REE geochemistry of Early Cambrian phosphorites of Masrana and Kimoi blocks, Uttarakhand, India

Khan, Saif; Khan, K. F.; Dar, Shamim A.

doi:10.1007/s12517-016-2477-8

Cited by 20 publications

(5 citation statements)

References 37 publications

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“…Source of oxidized seawater. The REE distribution patterns of sedimentary rocks can be used as an important indicator to determine the sedimentary environment [34,35,70,71]. The REE distribution patterns (Fig 15a -15f) of the Zhijin phosphorite profiles exhibit similar characteristics, i.e, strong negative Ce anomalies, weak positive Eu anomalies, MREE enrichment, and HREE depletion.…”

Section: Plos Onementioning

confidence: 95%

“…It was concluded that the lower Cambrian phosphorite should have formed in a marginal sea sedimentary environment. Ce anomalies can be used as an effective tracer for determining the redox conditions of the depositional environments of sediments and sedimentary rocks [34,35]. Since the values of Ce anomalies can be overestimated due to a high concentration of La [25] or to the artificial calculations [36], it is necessary to discuss the real Ce anomaly values.…”

Section: Sedimentary Environment Of Phosphoritesmentioning

confidence: 99%

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Studies on geochemical characteristics and biomineralization of Cambrian phosphorites, Zhijin, Guizhou Province, China

Gao

Yang

et al. 2023

PLoS ONE

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Phosphate rocks, an important ore resource in Guizhou Province, China, are mainly hosted within the Sinian Doushantuo Formation and the Cambrian Meishucun Formation. In addition, the phosphate rocks of the Cambrian Meishucun Formation are rich in biological fossils. Although numerous studies investigating the genesis of phosphate deposits have been performed, the relationship between biological activity and the formation of phosphate deposits in the lower Cambrian Meishucun Formation has not been convincingly explained. This study focuses on the biological fossil assemblage, the characteristics of phosphorus, and the relationship between biological and phosphorus enrichment of the lower Cambrian phosphorites. The primary objectives of our study are to analyze the role of organisms in the formation of phosphorites, restore the phosphorus-formation environment of the Cambrian Meishucun Formation, and construct a sedimentary model of the phosphorites in the Meishucun Formation. The results indicate that there is a significant positive correlation between biological activity and the deposition of phosphorites, that is, the higher the degree of biological enrichment and differentiation, the stronger the deposition. The geochemical analysis of several profiles in the Zhijin phosphorite block shows that the phosphorite block was deposited in an oxygen-rich environment and was affected by a high-temperature hydrothermal fluid. Upwelling ocean currents supplied abundant phosphorus and other nutrients, which provided the conditions for small shells and algae to flourish. Biochemical activity was a crucial factor in the deposition of the phosphorite.

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Section: Plos Onementioning

confidence: 95%

Section: Sedimentary Environment Of Phosphoritesmentioning

confidence: 99%

Studies on geochemical characteristics and biomineralization of Cambrian phosphorites, Zhijin, Guizhou Province, China

Gao

Yang

et al. 2023

PLoS ONE

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“…Ce anomalies can effectively determine the redox conditions of the depositional environments of sediments and sedimentary rocks [88,89]. Ce anomalies (Ce/Ce*) in the Taozichong Formation samples (Table S3) ranged from 0.24 to 0.85 (mean of 0.54), indicating negative anomalies.…”

Section: Redox Conditionsmentioning

confidence: 99%

The Paleoecological Environment during the Ediacaran–Cambrian Transition in Central Guizhou Province, China: Evidence from Zn Isotopes

Gao,

Yang,

Gao

et al. 2024

Minerals

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During the Ediacaran–Cambrian transition, a series of stratal continuous and well-preserved siliceous rock and phosphorite assemblages developed in Qingzhen, Guizhou Province, China, facilitating research on the biological evolution, marine chemistry, and palaeoecological environment of this period. Therefore, we investigated the paleontology, trace and rare earth elements, total organic carbon, total sulfur content, and Zn isotopes of the phosphorus-bearing rock series in the Taozichong Formation of the Cambrian period in Qingzhen. Geochemical analysis reveals that the sedimentary rocks in this area were formed in the oxygen-rich seawater environment and were not affected by high-temperature hydrothermal activity. The upwelling ocean current provided abundant rare earth elements and other nutrient elements, as well as conditions for the prosperity of biota in Qingzhen. In addition, the δ66Zn value (−0.21‰–0.41‰ range and 0.17‰ mean) in the Qingzhen phosphorous rock series was much lower than that in seawater, indicating a strong level of biological productivity. The variation trend of δ13C, δ18O, and δ66Zn exhibited four stages and three obvious drift events. The results suggest that climate change during this period led to the intermittent flourishing and extinction of organisms, which triggered the negative drift of δ13C and δ18O in the ocean, resulting in a coordinated response of δ66Zn. The unique ecological environment of the Taozichong Formation in Qingzhen also provides favorable conditions for the population continuation of Ediacaran-type benthic soft-bodied metazoon dominated by discoid fossils, Shaanxilithes, worm fossils, and sponge fossils in the Cambrian strata, as well as participation in the global biological explosion events. The study area provides new insights for rebuilding the global Ediacaran–Cambrian ecosystem during the transition period.

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“…Organic material can produce positive Eu anomalies under anoxic conditions (Kidder et al, 2003). Recently, studies indicated that reducing conditions can prevail during upwelling of deep anoxic waters rich in organic material and/or mixing with shallower oxic seawater prior to deposition (Khan et al, 2016).…”

Section: Ce and Eu Anomalymentioning

confidence: 99%

Mineralogy and Geochemistry of Uraniferous Sandstones in Fault Zone, Wadi El Sahu Area, Southwestern Sinai, Egypt: Implications for Provenance, Weathering and Tectonic Setting

Sallam

Mira

Tohamy

et al. 2021

Acta Geologica Sinica (Eng)

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Paleozoic rocks in the Wadi El Sahu area are affected by many major faults in different directions. A reverse fault trending NE‐SW is exposed for about 300 m of its length as it cuts through the Abu Hamata and Adedia formations on the south side of Wadi El Sahu. A secondary ascending hydrothermal solution carrying heavy metals and radioactive minerals passed through the fault plain and the surrounding fractures, forming mineralized and radioactive zone. The mineralized zone thickness ranges from 60 cm to 200 cm along the fault plain. These rocks were analyzed radiometrically using a portable gamma‐ray spectrometer, chemically by employing ICP‐ES and ICP‐MS, as well as mineralogically by both binocular and Environmental Scanning Electron microscope. Gold content was also determined by fire assay. REE and U contents reached up to 2682 and 1216 ppm, respectively. Mineralogical investigations indicated the presence of uraninite, torbernite, autunite, sklodowskite, kasolite as uranium minerals, thorite as a thorium mineral, monazite, allanite and xenotime as REE‐bearing minerals, zircon and columbite as accessory minerals, gold and nickel as precious and base metals, in addition to cassiterite, chalcopyrite, chalcocite and chrysocolla. High REE and U contents are attributed to the circulation of epigenetic U and REE‐bearing hydrothermal solutions along the fault plain and its surrounding fractures. Hydrothermal alteration processes could then be confirmed by the presence of the M‐type tetrad effect in the REE‐patterns of the ferruginous sandstone. The non‐chondritic ratio of Nb/Ta, Zr/Hf and Y/Ho in the studied sandstone may be attributed to the tetrad effect. The Ce and Eu anomaly with unusual REE‐patterns was represented by the presence of conjugated M‐W tetrad effects, indicating either the dual effect of hydrothermal solutions or groundwater with seawater. The results clarify that the tetrad‐effects could be used as evidence for the environment of deposition and as an indication for gold mineralization.

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REE geochemistry of Early Cambrian phosphorites of Masrana and Kimoi blocks, Uttarakhand, India

Cited by 20 publications

References 37 publications

Studies on geochemical characteristics and biomineralization of Cambrian phosphorites, Zhijin, Guizhou Province, China

Studies on geochemical characteristics and biomineralization of Cambrian phosphorites, Zhijin, Guizhou Province, China

The Paleoecological Environment during the Ediacaran–Cambrian Transition in Central Guizhou Province, China: Evidence from Zn Isotopes

Mineralogy and Geochemistry of Uraniferous Sandstones in Fault Zone, Wadi El Sahu Area, Southwestern Sinai, Egypt: Implications for Provenance, Weathering and Tectonic Setting

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