U-TH-PB DATING OF MONAZITE

This method has been most widely used in (i) the °K- °Ar system, (ii) the U-Th-He system, (iii) the U-Pb dating of zircon, and (iv) the U-Th-Pb dating of monazite using electron microprobe measurements. The last is a developing method with large errors because of the low analytical precision and because isotopes are not measured. 

U-Th-Pb Dating of Monazite Using Only Uranium, Thorium, and Lead Concentrations... 

Koppel V, Gimthert A, Griinenfelder M (1980) Patterns of U-Pb zircon and monazite ages in polymetamorphic nnits of the Swiss Central Alps. Schweiz mineral petrogr Mitt 61 97-119 Kosler J, Tnbrett MN, Sylvester PJ (2001) Application of laser ablation ICP-MS to U-Th-Pb dating of monazite. Geostand Newslett 25 375-386... 

Kohn, M.J. and Vervoort, J.D. (2008) U/Th-Pb dating of monazite by singlecollector ICP-MS pitfolls and potential. Geochem. Geophys. Geosyst., 9, Q04031. 

Ayers J. C., Dunkle S., Gao S., and Miller C. F. (2002) Constraints on timing of peak and retrograde metamorphism in the Dabie Shan ultrahigh-pressure metamorphic belt, east-central China, using U-Th-Pb dating of zircon and monazite. Chem. Geol. 186, 315-331. 

Monazite crystals within the ferrocarbonatite sample were dated using CHIME U-Th-Pb, and an age of 165 8 Ma was calculated. This age was used to evaluate the Sm-Nd ( nci= -6.0) and Rb-Sr ( Sr/ Sri65 = 0.71061) data these values are considerably different than the syenites and the sannaites. The high initial "sr/ Sr and low nci indicate that the... 

Polished thin sections of the host mineralized granite, SB-2671, and pegmatite with minor mineralization, SB-2670B, were selected for U-Th-Pb chemical monazite dating using to the method of Montel etal. (1996). 

Rubatto et al., 2001 Stem and Berman, 2001 Townsend et al., 2001). However, variable mineral dates also characterize many samples that show no obvious textural evidence of disturbance. In most cases, these dates differ in a predictable way (Hart, 1964 Armstrong et al., 1966 Wagner et al., 1977). For example, a typical amphibolite-facies pelitic schist will yield a (U-Th)/Pb monazite date older than its " °Ar/ Ar muscovite date, which will be, in turn, older than its " Ar/ Ar biotite date. Given the lack of textural evidence for other causes, the most likely mechanism to produce such inconsistencies is isotopic exchange between minerals and their surroundings. 

Standards. REE phosphates should be used as standards for the REE. Silicates or phosphates of U, Th, and Pb are also suggested as standards for these elements. For EMP dating of monazite, use of lead silicate or phosphate results in smaller ZAF corrections for typical monazite composition than does the use of lead chromate or sulfide. Lead-doped (500-5000 ppm) alkaline earth aluminosilicate glass produces the smallest ZAF corrections for typical monazite compositions, but may generate insufficient X-ray counts due to low lead concentration, compromising its use as a standard. 

Cherniak DJ, Watson EB, Harrison TM, Grove M (2000) Pb diffusion in monazite A progress report on a combined RBS/SIMS study. EOS Trans, Am Geophys Union 8TS25 Cocherie A, Albarede F (2001) An improved U-Th-Pb age calculation for electron microprobe dating of monazite. Geochim Cosmochim Acta 65 4509-4522... 

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