Monazite chemical composition: some implications for monazite geochronology

Zhu, Xiangkun; O’Nions, R.K.

doi:10.1007/s004100050555

Cited by 159 publications

(63 citation statements)

References 41 publications

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“…Therefore Gypsum percentage was upgraded to about 80% of the bulk constituents (Table 3). The samples that collected from the water squeezed out under the hot summer with temperature exceeds 45°C were chemically analyzed and the conducted results are presented in Table ( 4). The water samples show an elevated total content of Ca, Mg, Na, Mn, Al, Fe, K and some of the rare earth elements such as Cr and V. The concentrations of Al, Fe, Mn, and Na were exceeded the drinking water standards in the tested water samples.…”

Section: Phosphogypsum Chemical Compositionmentioning

confidence: 99%

“…The Gama rays insitu measurements determined by the Gama emanation detector revealed 300-550 count per second (cps), Whereas, the samples showed values ranged from 10 to 45 cps.The increments in the radiation values are attributed to the presence of radioactive elements, mainly U, K 40 and Radon [3].Its structural group consists of arsenate, phosphate and silicate that having the general formula ABO4; where A corresponds to REE, Th, U, etc., B corresponds to As 5+ , P 5+ or Si 4+ and O is the oxygen [4].The radioactive elements such as Th and U can be separated using a hydroxideacid or by using a concentrated sulfuric acid (H2SO4) [5].…”

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confidence: 99%

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The Chemical Composition of Phosphogypsum Disposal Piles in Aqaba-Jordan and the Physic-mechanical Treatments to Separate the Gypsum Group and Heavy Minerals

Jamal¹,

Khzahee²

2017

ijcrr

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Abstract:The alteration products of fertilizer industry from phosphate rocks produce Phosphogypsum as a sideproduct, where it containsconsiderable amounts of Gypsum and Anhydrite. The accumulated amounts of Phosphogypsumin Aqaba area over the last three decades are estimated to be more than 70 million metric tons.These products can be economically important when of the accompanied undesirable substances; mainly the radioactive elements and toxic materials have been removed. The radioactive elements,which believed to contribute natural radionuclides in the environment of Phosphogypsumdisposals, are Uranium, Thorium, Potassium 40 and the Radon gas.The rainfall on these piles isinfiltrated into the pour spaces downward and therefore Gypsum exists in the bottom of these deposits withno Anhydrite records.

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Section: Phosphogypsum Chemical Compositionmentioning

confidence: 99%

mentioning

confidence: 99%

The Chemical Composition of Phosphogypsum Disposal Piles in Aqaba-Jordan and the Physic-mechanical Treatments to Separate the Gypsum Group and Heavy Minerals

Jamal¹,

Khzahee²

2017

ijcrr

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“…A monazita representa uma importante ferramenta na discussão de questões geocronológicas pois seus conteúdos de U, Th e Pb obtidos por meio da microssonda eletrônica podem ser usados em datações químicas com bastante eficiência (Zhu & O'Nions, 1999). Através dessas mesmas análises os estudos das variações de padrões de ETR podem auxiliar na indicação do processo gerador de líquidos pegmatíticos dentro de um contexto geotectônico (Cerný et al, 2012).…”

Section: Discussões E Conclusãounclassified

ORIGEM E IDADE U-Th-Pb DO DISTRITO PEGMATÍTICO DE SANTA MARIA DE ITABIRA (MG) REVELADAS PELA MONAZITA

Ferreira¹,

Chaves²

2017

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Resumo: Imagens de elétrons retro-espalhados e microanálises químicas por microssonda eletrônica foram obtidas a partir de cristais de monazita pertencentes ao Distrito Pegmatítico de Santa Maria de Itabira nas lavras de Morro Escuro, Ponte da Raíz e Euxenita. Essas lavras estão nos municípios de Santa Maria de Itabira, Ferros, Guanhães e Sabinópolis, em Minas Gerais. As amostras coletadas fazem parte da Província Pegmatítica Oriental Brasileira (PPOB), situada em um contexto pós-colisional do Orógeno Araçuaí correspondente ao final do Ciclo Brasiliano. Os cristais mostram-se homogêneos, ou seja, livres de domínios/zoneamentos composicionais e seus teores de U, Th e Pb permitiram a obtenção de idade química média de 474 Ma para o distrito pegmatítico da região estudada. Seus padrões de terras raras normalizados ao condrito mostram anomalia positiva de Sm, elemento fortemente particionado em anfibólio. Esta anomalia sugere que no contexto pós-colisional do Orógeno Araçuaí houve a fusão parcial do biotita-hornblenda gnaisse (Grupo Guanhães), rocha encaixante dos pegmatitos, durante o processo de descompressão regional associado ao colapso do orógeno, gerando um magma granítico hidratado o bastante para permitir o avolumado crescimento de cristais dos pegmatitos desse Distrito Pegmatítico, incluindo a monazita. Este mineral atua, portanto, não só como um geocronômetro, mas também como importante indicador petrogenético dos pegmatitos estudados. This anomaly suggests that in the post-collisional context of the Araçuaí Orogen there was partial melting of the host rocks of the Guanhães Group (biotite-hornblende gneiss) during the regional decompression process linked with the collapse of the orogen. This contributed to formation of a granitic melt, which was hydrated enough to allow the large crystal growth of the Itambé pegmatites, including monazite. Therefore, this mineral represents not only a geochronometer, but also a petrogenetic indicator of the studied pegmatites.Keywords: Monazite; Santa Maria de Itabira (MG); U-Th-Pb chemical dating, electron microprobe; petrogenetic indicator INTRODUÇÃOOs estudos referentes a corpos pegmatíticos apresentam grande importância desde as últimas décadas, por se tratarem de rochas fonte da grande maioria dos minerais-gema, minerais industriais e de elementos raros. Os pegmatitos são interpretados como um produto de fracionamento ígneo de fusões graníticas ou se formam por processos anatéticos, a partir da fusão parcial da rocha encaixante (Černý, 1982). A maior parte dos minerais encontrados nos pegmatitos pertence a três classes predominantes: silicatos, fosfatos e óxidos. Além da importância econômica é possível extrair deles informações no que tange à caracterização químico-mineralógica e genética dos corpos pegmatíticos, bem como sua relação, quando existente, com corpos graníticos (Newman, 2009).A monazita, um fosfato de elementos terrasraras (ETR) essencialmente leves (Montel et al., 1996), é um mineral acessório muito comum em pegmatitos e difundido em diversas litologi...

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“…Nb, Ta and Th correlate well with TiO 2 , Al 2 O 3 , implying that both Ti-rich minerals and clay minerals are major hosts for these elements. Despite a small amount of monazite (~0.004%), it contributes up to 30% of the bulk Th concentration (about 10% ThO 2 in monazite from granitoids, Zhu and O'Nions, 1999). Unlike other incompatible elements, Zr and Hf show little correlation with both TiO 2 The bulk REE concentrations of the Zhanhua sag sediments show positive correlations with TiO 2 (r = 0.41) and, Th (r = 0.43), suggesting that Ti-and Th-rich minerals are also major hosts for REE.…”

Section: Elemental Distributions In Mineralsmentioning

confidence: 99%

Geochemistry of Neogene sedimentary rocks from the Jiyang basin, North China Block: The roles of grain size and clay minerals

et al. 2008

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Major and trace element compositions of 83 fine-grained sedimentary rocks (including 14 fine-grained sandstones, 24 siltstones and 45 mudstones) from the Zhanhua Sag of Jiyang basin in the North China Block were analyzed to investigate the effects of sedimentary processes (e.g., source provenance, mineral assemblage, grain size and chemical weathering etc.) on the bulk chemical compositions. Compared with the average upper continental crust (UCC), these rocks have higher TiO 2 , Al 2 O 3 , Fe 2 O 3 , Ba, Th, U, Nb, Ta, Zr, Hf, Y and REE, but lower SiO 2 , MnO, MgO, CaO, K 2 O, Na 2 O, P 2 O 5 , Cr, Co, Ni and Sr. From sandstones, siltstones to mudstones, there exist systematic increase in Rb, Cs, V, Cr, Co, Ni, Nb, Ta, Th, U and REE, and decrease in SiO 2 , K 2 O, Na 2 O and Ba. Such variation trends reflect a predominant role of grain size effect on the geochemistry of these sediments. K 2 O, Na 2 O, Ba, Zr and Hf positively correlate with SiO 2 and negatively correlate with Al 2 O 3 , whereas other elements generally show negative correlations with SiO 2 and positive correlations with Al 2 O 3 , suggesting that clay minerals are major hosts for most elements, while quartz and feldspar exert a dilution effect. The accessory heavy minerals exert a minor control on the bulk REE composition of the sediments, e.g., the contribution of heavy minerals (apatite, zircon, sphene, monazite etc.) to the bulk REE concentrations is less than 20%. Our results show that grain size and clay minerals are the two most important factors to control the bulk chemical compositions of the Zhanhua Sag sediments, and probably terrestrial fine-grained sediments in general.

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Monazite chemical composition: some implications for monazite geochronology

Cited by 159 publications

References 41 publications

The Chemical Composition of Phosphogypsum Disposal Piles in Aqaba-Jordan and the Physic-mechanical Treatments to Separate the Gypsum Group and Heavy Minerals

The Chemical Composition of Phosphogypsum Disposal Piles in Aqaba-Jordan and the Physic-mechanical Treatments to Separate the Gypsum Group and Heavy Minerals

ORIGEM E IDADE U-Th-Pb DO DISTRITO PEGMATÍTICO DE SANTA MARIA DE ITABIRA (MG) REVELADAS PELA MONAZITA

Geochemistry of Neogene sedimentary rocks from the Jiyang basin, North China Block: The roles of grain size and clay minerals

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