirling, Rob Middag, and Micha J. A. Rijkenberg. "Uranium stable isotope fractionation in the Black Sea: Modern calibration of the 238U/235U paleo-redox proxy." Geochimica et Cosmochimica Acta 203 (April 2017): 69–88. http://dx.doi.org/10.1016/j.gca.2016.12.014.

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23

Yang, Jie-Hua, Mei-Fu Zhou, Rui-Zhong Hu, Hong Zhong, Anthony E. Williams-Jones, Liang Liu, Xing-Chun Zhang, Ya-Zhou Fu, and Wei Mao. "Granite-Related Tin Metallogenic Events and Key Controlling Factors in Peninsular Malaysia, Southeast Asia: New Insights from Cassiterite U-Pb Dating and Zircon Geochemistry." Economic Geology 115, no. 3 (May 1, 2020): 581–601. http://dx.doi.org/10.5382/econgeo.4736.

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Abstract Permian-Triassic granites and associated tin deposits are widespread in the Eastern and Western belts of Peninsular Malaysia. The ages and key controlling factors of tin mineralization, however, are poorly constrained. Cassiterite separates from the Sintok and Rahman tin deposits in the Western belt, and Bandi, Setahum, Lembing, and Cherul tin deposits in the Eastern belt have U-Pb ages of 218.9 ± 3.4 and 226.8 ± 7.6 Ma, and 213.1 ± 3.9, 270.6 ± 4.6, 282.7 ± 4.6, and 281.3 ± 3.5 Ma, respectively. These ages directly constrain the tin mineralization in Peninsular Malaysia to two separate periods: 290 to 270 Ma and 230 to 210 Ma. Zircon crystals from tin-bearing granites in the Cherul and Sintok deposits have U-Pb ages of 276.0 ± 1.9 and 221.9 ± 0.6 Ma, respectively, consistent with the cassiterite U-Pb ages within uncertainties. Zircon crystals from barren granites of the Kuantan pluton in the Eastern belt have a U-Pb age of 260.5 ± 0.7 Ma, which is between the two tin mineralization periods. Zircon from these barren granites have εHf(t) values from −5.4 to 3.6, two-stage Hf model ages (TDM2) from 1.4 to 1.0 Ga, and Ce4+/Ce3+ ratios from 40 to 120. By comparison, zircon crystals from the tin-bearing granites have low εHf(t) values (−9.7 to −3.2) and Ce4+/Ce3+ ratios (4–67) and high TDM2 (1.8–1.4 Ga). Zircon ages, Hf isotopes, and trace elements indicate that the tin-bearing granitic magmas in Peninsular Malaysia had relatively low oxygen fugacity and were derived from reworking of Paleo- to Mesoproterozoic sedimentary rock-dominated crust in response to the Paleo-Tethyan subduction and continental collision. This study confirms that the nature of magma sources and redox states of magmas were key in the formation of the tin-rich granites and associated tin deposits and that the granite-related tin mineralization in Peninsular Malaysia was closely related to the evolution of the eastern Paleo-Tethys.

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24

Tessin, Allyson, Anthony Chappaz, Ingrid Hendy, and Nathan Sheldon. "Molybdenum speciation as a paleo-redox proxy: A case study from Late Cretaceous Western Interior Seaway black shales." Geology 47, no. 1 (November 30, 2018): 59–62. http://dx.doi.org/10.1130/g45785.1.

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25

Li, Dandan, Xiaolin Zhang, Dongping Hu, Da Li, Guijie Zhang, Xu Zhang, Hong-Fei Ling, Yilun Xu, and Yanan Shen. "Multiple S-isotopic constraints on paleo-redox and sulfate concentrations across the Ediacaran-Cambrian transition in South China." Precambrian Research 349 (October 2020): 105500. http://dx.doi.org/10.1016/j.precamres.2019.105500.

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26

Brüske, A., S. Weyer, M. Y. Zhao, N. J. Planavsky, A. Wegwerth, N. Neubert, O. Dellwig, K. V. Lau, and T. W. Lyons. "Correlated molybdenum and uranium isotope signatures in modern anoxic sediments: Implications for their use as paleo-redox proxy." Geochimica et Cosmochimica Acta 270 (February 2020): 449–74. http://dx.doi.org/10.1016/j.gca.2019.11.031.

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27

Zindorf, Mark, Darci Rush, John Jaeger, Alan Mix, Michelle L. Penkrot, Bernhard Schnetger, Frances R. Sidgwick, et al. "Reconstructing oxygen deficiency in the glacial Gulf of Alaska: Combining biomarkers and trace metals as paleo-redox proxies." Chemical Geology 558 (December 2020): 119864. http://dx.doi.org/10.1016/j.chemgeo.2020.119864.

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28

Song, HuYue, JinNan Tong, Li Tian, HaiJun Song, HaiOu Qiu, YuanYuan Zhu, and Thomas Algeo. "Paleo-redox conditions across the Permian-Triassic boundary in shallow carbonate platform of the Nanpanjiang Basin, South China." Science China Earth Sciences 57, no. 5 (March 17, 2014): 1030–38. http://dx.doi.org/10.1007/s11430-014-4843-2.

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29

Khan, Saif A., Shamim A. Dar, K. F. Khan, and Yasir Karim. "Geochemical characteristics of Early Cambrian phosphate bearing sedimentary rocks from the Mussoorie Syncline, India: Implications for paleo-redox conditions." Geosystems and Geoenvironment 1, no. 3 (August 2022): 100046. http://dx.doi.org/10.1016/j.geogeo.2022.100046.

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30

Abedini, Ali, and Ali Asghar Calagari. "Geochemistry of claystones of the Ruteh Formation, NW Iran: Implications for provenance, source-area weathering, and paleo-redox conditions." Neues Jahrbuch für Mineralogie - Abhandlungen Journal of Mineralogy and Geochemistry 194, no. 2 (June 1, 2017): 107–23. http://dx.doi.org/10.1127/njma/2017/0040.

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31

El-Shafeiy, Moataz, Ahmed El-Kammar, Ahmed El-Barkooky, and Philip A. Meyers. "Paleo-redox depositional conditions inferred from trace metal accumulation in two Cretaceous-Paleocene organic-rich sequences from Central Egypt." Marine and Petroleum Geology 73 (May 2016): 333–49. http://dx.doi.org/10.1016/j.marpetgeo.2016.03.007.

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Sato, Tomohiko, Yukio Isozaki, Katsumi Shozugawa, and Motoyuki Matsuo. "57Fe Mössbauer spectroscopic analysis of deep-sea pelagic chert: Effect of secondary alteration with respect to paleo-redox evaluation." Journal of Asian Earth Sciences 42, no. 6 (November 2011): 1403–10. http://dx.doi.org/10.1016/j.jseaes.2011.08.004.

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Feng, Lian-Jun, Xue-Lei Chu, Jing Huang, Qi-Rui Zhang, and Hua-Jin Chang. "Reconstruction of paleo-redox conditions and early sulfur cycling during deposition of the Cryogenian Datangpo Formation in South China." Gondwana Research 18, no. 4 (November 2010): 632–37. http://dx.doi.org/10.1016/j.gr.2010.02.011.

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Wang, Yi, Ingrid L. Hendy, Jennifer C. Latimer, and Dario Bilardello. "Diagenesis and iron paleo-redox proxies: New perspectives from magnetic and iron speciation analyses in the Santa Barbara Basin." Chemical Geology 519 (August 2019): 95–109. http://dx.doi.org/10.1016/j.chemgeo.2019.04.018.

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35

Adegoke, Adebanji Kayode, Wan Hasiah Abdullah, Mohammed Hail Hakimi, Babangida M. Sarki Yandoka, Khairul Azlan Mustapha, and Adeyinka Oluyemi Aturamu. "Trace elements geochemistry of kerogen in Upper Cretaceous sediments, Chad (Bornu) Basin, northeastern Nigeria: Origin and paleo-redox conditions." Journal of African Earth Sciences 100 (December 2014): 675–83. http://dx.doi.org/10.1016/j.jafrearsci.2014.08.014.

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36

Obasi, Romanus Ayoola, Henry Y. Madukwe, and Temitope Olaosun. "Source Area Weathering, Paleo-Environment and Paleo-Climatic Conditions of Soils from Bitumen Rich Ode Irele Area of Ondo State, Nigeria." European Journal of Engineering Research and Science 4, no. 3 (March 13, 2019): 59–67. http://dx.doi.org/10.24018/ejers.2019.4.3.1159.

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The study is aimed at determining the source-weathering, paleo-redox and paleoclimatic conditions of soil from Ode Irele area of Ondo State, Nigeria. X-Ray Fluorescence (XRF) and the Laser Ablation Inductively Coupled Plasma-Mass Spectrometry ICP-MS) analyses wereusd to determine the major, trace and rare earth element compositios used for the study. The Chemical index of alteration (CIA), Chemical index of weathering (CIW), Plagioclase index of alteration (PIA), Mineralogical index of alteration (MIA), Th/U nd a plot of CIA against Al2O3 as well as the A-CN-K Ternary diagram suggest a high degree of weathering of the source rocks. The positive correlation between Al2O3 with TiO2, K2O, Fe2O3 and MgO implies that they occur in clay minerals formed from weathering. The average K2O/Al2O3 ratios of the investigated samples is ≈0.006, which suggests prevalence of clay minerals relative to other minerals. Low U/Th ratio ranging between 0.14 and 0.50 (average 0.18) relative to PAAS (0.21) and UCC (0.26) suggests deposition under oxic conditions. V/Vi + Ni ratios indicate suboxic to anoxic environment of deposition. However, plots of V/V+ Ni vs Ni/Co and V/Cr vs Ni/Co indicate oxic, dysoxic and suboxic to anoxic environments all suggesting deposition under oxic and suboxic conditions. The Ode Irele sediments was deposited in low saline water with a strong continental rather than marine influence in an arid and semi-arid climatic condition; the low average ratio of P2O5/Al2O3 (0.014) is in unison with freshwater environments.

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Obasi, Romanus Ayoola, Henry Y. Madukwe, and Temitope Olaosun. "Source Area Weathering, Paleo-Environment and Paleo-Climatic Conditions of Soils from Bitumen Rich Ode Irele Area of Ondo State, Nigeria." European Journal of Engineering and Technology Research 4, no. 3 (March 13, 2019): 59–67. http://dx.doi.org/10.24018/ejeng.2019.4.3.1159.

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The study is aimed at determining the source-weathering, paleo-redox and paleoclimatic conditions of soil from Ode Irele area of Ondo State, Nigeria. X-Ray Fluorescence (XRF) and the Laser Ablation Inductively Coupled Plasma-Mass Spectrometry ICP-MS) analyses wereusd to determine the major, trace and rare earth element compositios used for the study. The Chemical index of alteration (CIA), Chemical index of weathering (CIW), Plagioclase index of alteration (PIA), Mineralogical index of alteration (MIA), Th/U nd a plot of CIA against Al2O3 as well as the A-CN-K Ternary diagram suggest a high degree of weathering of the source rocks. The positive correlation between Al2O3 with TiO2, K2O, Fe2O3 and MgO implies that they occur in clay minerals formed from weathering. The average K2O/Al2O3 ratios of the investigated samples is ?0.006, which suggests prevalence of clay minerals relative to other minerals. Low U/Th ratio ranging between 0.14 and 0.50 (average 0.18) relative to PAAS (0.21) and UCC (0.26) suggests deposition under oxic conditions. V/Vi + Ni ratios indicate suboxic to anoxic environment of deposition. However, plots of V/V+ Ni vs Ni/Co and V/Cr vs Ni/Co indicate oxic, dysoxic and suboxic to anoxic environments all suggesting deposition under oxic and suboxic conditions. The Ode Irele sediments was deposited in low saline water with a strong continental rather than marine influence in an arid and semi-arid climatic condition; the low average ratio of P2O5/Al2O3 (0.014) is in unison with freshwater environments.

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Madhavaraju, J., Hannes Löser, Yong Il Lee, R. Lozano Santacruz, and T. Pi-Puig. "Geochemistry of Lower Cretaceous limestones of the Alisitos Formation, Baja California, México: Implications for REE source and paleo-redox conditions." Journal of South American Earth Sciences 66 (March 2016): 149–65. http://dx.doi.org/10.1016/j.jsames.2015.11.013.

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39

Walters, Andrew P., Stephen R. Meyers, Alan R. Carroll, Tina R. Hill, and Michael D. Vanden Berg. "Lacustrine cyclicity in the early Eocene Green River Formation, Uinta Basin, Utah: Evidence from X-ray fluorescence core scanning." Journal of Sedimentary Research 90, no. 4 (April 16, 2020): 429–47. http://dx.doi.org/10.2110/jsr.2020.24.

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ABSTRACT The Green River Formation preserves an extraordinary archive of terrestrial paleoclimate during the Early Eocene Climatic Optimum (EECO; ∼ 53–50 Ma), expressing multiple scales of sedimentary cyclicity previously interpreted to reflect annual to Milankovitch-scale forcing. Here we utilize X-ray fluorescence (XRF) core scanning and micro X-ray fluorescence (micro-XRF) scanning in combination with radioisotopic age data to evaluate a rock core record of laminated oil shale and carbonate mudstone from Utah's Uinta Basin, with the parallel objectives of elucidating the paleo-environmental significance of the sedimentary rhythms, testing a range of forcing hypotheses, and evaluating potential linkages between high- and low-frequency forcing. This new assessment reveals that the ∼ 100-μm-scale laminae—the most fundamental rhythm of the Green River Formation—are most strongly expressed by variations in abundance of iron and sulfur. We propose that these variations reflect changes in redox state, consistent with annual stratification of the lake. In contrast to previous studies, no support was found for ENSO or sunspot cycles. However, millimeter- to centimeter-scale rhythms—temporally constrained to the decadal to centennial scale—are strongly expressed as alternations in the abundance of silicate- versus carbonate-associated elements (e.g., Al and Si vs. Ca), suggesting changes in precipitation and sediment delivery to the paleo-lake. Variations also occur at the meter scale, defining an approximate 4 m cycle interpreted to reflect precession. We also identify punctuated intervals, associated principally with one phase of the proposed precession cycle, where Si disconnects from the silicate input. We propose an alternative authigenic or biogenic Si source for these intervals, which reflects periods of enhanced productivity. This result reveals how long-term astronomical forcings can influence short-term processes, yielding insight into decadal- to millennial-scale terrestrial climate change in the Eocene greenhouse earth.

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Lee, Kee Hwan, Chang Hwan Kim, Chan Hong Park, Kiho Yang, Sang Hoon Lee, In Soo Lee, You Jin Kwack, Jae Woo Kwak, Jaewoo Jung, and Jinwook Kim. "Microbial Diversity Responding to Changes in Depositional Conditions during the Last Glacial and Interglacial Period: NE Ulleung Basin, East Sea (Sea of Japan)." Minerals 10, no. 3 (February 26, 2020): 208. http://dx.doi.org/10.3390/min10030208.

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Microbial interaction with minerals are significantly linked with depositional conditions during glacial and interglacial periods, providing a unique redox condition in the sedimentary process. Abiotic geophysical and geochemical properties, including sedimentary facies, magnetic susceptibility, grain size, clay mineralogy, and distribution of elemental compositions in the sediments, have been widely used to understand paleo-depositional environments. In this study, microbial abundance and diversity in the core sediments (6.7 m long) from the northeastern slope of Dokdo Island were adapted to characterize the conventionally defined sedimentary depositional units and conditions in light of microbial habitats. The units of interglacial (Unit 1, <11.5 ka) and late glacial (Unit 2, 11.5–14.5 ka) periods in contrast to the glacial period (Unit 3, >14.5 ka) were distinctively identified in the core, showing a sharp boundary marked by the laminated Mn-carbonate (CaM) mud between bioturbated (Unit 1 and 2) and laminated mud (Unit 3). Based on the marker beds and the occurrence of sedimentary facies, core sediments were divided into three units, Unit 1 (<11.5 ka, interglacial), Unit 2 (11.5–14.5 ka, late glacial), and Unit 3 (>14.5 ka, glacial), in descending order. The sedimentation rate (0.073 cm/year), which was three times higher than the average value for the East Sea (Sea of Japan) was measured in the late glacial period (Unit 2), indicating the settlement of suspended sediments from volcanic clay in the East Sea (Sea of Japan), including Doldo Island. The Fe and Mg-rich smectite groups in Unit 2 can be transported from volcanic sediments, such as from the volcanic island in the East Sea or the east side of Korea, while the significant appearance of the Al-rich smectite group in Unit 1 was likely transported from East China by the Tsushima Warm Current (TWC). The appearance of CaM indicates a redox condition in the sedimentary process because the formation of CaM is associated with an oxidation of Mn2+ forming Mn-oxide in the ocean, and a subsequent reduction of Mn-oxide occurred, likely due to Mn-reducing bacteria resulting in the local supersaturation of Mn2+ and the precipitation of CaM. The low sea level (−120 m) in the glacial period (Unit 3) may restrict water circulation, causing anoxic conditions compared to the late glacial period (Unit 2), inducing favorable redox conditions for the formation of CaM in the boundary of the two units. Indeed, Planctomycetaceae, including anaerobic ammonium oxidation (ANAMMOX) bacteria capable of oxidizing ammonium coupled with Mn-reduction, was identified in the CaM layer by Next Generation Sequencing (NGS). Furthermore, the appearance of aerobic bacteria, such as Alphaproteobacteria, Gammaproteobacteria, and Methylophaga, tightly coupled with the abundance of phytoplankton was significantly identified in Unit 1, suggesting open marine condition in the interglacial period. Bacterial species for each unit displayed a unique grouping in the phylogenetic tree, indicating the different paleo-depositional environments favorable for the microbial habitats during the glacial and interglacial periods.

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41

Frei, Robert, Cora Paulukat, Sylvie Bruggmann, and Robert M. Klaebe. "A systematic look at chromium isotopes in modern shells – implications for paleo-environmental reconstructions." Biogeosciences 15, no. 16 (August 20, 2018): 4905–22. http://dx.doi.org/10.5194/bg-15-4905-2018.

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Abstract. The chromium isotope system (53Cr ∕ 52Cr, expressed as δ53Cr relative to NIST SRM 979) in marine biogenic and non-biogenic carbonates is currently being evaluated as a proxy for the redox state of the ocean. Previous work has concentrated on using corals and foraminifera for this purpose, but investigations focusing on the behavior of Cr in bivalves as potential archives are lacking. Due to their often good preservation, fossil marine biogenic carbonates have the potential to serve as useful archives for the reconstruction of past ocean redox fluctuations and eventually link those to climatic changes throughout Earth's history. Here, we present an evaluation of the Cr isotope system in shells of some modern bivalves. Shell species from Lucidinadae, Cardiidae, Glycimerididae and Pectenidae, collected systematically from one Mediterranean location (Playa Poniente, Benidorm, Spain) over a 3-year period reveal δ53Cr values ranging from 0.15 ‰ to 0.65 ‰, values that are systematically below the local seawater δ53Cr value of 0.83±0.05 ‰. This attests to a significant reduction of dissolved seawater chromium in the process leading to calcification and thus for control of Cr isotope fractionation during biological routes. A similar, constant offset in δ53Cr values relative to surface seawater is observed in shells from Mytilius edulis from an arctic location (Godhavn, Disko Bay, Greenland). Chromium concentrations in the studied shells are significantly controlled by organic matter and typically range from 0.020 to 0.100 ppm, with some higher concentrations of up to 0.163 ppm recorded in Pectenidae. We also observe subtle, species-dependent differences in average Cr isotope signatures in the samples from Playa Poniente, particularly of Lucidinadae and Cardiidae, with considerably depressed and elevated δ53Cr values, respectively, relative to the other species investigated. Intra-species heterogeneities, both in Cr concentrations and δ53Cr values, are favorably seen to result from vital effects during shell calcification rather than from heterogeneous seawater composition. This is because we observe that the surface seawater composition in the particular Playa Poniente location remained constant during the month of July of the 3 years we collected bivalve samples. Intra-shell heterogeneities – associated with growth zones reflecting one to several years of growth, both in δ53Cr and Cr concentrations – are observed in a sample of Placuna placenta and Mimachlamys townsendi. We suspect that these variations are, at least partially, related to seasonal changes in δ53Cr of surface seawaters. Recognizing the importance of organic substances in the bivalve shells, we propose a model whereby reduction of Cr(VI) originally contained in the seawater as chromate ion and transported to the calcifying space, to Cr(III), is effectively adsorbed onto organic macromolecules which eventually get included in the growing shell carbonates. This study, with its definition of statistically sound offsets in δ53Cr values of certain bivalve species from ambient seawater, forms a base for future investigations aimed at using fossil shells as archives for the reconstruction of paleo-seawater redox fluctuations.

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Kasanzu, Charles H., Makenya A. H. Maboko, and Shukrani Manya. "Isotopic and geochemical constraints on the protolith, redox state and paleo-tectonic setting of the Malagarasi Supergroup of north-western Tanzania." Journal of African Earth Sciences 184 (December 2021): 104346. http://dx.doi.org/10.1016/j.jafrearsci.2021.104346.

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43

Nakada, Ryoichi, Yoshio Takahashi, and Masaharu Tanimizu. "Isotopic and speciation study on cerium during its solid–water distribution with implication for Ce stable isotope as a paleo-redox proxy." Geochimica et Cosmochimica Acta 103 (February 2013): 49–62. http://dx.doi.org/10.1016/j.gca.2012.10.045.

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44

Lucotte, Marc, Alfonso Mucci, Claude Hillaire-Marcel, and Sophie Tran. "Early diagenetic processes in deep Labrador Sea sediments: reactive and nonreactive iron and phosphorus." Canadian Journal of Earth Sciences 31, no. 1 (January 1, 1994): 14–27. http://dx.doi.org/10.1139/e94-003.

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A sequential extraction procedure was applied to separate the oxides and lithogenous phases of iron and manganese and the organic and inorganic phosphorus phases in four box cores and one piston core from the slopes and rises of the Labrador Sea. Sedimentation rate, rather than the location in the basin, appears as a master variable of the diagenetic transformations of Fe, Mn, and P. High sedimentation rate, characteristic of two of the box cores, led to the creation of zones near the redox boundary of partial reprecipitation of dissolved Fe, Mn, and P released in the deeper reducing portions of the sediments. In contrast, surficial sediments from box cores with 10 times lower sedimentation rate only have sufficient reductive capacity to remobilize Mn hydroxides while leaving the Fe oxyhydroxides intact. Under these conditions, there is evidence for a redistribution of reactive inorganic P leading to the crystallization of carbonate fluorapatite in the top 30 cm of the cores. Gradual transformation of buried orthophosphate to authigenic apatite under suboxic conditions is also observed in the top 400 cm of the high sedimentation rate piston core. As in the box cores, the reaction is complete after several thousand years of burial and occurs in sediments characterized by low CaCO3 content. Depending upon the sedimentation rates, the carbonate fluor-apatite crystallization may be superimposed on the changes in detrital sedimentary fluxes accompanying the onset of deglaciation. A proxy indicator of paleo-redox conditions, and thus of biodegradable organic matter accumulation at the sediment–water interface, is given by the ratio of iron oxides to the reactive inorganic P (solid orthophosphate plus authigenic apatite).

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45

Hohl, Simon V., Shao-Yong Jiang, Sebastian Viehmann, Wei Wei, Qian Liu, Hai-Zhen Wei, and Stephen J. G. Galer. "Trace Metal and Cd Isotope Systematics of the Basal Datangpo Formation, Yangtze Platform (South China) Indicate Restrained (Bio)Geochemical Metal Cycling in Cryogenian Seawater." Geosciences 10, no. 1 (January 19, 2020): 36. http://dx.doi.org/10.3390/geosciences10010036.

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The behaviour of bioavailable trace metals and their stable isotopes in the modern oceans is controlled by uptake into phototrophic organisms and adsorption on and incorporation into marine authigenic minerals. Among other bioessential metals, Cd and its stable isotopes have recently been used in carbonate lithologies as novel tracer for changes in the paleo primary productivity and (bio)geochemical cycling. However, many marine sediments that were deposited during geologically highly relevant episodes and which, thus, urgently require study for a better understanding of the paleo environment are rather composed of a mixture of organic matter (OM), and detrital and authigenic minerals. In this study, we present Cd concentrations and their isotopic compositions as well as trace metal concentrations from sequential leachates of OM-rich shales of the Cryogenian basal Datangpo Formation, Yangtze Platform (South China). Our study shows variable distribution of conservative and bioavailable trace metals as well as Cd isotope compositions between sequential leachates of carbonate, OM, sulphide, and silicate phases. We show that the Cd isotope compositions obtained from OM leachates can be used to calculate the ambient Cryogenian surface seawater of the restricted Nanhua Basin by applying mass balance calculations. By contrast, early diagenetic Mn carbonates and sulphides incorporated the residual Cd from dissolved organic matter that was in isotopic equilibrium with deep/pore waters of the Nanhua Basin. Our model suggests that the Cd isotopic composition of surface seawater at that time reached values of modern oxygenated surface oceans. However, the deep water Cd isotope composition was substantially heavier than that of modern fully oxygenated oceans and rather resembles deep waters with abundant sulphide precipitation typical for modern oxygen minimum zones. This argues for incomplete recycling of Cd and other bioavailable metals shortly after the Sturtian glaciation in the redox stratified Cryogenian Nanhua Basin. Our study highlights the importance of sequential leaching procedures when dealing with impure authigenic sediments such as OM-rich carbonates, mudstones, or shales to achieve reliable trace metal concentrations and Cd isotope compositions as proxies for (bio)geochemical metal cycling in past aquatic systems.

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Lathika, N., Waliur Rahaman, Mohd Tarique, Naveen Gandhi, Avinash Kumar, and Meloth Thamban. "Deep water circulation in the Arabian Sea during the last glacial cycle: Implications for paleo-redox condition, carbon sink and atmospheric CO2 variability." Quaternary Science Reviews 257 (April 2021): 106853. http://dx.doi.org/10.1016/j.quascirev.2021.106853.

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47

Luz, Filipa, António Mateus, Carlos Rosa, and Jorge Figueiras. "Geochemistry of Famennian to Visean Metapelites from the Iberian Pyrite Belt: Implications for Provenance, Paleo-Redox Conditions and Vectoring to Massive Sulfide Deposits." Natural Resources Research 29, no. 6 (May 25, 2020): 3613–52. http://dx.doi.org/10.1007/s11053-020-09686-4.

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Byrne, Robert H., and Linda S. Bingler. "Comment on “Cerium: A chemical tracer for paleo-oceanic redox conditions” by Y.-G. Liu, M. R. U. Miah and R. A. Schmitt." Geochimica et Cosmochimica Acta 53, no. 6 (June 1989): 1475–76. http://dx.doi.org/10.1016/0016-7037(89)90081-1.

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49

Scholz, Florian, Christopher Siebert, Andrew W. Dale, and Martin Frank. "Intense molybdenum accumulation in sediments underneath a nitrogenous water column and implications for the reconstruction of paleo-redox conditions based on molybdenum isotopes." Geochimica et Cosmochimica Acta 213 (September 2017): 400–417. http://dx.doi.org/10.1016/j.gca.2017.06.048.

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50

Pattan, J. N., N. J. G. Pearce, and P. G. Mislankar. "Constraints in using Cerium-anomaly of bulk sediments as an indicator of paleo bottom water redox environment: A case study from the Central Indian Ocean Basin." Chemical Geology 221, no. 3-4 (October 2005): 260–78. http://dx.doi.org/10.1016/j.chemgeo.2005.06.009.

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