Abstract
tained with a flat peak top, while the sensitivity of Pb was about 4 cps/nA/ppm. A monazite from North-Central Madagascar with a U-Pb age of 524.9 ± 3.1 Ma (2σ) obtained by thermal ionization mass spectrometry was used as a reference for Pb + /UO + - UO2 + /UO + calibration. Based on the positive correlation, we have determined the 206 Pb/ 238 U ratios of samples. 207 Pb/ 206 Pb ratios were measured by a magnet scanning with a single collector mode. Then 44 monazite grains extracted from a sedimentary rock in Taiwan were analyzed. Observed ages were compared with the U-Th-Pb chemical ages by electron microprobe. 238 U- 206 Pb ages agree well with those of the chemical ages except for some samples. The discrepancy may be due to an over-estimation of radiogenic Pb by the chemical method. 207 Pb- 206 Pb ages also agree with the chemical ages while there are a few discordant samples. Taking into account the concordant samples, there are three main age groups, 230 Ma, 440 Ma and 1850 Ma of monazites. The age distribution suggests that the provenance of detrital monazites is possibly the North China Craton or the Qinling-Dabie-Sulu zone between the North China and South China blocks.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
