Monazite analysis; from sample preparation to microprobe age dating and REE quantification

Scherrer, Nadim; Engi, Martin; Gnos, Edwin; Jakob, Vreni; Liechti, Adrian (2000). Monazite analysis; from sample preparation to microprobe age dating and REE quantification Schweizerische Mineralogische Und Petrographische Mitteilungen, 80, pp. 93-105.

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Despite the recognized importance of monazite in geochronology and petrology, a range of fundamental analytical and preparational problems remains. For example, chemical Th-U-Pb dating of monazite requires special lead-free sample preparation. This is achieved efficiently and at high quality with specially developed grooved ND-PE polyethylene polishing disks. Techniques useful in locating and characterizing monazite are evaluated. Back scattered electron imaging is an effective way to determine zonation patterns, particularly with respect to thorium. Quantitative analysis of monazite by EMP is delicate and time consuming. A whole series of X-ray peak interferences has been ignored in published work. For example, for monazite containing 12% Th, the commonly disregarded interference of Th hit on Pb hla causes an overestimation of 11% (relative) in Pb. This propagates to an age overestimation of similar to 50 Ma for a sample of 400 to 500 Ma in age. A judicious choice of X-ray peaks used in quantitative EMP analysis avoids or minimises peak overlap for all elements, including REE. Only for U a correction factor is required: U wt%(corrected) = U wt%(measured) - (0.0052 * T wt%(measured)) based on the analytical lines U Mb and Th Ma.

Item Type:	Journal Article (Original Article)
Division/Institute:	Bern Academy of the Arts Bern Academy of the Arts > Institute Materiality in Art and Culture
Name:	Scherrer, Nadim0000-0002-6576-885X; Engi, Martin; Gnos, Edwin; Jakob, Vreni and Liechti, Adrian
Subjects:	Q Science > QE Geology
ISSN:	0036-7699
Language:	English
Submitter:	Nadim Scherrer
Date Deposited:	10 Feb 2021 15:20
Last Modified:	20 Apr 2021 14:42
Related URLs:	Publication
Web of Science ID:	000086838700008
Additional Information:	Notes: 310QK Times Cited:86 Cited References Count:35 Custom 1: Article Date: 2000
Uncontrolled Keywords:	EMPA REE monazite polishing sample preparation chemical dating Th-U-Pb dating u-pb systematics electron-microprobe amphibolite-facies accessory minerals th xenotime geochronology metapelites chemistry behavior
ARBOR DOI:	10.24451/arbor.13533
URI:	https://arbor.bfh.ch/id/eprint/13533