Geochemistry of rare earth elements in early-diagenetic miocene phosphatic concretions of Patagonia, Argentina: Phosphogenetic implications

Fazio, Ariel; Scasso, Roberto A.; Castro, Liliana Norma; Carey, Steven

doi:10.1016/j.dsr2.2007.04.013

Cited by 41 publications

(13 citation statements)

References 29 publications

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“…Redox conditions typically change from oxidizing to reducing during sediment burial, therefore promoting Fe and Mn reduction to soluble states and releasing P, from which phosphate minerals may be precipitated. This process, enhanced by water circulation through burrows at the Miocene sea water–sediment interface, was responsible for the formation of Gaiman concretions (Scasso & Castro, ; Fazio et al ., ). Improved ion diffusion and pore water renewal in the sediments resulted in a widened oxic–suboxic zone.…”

Section: Phosphatic Horizons and Phosphogenesismentioning

confidence: 97%

“…In addition, sediment mixing and reworking by organisms, and micro‐environments from organic matter decay within fossils and burrows, contributed to phosphatic concretion formation. Rare earth element patterns in early diagenetic concretions of the Gaiman Formation suggest quantitative precipitation from early diagenetic pore waters, reproducing the flat pattern of oxic–suboxic recent pore waters (normalized to PAAS), which result from remineralization of organic coatings rich in Ce and other light rare earth elements (Fazio et al ., ).…”

Section: Phosphatic Horizons and Phosphogenesismentioning

confidence: 97%

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Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

et al. 2013

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The precipitation/replacement of Ca-phosphate is a complex process that commonly takes place during the early diagenesis in marine sediments. The unusual occurrence of shallow marine, early diagenetic phosphatic deposits associated with glassy tuffs in the Neogene Gaiman Formation, in the Chubut Province, Patagonia, Argentina, constitutes a good case example for the study of replacement and precipitation of Ca-phosphate on an unstable substrate. Isocon diagrams illustrate that chemical changes during glass diagenesis include gains in loss on ignition and Ca, and losses of K. These changes are the result of glass hydration during sea water-glass interaction, together with adsorption and diffusion of ions into the bulk shard; combined, these represent an incipient process of volcanic glass replacement by Caphosphate. Subsequent early diagenetic P enrichment in the pore solutions led to phosphate precipitation, associated with pitting on the glass shards and pumice. The associated development of a reactive surface promoted the incorporation of P and Ca into their margins. Lastly, precipitation of calcium phosphate filled the vesicles and other open cavities, inhibiting further glass dissolution. The high porosity and reactivity of the volcanic glass provided an appropriate substrate for phosphate precipitation, leading to the development of authigenic apatite concretions in the volcanic-glass bearing strata of the Gaiman Formation. This research is of significance for those concerned with marine phosphatic deposits and sheds light on the processes of early diagenetic phosphate precipitation by replacement of an atypical, unstable substrate like hydrated volcanic glass.

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Section: Phosphatic Horizons and Phosphogenesismentioning

confidence: 97%

Section: Phosphatic Horizons and Phosphogenesismentioning

confidence: 97%

Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

et al. 2013

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“…The results of whole-rock major, trace and rare earth elements concentrations in all samples are reported in S1-S3 Tables. The REE parameters analyzed are as follows: δCe = Ce/Ce � = Ce N /0.5(La N +Pr N ) [25], δEu = Eu/Eu � = Eu N /(Sm N ×Gd N ) 0.5 [26], Pr/Pr � = Pr N /0.5(Ce N +Nd N ) [25], and Y/Y � = 2Y N /(Dy N +Ho N ) [27], where N denotes normalization relative to Post-Archean Australian Shale (PAAS) [26].…”

Section: Plos Onementioning

confidence: 99%

“…The Y anomaly (Y/Y � ) and La/ Nd ratios exhibit positive anomalies in seawater [27,52], and they are not affected by redox changes; however, in sediments, these anomalies may decrease with increasing diagenesis [53]. Therefore, the Y/Y � and La/Nd ratios are valuable indicators for estimating post-depositional changes related to variations in the compositions of the circulating fluids [23,27,37]. Shields and Stille [53] reported that the Y/Y � and La/Nd ratios of modern seawater are 1.5-2.3 and 0.8-1.3, respectively.…”

Section: Plos Onementioning

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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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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“…Segundo Bentor (1980), rochas sedimentares com conteúdo de fosfatos maior que o usual -maior que 5% -são a definição clássica de fosforitas. Diversos autores utilizam a composição química e a textura de fosforitas como critérios para avaliação das condições paleoclimáticas/paleoambientais das bacias em que ela se formaram (Ilyin, 1998;Hüneke, 2006;Dypvik e Zakharov, 2010;Garnit et al, 2012, entre outros) ou para a identificação de modelos fosfogenéticos (Föllmi, 1996;Fazio et al, 2007;Filippelli, 2011).…”

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Ocorrência de intercalação de rocha fosfática na Formação Ponta Grossa em Rio Verde de Mato Grosso, Mato Grosso do Sul: implicações paleoambientais

Montibeller

Zanardo

Navarro

2018

Geol. USP. Sér. Cient.

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Disponível on-line no endereço www.igc.usp.br/geologiausp -241 -Resumo Entre as rochas da Formação Ponta Grossa, aflorantes no município de Rio Verde de Mato Grosso, é registrada a presença de camadas constituídas predominantemente por apatita, não fossilíferas, que ocorrem como estratos destacados intercalados em folhelhos cinzas-escuros a pretos. Petrograficamente, essa rocha fosfática apresenta estrutura sutilmente laminada e não são observadas feições indicativas de algas, restos fósseis ou de estruturas orgânicas. Possui teores de P 2 O 5 variando entre 12,96 e 23,35%, teores de CaO variando entre 19,85 e 33,04%, e possui alta concentração de elementos terras raras (ETR) em relação à média da crosta continental superior. Essa ocorrência não possui evidências de ação biogênica -o que é confirmado pela microscopia eletrônica -e possui relictos de oxi-hidróxidos, preferencialmente de ferro, com pequena quantidade de manganês, sugerindo origem pela dessorção de fosfato por comportamento redox a partir desses relictos. As condições de formação dessas fosforitas -se não condicionadas a aporte externo de oxi-hidróxidos de ferro pela proximidade da costa, por ambientes deltaicos ou por contribuições hidrotermais e/ou vulcânicas -colocam as camadas fosfáticas de Rio Verde de Mato Grosso, Mato Grosso do Sul, em condições de ambiente marinho plataformal raso, com profundidade entre 200 e 300 m, de águas frias e com baixa salinidade, preferencialmente anóxico, e suscetível a estabelecimento de zona de ressurgência.Palavras-chave: Fosforita; Fosfogênese; Devoniano; Bacia do Paraná; Formação Ponta Grossa. AbstractAmongst rocks of the Ponta Grossa Formation cropping out in Rio Verde de Mato Grosso, there are levels consisting predominantly of apatite, without fossil traces, which occur as layers hosted in gray to black shales. Petrographically, this phosphatic level has subtly layered structure and no features indicative of algae, fossil remains or organic structures. It has P 2 O 5 content varying between 12.96 and 23.35%, CaO ranging between 19.85 and 33.04%, and high concentration of rare earth elements (REE) when compared to the average content of the upper continental crust. This occurrence exhibits no evidence of biogenic action, which is confirmed by electron microscopy, yet it contains relicts of oxy-hydroxides, predominantly of iron, with small amount of manganese, suggesting origin from phosphate desorption due to the redox behavior of these oxy-hydroxides. If these phosphorites were not subject to external supply of iron oxy-hydroxides due to proximity to the coast, deltaic environments or hydrothermal and/or volcanic contributions, then the phosphatic levels of Rio Verde de Mato Grosso, Mato Grosso do Sul, probably formed on a shallow marine platform at depths between 200 and 300 m, in cold, low salinity and preferably anoxic water, subject to upwelling.

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Geochemistry of rare earth elements in early-diagenetic miocene phosphatic concretions of Patagonia, Argentina: Phosphogenetic implications

Cited by 41 publications

References 29 publications

Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

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

Ocorrência de intercalação de rocha fosfática na Formação Ponta Grossa em Rio Verde de Mato Grosso, Mato Grosso do Sul: implicações paleoambientais

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