Dolomitization of shallow-water, mixed silicilastic-carbonate sequences: The Lower Triassic ramp succession of the Transdanubian Range, Hungary

Győri, Orsolya; Haas, János; Hips, Kinga; Lukoczki, Georgina; Budai, Tamás; Demény, Attila; Szőcs, Emese

doi:10.1016/j.sedgeo.2019.105549

Cited by 11 publications

(7 citation statements)

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“…These faults reached the Permian red sandstone. Fluids could have ascended along these faults, partly dolomitizing the lower Triassic limestone and establishing some base metal ore indications along the boundary of organic-matter-rich horizons (Győri et al , 2014). It is possible, therefore, that the dissolved U was derived from the early diagenesis stage of the Permian red sandstone.…”

Section: Discussionmentioning

confidence: 99%

“…The phosphorite layers were formed with microbial mediation from the dissolved phosphate of seawater, induced partly by the nearby volcanic activity and the effects of a monsoon-derived upwelling (Budai et al , 2017). The mostly super-chondritic Y/Ho ratios and positive Y anomalies suggest a predominant seawater source for apatite formation and the lower Y/Ho values may indicate some hydrothermal input (Bau, 1996) that may be connected to the gradual weakening of the hydrothermal activity related to the Triassic volcanism (Pálfy et al , 2003) or to the hydrothermal fluids derived along normal faults (Győri et al , 2014). This is supported by the stable isotope data (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Geochemical characteristics of Triassic and Cretaceous phosphorite horizons from the Transdanubian Mountain Range (western Hungary): genetic implications

et al. 2018

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The carbonate-dominated Mesozoic sequence of the Transdanubian Mountain Range contains Triassic, uranium-enriched phosphorite layers and Cretaceous, REE-enriched nodular phosphorite. Detailed investigation of these deposits may have an economic benefit because of their large U and REE contents. The dominant minerals in the Triassic phosphorite are carbonate-bearing fluorapatite (CFA) and calcite. According to the electron-probe microanalysis (EPMA) the U is mainly associated with the CFA crystals. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) measurement shows that CFA contains 137–612 ppm U and 113–261 ppm total REE + Y. The LA-ICP-MS U-Pb age of the uppermost phosphorite horizon is 237 ± 11 Ma, which conforms with the stratigraphic age of the host limestone.The Cretaceous nodular phosphorite occurs on the base of an Aptian crinoid-bearing limestone mostly in the form of encrustations around bio- and silicic-clasts, but the clasts also contain phosphorite. The main minerals in these crusts are CFA, calcite, quartz, glauconite and Fe-oxide-hydroxides. Based on EPMA the REE enrichment is related to CFA and LA-ICP-MS measurements show that it contains 748–2953 ppm total REE + Y.The redox-sensitive proxies and the shape of NASC normalized REE patterns indicate that both phosphorites formed in anoxic environments. There are significant differences between these deposits such as appearance, rock-forming minerals, and U and REE contents which indicate differences in their sedimentary environments. The present results suggest that the Triassic phosphorite was formed by inorganic precipitation in a reducing environment close to sea-mounts. The Cretaceous occurrence resulted from a concentric growth mechanism in cold, ascending seawater at the continental margin environment during the anoxic Selli Event (OAE 1a) and/or Paquier Episode (OAE 1b). The critical raw material contents were derived from other sources.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Geochemical characteristics of Triassic and Cretaceous phosphorite horizons from the Transdanubian Mountain Range (western Hungary): genetic implications

et al. 2018

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“…Additionally, micro-stylolites with oxides in grainstone and wackestone likely served as fluid conductors during the diagenesis and compaction as documented by several authors (e.g. Vandeginste & John 2013;Gyori et al 2020;Gomez-Rivas et al 2022). The microfenestra fabric may also have formed during these processes.…”

Section: Depositional Environmentmentioning

confidence: 78%

Pennsylvanian Conodonts and Microfacies From Northeastern Mexico (Tamatán Group, Ciudad Victoria Block)

CASAS-PEÑA,

NAVAS-PAREJO,

JENCHEN

et al. 2024

RIPS

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The biostratigraphic analysis of the Paleozoic sedimentary successions in Mexico is crucial for understanding their age, depositional setting, and paleogeographic implications. This study examined conodonts and microfacies of calcareous strata within the Del Monte Formation of the Tamatán Group in northeastern Mexico. Field observations have led to the identification of three units within the Del Monte Formation: Unit 1, characterized by calcareous sandstone, bioclastic limestone, shale, occasional conglomerate, and dolomitized beds; Unit 2, consisting of conglomerate and/or breccia associated with debris flows; and Unit 3 including turbiditic sandstone and shale. Conodonts were only recognized in Unit 1, with such genera as Idiognathoides, Neognathodus, Idiognathodus and less frequently, Streptognathodus, Adetognathus, and Diplognathodus. The faunal associations include Idiognathoides cf. Id. corrugatus Harris & Hollingsworth, 1933, Idiognathoides sulcatus sulcatus Higgins & Bouckaert, 1968, Idiognathoides convexus (Ellison & Graves, 1941), Idiognathoides asiaticus Nigmadganov & Nemyrovskaya, 1992, Neognathodus cf. N. atokaensis Grayson, 1984, Neognathodus aff. bothrops Merrill, 1972, Neognathodus nataliae Alekseev & Gerelzezeg, 2001 (in Alekseev & Goreva 2001), Streptognathodus parvus Dunn, 1966, Idiognathodus incurvus Dunn, 1966, and Idiognathodus aff. delicatus Gunnell, 1931, suggesting Morrowan and Atokan (Pennsylvanian) ages for the dolomitic limestone and grainstone beds. Five types of microfacies (MF) and several marine facies zone (FZ) have been detected: MF1-bioclastic grainstone and MF2-wackestone deposited at the platform margin (FZ 6 and FZ 7), MF3-dolomitized wackestone representing an inner restricted platform (FZ 8), MF4-mudstone from a deeper water zone (FZ 4), and MF5-siliciclastic beds with bioclasts indicating a high-energy barrier associated with a platform margin (FZ 6). The findings confirm a shallow to deep platform and imply a connection among Mexican peri-Gondwanan basins, including the Tamatán Basin, indicating similarities in sedimentary facies and/or depositional environments linked to the Rheic Ocean during the Early to Middle Pennsylvanian.

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“…The term “mixed” was first used to state sediments composed of textural mixtures of carbonate and siliciclastic minerals . Mixed siliciclastic–carbonate sequences formed in various depositional settings are common in both marine and lacustrine environments. , Fine-grained sediments are those rocks with grain sizes smaller than 0.0625 mm . The fine-grained terrigenous and carbonate components in the mixed sediments record abundant information about sediment dynamics and the environment .…”

Section: Introductionmentioning

confidence: 99%

Effect of Petroleum Generation and Retention on Nanopore Structure Change in Laminated and Massive Shales─Insights from Hydrous Pyrolysis of Lacustrine Source Rocks from the Permian Lucaogou Formation

Yang

Xiang

et al. 2023

ACS Omega

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The lacustrine shale of the Middle Permian Lucaogou Formation in the Jimusar Sag is the principal prospective unconventional target in the Junggar Basin. The effect of petroleum generation and retention on nanopore structure change during thermal maturity in lacustrine shale is still unclear. In this study, two laminated and two massive shale samples from the Permian Lucaogou Formation were selected to study this change by closed hydrous pyrolysis. The pyrolysis temperatures were 295, 320, 345, 370, and 400 °C, which cover from the mature to the post-mature stage. Total organic carbon (TOC), Rock-Eval, and low-pressure N2 adsorption tests on pyrolyzed shale samples before and after extractable organic matter (EOM) extraction were conducted systematically. The results indicate that (1) the petroleum generation on nanopore structure change is in stages. The peak nanopore volume expanding stage is the late oil window (R o = 0.9–1.35%). At the post-mature stage (R o > 1.35%), the mesopore volume decreased and the majority of the nanopore space is from macropores. (2) The presence of EOM decreased both mesopores and macropores in the peak oil window. (3) The organic-rich laminated shale generated more macropores than massive shale with increasing thermal maturity. The results of this study shed light on the dynamic effect of laminae fabric, petroleum generation, and retention on shale nanopore structure change across the oil window.

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Dolomitization of shallow-water, mixed silicilastic-carbonate sequences: The Lower Triassic ramp succession of the Transdanubian Range, Hungary

Cited by 11 publications

References 68 publications

Geochemical characteristics of Triassic and Cretaceous phosphorite horizons from the Transdanubian Mountain Range (western Hungary): genetic implications

Geochemical characteristics of Triassic and Cretaceous phosphorite horizons from the Transdanubian Mountain Range (western Hungary): genetic implications

Pennsylvanian Conodonts and Microfacies From Northeastern Mexico (Tamatán Group, Ciudad Victoria Block)

Effect of Petroleum Generation and Retention on Nanopore Structure Change in Laminated and Massive Shales─Insights from Hydrous Pyrolysis of Lacustrine Source Rocks from the Permian Lucaogou Formation

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