Evolution and origins of pyrite in sandstone-type uranium deposits, northern Ordos Basin, north-central China, based on micromorphological and compositional analysis

Yue, Liang; Jiao, Yangquan; Wu, Liqun; Rong, Hui; Fayek, Mostafa; Xie, Huili

doi:10.1016/j.oregeorev.2020.103334

Cited by 24 publications

(8 citation statements)

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“…S6). In addition, based on our observations and recent work described in detail by Yue et al (2020), it is common to see the framboidal pyrite overprinted by euhedral pyrite and pyrite cement, respectively, in mineralized grey sandstones (Fig. S7).…”

Section: Occurrence and Paragenesis Of Fe-bearing Mineralssupporting

confidence: 77%

Transformation of Fe-bearing minerals from Dongsheng sandstone-type uranium deposit, Ordos Basin, north-central China: Implications for ore genesis

Yue

Jiao

Fayek

et al. 2022

American Mineralogist

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Iron-bearing mineral assemblages and their distribution patterns directly reflect the redox environment in sediments, which plays a decisive role in the migration and precipitation of U. The Dongsheng sandstone-type U deposit hosted in fluvial and/or deltaic sandstones of the lower member of the Middle Jurassic Zhiluo Formation in the northeastern Ordos Basin has experienced multiple fluid events that impacted the redox conditions. Highly enriched in barren grey sandstones, pre-ore U (Umean = 12.05 ppm) associated with Fe-Ti oxides, clay minerals and organic matter is likely one of the key sources of U for the mineralization. Different contents of Fe-bearing minerals including biotite, Fe-Ti oxides, pyrite, hematite, goethite, and chlorite that were formed or altered under different redox conditions, resulted in sandstone units with distinct colors. The red sandstone is hematite-rich, indicating a highly oxidizing environment. The green sandstone is chlorite-rich This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Section: Occurrence and Paragenesis Of Fe-bearing Mineralssupporting

confidence: 77%

Transformation of Fe-bearing minerals from Dongsheng sandstone-type uranium deposit, Ordos Basin, north-central China: Implications for ore genesis

Yue

Jiao

Fayek

et al. 2022

American Mineralogist

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“…As a result, when completely grown (blue bar, Figure ), some F Py (ordered-F Py ) may appear as spherical clusters of E Py and semispherical for partially formed or decaying F Py (yellow bar; Figure ). Polyframboids are a collection of F Py s that are typically formed in OM, where thermal fluid and sulfate-reduction-bacterial (SRB) processes are engaged in the development of E Py from F Py and cement Py . In zones of significant tectonic activity, D Py (Figure c) and pyrite whiskers (W Py s) (Figure ) are widespread.…”

Section: Resultsmentioning

confidence: 99%

“…Polyframboids are a collection of FPys that are typically formed in OM, where thermal fluid and sulfate-reduction-bacterial (SRB) processes are engaged in the development of EPy from FPy and cement Py. 5 In zones of significant tectonic activity, DPy (Figure 2c) and pyrite whiskers (WPys) (Figure 5) are widespread.…”

Section: Pyrite Varieties Discovered In the Samplesmentioning

confidence: 99%

“…Pyrite ( Py ), a naturally occurring iron disulfide (FeS 2 ) mineral, is quite common in marine and terrestrial sediment deposits. , Py can exist in many forms, such as euhedral pyrite (E Py ) crystals, pyrite framboids (F Py ), worm shapes, irregular masses, botryoidal-subspherical aggregates, fossil casts, and nodules , to its origins, − oxidation reactions, , morphological evolution, ,, and redox significance. , …”

Section: Introductionmentioning

confidence: 99%

“…1,2 Py can exist in many forms, such as euhedral pyrite (EPy) crystals, pyrite framboids (FPy), worm shapes, irregular masses, botryoidal-subspherical aggregates, fossil casts, and nodules. 3 Py has been extensively studied, from its elemental compositions 4,5 to its origins, 5−7 oxidation reactions, 8,9 morphological evolution, 5,10,11 and redox significance. 12,13 Two forms of Py, syngenetic and diagenetic, have been defined based on the interplay of the environment with reactions of sulfates, organic matter (OM), and reactive iron.…”

Section: Introductionmentioning

confidence: 99%

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Pyrite Dissolution in the Cretaceous Yogou Formation of the Niger (Chad) Basin: Implications for Basin Evolution under a Rift Tectonic Setting

et al. 2022

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This is the first study of pyrite minerals in the entire West and Central African Rift System (WCARS). Several polished organic-rich core samples from the Cretaceous Yogou Formation of the Niger (Chad) Basin located in the WCARS were investigated for their pyrite content using FE-SEM and SEM-EDS imaging techniques. An attempt was made to classify the types and provenance of the pyrites and to highlight the control of rift fractures on the oxidation and dissolution of pyrites in the region. Three major types of pyrites are present in the studied formation, including euhedral pyrite (EPy) crystals, pyrite framboids (FPy), and sunflower pyrites (SPy). A statistical analysis of 307 FPy shows that the framboids are diagenetically formed with an average diameter of 6.61 μm. SPy is present in a relatively low amount compared to framboids. The pyrites underwent a variety of diagenetic modifications, from mechanical compaction to oxidation, dissolution, and recrystallization. Unoxidized pyrites primarily contain Fe, S, and C, but oxidized pyrites also contain O, Al, and Si. There is a strong correlation between the fractures and the spatial distribution of the physicochemical alteration of the pyrite in the study. Dissolution in relatively deep-buried samples occurs mainly along fracture planes. The fractures provide a pathway for oxidants and other metal elements to reach the pyrites. The pattern of pyrite dissolution reflects the timing of fracture formation and fracture activities as a purveyor or drainage for fluids in the organic-rich samples investigated. The pyrites are associated intimately with organic matter (OM); thus, the relationship between the fracture and the pyrites’ transformation is significant in the assessment of organic matter preservation at deep-burial depth.

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Cementation Characteristics and Their Effect on Quality of the Upper Triassic, the Lower Cretaceous, and the Upper Cretaceous Sandstone Reservoirs, Euphrates Graben, Syria

et al. 2021

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This article presents the results of cementation characteristics and their effect on sandstone reservoir quality of the Upper Triassic Mulussa F, the Lower Cretaceous Lower Rutbah, and the Upper Cretaceous Post Judea Sandstone formations in selected fields in the Euphrates Graben area, Syria. This study emphasises the role of cementation in the evaluation of the diagenetic history of the sediments, developing effective porosity, as well as evaluation of reservoirs stimulation procedures and potential for formation damage of the sandstone reservoirs. Quartz cement is present as well developed tabular or pyramidal syntaxial overgrowths. Kaolinite cement is present as vermicular aggregates which are most abundant within sandstones of the Mulussa F Formation. Carbonate cements include siderite and dolomite. Four lithofacies were identified within the studied formations; lithofacies-1 and 2 correspond to fluvial depositional environments, lithofacies-3 and 4 correspond to fluvial to estuarine channel environments. The Post Judea Sandstone and the Lower Rutbah reservoir units are typically lithofacies-3 sequences in which quartz overgrowths are the dominant cement. Because the total cement is more extensive in the Post Judea Sandstone Formation than in the Lower Rutbah Formation, resulting in high porosity (up to 26%) and permeability (6 000 mD), the reservoir quality is predicted to be best in the Post Judea Sandstone Formation. The reservoir units in the Mulussa F Formation contain the highest cement volumes comprised of early siderite and kaolinite, which, with the development of compaction-resisting quartz overgrowths and resultant compactional pore volume loss, has resulted in typically lower porosity being preserved than in the Lower Rutbah and Post Judea Sandstone formations.

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Evolution and origins of pyrite in sandstone-type uranium deposits, northern Ordos Basin, north-central China, based on micromorphological and compositional analysis

Cited by 24 publications

References 58 publications

Transformation of Fe-bearing minerals from Dongsheng sandstone-type uranium deposit, Ordos Basin, north-central China: Implications for ore genesis

Transformation of Fe-bearing minerals from Dongsheng sandstone-type uranium deposit, Ordos Basin, north-central China: Implications for ore genesis

Pyrite Dissolution in the Cretaceous Yogou Formation of the Niger (Chad) Basin: Implications for Basin Evolution under a Rift Tectonic Setting

Cementation Characteristics and Their Effect on Quality of the Upper Triassic, the Lower Cretaceous, and the Upper Cretaceous Sandstone Reservoirs, Euphrates Graben, Syria

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