Origin of dolomitic rocks in the lower Permian Fengcheng formation, Junggar Basin, China: evidence from petrology and geochemistry

Zhu, Shifa; Qin, Yi; Liu, Xin; Wei, Chengjie; Zhu, Xiaomin; Zhang, Wei

doi:10.1007/s00710-016-0467-x

Cited by 25 publications

(16 citation statements)

References 35 publications

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“…In the following diagenetic stages, the void‐filling calcite could be easily dolomitized if porewaters were mixed with higher‐salinity water. The pervasive dolomitization of void‐filling calcite in the transitional zone might result from water mixing of high‐salinity lake water and low‐salinity groundwater during lake transgression after a lake level drop, or from the dissolution of other Mg‐rich minerals (Zhu et al ., 2017), resembling the dolomite origins within the Cretaceous pre‐salt carbonates on the south Atlantic coastal margins (Tosca & Wright, 2015).…”

Section: Discussionmentioning

confidence: 96%

“…Such supposed catalyst(s) should enable dolomite to compete for Mg 2+ ions from porewaters or could cause the dissolution of generated Mg‐evaporites and Mg‐clays to re‐release the stabilized Mg for subsequent dolomite formation. Given the coeval resulting instability of Mg‐evaporites and Mg‐clays, the main function of the catalyst(s) was most likely to induce the decrease of porewater pH, because both Mg‐clays and Na‐Mg‐carbonates are unstable when pH drops to below 8 (Tosca & Wright, 2015; Zhu et al ., 2017). In the shallow subsurface, the drop of porewater pH can be caused by a variety of biogeochemical processes, such as respiration reactions, most re‐oxidation reactions, mineralization processes of organic matter by sulphate reduction, methanogenesis and anaerobic methane oxidation (Cerling, 1996; Soetaert et al ., 2007; Meister, 2013; Tosca & Wright, 2015; Wright & Barnett, 2015), among which the mineralization processes of organic matter in decreasing pH are conditional, depending on the initial solution pH (Soetaert et al ., 2007).…”

Section: Discussionmentioning

confidence: 99%

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Constraints on dolomite formation in a Late Palaeozoic saline alkaline lake deposit, Junggar Basin, north‐west China

2023

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Alkaline lakes (pH > 9) are among the few modern sedimentary environments that are hydrochemically favourable for low‐temperature dolomite formation. While Mg‐clays and Mg‐evaporites also form more easily in alkaline environments, few studies have focused on how the kinetically inhibited dolomite wins the competition for Mg2+. Here, a basin‐wide survey of the distribution, paragenesis and stable C, O and Mg isotopes of main Mg‐rich minerals in the Late Palaeozoic saline alkaline lake deposit of the north‐west Junggar Basin, north‐west China, is conducted to study the influence of the formation and diagenesis of eitelite, northupite and Mg‐clays on dolomite formation. Large, isolated dolomite crystals (20 to 70 μm in diameter), show positive δ13C values (ranging from +1 to +7‰) and a restricted distribution in the mudstones of the lake‐transitional zone. These crystals have been interpreted as organogenic dolomite driven by methanogenesis via fermentation of organic substrates. The δ18O values of dolomitic mudstones (from −7.4 to +3.4‰), calcitic mudstones (from −15.1 to −3.3‰) and bedded Na‐carbonate evaporites (from +0.08 to +3.7‰), together with their Mg isotopic compositions, suggest that dolomite was not enriched in the most concentrated environments or during stages with most Mg sources, but in the organic‐rich deposits containing few other authigenic Mg‐rich minerals. Dolomite is at a competitive disadvantage for Mg2+ ions compared to Mg‐evaporite and Mg‐clay minerals due to its slow crystallization rates and the deficiency of micritic calcium carbonate precursors. However, it can nucleate and progressively grow into large crystals (>20 μm) if bacterial methanogenesis could effectively lower porewater pH (<8.5) and induce the dissolution of generated eitelite, northupite or Mg‐clays. These findings suggest that high salinity and/or high alkalinity are not always favourable conditions for dolomite formation and highlight the active role of pH fluctuations in inducing low‐temperature dolomite formation.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Constraints on dolomite formation in a Late Palaeozoic saline alkaline lake deposit, Junggar Basin, north‐west China

2023

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“…However, vanadium mineral consituent in the black shale-hosted vanadium deposit has kept blank. Previous studies indicate that the occurrences of vanadium includes adsorpting on the surface of ferric and aluminum oxides (Micera and Dallocchio 1988;Peacock and Sherman, 2004;Zhu et al 2018), enriching in clay minerals by isomorphism (Peacock and Sherman 2004;Zhang et al 2015;Wang et al 2017;Zhou et al 2020) and occuring in vanadium-organic compounds (Maylotte et al 1981;Mercer et al 1992;Gol'dberg et al 2010). However, only less than 2% vanadium in the black shale can be extracted , which dues to the difficulty of extracting micro clay minerals from black shale and the indistinct occurrence modes (Xue et al 2021b).…”

Section: It Has Been Confirmed That Vanadium Minerals Can Formed On V...mentioning

confidence: 99%

Mannardite as the main vanadium-hosting mineral in black shale-hosted vanadium deposits, South China

Yang,

Li,

Ouyang

et al. 2024

American Mineralogist

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Black shale-hosted vanadium (V) deposits accounts for about 80% vanadium resource in the world, but only less than 2% vanadium in the black shale can be extracted mainly due to insufficient recognition on the occurrence mode of vanadium. It is commonly agreed that most vanadium in the black shale is hosted in clay minerals and organic matters, but it is not clear how the other parts of vanadium exist and whether there is vanadium mineral, which limits the understanding of metallogenic mechanism of black shale-hosted vanadium 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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“…Based on zircon U-Pb ages of X76 Well in the Mahu Sag, the Fengcheng Formation most possibly deposited at ca.305-296 Ma (Wang et al, 2020). In the sedimentation period of the F3, with exogenous input amount increasing, the salinity decreased, and the sediments were similar to those of the top of the F1 (Zhi et al, 2021;Zhu et al, 2017). In the sedimentation period of the Fengcheng Formation, the Mahu palaeolake generally underwent a transgression process, including shoreshallow lake (the sedimentation period of F1) to deep lake, shallow lake and semi-deep lake (F2 and F3 Members).…”

Section: Geological Settingmentioning

confidence: 99%

The floating astronomical time scale for the terrestrial Early Permian Fengcheng Formation from the Junggar Basin and its stratigraphic and palaeoclimate implications

et al. 2022

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The Permian Fengcheng Formation of the Mahu Sag in the Jungar Basin is one of the most important hydrocarbon source rocks in Xinjiang oil field. The preservation of the geological records of Milankovitch cycles can be studied to understand the history of the Earth's evolution and sedimentary processes, and high-resolution astronomical time scales (ATS) can be obtained by analysing (quasi) periodic sedimentary signals in geological records. In this study, the natural gamma ray (GR) and density (DEN) logging data are used to carry out a detailed spectrum analysis, including 2π-Multi-taper Method (MTM), Evolutive Harmonic Analysis (EHA), Correlation coefficient method (COCO) and DYNOT simulation. GR and DEN data analysis results

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Origin of dolomitic rocks in the lower Permian Fengcheng formation, Junggar Basin, China: evidence from petrology and geochemistry

Cited by 25 publications

References 35 publications

Constraints on dolomite formation in a Late Palaeozoic saline alkaline lake deposit, Junggar Basin, north‐west China

Constraints on dolomite formation in a Late Palaeozoic saline alkaline lake deposit, Junggar Basin, north‐west China

Mannardite as the main vanadium-hosting mineral in black shale-hosted vanadium deposits, South China

The floating astronomical time scale for the terrestrial Early Permian Fengcheng Formation from the Junggar Basin and its stratigraphic and palaeoclimate implications

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