The Diamantina monazite: a new low-Th reference material for microanalysis

Gonçalves, Guilherme O.; Lana, Cristiano; Scholz, Ricardo; Buick, Ian S.; Gerdes, Axel; Kamo, Sandra L.; Corfu, Fernando; Rubatto, Daniela; Wiedenbeck, Michael; Nalini, Hermínio A. Jr.; Oliveira, Luiz Carlo A. (2017). The Diamantina monazite: a new low-Th reference material for microanalysis. Geostandards and Geoanalytical Research, 42(1), pp. 25-47. Wiley 10.1111/ggr.12192

[img] Text
Goncalvers_Diamantina17.pdf - Published Version
Restricted to registered users only
Available under License Publisher holds Copyright.

Download (3MB) | Request a copy

Most monazite reference materials (RMs) for in situ U-Pb geochronology are rich in Th; however, many hydrothermal ore deposits contain monazite that is low in trace element contents, including Th, U and Pb. Because of potential problems with matrix effects and the lack of appropriate matrix-matched RMs, such variations can bias dating of hydrothermal deposits. In this paper, we describe a polycrystalline low-U and low-Th Diamantina monazite from the Espinhaço Range, SE Brazil. It has a U-Pb ID-TIMS weighted mean 207Pb*/235U ratio of 0.62913 ± 0.00079, 206Pb*/238U of 0.079861 ± 0.000088 and 207Pb*/206Pb* of 0.057130 ± 0.000031, yielding a weighted mean 206Pb*/238U date of 495.26 ± 0.54 Ma (95% c.l.). In situ dates acquired with different methods (LA-(Q, SF, MC)-ICP-MS and SIMS) are within uncertainty of the ID-TIMS data. U-Pb LA-(Q, MC)-ICP-MS runs, using Diamantina as a primary RM, reproduced the ages of other established RMs within < 1% deviation. The LA-MC-ICP-MS analyses yielded homogeneous Sm-Nd isotopic compositions (143Nd/144Nd = 0.511427 ± 23, 2s; 147Sm/144Nd = 0.1177 ± 13, 2s) and εNd(495 Ma) of −18.7 ± 0.5 (2s). SIMS oxygen isotope determinations showed measurement reproducibility better than ± 0.3‰ (2s), confirming Diamantina's relative homogeneity at test portion masses below 1 ng.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Rubatto, Daniela

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1639-4488

Publisher:

Wiley

Language:

English

Submitter:

Daniela Rubatto

Date Deposited:

07 May 2018 14:39

Last Modified:

20 Jun 2018 08:43

Publisher DOI:

10.1111/ggr.12192

BORIS DOI:

10.7892/boris.112638

URI:

https://boris.unibe.ch/id/eprint/112638

Actions (login required)

Edit item Edit item
Provide Feedback