Exploration of 26Al dating method based on deep-sea ferromanganese crust

Deep-sea ferromanganese crusts(DSFCs)serve as natural archives recording Earth's evolutionary history and represent significant submarine mineral resources. Accurate and reliable chronological information forms the fundamental basis for related studies. The atmospheric cosmogenic nuclide 10Be dating method has been successfully applied in chronological studies of DSFCs. While 26Al, which shares similar origins and pathways with 10Be but has a shorter half-life, may potentially provide more precise chronological information due to its stronger exponential decay characteristics, successful applications have not been reported to date owing to variations in marine sedimentation processes and interference from in situ 26Al background signals. This study utilized the Tianjin University Accelerator Mass Spectrometry system(TJUAMS)to investigate the application of 26Al dating techniques for DSFC chronology. A representative DSFC sample (10°40'05″N, 168°13'18″W; water depth in 2869 m) was selected as the research subject, with 10Be dating results serving as control references. Through optimization of experimental methods, refinement of data analysis, and cross-comparison of results, a systematic methodological exploration was conducted. The results indicate that all three approaches of 26Al/27Al ratios, 26Al concentrations and 26Al/10Be nuclide pairs are feasible for DSFC chronological studies.