Lanthanide tetrad effect in limestone: a tool to environment analysis of the Ruteh Formation, NW Iran.

Abedini, Ali

doi:10.13168/agg.2018.0017

Cited by 14 publications

(6 citation statements)

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“…The high Sr and Mn contents in the concretions indicated the presence of hot and arid climatic features and were also related to the microbial mineralization of Mn and Sr ions (Tazaki and Morii, 2008). Some REE parameters such as the LREE/HREE, Eu/Eu*, and Ce/Ce* ratios can be used to elucidate the formation mechanisms of sedimentary rocks such as limestone (Abedini and Calagri, 2017;Abedini et al, 2018Abedini et al, , 2020Abedini and Khosravi, 2022). According to the curves of the REEs parameters in all samples (Figure 8), the total REE content, Eu/Eu*, Ce/Ce*, and LREE/HREE value differed significantly among points 11-13 in the core, points 2-10 in the body, and point 1 in the shell of the concretions.…”

Section: Discussionmentioning

confidence: 99%

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Lin

Fang²,

Xu³

2023

Front. Earth Sci.

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Paleoenvironmental information is better preserved in carbonate concretions. In this study, carbonate concretions in the Cretaceous Nenjiang shale, Songliao Basin, were examined to determine whether molecular fossils reflective of the paleoenvironment were better preserved at these sites. Organic and inorganic geochemical characteristics of the concretions and surrounding rocks were analyzed using a series of techniques, including SEM, LA-ICP-MS, GC-MS-MS, and GC-IRMS. The concretions are composed of high content microcrystalline dolomite. The δ13Ccarb and δ18Ocarb values of the concretionary dolomite were significantly higher than those of the surrounding rocks. The dolomite show enrichment in the LREEs and have a negative Eu anomaly. The concretion biomarkers showed distribution characteristics similar to those of surrounding rocks. This suggested that the molecular fossils preserved in concretions were mainly inherited from surrounding rocks. However, the concretions contained more C27 sterane and hopanes, with the hopane/sterane ratio being significantly higher than that of surrounding rocks (1.49 v. 0.86). Moreover, the relative content of 2-methylhopane was 2.4–6.6 times that of the surrounding rocks. This indicated changes in the biological equilibrium of source organisms within and outside the concretions. It was possible that the unstable organic matter at the core increased the bacterial concentration and activity inside the concretions. Both the hydrogen index and biomarker-derived indicators implied that the transformation of organic matter in concretions was minimized when compared with their host rock. The isotope δ13C16-30 was 1‰–3‰ more prevalent in individual N-alkane hydrocarbons in the concretions than in surrounding rocks, likely owing to differences in lithology, bacterial action, and degree of weathering. The study concluded that carbonate concretions could preserve molecular fossils better than the surrounding rocks, and the in-depth organic geochemical analysis of concretions could provide a valuable reference for research into early life forms.

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Section: Discussionmentioning

confidence: 99%

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Lin

Fang²,

Xu³

2023

Front. Earth Sci.

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“…Under these conditions, the mineral phases precipitated from such solutions can produce negative Eu in mineral phases. Abedini et al (2016Abedini et al ( & 2019 suggested that a negative Eu anomaly can be attributed to low pH of fluids/solutions during geochemical processes.…”

Section: Zr/hfmentioning

confidence: 99%

Geological, Mineralogical and Geochemical Aspects of the Granitic Rocks at Umm Nafie Area, North Eastern Desert, Egypt

Elbalakssy

STEET²,

TOHAMY³

2020

Nuclear Sciences Scientific Journal

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Wadi Umm Nafie area is located between lat. 26˚18`-27˚05`N and long. 33˚23`and 33˚29`E. The rocks cropping out in the area are older granitoids and younger granites. The studied area displays secondary structures which are represented by joints and faults. The most predominant fault sets are trending in NE-SW, NNW-SSE and NW-SE directions. Petrographically, the older granitoids are classified as quartz diorites and the younger granites as syenogranites. The radioactivity of the syenogranites is significantly high, comparing with the older granitoids. The anomalous syenogranite (about 1x5m dimensions) exhibits equivalent uranium occurrences that vary considerably in their contents from 115.5 to 125 ppm with an average of 122.8 ppm and from 139.2 to 168.6 ppm equivalent thorium with an average of 155.4 ppm. Th-U, Zr-U, Zr-Th, , Nb-U, Nb -Th relationships show ill-defined trends, suggesting that radioelements distribution aren't controlled by accessory minerals but essentially related to the latter hydrothermal solutions. Anomalous syenogranite is affected by various phases of hydrothermal alteration processes along brittle structures, comprising hematitization, chloritization, epidotization, silicification and kaolinitization. Unusual REEs patterns and non-CHARAC ratios of isovalents confirm that the anomalous syenogranite is affected by late stage hydrothermal solutions resulting fluid-rock interaction and M-type tetrad effect. U and REEs could be leached from the sheared syenogranite at low pH conditions and precipitated in alkaline environments by hematitization process. The main minerals occur in the highly radioactive syenogranite are thorite, uranothorite, betafite, yttrocolumbite, samarskite, ishikawaite, polycrase and fergusonite, in addition to zircon, xenotime, allanite, cerite and monazite.

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“…Zr-Hf and Nb-Ta are known as geochemical pairs, also having similar charges and ionic radii, which are used as geochemical indicators to investigate the processes involved during the genesis of deposits. Despite the similar behavior of these geochemical pairs in geological environments, the variations of Y/Ho, Nb/Ta and Zr/Hf ratios (Table 3) are due to different factors such as fluids, solutions, mineral phases, fluid-rock interaction, ligands, complexation and the tetrad effect during the evolution of deposits (Minami et al, 1998;Spandler and Morris, 2016;Rezaei Azizi et al, 2017;Abedini et al, 2018c). Bau (1996) suggested that Y-Ho and Zr-Hf are mostly controlled by their ionic charge and radius (CHARAC) behavior during geochemical processes.…”

Section: Geochemical Constraints From Trace and Rare Earth Element DImentioning

confidence: 99%

The Hizeh‐Jan Kaolin Deposit of NW Iran: the Tetrad Effect in REE Distribution Patterns

Abedini

Azizi

2019

Acta Geologica Sinica (Eng)

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The Hizeh‐Jan kaolin deposit (northwest of Varzeghan, East‐Azarbaidjan Province, NW Iran) is a product of the alteration of Eocene andesitic rocks. Based on mineralogical examinations, kaolinite, quartz, smectite, pyrophyllite, muscovite‐illite, alunite, calcite, diaspore, goethite and hematite are the most abundant mineral phases in this deposit. The geochemical indicators, such as Y/Ho and Zr/Hf, indicate the non‐CHARAC (non‐Charge‐radius control) behavior of these pairs, which are likely to be due to the occurrence of the tetrad effect phenomenon in this deposit. Simultaneous concave and convex shapes in the chondrite‐normalized REE distribution patterns are a remarkable feature of the kaolin samples. Bivariate diagrams of the size of the third tetrad effect (T3) versus geochemical parameters such as Y/Ho, Nb/Ta and Zr/Hf ratios display two distinct populations for the kaolin samples. The first population is characterized by high T3 values (>0.13), which are near or on the fault zone. The second population is characterized by low T3 values (<0.13), and are farther from the fault zone. The obtained results from the geochemical data have furnished compelling evidence that fluid‐rock interaction, overprint of hypogene processes by supergene ones, and structural control, are key controlling factors for the occurrence of tetrad effects in REE distribution patterns in the Hizeh‐Jan kaolin deposit.

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Lanthanide tetrad effect in limestone: a tool to environment analysis of the Ruteh Formation, NW Iran.

Cited by 14 publications

References 88 publications

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Geological, Mineralogical and Geochemical Aspects of the Granitic Rocks at Umm Nafie Area, North Eastern Desert, Egypt

The Hizeh‐Jan Kaolin Deposit of NW Iran: the Tetrad Effect in REE Distribution Patterns

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