Abstract:
The LA–ICP–MS U–Pb dating technique is a crucial tool that has been widely employed in geological sciences. Despite its relative maturity, several critical issues still require attention in practical applications. This article provides a brief discussion of five critical aspects of this technique, including sample preparation, selection of dating results, lead loss, common lead, and presentation and interpretation of dating results. Firstly, for the U–Pb dating of complex minerals, it is recommended to employ mineral identification and location techniques in combination with LA–ICP–MS instruments for in–situ analysis directly on rock thin sections or polished sections, without mineral separation. However, attention must be paid to Pb contamination in sample preparation. Secondly, for the selection of dating results for detrital minerals, the
206Pb/
207Pb age is utilized to represent the crystallization age of grains older than 1.5 Ga, while the
206Pb/
238U age is employed for grains younger than 1.5 Ga. The determination and selection of the maximum depositional age of sedimentary rocks mainly rely on statistical methods and sometimes require the combination of geochemical data and geological background information as supplementary criteria. Thirdly, for young samples with continuous age distribution on the concordia line, various methods such as the concordia diagram, weighted mean diagram, CL images, and element contents should be used to identify whether there is an inconsistent lead loss line or not. Furthermore, this article focuses on a rarely used common lead correction method for detrital mineral U–Pb dating. Finally, this article emphasizes the theoretical basis that, when evaluating the quality of the weighted mean value, the closer the MSWD is to 1, the higher the data quality is. In summary, to conduct U–Pb dating studies on minerals using LA–ICP–MS technology, it is essential to consider multiple factors comprehensively to obtain accurate, reliable, and geologically meaningful dating results.