Geomagnetic field modulation of cosmogenic ¹²⁹I recorded in Chinese loess sequences

The larger dispersion of pre-nuclear Iodine-129/Iodine-127 (¹²⁹I/¹²⁷I) in terrestrial sediments and the complexity of environmental factors made terrestrial ¹²⁹I dating extremely difficult. Sorting and dissociating possible influences will hopefully lead to a pattern of change in the pre-nuclear ¹²⁹I/¹²⁷I and accordingly an initial value for terrestrial dating. Here, we present the iodine isotope records of two loess-paleosol sections from Chinese Loess Plateau. The coupled variations of the ¹²⁹I fluxes and other paleomagnetic field records, with known paleomagnetic excursions being clearly matched, indicated the prominent modulation of cosmogenic ¹²⁹I production rate by paleomagnetic field, while the variation of ¹²⁷I concentrations again verified the climate control. Discrepancies in amplitudes of ¹²⁹I fluxes and other paleomagnetic field records were supposed to be a result of possible climate impact and organic matter degradation. These findings add new information to our knowledge of iodine-isotope composition, and are instructive for future study methodology.