Application of inductively coupled plasma quadrupole mass spectrometry for the determination of monazite ages by lead isotope ratios

Abstract

A fim de avaliar a aplicabilidade da espectrometria de massa com plasma indutivamente acoplado à determinação de idades Pb/Pb, U/Pb e Th/Pb de monazitas, estudos foram realizados, inicialmente, em padrões isotópicos de referência para chumbo (NIST SRM 981 e 982). Posteriormente, a metodologia otimizada foi aplicada a areias monazíticas de três diferentes locais, Pão de Açúcar (Rio de Janeiro), Buena (Estado do Rio de Janeiro) e Praia Negra (Guarapari, Estado do Espirito Santo); as idades médias obtidas, (581 ± 21)Ma, (552 ± 32)Ma e (535 ± 3)Ma, respectivamente, estão de acordo com os valores da literatura para amostras de zircão e de monazita dos mesmos locais. Idades Th/Pb com mono-grãos foram também determinadas para a amostra de monazita da Praia Negra, nove grãos foram analisados e o valor médio, (530 ± 26)Ma, está no acordo com o valor obtido com alíquotas maiores. Finalmente, o método foi aplicado a uma amostra do torianita do Estado de Amapá e as idades obtidas Th-Pb, U-Pb e Pb-Pb foram de (2,15 ± 0,05)Ga, (2,03 ± 0,01)Ga e (2,044 ± 0,006)Ga, respectivamente, com um valor médio de (2,08 ± 0,07)Ga, coerente com a idade de (2,08 ± 0,02)Ga do complexo de Bacuri, Amapá, relatada na literatura.In order to evaluate the applicability of inductively coupled plasma quadrupole mass spectrometry to the determination of Pb/Pb, U/Pb and Th/Pb ages of monazite, studies were carried out initially applying lead atom ratio reference standards (NIST SRM 981 and 982). Further, the optimized methodology was applied to monazite sands from three different sites, Sugar Loaf Hill (Rio de Janeiro city), Buena (Rio de Janeiro state) and Black Sands Beach (Guarapari, Espirito Santo state); the obtained mean ages, (581 ± 21)Myears, (552 ± 32)Myears and (535 ± 3)Myears, respectively, are in agreement with the literature values for zircon and monazite samples from the same sites. Single grain Th/Pb ages were also determined for the monazite sample from Black Sands beach, nine grains were analyzed and the mean value, (530 ± 26)Myears, is in agreement with the value obtained with bulk samples. Finally, the method was applied to a thorianite sample from Amapá state and the observed Th-Pb, U-Pb and Pb-Pb ages obtained were (2.15 ± 0.05)Gyears, (2.03 ± 0.01)Gyears anda (2.044 ± 0.006)Gyears respectively, with a mean value of (2.08 ± 0.07)Gyears. This value is coherent with the (2.08 ± 0.02)Gyears age of the Bacuri complex, Amapá, reported in the literature.

Differentiation Among Brazilian Wine Regions Based on Lead Isotopic Data

“…A second source of uncertainty in the measurements that should be taken into account is the dead time of the detector equipment. 3,12,13 14 Focusing on wine consumers, this study applied the lead isotopic ratio for the first time to study the geographical origin of Brazilian red wines.…”

Lead Content and Isotope Composition in Surface Sediments in Western Xiamen Bay and Its Vicinity: Implication for Possible Source

“…Lead isotopic analyses were carried out using a Perkin-Elmer ICP-QMS SCIEX Elan 9000 as described in the literatures [11][12][13] . Precision and accuracy were verified using a standard reference material from the National Institute of Standards and Technology (SRM 981 common lead isotopic material).…”

Lead/Cadmium Contamination and Lead Isotopic Ratios in Vegetables Grown in Peri-Urban and Mining/Smelting Contaminated Sites in Nanjing, China

“…The limits of detection for Pb and Cd were 0.005 and 0.002 lg L -1 in the present study. Lead isotopic analyses were conducted using a Perkin-Elmer ICP-MS SCIEX Elan 9000 as already described in the literature (Quétel et al 1997;Bindler et al 2004;Godoy et al 2007). Precision and accuracy were verified using a standard reference material from the National Institute of Standards and Technology (SRM 981 common lead isotopic material).…”